JP7243374B2 - film roll - Google Patents

Description

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

Polyester film is used for various industrial materials such as magnetic recording media, electrical insulation, capacitors, packaging, etc., taking advantage of its excellent thermal properties, dimensional stability, mechanical properties, electrical properties, heat resistance and surface properties. It is Among them, in the case of base films for magnetic recording media in particular, as the recording density of magnetic recording media increases, film thickness reduction and smoothening are progressing, and the degree of difficulty in film winding is increasing.

In response to such problems, Patent Document 1 provides a film roll with a good winding shape without wrinkles or sag that occurs over time by keeping the diameter of the film winding portion of the film roll within a certain value in the width direction. A technique to do so has been proposed.

International publication WO2001/048061 pamphlet

However, in the case of base films for magnetic recording media, film thickness is becoming thinner and smoother in recent years, and film rolls are becoming longer. , the occurrence of charging defects such as local plastic deformation due to the film being charged and discharged, and defects such as the edge height where the film roll ends warp. It has become impossible to obtain a film roll with good appearance quality.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a film roll manufacturing method and a film roll that can obtain a film roll having good wound appearance quality without wrinkles or charging defects.

The film roll of the present invention is a film roll in which a film is wound around a cylindrical core, and the difference between the maximum value and the minimum value of the core outer diameter of the core portion where the film is not wound is 100 μm or less, The hardness of the wound film portion is 90 degrees or more.

Further, in the film roll of the present invention for solving the above problems, the core preferably satisfies the following formula (1).

Here, E [GPa] is the circumferential bending elastic modulus of the core, a [mm] is the inner radius of the core, and b [mm] is the outer radius of the core.

Further, in the film roll of the present invention, the core preferably has a circumferential bending elastic modulus of 50 GPa or more.

Further, in the film roll of the present invention, the material of the core is preferably fiber-reinforced plastic.

Moreover, it is preferable that the film roll of this invention is 10 micrometers or less in thickness of the said film.

In the film roll of the present invention, the longitudinal length of the film is preferably 8000 m or more.

In the film roll of the present invention, the maximum height roughness Rz of the surface of the film is preferably 100 nm or less on both the front and back surfaces.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the film roll with the favorable winding appearance quality which does not have a wrinkle and a charging defect, and a film roll can be obtained.

FIG. 1 is a schematic side view of a film slitting process using a film roll manufacturing method according to an embodiment of the present invention. FIG. 2 is a sectional view showing the contact state between the contact pressure roller and the film roll. FIG. 3 is a cross-sectional view showing a contact state between the contact pressure roller and the film roll, which is different from that shown in FIG. FIG. 4 is a perspective view for explaining a method for measuring the circumferential bending elastic modulus.

Hereinafter, a method for manufacturing a film roll of the present invention will be described with reference to the drawings. In addition, this invention is not interpreted as being limited to this.

First, each term used in the present invention has the following meaning. Note that the average means an arithmetic average unless otherwise specified.

"Core inner radius" means that the measurement start position is 5 mm inside from either core end, and the entire width is measured every 50 mm using a length measuring instrument with a dimensional accuracy that can measure dimensions of 5 μm or less. The diameter inside the core is measured, and the average value of all the measured points is taken as half the value.

"Core outer diameter" refers to the starting position of the measurement, which is 5 mm inside from either core end, and uses a length measuring instrument with a dimensional accuracy of 30 μm or less to measure the overall width every 50 mm. Measure the outer diameter of the core over the entire length, and take the average value of all measurement points.

The "core outer radius" is a value that is half the core outer diameter.

"Maximum and minimum core outer diameter of the core part" refers to the core part where the film is not wound, the measurement start position is 5 mm inside from the core end, and the dimensional accuracy is measured to 30 μm or less. Measure the outer diameter of the core over the entire width every 20 mm using a length measuring instrument with possible dimensional accuracy, plot the width direction on the X axis and the outer diameter of the core on the Y axis, and obtain the maximum value of the curve and the minimum value. By measuring the amount of shrinkage of the outer diameter of the core due to film winding, the height of the edge of the film roll edge is indirectly measured. Does not include steps, scratches or protrusions.

The “circumferential bending elastic modulus” is a value obtained by calculating the elastic modulus using the following formula (3).

Here, E [Pa] is the circumferential bending elastic modulus, P [N] is the load, r [m] is the center radius of the test piece, δ [m] is the deflection, I [m ⁴ ] is the second moment of area (B ×t ³ /12, where B represents the length of the test piece [m] and t represents the thickness of the test piece [m] (see FIG. 4).

"Hardness of film part" refers to a film roll that has passed 24 hours or more after winding the film, according to JIS K7312. 10 points in the width direction of the roll (the entire width excluding 10 mm of each roll end is divided into 10 equal parts, and the central part of each equal part is measured) is taken as the average.

The “maximum height roughness” was measured using a stylus method high-definition fine shape measuring instrument in accordance with JIS B0601 (1994) under the following conditions to measure the maximum roughness (Rz) of the film.
Measuring device: Three-dimensional fine shape measuring instrument (Model ET-4000A manufactured by Kosaka Laboratory)
Analysis equipment: 3D surface roughness analysis system (Model TDA-31 manufactured by Kosaka Laboratory)
Stylus: tip radius 0.5 μmR, diameter 2 μm, diamond stylus pressure: 100 μN
Measurement direction/calculation method: Measure 10 times each in the longitudinal direction of the film and in the width direction of the film. Let the average value of the 20 measurements be surface roughness.

FIG. 1 is a schematic side view showing an example in which the film roll manufacturing method of the present invention is applied to a slitting process which is a part of the film manufacturing process and processing process. Here, the slitting step is a step of cutting the film into a required size width and winding it into a roll. In FIG. 1, a film 10 is unwound from a raw roll 6 and conveyed by guide rollers 7 . After that, the film 10 is divided in the width direction by the upper blade 9 on the lower blade roller 8 and wound up on the core 11 while pressing the contact pressure roller 5 to form a film roll 12 . A static eliminator 13 is installed facing the film roll 12 .

