JP7285881B2 - Film roll and method for manufacturing film roll - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film roll having knurled portions at both ends and a wound resin film, and a method for producing the film roll.

A resin film used as a transparent protective film for a polarizing plate is generally produced as a long film by a melt extrusion molding method or the like, and then wound into a roll to form a film roll (film roll). Stored and transported. When the film roll is wound or transported, there is a possibility that the film roll becomes telescopic due to winding misalignment.

In order to suppress the occurrence of this winding misalignment, an air layer is secured between the resin films in the film roll body by knurling the ends of the resin film. As one of such knurling processes, a method is known in which convex portions are formed on a resin film by irradiating the resin film with a laser beam to locally heat-melt or ablate the surface of the resin film. (See Patent Documents 1 and 2, for example).

JP 2017-021323 A JP 2017-047978 A

However, if the projections formed by the laser irradiation are too low, the air space between the resin films becomes narrow and the resin films come into contact with each other, resulting in the generation of a gauge band. On the other hand, if the projection is too high, the air layer between the resin films will be widened, and buckling deformation that causes knicking defects will occur over time. That is, there is a problem that winding defects such as a gauge band and buckling deformation may occur in the film roll due to variations in the height of the projections formed by the laser irradiation.

Moreover, the above-mentioned convex portion is formed only on the upper surface of the resin film. Therefore, if the tension or the pressing force of the touch roll fluctuates and becomes stronger when the resin film is wound, the protrusions are crushed and the predetermined height cannot be maintained, and the resin films come into contact with each other and a gauge band occurs. There is a problem that there is a case where the

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a film roll capable of suppressing occurrence of winding defects, and a method for manufacturing the film roll.

The present inventors have found that the above object can be achieved by forming circumferential projections on both sides of a resin film, and have completed the present invention.

That is, according to the present invention, there is provided a film roll comprising a wound resin film, the resin film having knurling portions at both ends in the width direction of the resin film, and the knurling portions comprising: It comprises a plurality of unit knurls that are regularly arranged at intervals from each other, and each of the unit knurls is formed on the upper surface of the resin film and protrudes upward in a circumferential first shape. and a circumferential second protrusion that is formed on the lower surface of the resin film and protrudes downward. In plan view, the second protrusion corresponds to the first protrusion. A film roll is provided which is arranged inside the first protrusion and is arranged concentrically with the first convex portion.

Moreover, in the film roll of the present invention, the second protrusion may have a height lower than the height of the first protrusion.

Further, in the film roll of the present invention, the first convex portion forms a single circular shape on the upper surface of the resin film, and the second convex portion forms a single circular shape on the lower surface of the resin film. It may form a shape.

Further, in the film roll of the present invention, the thickness of the resin film is 20 μm to 50 μm, the knurling portion is arranged within a range of 2 mm to 30 mm from the edge of the resin film, and the knurling portion The number density of unit nars is 8 pieces/cm ² to 100 pieces/cm ² , the diameter of the first projections is greater than 40 μm and 1500 μm or less, and the diameter of the second projections is 40 μm. The height of the first protrusions is 4 μm to 6 μm, the standard deviation of the height of the first protrusions is 3 μm or less, and the height of the second protrusions is less than 1500 μm. The height may be 2 μm to 4 μm, and the standard deviation of the height of the second protrusions may be 2 μm or less.

Further, according to the present invention, in the method for manufacturing the film roll, the first step of forming the knurling portions at both ends of the resin film in the width direction, and the second step of winding the resin film. wherein the first step comprises irradiating the resin film with a laser beam and scanning the laser beam along a circumferential scanning path to form the unit nard. A method for manufacturing a film roll comprising:

Moreover, in the method for manufacturing a film roll of the present invention, the spot diameter of the laser beam may be equal to or larger than the diameter of the scanning path.

Further, in the method for manufacturing a film roll of the present invention, the irradiation output of the laser light is 3 W to 30 W, the irradiation pulse of the laser light is 5 kHz to 20 kHz, and the spot diameter of the laser light is The scanning speed of the laser beam may be 500 mm/sec to 10000 mm/sec, and the diameter of the scanning path of the laser beam may be 20 μm to 500 μm.

According to the present invention, since the first and second protrusions formed on the resin film each have a circumferential shape, when the unit nard is formed by laser irradiation, the irradiation amount of the laser light is localized. There are no places that change dramatically. Therefore, it is possible to reduce variations in the height of the unit knurl, and to suppress the occurrence of winding defects in the film roll.

Further, according to the present invention, since the first and second protrusions are formed on both upper and lower surfaces of the resin film, many contacts are interposed between the wound resin films. Therefore, even if the tension or the pressing force of the touch roll fluctuates and becomes stronger when the resin film is wound, the first and second protrusions are prevented from being crushed and lowered. It is possible to suppress the occurrence of winding defects in the film roll.

Moreover, according to the present invention, in plan view, the second protrusion is arranged inside the first protrusion, and the second protrusion is arranged concentrically with the first protrusion. A second protrusion is arranged on the back side of the first protrusion so as to overlap with the first protrusion. For this reason, when the resin film is wound, the tension and the pressing force of the touch roll fluctuate and become stronger, and even if one of the first or second protrusions is pushed in, the second or first Since the other of the projections resists the pushing, it is possible to further suppress the first and second projections from being crushed and lowered.

FIG. 1 is a perspective view showing a film roll in an embodiment of the invention. FIG. 2 is a plan view showing the resin film of the film roll in the embodiment of the invention, and is an enlarged view of part II in FIG. FIG. 3(a) is a plan view showing a unit naru in an embodiment of the present invention, which is an enlarged view of the IIIA section in FIG. 2, and FIG. 3(b) shows a unit naru in an embodiment of the present invention. FIG. 3B is a cross-sectional view taken along line IIIB-IIIB in FIG. 3A. FIG. 4 is a perspective view showing the manufacturing process of the film roll in the embodiment of the present invention. 5(a) and 5(b) are diagrams showing the relationship between the spot diameter of the laser beam and the radius of the scanning pattern in the embodiment of the present invention, and FIG. 5(a) is a plan view, FIG. 5(b) is a cross-sectional view taken along line VB-VB in FIG. 5(a). FIG. 6A is a cross-sectional view showing a laminated portion of a resin film of a film roll according to an embodiment of the present invention, and FIG. 6B is a sectional view showing a laminated portion of a resin film of a film roll according to a comparative example. It is a cross-sectional view showing the.

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing a film roll 1 in this embodiment. FIG. 2 is a plan view showing the resin film 20 of the film roll 1 according to the present embodiment, and is an enlarged view of part II of FIG.

As shown in FIG. 1 , the film roll 1 of this embodiment includes a cylindrical core 10 and a resin film 20 wound around the core 10 . As will be described later, the film roll 1 is formed by winding a long resin film 20 around a winding core 10, and the wound resin film 20 is laminated in the film roll 1. section (see FIG. 6(a)).

This film roll 1 is an intermediate product roll obtained by temporarily winding the resin film 20 before making it into a final product. A final product is manufactured by unwinding the resin film 20 from the intermediate product roll and performing necessary processing such as slitting.

The application of the resin film 20 of the film roll 1 is not particularly limited, but for example, an optical film for an image display device such as a liquid crystal display device can be exemplified, and more specifically, a transparent protective film. , a polarizing film, a brightness enhancement film, a light diffusion film, a light collecting film, a reflective film, and the like. In particular, the resin film 20 of this embodiment is preferably used as a transparent protective film laminated on a polarizer to form a polarizing plate.

Although the resin film 20 is not particularly limited, the resin film 20 has a thickness T ₁ of 20 μm to 50 μm (see FIG. 3B), since the projections 41 and 42 are simultaneously formed on both sides of the resin film 20 by laser processing, which will be described later. (20 μm≦T ₁ ≦50 μm). Also, the resin film 20 has a width W ₁ of 300 mm to 2500 mm (300 mm≦W ₁ ≦2500 mm), although the width is not particularly limited.

This resin film 20 is made of a thermoplastic resin that is excellent in transparency, mechanical strength, thermal stability, water barrier properties, isotropy, and the like. The thermoplastic resin constituting the resin film 20 is not particularly limited, but resins such as those described in Japanese Patent No. 5578759 can be exemplified. Examples include cellulose resins, polyester resins, polyethersulfone resins, Polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth)acrylic resins, cyclic polyolefin resins, polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof can be mentioned. In particular, when the resin film 20 is used as a transparent protective film for a polarizing plate, the resin film 20 is preferably made of (meth)acrylic resin.