Each roller is rotatably supported by a bearing, and the bearing is appropriately supported by a frame or the like. The contact pressure roller 5, the guide roller 7 and the lower blade roller 8 may be driven rollers that rotate due to friction with the film 10, or may be drive rollers using a motor or the like. When it is driven by a motor or the like, it is preferable that the rotation speed of the roller is substantially the same as the conveying speed of the film 10 so that the film 10 does not triboelectrify due to slippage between the roller and the film 10 . The core 11 is preferably held by a chuck supported by bearings and driven to rotate by a motor or the like. Further, the electric potential of the film roll 12 can be kept low by the static eliminator 13 installed facing the film roll 12 . The static eliminator 13 is a device that generates ions in the air and neutralizes the charge on the film 10 with the ions. In addition, a nip roller or a suction roller for gripping the film 10 to accurately control the tension and speed, or a wrinkle smoothing roller for expanding the width of the film 10 in the width direction may be appropriately arranged in the slitting process.

The inventors of the present invention investigated the cause of deterioration of the winding appearance due to wrinkles and electrification defects occurring at random positions in the width direction of the film roll when manufacturing the film roll. It was found that this is due to triboelectrification caused by rubbing. Tight winding is caused by the inclusion of air between the film layers of the film roll while the film is being wound, and the effect of compressive stress that increases as the film roll becomes thicker. It is generated by the gradual escape of air between film layers. Therefore, by winding the film while removing the air between the film layers, it is possible to suppress the occurrence of tight winding and obtain a film roll with a good winding shape.

As a result of intensive studies based on this knowledge, it was found that the film can be wound so that the hardness of the wound film portion is 90 degrees or more at any time after 24 hours have passed since the film winding was completed. , the air is sufficiently eliminated, and a film roll with a good wound appearance in which tight winding is suppressed at a high level can be obtained. If the hardness of the wound film portion is less than 90 degrees at any time after 24 hours have passed since the winding of the film was completed, the air is not sufficiently removed, so wrinkles due to further tightening of the winding. It becomes difficult to suppress charging defects. Here, more preferably, the hardness of the wound film portion is 95 degrees or more at an arbitrary time after 24 hours have passed since the end of winding the film. By setting it as this range, the effect of suppressing tight winding can be enhanced. Moreover, it is preferable to wind the film so that the hardness of the wound film portion becomes 90 degrees or more within 30 hours from the end of winding or after 30 hours have passed. The meaning of "an arbitrary time after 24 hours from the end of film winding" means the timing of measuring the hardness of the film, and the stage 24 hours after the end of film winding. There is no problem in winding so that the hardness of the film portion is already 90 degrees or more.

As a method for manufacturing a film roll that obtains the hardness of the film portion as described above, there are a method of winding the film with high tension in the winding process, a method of winding the film with high surface pressure, and a method of winding the film against the contact pressure roller. A backup roller that presses the contact pressure roller from the opposite side of the roll contact pressure part is provided to increase the contact pressure while suppressing the deflection of the contact pressure roller due to high contact pressure to obtain a uniform contact pressure distribution in the width direction. It can be preferably used. In addition, it is known that a general film starts to gradually tighten after the end of winding, and the winding hardness saturates after a certain period of time. Therefore, in order to make the wound hardness of the wound film part 90 degrees or more at an arbitrary time after 24 hours have elapsed from the end of winding, the winding tension and winding up are required depending on the properties of the target film. By experimentally obtaining the hardness of the film at the time and the behavior of the tight winding, the winding conditions can be set with reference to the contents to be described later.

As for the method of winding the film with high tension, it is preferable to set the winding tension in the range of 100 N/m to 500 N/m. When the winding tension is 100 N/m or more, the hardness of the wound film portion is often 90 degrees or more at an arbitrary time after 24 hours have passed from the end of winding. In addition, if the winding tension is 500 N/m or less, it is easy to control the tension, there is little winding deviation in the width direction of the film, and it is often possible to obtain a good winding shape with uniform film end faces. . Here, it is more preferable to set the range of the winding tension to 150 N/m or more and 400 N/m or less. When the winding tension is 150 N/m or more, the hardness of the wound film portion is often 95 degrees or more at an arbitrary time after 24 hours have passed from the end of winding. In addition, if the winding tension is 400 N/m or less, it becomes easy to separate the transport tension and the winding tension of the film, and the speed difference between the film and the transport roller is less likely to occur, so the film can be processed without scratches or defects. It is often possible to transport

As a method of winding the film with a high surface pressure, it is preferable to apply a winding surface pressure in the range of 50 N/m or more and 1000 N/m or less. When the winding surface pressure is 50 N/m or more, the hardness of the wound film portion is often 90 degrees or more at an arbitrary time after 24 hours have elapsed from the end of winding. Further, when the winding surface pressure is 1000 N/m or less, it is often possible to wind the film without charging defects caused by excessively high contact pressure between the contact pressure roller and the film roll. Here, it is more preferable to apply a winding surface pressure of 100 N/m or more and 800 N/m or less. When the winding surface pressure is 100 N/m or more, the hardness of the wound film portion is often 95 degrees or more at an arbitrary time after 24 hours have passed from the end of winding. Further, when the winding surface pressure is 800 N/m or less, it is easy to control the deflection of the contact pressure roller, so that a uniform surface pressure distribution in the width direction tends to be obtained in many cases.

In addition, as a method of using a backup roller as the contact pressure roller, the outer diameter of the contact pressure roller is 30 mm or more and 60 mm or less, the winding surface pressure of the contact pressure roller is 100 N/m or more and 1000 N/m or less, and the outer diameter of the backup roller is is 40 mm or more and 70 mm or less, and the surface pressure of the backup roller is preferably 200 N/m or more and 800 N/m or less. The outer diameter of the contact pressure roller is 30 mm or more and 60 mm or less, the winding surface pressure of the contact pressure roller is 100 N/m or more, the outer diameter of the backup roller is 40 mm or more and 70 mm or less, and the surface pressure of the backup roller is 200 N/m or more. As a result, the hardness of the wound film portion is often 90 degrees or more at an arbitrary time after 24 hours have passed. Further, the outer diameter of the contact pressure roller is 30 mm or more and 60 mm or less, the winding surface pressure of the contact pressure roller is 1000 N/m or less, the outer diameter of the backup roller is 40 mm or more and 70 mm or less, and the surface pressure of the backup roller is 800 N/m. By doing the following, it becomes easier to obtain a uniform surface pressure distribution in the width direction while suppressing wear of the contact pressure roller and the backup roller.

As described above, by winding the film while removing the air between the film layers, it is possible to obtain a good wound shape without wrinkles or defects at random positions in the width direction of the film roll. On the other hand, when the present inventors conducted a film winding test for the purpose of eliminating air between film layers using the above-described means, wrinkles and electrification defects were found locally near the ends of the film roll. A new problem emerged.