The method of manufacturing the resin film 20 is not particularly limited, but known methods such as a melt extrusion molding method, a casting method, and a calendering method can be employed. The melt extrusion molding method includes the T die casting method and the inflation method, but from the viewpoint of productivity and the like, it is preferable to manufacture the resin film 20 using the T die casting method.

The resin film 20 of this embodiment has knurling portions 31 and 32 at both ends in the width direction of the resin film 20 . Each of the knurling portions 31 and 32 is composed of a plurality of unit knurls 40 formed by laser processing, which will be described later.

One knurling portion 31 is a belt-like region extending along one end portion 20 a of the resin film 20 . More specifically, as shown in FIG. 2, the knurling portion 31 is a strip-shaped area defined by a first imaginary straight line _VL1 and a second imaginary straight line _VL2 . Here, the first imaginary straight line _VL1 passes through the outer circumference of the unit knurl 40 located closest to one end 20a in the width direction of the resin film 20 and extends parallel to the end 20a. It is a virtual straight line that exists. In addition, the second imaginary straight line VL ₂ passes through the outer periphery of the unit knurl 40 located farthest from one end 20a in the width direction of the resin film 20, and extends parallel to the end 20a. It is a virtual straight line that

The other knurling portion 32 is a region extending in a strip shape along the other end portion 20 b of the resin film 20 . More specifically, although not shown, the knurling portion 32 is also a belt-like region defined by the third imaginary straight line and the fourth imaginary straight line. Here, the third imaginary straight line passes over the outer periphery of the unit knurl 40 located closest to the other end 20b in the width direction of the resin film 20 and extends parallel to the end 20b. It is an imaginary straight line. In addition, the fourth imaginary straight line passes through the outer periphery of the unit knurl 40 located farthest from the end 20b in the width direction of the resin film 20, and extends parallel to the end 20a. is a straight line of

One knurling portion 31 is provided within a predetermined range from one end portion 20 a of the resin film 20 . Similarly, the other knurling portion 32 is also provided within a predetermined range from the other end portion 20 b of the resin film 20 . This predetermined range is preferably 2 mm or more and preferably 30 mm or less. If the width of the knurling portions 31 and 32 is too narrow, the effect may not be sufficiently exhibited, and if the width of the knurling portions 31 and 32 is too wide, the yield of the resin film 20 may decrease.

FIG. 3(a) is a plan view showing the unit knurl 40 in this embodiment, and is an enlarged view of the IIIA portion of FIG. FIG. 3(b) is a cross-sectional view showing the unit knurl 40 in this embodiment, and is a cross-sectional view taken along line IIIB-IIIB in FIG. 3(a).

Each unit knurl 40 is formed by locally thermally melting or ablating the resin film 20 by irradiating the upper surface 21 of the resin film 20 with a laser beam 121, as will be described later. Therefore, as shown in FIGS. 3A and 3B, each unit knurl 40 includes an upper projection 41 formed on the upper surface 21 of the resin film 20. As shown in FIG. The upper convex portion 41 protrudes upward from the periphery of the upper surface 21 of the resin film 20, and has a single circumferential (annular) shape in a plan view. Inside 41 there is only a circular recessed upper recess 411 .

In addition, in the example shown in FIG. 3A, the circumferential shape of the upper convex portion 41 is a perfect circle, but the circumferential shape of the upper convex portion 41 is not particularly limited to this. That is, if the circumference of the upper convex portion 41 is a circular annular shape with no corners and the ratio of the minor axis to the major axis is 80% or more, the circular shape may be an ellipse or an elongated shape. Circles (shapes in which semicircles are connected by a pair of straight lines), polygons with rounded corners, and the like are also included.

In addition, in the present embodiment, the unit knurls 40 are formed by scanning the laser light circumferentially without gaps as described later. A side protrusion 42 is included. The lower convex portion 42 protrudes downward from the periphery of the lower surface 22 of the resin film 20, and has a single circumferential (annular) shape in a plan view. Inside the projection 42, only a circular recessed lower recess 421 is present.

In addition, in the example shown in FIG. 3A, the circumferential shape of the lower convex portion 42 is a perfect circle, but the circumferential shape of the lower convex portion 42 is not particularly limited to this. That is, if the circumference of the lower projection 42 is a circular circular shape with no corners and the ratio of the minor axis to the major axis is 80% or more, the circular shape may be an ellipse, an ellipse, or an ellipse. Ellipses (shapes in which semicircles are connected by a pair of straight lines) and polygons with rounded corners are also included.

Further, the lower convex portion 42 is arranged inside the upper convex portion 41 in plan view, and is arranged concentrically with the upper convex portion 41 . That is, the lower convex portion 42 is arranged on the back side of the upper convex portion 41 so as to overlap the upper convex portion 41 .

The height H ₁ of the upper convex portion 41 is not particularly limited, but is preferably 4 μm to 6 μm (4 μm≦H ₁ ≦6 μm), and the standard deviation σ ₁ of the height H ₁ of the upper convex portion 41 is It is preferably 3 μm or less (σ ₁ ≦3 μm). The height _H1 of the upper convex portion 41 is within the above range, and the standard deviation _σ1 of the height _H1 of the upper convex portion 41 is equal to or less than the upper limit value. Variation in height _H1 can be suppressed, and occurrence of winding defects such as gauge band and buckling deformation can be suppressed.

On the other hand, although the height H ₂ of the lower protrusion 42 is not particularly limited, it is preferably 2 μm to 4 μm ( ₂ μm≦H ₂ ≦4 μm). The standard deviation σ ₂ of is preferably 2 μm or less (σ ₂ ≦2 μm). The height H ₂ of the lower convex portion 42 is within the above range, and the standard deviation σ ₂ of the height H ₂ of the lower convex portion 42 is equal to or less than the upper limit value, so that the lower convex portion Variation in the height _H2 of 42 can be suppressed, and occurrence of winding defects such as gauge band and buckling deformation can be suppressed.

In this embodiment, the height _H2 of the lower protrusion 42 is lower than the height _H1 of the upper protrusion 41 ( _H2 < _H1 ). Therefore, when the resin film 20 is wound, the tension and the pressing force of the touch roll 110 fluctuate and become stronger, and even if the upper protrusion 41 is pushed in, the height H of the lower protrusion 42 is increased. ₂ , it is possible to prevent the upper protrusion 41 from collapsing beyond the height of the lower protrusion 42. As shown in FIG.

Here, the height _H1 of the upper convex portion 41 is the height from the upper reference plane. This upper reference plane is centered on the upper surface 21 of the resin film 20 at the center of the upper convex portion 41 to be measured, and is between the center of the upper convex portion 41 and the center of the other upper convex portion 41. is the average height of the imaginary circumference passing through the midpoint of . Here, the other upper convex portion 41 is the upper convex portion 41 positioned closest to the upper convex portion 41 to be measured on the upper surface 21 of the resin film 20 .

Similarly, the height _H2 of the lower protrusion 42 is the height from the lower reference plane. This lower reference plane is centered on the lower surface 22 of the resin film 20 at the center of the lower convex portion 42 to be measured, and the center of the lower convex portion 42 and the other lower convex portion 42 It is the average height of the imaginary circumference passing through the midpoint between the centers. Here, the other lower convex portion 42 is the lower convex portion 42 positioned closest to the lower convex portion 42 to be measured on the lower surface 22 of the resin film 20 .

The heights H ₁ and H ₂ of the upper and lower convex portions 41 and 42 are preferably measured using an optical interference type optical measuring instrument (for example, WI-5000 manufactured by Keyence Corporation). By using such a non-contact type measuring device, it is possible to avoid crushing of the upper and lower convex portions 41 and 42 during measurement.

In addition, the standard deviation σ ₁ of the height H ₁ of the upper convex portion 41 is not particularly limited. It may be calculated by measuring the height _H1 of the convex portion 41 . Similarly, the standard deviation σ ₂ of the height H ₂ of the lower protrusion 42 is also not particularly limited, but all the standard deviations σ 2 existing within a range of 50 mm along the longitudinal direction of the resin film 20 on the lower surface 22 of the resin film 20 may be calculated by measuring the height _H2 of the lower convex portion 42 of .