Therefore, the inventors of the present invention intensively studied the causes of the occurrence of wrinkles and charging defects in the vicinity of the ends of the film roll. I found something.

FIG. 2 shows a cross-sectional view showing an example of the contact state between the contact pressure roller and the film roll. Winding the film while excluding air between the film layers increases the radial compressive stress that the wound film exerts on the core, causing the core to compress and deform toward the center. As a result, a difference in the amount of shrinkage of the core occurs between the center and the ends of the film winding portion, and the ends of the wound film roll warp up along the surface undulations of the core, and the film roll has a high edge shape. .

When the film roll has a high edge shape, the contact area between the contact pressure roller used in the winding process and the film roll becomes small, so the vicinity of the edge of the film roll where the edge height occurs receives high surface pressure locally. It will happen. As a result, the amount of triboelectrification between the contact pressure roller and the film roll increases at the portion receiving high surface pressure, and it is thought that charging defects and wrinkles originating from the charging defects are generated near the ends of the film roll. .

Therefore, as a result of intensive studies based on this knowledge, by using a core that satisfies the following formula (1), the shrinkage amount of the core is reduced, the edge height shape of the film roll is relaxed, and the air between the film layers It has been found that even when the film is wound in such a manner as to eliminate the , it is possible to obtain a film roll having a good appearance without wrinkles or electrification defects at the ends of the film roll.

Here, E [GPa] is the circumferential bending elastic modulus of the core, a [mm] is the inner radius of the core, and b [mm] is the outer radius of the core.

The left side of equation (1) is expressed from the cross-sectional shape of the core and the factors of the circumferential bending elastic modulus. This means that the contraction deformation amount of the core is reduced. By satisfying the formula (1), the air between the film layers is eliminated using the method described above, and the hardness of the wound film portion at an arbitrary time after 24 hours have passed since the end of winding the film is Even when the film is wound at an angle of 90 degrees or more, the edge height is suppressed to 100 μm or less, which is a level at which wrinkles and charging defects do not occur at the ends of the film roll.

FIG. 3 is a cross-sectional view showing an example of the contact state between the contact pressure roller and the film roll when using a core that satisfies the formula (1). Since the contraction amount of the core is reduced as shown in FIG. 3 by satisfying the expression (1), the edge height is suppressed. As a result, the film roll can be pressed evenly across the width of the film roll to the ends, and air can be removed over the entire width of the film roll, resulting in a well-wound film roll.

More preferably, by using a core that satisfies formula (2), it becomes possible to further reduce the amount of shrinkage of the core, and it becomes possible to wind a longer film without wrinkles or defects.

Here, E [GPa] represents the circumferential bending elastic modulus of the core, a [mm] the inner radius of the core, and b [mm] the outer radius of the core.

The circumferential bending elastic modulus of the core is preferably 50 GPa or more. When the circumferential bending elastic modulus of the core is 50 GPa or more, taking 3-, 6-, 8-, and 9-inch cores that are generally used for film winding, the thickness of the 3-inch core is 1.2 mm or more. , if the wall thickness is 4.8 mm or more for a 6-inch core, 8.8 mm or more for an 8-inch core, and 11.2 mm or more for a 9-inch core, the expression (1) is satisfied, In many cases, the amount of shrinkage of each core is 100 μm or less. More preferably, the core has a circumferential bending elastic modulus of 70 GPa or more. When the core has a circumferential bending elastic modulus of 70 GPa or more, the thickness of the core can be further reduced, so that the material cost of the core can be reduced, and handling performance is improved by reducing the weight. .

The method for measuring the bending elastic modulus in the circumferential direction of the core is as described in Examples.

The material of the core is not particularly limited, but materials such as paper, plastic, steel, aluminum, and fiber-reinforced plastic are generally used. Among these, steel, aluminum, and fiber-reinforced plastic materials are preferable because they have the strength to withstand the compressive stress caused by winding the film.Furthermore, the fiber is lightweight and easy to handle while having strength. Preferably, a reinforced plastic material is used.

Next, the film roll of the present invention will be described with specific examples. However, the present invention should not be construed as being limited to such examples.

The film roll of the present invention can be manufactured by the film roll manufacturing method of the present invention. As described above, wind the film while removing air between the film layers, and wind the film so that the hardness of the wound film part is 90 degrees or more at any time after 24 hours have passed since the film was wound. As a result, it is possible to obtain a film roll in which wrinkles and electrification defects that occur randomly in the width direction of the film roll are prevented. Furthermore, by using a core that satisfies the above formula (1), shrinkage of the core is suppressed, wrinkles and electrification defects at the ends of the film roll are suppressed, and it is possible to obtain a film roll with a good winding shape. .

As a result of actually using a core that satisfies the formula (1) and winding a film while excluding air between film layers, the present inventors obtained a film roll with a good wound appearance free of wrinkles and charging defects. did it. Therefore, in order to confirm the shrinkage amount of the core and the edge height of the film roll, a core satisfying the formula (1) and a core not satisfying the formula (1) were prepared, and a film winding test was performed under the same conditions. As a result, the cores satisfying the formula (1) had a smaller amount of shrinkage than the cores not satisfying the formula (1), and the edge height shape was relaxed. As a result, it was found that the effect of suppressing the height of the helicopter was low.

Therefore, based on the above results, further investigation was carried out. As a result, in addition to the amount of shrinkage of the core, which is the main factor of the edge height, the shape of the cut surface of the film edge, the thickness change due to moisture absorption expansion from the cut surface, and the thickness of the film roll. It was found that the thickness unevenness during film formation and the influence of the cylindricity of the core are also included. In other words, it was newly found that the exact amount of shrinkage of the core cannot be determined only by measuring the shape of the raw material.

Therefore, as a result of investigating the shrinkage amount of the core portion of the film roll, it was found that if the difference between the maximum and minimum core outer diameters of the core portion where the film was not wound was 100 μm or less, the film could be rolled without wrinkles or charging defects. It was found that the edge height was suppressed to the extent that a film roll with good appearance was obtained. On the other hand, if the difference between the maximum value and the minimum value of the core outer diameter of the core portion is 100 μm or more, the effect of suppressing edge height is low, and the effect of preventing charging defects cannot be obtained.