Although the diameter _D1 of the upper protrusion 41 is not particularly limited, it is preferably greater than 40 μm and equal to or less than 1500 μm (40 μm<D ₁ ≦1500 μm). Although the diameter _D2 of the lower projection 42 is not particularly limited, it is preferably 40 μm or more and less than 1500 μm (40 μm≦D ₂ <1500 μm). If the diameters D ₁ and D ₂ of the upper and lower convex portions 41 and 42 are outside the above range, the knurling portions 31 and 32 may not exhibit their effects sufficiently.

As shown in FIGS. 3A and 3B, the diameter _D1 of the upper convex portion 41 is a circle formed by connecting the highest points in the radial direction of the upper convex portion 41 in the circumferential direction. is the diameter of the circumferential ridgeline _RL1 ; Similarly, the diameter _D2 of the lower convex portion 42 is the diameter of the circumferential ridgeline _RL2 formed by connecting the highest points of the lower convex portion 42 in the radial direction in the circumferential direction.

As shown in FIG. 2, one knurling portion 31 is constructed by arranging the plurality of unit knurls 40 described above regularly at intervals. Specifically, in this knurling portion 31, one unit knurl row 45 is formed by arranging four unit knurls 40 at equal intervals along the width direction of the resin film 20 at a first pitch _P1 . ing. A plurality of unit knurl rows 45 are arranged at equal intervals along the longitudinal direction of the resin film 20 at a second pitch _P2 . The unit knurl rows 45 adjacent to each other along the longitudinal direction of the resin film 20 are arranged with a shift of ₃ third pitches P, which corresponds to half the first pitch _P1 , in the width direction of the resin film 20. , and the plurality of unit knurl rows 45 are arranged alternately. That is, in the present embodiment, one knurling portion 31 is configured by arranging a plurality of unit knurls 40 in a staggered manner.

Although not particularly shown, the other knurling portion 32 is also formed by regularly arranging a plurality of unit knurls 40 at intervals, similarly to the one knurling portion 31 described above. Specifically, in the present embodiment, the other knurling portion 32 is configured by arranging a plurality of unit knurls 40 in a staggered manner.

The number density ND of the unit knurls 40 in the knurling portions 31 and 32 is not particularly limited, but is preferably 8/cm ² to 100/cm ² (8/cm ² ≤ ND ≤ 100/cm ^{2 )} . ). If the number density ND of the unit knurls 40 is smaller than the above lower limit, the effects of the knurling portions 31 and 32 may not be sufficiently exhibited. On the other hand, if the number density ND of the unit knurls 40 exceeds the above upper limit, the resin film 20 may easily break at the knurling portions 31 and 32 .

The number of unit knurls 40 forming the knurling portions 31 and 32 is not particularly limited to the above. Also, the arrangement of the unit knurls 40 in the knurling portions 31 and 32 is not particularly limited as long as the plurality of unit knurls 40 are regularly arranged with a space therebetween. For example, the knurling portions 31 and 32 may be configured by arranging a plurality of unit knurls 40 in a grid pattern (matrix pattern).

Next, a method for manufacturing the film roll 1 described above will be described with reference to FIGS. 4 to 6(b).

FIG. 4 is a perspective view showing the manufacturing process of the film roll 1 in this embodiment. 5(a) and 5(b) are diagrams showing the relationship between the spot diameter SD of the laser beam 121 and the radius PD of the scanning pattern 123 in this embodiment, and FIG. 5(a) is a plan view, FIG. 5(b) is a sectional view along line VB-VB in FIG. 5(a). FIG. 6(a) is a cross-sectional view showing the laminated portion of the resin film 20 of the film roll 1 according to the present embodiment, and FIG. FIG. 4 is a cross-sectional view showing a laminated portion;

In the film roll 1 described above, the widthwise ends 20a . It is manufactured by a manufacturing method including a knurling step of forming knurling portions 31 and 32 in 20b and a winding step of winding the resin film 20 on which the knurling portions 31 and 32 are formed. The resin film 20 may be continuously supplied to the knurling process from the molding process in which the resin film 20 is molded into a film shape using the T-die casting method or the like.