Moreover, in the film roll of the present invention, the thickness of the wound film is not particularly limited, but the film thickness is preferably 10 μm or less. Generally, the thinner the film, the longer the film winding length and the greater the compressive stress of the film, so the effect of the present invention is extremely large. That is, the thinner the film is, the more difficult it becomes to obtain a uniform contact pressure distribution in the width direction. The achievability of distributions often makes the present invention even more effective. More preferably, the thickness of the film is 5.0 μm or less, and the present invention can obtain a uniform contact pressure distribution in the width direction even with such a thin film. The effect of the invention can be even greater.

The length of the film wound around the film roll of the present invention in the longitudinal direction is also not particularly limited, but is preferably 8000 m or more. When the length of the film in the longitudinal direction is 8,000 m or more, the compressive stress toward the inside of the film roll increases, so that the amount of shrinkage of the core increases and the height of the edge tends to occur, which is the effect of the present invention. is often obtained.

In addition, the longer the film roll, the greater the number of windings (the number of laminated films), and the more the amount of air contained in the film roll. For this reason, the longer the film, the more wrinkles and electrification defects are likely to occur due to tight winding, and the winding shape is often deteriorated. More preferably, when the winding length of the film is 10,000 m or more, the compressive stress of the film is further increased, so that the effects of the present invention are often even greater.

The maximum height roughness Rz of the surface of the film wound on the film roll of the present invention is not particularly limited, but is preferably 100 nm or less on both the front and back surfaces. If the maximum height roughness Rz of the surface of the film is 100 nm or less, the contact area between the films laminated on the film roll is large, and triboelectrification is likely to occur when winding is tight, so the effect of the present invention is exhibited. It is often easy. Here, when the maximum height roughness Rz of the surface of the film is 30 nm or less, the effects of the present invention are enhanced in many cases, which is more preferable.

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples. Various evaluation and measurement methods are shown below.
[Measurement method of core circumferential bending elastic modulus]
Measured by sampling from the core. Also, as understood from the formula (3), E is not affected by the shape of the core (inner diameter, outer diameter and length), so it can be obtained by fabricating a test piece using the same material as the core.

Measurement is performed by using a universal testing machine to measure the deflection when a load is applied in the elastic deformation region of the test piece in the radial direction, and obtained by the following equation (3).

In each example and comparative example, a ring-shaped test piece for measurement (outer diameter: 167 mm, inner diameter: 150 mm, width: 50 mm) was manufactured using the same material as the core, and measurements were carried out.

Here, E [Pa] is the circumferential bending elastic modulus, P [N] is the load, r [m] is the central radius of the measurement sample (test piece), δ [m] is the deflection, and I [m ⁴ ] is the cross section. Second moment (B×t ³ /12, where B is the length of the test piece [m] and t is the thickness of the test piece [m]) (see FIG. 4). The center radius is obtained by [outer diameter + inner diameter]/4.

"Method for measuring film hardness"
After 25 to 28 hours have passed since the film was wound, the film roll was tested in accordance with JIS K7312 using an Asker rubber hardness tester C type manufactured by Kobunshi Keiki Co., Ltd., and 10 points in the width direction of the film roll (roll The width was divided into 10 halves, excluding 10 mm at each end, and the center of each halve was measured) and averaged.

[How to measure core outer diameter]
Using a pie tape manufactured by Fastec Co., Ltd., the outer diameter of the core at a position 20 mm from both ends of the film winding portion was measured and averaged.

[Method for measuring maximum core outer diameter]
The maximum value of the outer diameter of the core where the film is not wound is measured every 20 mm from the edge of the film to the edge of the core using a pie tape manufactured by Fastec Co., Ltd.

[Method for measuring minimum outer diameter of core]
Shown is the minimum value of the outer diameter of the core where the film is not wound, measured every 20 mm from the edge of the film to the edge of the core using a pie tape manufactured by Fastec Co., Ltd.

[Maximum height roughness Rz]
The maximum roughness (Rz) of the polyester film was measured under the following conditions in accordance with JIS B0601 (1994) using a high-definition fine shape measuring instrument of the stylus method.
Measuring device: Three-dimensional fine shape measuring instrument (Model ET-4000A manufactured by Kosaka Laboratory)
Analysis equipment: 3D surface roughness analysis system (Model TDA-31 manufactured by Kosaka Laboratory)
Stylus: tip radius 0.5 μmR, diameter 2 μm, diamond stylus pressure: 100 μN
Measurement direction/calculation method: Measure 10 times each in the longitudinal direction of the film and in the width direction of the film. The average value of the 20 measurements was taken as the surface roughness. Both the front and back surfaces were measured, and Table 1 shows the larger value.

[Method for evaluating charging defects]
100 film rolls were wound under the conditions of each example and comparative example, and the occurrence of charging defects was checked. The presence or absence of charging defects was evaluated by sprinkling toner for copying on the film and visually inspecting it, utilizing the phenomenon that toner adheres to the locations where charging occurs. If charging defects are observed in 3 or less out of 100 film rolls wound up, "○" is found. If charging defects are found in 4 or more and 9 or less out of 100 rolls, "△" is found. 100 charging defects. When 10 or more were found in the middle, it was determined as "x". "△" or "◯" indicates pass, "△" indicates good, and "◯" indicates excellent.

[Wrinkle evaluation method]
100 film rolls were wound under the conditions of each example and comparative example, and the occurrence of wrinkles was checked. If 3 or less out of 100 wrinkles were found on the wound film roll, "○" was found. When the above was confirmed, it was determined as "x". "△" or "◯" indicates pass, "△" indicates good, and "◯" indicates excellent.

[How to measure edge height]
The displacement of the roll diameter of the film roll in the width direction (original fabric shape) is measured using an original fabric shape measuring instrument (manufactured by Kitano Kikaku Co., Ltd.), the maximum height in the range from the end of the film roll in the width direction to 100 mm, The edge height of the film roll was defined as the difference in height of the portion 200 mm inward from the extreme end in the width direction. A dial gauge (manufactured by Mitutoyo Co., Ltd.) is mounted on a pedestal that can be balanced on the film roll and can be slid in parallel. adjusted to Next, the contact point was moved to the extreme end from a portion 100 mm inside from the extreme end while keeping the contact point in contact with the film roll, and the scale at which the value was maximum was read. A total of 10 points (5 points on one side×both ends) were measured at arbitrary positions, and the average value of the 10 points was taken as the edge height of the film roll.

100 film rolls were wound under the conditions of each example and comparative example, and the occurrence of edge height was investigated.

If the edge height of the wound film roll exceeds 100 μm is confirmed in 3 or less out of 100 rolls, "○", and the edge height exceeds 100 μm is 4 or more out of 100 9 When less than this was confirmed, it was judged to be "△", and when 10 or more out of 100 were confirmed to have an edge height of more than 100 μm, it was judged to be "×". "△" or "◯" indicates pass, "△" indicates good, and "◯" indicates excellent.

[Example 1]
A polyethylene terephthalate (PET) film having an average thickness of 12 μm and a Rz of 110 nm on the side having the larger maximum height roughness Rz among both surfaces of the film was used. In addition, using a fiber reinforced resin core with a circumferential bending elastic modulus of 30 GPa, an outer radius of 83.5 mm, and an inner radius of 75 mm, a winding speed of 200 m / min, a tension of 100 N / m, a surface pressure of 150 N / m, a width of 1000 mm, A film roll with a longitudinal length of 7000 m was wound up. The value obtained from the left side of equation (1) was 49, the difference between the maximum and minimum core outer diameters was 90 µm, and the hardness of the film portion was 93 degrees 25 hours after the end of film winding. rice field.

[Example 2]
A fiber-reinforced resin core having a circumferential bending elastic modulus of 45 GPa, an outer radius of 83.5 mm, and an inner radius of 75 mm was used. Other conditions were the same as in Example 1. The value obtained on the left side of equation (1) is 33, the difference between the maximum and minimum core outer diameters is 60 μm, and the hardness of the wound film portion after 26 hours have passed since the film winding was completed. was 92 degrees.

[Example 3]
A fiber-reinforced resin core having a circumferential bending elastic modulus of 55 GPa, an outer radius of 83.5 mm, and an inner radius of 75 mm was used. Other conditions were the same as in Example 1. The value obtained from the left side of equation (1) was 27, the difference between the maximum and minimum core outer diameters was 49 μm, and the hardness of the film portion was 91 degrees 25 hours after the end of film winding. rice field.

[Example 4]
An aluminum core with a circumferential bending elastic modulus of 73 GPa, an outer radius of 83.5 mm, and an inner radius of 75 mm was used. Other conditions were the same as in Example 1. The value obtained from the left side of equation (1) was 20, the difference between the maximum and minimum core outer diameters was 37 μm, and the hardness of the film portion was 93 degrees after 27 hours had passed since the end of film winding. rice field.

[Example 5]
An aluminum core with a circumferential bending elastic modulus of 73 GPa, an outer radius of 80.0 mm, and an inner radius of 75 mm was used. Other conditions were the same as in Example 1. The value obtained from the left side of equation (1) was 33, the difference between the maximum and minimum core outer diameters was 61 μm, and the hardness of the film portion was 93 degrees 28 hours after the end of film winding. rice field.

[Example 6]
A polyethylene terephthalate (PET) film having an average thickness of 8.0 μm and having a Rz of 110 nm on the surface having the larger maximum height roughness Rz among both surfaces of the film was used. Further, using the same core as the core used in Example 2, the winding speed was 200 m/min, the tension was 150 N/m, and the surface pressure was 150 N/m. . The value obtained on the left side of Equation (1) is 33, the difference between the maximum and minimum core outer diameters is 90 μm, and the hardness of the wound film portion after 25 hours have passed since the film winding was completed. was 94 degrees.

[Example 7]
Using the same core as the core used in Example 3, the same film as the film used in Example 6 was wound under the same winding conditions as in Example 6 (the same winding conditions mean that the speed, tension, and surface pressure are the same. The same applies hereinafter) was wound up on a film roll having a width of 1000 mm and a length of 7000 m in the longitudinal direction. The value obtained on the left side of Equation (1) is 27, the difference between the maximum and minimum core outer diameters is 74 μm, and the hardness of the wound film portion after 25 hours have passed since the film winding was completed. was 95 degrees.

[Example 8]
A polyethylene terephthalate (PET) film having an average thickness of 4.0 μm and a Rz of 110 nm on the surface having the larger maximum height roughness Rz among both surfaces of the film was used. Also, using the same core as that used in Example 3, the core was wound up on a film roll having a longitudinal length of 7000 m at a winding speed of 200 m/min, a tension of 200 N/m, and a surface pressure of 150 N/m. The value obtained on the left side of equation (1) is 27, the difference between the maximum and minimum core outer diameters is 98 μm, and the hardness of the wound film portion after 27 hours have passed since the end of film winding. was 97 degrees.

[Example 9]
Using the same core as the core used in Example 4, the same film as the film used in Example 8 was wound up on a film roll having a width of 1000 mm and a length of 7000 m in the longitudinal direction under the same winding conditions as in Example 8. . The value obtained on the left side of Equation (1) is 20, the difference between the maximum and minimum core outer diameters is 74 μm, and the hardness of the wound film portion after 26 hours have passed since the end of film winding. was 97 degrees.

[Example 10]
A polyethylene terephthalate (PET) film having an average thickness of 12 μm and a Rz of 90 nm on the surface having the larger maximum height roughness Rz of both surfaces of the film was used. Further, using the same core as that used in Example 2, under the same winding conditions as in Example 6, the film was wound up on a film roll having a width of 1000 mm and a longitudinal length of 7000 m. The value obtained on the left side of Equation (1) is 33, the difference between the maximum and minimum core outer diameters is 90 μm, and the hardness of the wound film portion after 25 hours have passed since the film winding was completed. was 96 degrees.

[Example 11]
Using the same core as the core used in Example 3, the same film as the film used in Example 10 was wound up on a film roll having a width of 1000 mm and a length of 7000 m in the longitudinal direction under the same winding conditions as in Example 6. . The value obtained on the left side of Equation (1) is 27, the difference between the maximum and minimum core outer diameters is 74 μm, and the hardness of the wound film portion after 25 hours have passed since the film winding was completed. was 94 degrees.

[Example 12]
A polyethylene terephthalate (PET) film having an average thickness of 12 μm and having a Rz of 30 nm on the side of the film having the larger maximum height roughness Rz was used. Further, using the same core as that used in Example 3, under the same winding conditions as in Example 8, the film was wound up on a film roll having a width of 1000 mm and a longitudinal length of 7000 m. The value obtained on the left side of Equation (1) is 27, the difference between the maximum and minimum core outer diameters is 97 μm, and the hardness of the wound film portion after 25 hours have passed since the film winding was completed. was 98 degrees.

[Example 13]
Using the same core as the core used in Example 4, the same film as the film used in Example 12 was wound up on a film roll having a width of 1000 mm and a length of 7000 m in the longitudinal direction under the same winding conditions as in Example 8. . The value obtained on the left side of Equation (1) is 20, the difference between the maximum and minimum core outer diameters is 75 μm, and the hardness of the wound film portion after 25 hours have passed since the film winding was completed. was 97 degrees.

[Example 14]
Using the same core as that used in Example 2, using the same film as that used in Example 1, and under the same winding conditions as in Example 6, the core was wound up on a film roll having a longitudinal length of 10,000 m. The value obtained on the left side of Equation (1) is 33, the difference between the maximum and minimum core outer diameters is 98 μm, and the hardness of the wound film portion after 27 hours have passed since the film winding was completed. was 96 degrees.

[Example 15]
Using the same core as that used in Example 3, using the same film as that used in Example 1, and under the same winding conditions as in Example 6, the film was wound up on a film roll having a longitudinal length of 10,000 m. The value obtained on the left side of equation (1) is 27, the difference between the maximum and minimum core outer diameters is 81 μm, and the hardness of the wound film portion after 27 hours have passed since the film winding was completed. was 95 degrees.

[Example 16]
Using the same core as that used in Example 3, using the same film as that used in Example 1, and under the same winding conditions as in Example 8, the film was wound up on a film roll having a longitudinal length of 15,000 m. The value obtained on the left side of equation (1) is 27, the difference between the maximum and minimum core outer diameters is 98 μm, and the hardness of the wound film portion after 27 hours have passed since the end of film winding. was 97 degrees.

[Example 17]
Using the same core as the core used in Example 4, the same film as in Example 1 was wound up on a film roll having a longitudinal length of 15,000 m under the same winding conditions as in Example 8. The value obtained on the left side of equation (1) is 20, the difference between the maximum and minimum core outer diameters is 85 μm, and the hardness of the wound film portion after 25 hours have passed since the end of film winding. was 98 degrees.

[Example 18]
A polyethylene terephthalate (PET) film having an average thickness of 4.0 μm and having a Rz of 30 nm on the side having the larger maximum height roughness Rz among both surfaces of the film was used. Further, using the same core as that used in Example 4, the core was wound up on a film roll having a longitudinal length of 15,000 m under the same winding conditions as in Example 8. The value obtained on the left side of equation (1) is 20, the difference between the maximum and minimum core outer diameters is 85 μm, and the hardness of the wound film portion after 27 hours have passed since the end of film winding. was 98 degrees.

[Comparative Example 1]
A paper core having a circumferential bending elastic modulus of 2.0 GPa, an outer radius of 83.5 mm and an inner radius of 75 mm was used. Other conditions were the same as in Example 1. The value obtained from the left side of equation (1) was 739, the difference between the maximum and minimum core outer diameters was 1353 μm, and the hardness of the film portion was 92 degrees after 25 hours had passed since the end of film winding. rice field.

[Comparative Example 2]
A PVC resin core having a circumferential bending elastic modulus of 2.5 GPa, an outer radius of 83.5 mm, and an inner radius of 75 mm was used. Other conditions were the same as in Example 1. The value obtained from the left side of equation (1) was 591, the difference between the maximum and minimum core outer diameters was 1082 μm, and the hardness of the film portion was 93 degrees after 25 hours had passed since the end of film winding. rice field.

[Comparative Example 3]
An ABS resin core having a circumferential bending elastic modulus of 8.0 GPa, an outer radius of 83.5 mm, and an inner radius of 75 mm was used. Other conditions were the same as in Example 1. The value obtained from the left side of equation (1) was 185, the difference between the maximum and minimum core outer diameters was 338 µm, and the hardness of the film portion was 93 degrees after 25 hours had passed since the end of film winding. rice field.

[Comparative Example 4]
A fiber-reinforced resin core having a circumferential bending elastic modulus of 15 GPa, an outer radius of 83.5 mm, and an inner radius of 75 mm was used. Other conditions were the same as in Example 1. The value obtained from the left side of equation (1) was 99, the difference between the maximum and minimum core outer diameters was 180 μm, and the hardness of the film portion was 92 degrees 25 hours after the end of film winding. rice field.

[Comparative Example 5]
Using the same core as the core used in Example 2, the same film as the film used in Example 1 was wound at a winding speed of 200 m / min, a tension of 90 N / m, a surface pressure of 150 N / m, a width of 1000 mm, and a longitudinal direction. was wound up on a 7000 m long film roll. The value obtained on the left side of equation (1) is 33, the difference between the maximum and minimum core outer diameters is 44 μm, and the hardness of the wound film portion after 25 hours have passed since the film winding was completed. was 85 degrees.

[Comparative Example 6]
Using the same core as the core used in Example 2, the same film as the film used in Example 6 was wound up on a film roll having a width of 1000 mm and a length of 7000 m in the longitudinal direction under the same winding conditions as in Example 1. . The value obtained on the left side of equation (1) is 33, the difference between the maximum and minimum core outer diameters is 60 μm, and the hardness of the wound film portion after 26 hours have passed since the film winding was completed. was 87 degrees.

[Comparative Example 7]
Using the same core as the core used in Example 3, the same film as the film used in Example 8 was wound up on a film roll having a width of 1000 mm and a length of 7000 m in the longitudinal direction under the same winding conditions as in Example 6. . The value obtained on the left side of equation (1) is 27, the difference between the maximum and minimum core outer diameters is 74 μm, and the hardness of the wound film portion after 27 hours have passed since the film winding was completed. was 86 degrees.

[Comparative Example 8]
Using the same core as the core used in Example 2, the same film as the film used in Example 10 was wound up on a film roll having a width of 1000 mm and a length of 7000 m in the longitudinal direction under the same winding conditions as in Example 1. . The value obtained on the left side of equation (1) is 33, the difference between the maximum and minimum core outer diameters is 60 μm, and the hardness of the wound film portion after 26 hours have passed since the film winding was completed. was 88 degrees.

[Comparative Example 9]
Using the same core as the core used in Example 3, the same film as the film used in Example 12 was wound up on a film roll having a width of 1000 mm and a longitudinal length of 7000 m under the same winding conditions as in Example 6. . The value obtained on the left side of Equation (1) is 27, the difference between the maximum and minimum core outer diameters is 73 μm, and the hardness of the wound film portion after 25 hours have passed since the end of film winding. was 87 degrees.

[Comparative Example 10]
Using the same core as the core used in Example 2, the same film as the film used in Example 1 was wound up on a film roll having a width of 1000 mm and a length of 10000 m in the longitudinal direction under the winding conditions used in Example 1. rice field. The value obtained on the left side of Equation (1) is 33, the difference between the maximum and minimum core outer diameters is 66 μm, and the hardness of the wound film portion after 25 hours have passed since the end of film winding. was 88 degrees.

[Comparative Example 11]
Using the same core as the core used in Example 3, the same film as the film used in Example 1 was wound up on a film roll having a width of 1000 mm and a longitudinal length of 15000 m under the winding conditions used in Example 6. rice field. The value obtained on the left side of equation (1) is 27, the difference between the maximum and minimum core outer diameters is 84 μm, and the hardness of the wound film portion after 28 hours have passed since the end of film winding. was 86 degrees.

Table 1 shows the results of Examples and Comparative Examples.

In Comparative Examples 1 to 4, cores made of paper, resin, and fiber-reinforced resin, which do not satisfy formula (1), were used. As a result, in each comparative example, the difference between the maximum and minimum core outer diameters was 100 μm or more, and all 100 film rolls had wrinkles during or after winding, and the winding appearance was poor. rice field.

On the other hand, in Example 1, although the same film as in Comparative Examples 1 to 4 was wound under the same conditions, charging defects occurred in 1 out of 100 films, and wrinkles occurred in 5 films. Two of them had a volume of more than 100 μm. The evaluation result of wrinkles was △, but the rolled appearance was generally good.

In Example 2, a core having a higher circumferential bending elastic modulus than that in Example 1 was used. As a result, the difference between the maximum value and the minimum value of the outer diameter of the core was reduced to 60 μm compared to Example 1. Out of 100, 1 had a charging defect, 2 had wrinkles, and 0 had an edge height of more than 100 μm.

In Example 3, a core having a higher circumferential bending elastic modulus than that in Example 2 was used. As a result, the difference between the maximum value and the minimum value of the outer diameter of the core was reduced to 49 μm compared to Example 1. One out of 100 had charging defects, 1 had wrinkles, and 0 had an edge height of more than 100 μm.

In Example 4, a core having a higher circumferential bending elastic modulus than that in Example 3 was used. As a result, the difference between the maximum value and the minimum value of the outer diameter of the core was smaller than in Example 2, and was 37 μm. Out of 100, 0 had charging defects, 0 had wrinkles, and 0 had an edge height of more than 100 μm.

In Example 5, a core having the same circumferential bending elastic modulus as in Example 4 and having a small wall thickness was used. Out of 100, 1 had a charging defect, 2 had wrinkles, and 0 had an edge height of more than 100 μm. In addition, by reducing the weight, handling performance has been improved.

In Comparative Example 5, the film roll was wound with a lower winding tension than in Example 1. As a result, the hardness of the wound film portion was 85 degrees after 25 hours had passed since the winding of the film was completed. The removal of air between film layers was insufficient, 35 of 100 films had charging defects, 12 wrinkled films, and 0 films had an edge height of more than 100 µm. was bad.

In Comparative Example 6, a thinner film roll than in Example 2 was wound. As a result, the hardness of the wound film portion was 87 degrees after 26 hours had passed since the winding of the film was completed. Air removal between film layers was insufficient, 15 out of 100 films had charging defects, 25 films had wrinkles, and 2 films had an edge height of more than 100 μm. was bad.

In Example 6, the film roll was wound with an increased winding tension, in consideration of the insufficient air exclusion between the film layers in Comparative Example 6. As a result, the hardness of the wound film portion was 94 degrees after 25 hours had passed since the winding of the film was completed, and air was sufficiently removed between the film layers. On the other hand, increasing the tension increased the amount of shrinkage of the core, and the difference between the maximum and minimum core outer diameters was 90 μm. 4 out of 100 had charging defects, 3 had wrinkles, and 5 had edge heights exceeding 100 μm. The rolled appearance was generally good.

In Example 7, a core having a higher circumferential bending elastic modulus than in Example 6 was used for winding, taking into consideration that the amount of shrinkage of the core increased in Example 6. As a result, the difference between the maximum and minimum core outer diameters was reduced to 74 μm. Out of 100, 1 had a charging defect, 2 had wrinkles, and 2 had an edge height of more than 100 μm.

In Comparative Example 7, a thinner film roll than in Example 7 was wound up. As a result, the hardness of the wound film portion after 27 hours from the end of film winding was 86 degrees. Air removal between film layers was insufficient, 13 out of 100 films had charging defects, 24 films had wrinkles, and 2 films had an edge height of more than 100 μm. was bad.

In Example 8, the film roll was wound with an increased winding tension, in consideration of the insufficient air exclusion between the film layers in Comparative Example 7. As a result, the hardness of the wound film portion was 97 degrees after 27 hours had passed since the winding of the film was completed, and air was sufficiently removed between the film layers. On the other hand, as in Example 6, the amount of contraction of the core was increased by increasing the tension, and the difference between the maximum value and the minimum value of the outer diameter of the core was 98 μm. 8 out of 100 had charging defects, 2 had wrinkles, and 9 had an edge height of more than 100 μm. The rolled appearance was generally good.

In Example 9, a core having a higher circumferential bending elastic modulus than in Example 8 was used for winding, taking into consideration that the amount of shrinkage of the core increased in Example 8. As a result, the shrinkage amount of the core was reduced, and the difference between the maximum and minimum core outer diameters was reduced to 74 μm. 1 out of 100 had charging defects, 0 had wrinkles, and 2 had an edge height of more than 100 μm.

Comparative Example 8 wound a smoother film roll compared to Example 2. As a result, air was not sufficiently removed between the film layers, and the hardness of the wound film portion was 88 degrees after 26 hours had passed since the winding of the film was completed. Air removal between film layers was insufficient, 26 out of 100 had charging defects, 16 had wrinkles, and 0 had an edge height of more than 100 µm. was bad.

In Example 10, the film roll was wound with a higher take-up tension than in Comparative Example 8, based on the fact that the air between the film layers was insufficiently removed in Comparative Example 8. As a result, the hardness of the wound film portion was 96 degrees after 25 hours had passed since the winding of the film was completed, and air was sufficiently removed between the film layers. On the other hand, as in Examples 6 and 8, the amount of contraction of the core was increased by increasing the tension, and the difference between the maximum and minimum values of the outer diameter of the core was 90 μm. Out of 100, 7 had charging defects, 2 had wrinkles, and 7 had an edge height of more than 100 μm. The rolled appearance was generally good.

In Example 11, taking into consideration that the amount of shrinkage of the core increased in Example 10, a core having a higher circumferential bending elastic modulus was used for winding. As a result, the difference between the maximum and minimum core outer diameters was reduced to 74 μm. Out of 100, 3 had charging defects, 1 had wrinkles, and 3 had an edge height of more than 100 μm.

In Comparative Example 9, a film with smaller maximum height roughness than in Example 11 was wound up. As a result, the hardness of the wound film portion was 87 degrees after 25 hours had passed since the winding of the film was completed. Air removal between film layers was insufficient, and 32 out of 100 films had charging defects, 27 wrinkled films, and 1 film had an edge height of more than 100 μm. was bad.

In Example 12, the film roll was wound with an increased winding tension, in consideration of the insufficient air exclusion between the film layers in Comparative Example 9. As a result, the hardness of the wound film portion was 98 degrees after 25 hours had passed since the winding of the film was completed, and air was sufficiently removed between the film layers. On the other hand, as in Examples 6, 8, and 10, the amount of contraction of the core was increased by increasing the tension, and the difference between the maximum and minimum values of the outer diameter of the core was 97 μm. Out of 100, 8 had charging defects, 3 had wrinkles, and 8 had edge heights of more than 100 μm. The rolled appearance was generally good.

In Example 13, taking into account that the shrinkage amount of the core increased in Example 12, a core having a higher circumferential bending elastic modulus was used for winding. As a result, the shrinkage amount of the core was reduced, and the difference between the maximum and minimum core outer diameters was reduced to 75 μm. Out of 100, 0 had charging defects, 1 had wrinkles, and 0 had an edge height of more than 100 μm.

In Comparative Example 10, a longer film roll than in Example 2 was taken up. As a result, air was not sufficiently removed between the film layers, and the hardness of the wound film portion was 88 degrees after 25 hours had passed since the winding of the film was completed. Out of 100, 10 had charging defects, 13 had wrinkles, and 0 had an edge height of more than 100 μm.

In Example 14, the film roll was wound with an increased winding tension, in consideration of the insufficient air exclusion between the film layers in Comparative Example 10. As a result, the hardness of the wound film portion was 96 degrees after 27 hours had passed since the winding of the film was finished, and air was sufficiently removed between the film layers. On the other hand, by increasing the tension as in Examples 6, 8, 10 and 12, the shrinkage of the core increased, and the difference between the maximum and minimum core outer diameters was 98 μm. Eight out of 100 had charging defects, two had wrinkles, and eight had edge heights of more than 100 μm. The rolled appearance was generally good.

In Example 15, taking into account that the shrinkage amount of the core increased in Example 14, a core having a higher circumferential bending elastic modulus was used for winding. As a result, the difference between the maximum and minimum core outer diameters was reduced to 81 μm. Out of 100, 1 had a charging defect, 1 had wrinkles, and 1 had an edge height of more than 100 μm.

In Comparative Example 11, a longer film roll than in Example 15 was taken up. As a result, the removal of air between the film layers became insufficient, and the hardness of the wound film portion was 86 degrees after 28 hours had passed since the winding of the film was completed. Out of 100 sheets, 18 sheets had charging defects, 29 sheets had wrinkles, and 2 sheets had an edge height of more than 100 μm.

For Example 16, given the inadequate air exclusion between the film layers in Example 15, the take-up tension was increased to wind the film roll. As a result, the hardness of the wound film portion was 97 degrees after 27 hours had passed since the winding of the film was completed, and air was sufficiently removed between the film layers. On the other hand, by increasing the tension as in Examples 6, 8, 10 and 12, the shrinkage of the core increased, and the difference between the maximum and minimum core outer diameters was 98 μm. Out of 100, 6 had charging defects, 1 had wrinkles, and 8 had edge heights of more than 100 μm. The rolled appearance was generally good.

In Example 17, taking into account that the amount of shrinkage of the core increased in Example 16, a core having a higher circumferential bending elastic modulus was used for winding. As a result, the shrinkage amount of the core was reduced, and the difference between the maximum and minimum core outer diameters was reduced to 85 μm. Out of 100, 2 had charging defects, 0 had wrinkles, and 2 had an edge height of more than 100 μm.

In Example 18, a core having a high circumferential bending elastic modulus was used, and high tension conditions were applied to the thin film and smooth film, and the film was wound into a long length. The amount of shrinkage of the core was reduced by using a core with a high circumferential flexural modulus while excluding the air between the film layers under high tension conditions. Out of 100, 3 had charging defects, 2 had wrinkles, and 2 had an edge height of more than 100 μm.

The present invention can be applied not only to a method for manufacturing a film roll for winding a film into a roll and to a wound film roll, but also to a technique for handling sheet-like materials, but the scope of application is not limited to these. .

1, 11: cores 2, 10: film 3: core 4: rubber layer 5: contact pressure roller 6: raw roll 7: guide roller 8: lower blade roller 9: upper blade 12: film roll 13: static eliminator 14: winding Feeding section 15: Conveying section 16: Slit section 17: Winding section 18: Test piece A: Conveying direction

Claims (7)

A film roll in which a film is wound around a cylindrical core, wherein the difference between the maximum and minimum core outer diameters of the core portion where the film is not wound is 100 μm or less, and the wound film portion is A film roll having a hardness of 90 degrees or more. 2. The film roll according to claim 1 , wherein the core satisfies the following formula (1).

Here, E [GPa] is the circumferential bending elastic modulus of the core, a [mm] is the inner radius of the core, and b [mm] is the outer radius of the core. The film roll according to claim 1 or 2 , wherein the core has a circumferential bending elastic modulus of 50 GPa or more. 4. The film roll according to any one of claims 1 to 3 , wherein the material of said core is fiber reinforced plastic. The film roll according to any one of claims 1 to 4 , wherein the film has a thickness of 10 µm or less. The film roll according to any one of claims 1 to 5 , wherein the longitudinal length of the film is 8000 m or more. 7. The film roll according to any one of claims 1 to 6 , wherein the surface of the film has a maximum height roughness Rz of 100 nm or less on both the front and back surfaces.

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