Specifically, as shown in FIG. 4, the winding core 10 is rotated by a winding device (not shown), and the long resin film 20 is continuously transported along the longitudinal direction of the resin film 20. , the resin film 20 is wound around the winding core 10 while being pressed by the touch roll 110. - 特許庁Also, before the resin film 20 contacts the touch roll 110, the laser irradiation device 120 irradiates the upper surface 21 of the resin film 20 with a laser beam 121 so that both ends 20a . Knurling portions 31 and 32 are formed in 20b.

In this embodiment, while the resin film 20 is conveyed toward the touch roll 110, the resin film 20 is irradiated with the laser beam 121 to form the unit knurls 40, but the present invention is not particularly limited to this. For example, the conveyance of the resin film 20 may be stopped each time the laser beam 121 is irradiated to form the unit knurls 40 .

In the present embodiment, in the knurling process, the laser irradiation device 120 irradiates a circular spot 122 of the laser light 121, and the laser light 121 is scanned along a circumferential scanning path 123 to obtain the above-described upper side. and the unit knurls 40 including the lower protrusions 41 and 42 are formed. A method using galvano scanning, XY stage scanning, or the like can be used for scanning with laser light.

As described above, in this embodiment, the upper and lower convex portions 41 and 42 formed on the resin film 20 have a circular shape with no corners or ends, and the scanning path 123 of the laser beam 121 is circular, there is no location where the irradiation amount of the laser beam 121 varies locally. Therefore, the height variation of the unit knurls 40 can be reduced, and the occurrence of winding defects on the film roll 2 can be suppressed. In particular, since a film made of (meth)acrylic resin tends to deform over time due to residual stress, it is particularly effective when the resin film 20 is made of (meth)acrylic resin.

In this knurling step, as shown in FIGS. 5A and 5B, the spot 122 of the laser beam 121 preferably has a perfect circular shape, and the spot diameter SD of the laser beam 121 is It is preferably 20 μm to 1000 μm (20 μm≦SD≦1000 μm). On the other hand, the scanning path 123 of the laser beam 121 also preferably has a perfect circular shape, and the diameter PD of the scanning path 123 is also preferably 20 μm to 500 μm (20 μm≦PD≦500 μm). Further, the scanning speed of the laser light 121 by the laser irradiation device 120 is preferably 500 mm/sec to 10000 mm/sec. The diameter PD of the scanning path 123 of the laser beam 121 means the diameter of the trajectory of the center LC of the spot 122 of the laser beam 121 moving on the upper surface 21 of the resin film 20 .

In the example shown in FIG. 5A, the scanning path 123 of the laser beam 121 has a perfect circle, but the scanning path 123 is not particularly limited to this. That is, if the circumference of the scanning path 123 is a circular annular shape with no corners and the ratio of the minor axis to the major axis is 80% or more, it can be an ellipse or an ellipse in addition to a perfect circle. (a shape in which semicircles are connected by a pair of straight lines), polygons with rounded corners, and the like are also included.

Thus, in this embodiment, the spot diameter SD of the laser beam 121 is greater than or equal to the diameter PD of the scanning path 123 (SD≧PD). Therefore, as shown in FIGS. 5A and 5B, the trajectory of the spot 122 of the laser beam 121 moving along the scanning path 123 overlaps or contacts at the center of the scanning path 123. , so that the laser beam 121 can be scanned circumferentially without gaps. In this way, since the trajectory of the laser beam 121 has a circular shape without gaps, the laser beam 121 can be concentrated on the upper surface 21 of the resin film 20 . In the present embodiment, the spot 122 of the laser beam 121 is moved only once along the scanning path 123. However, the present invention is not limited to this. You can move it.

By setting the spot diameter SD of the laser beam 121 to be equal to or larger than the diameter PD of the scanning path 123 and concentrating the laser beam 121 on the upper surface 21 of the resin film 20 in this manner, the resin film 20 is formed as shown in FIG. On the upper and lower surfaces 21 and 22, the resin material at the locations irradiated with the laser beam 121 is fluidized and pushed out. As a result, an upper convex portion 41 having an inner upper concave portion 411 is formed on the upper surface 21 of the resin film 20 , and a lower convex portion 42 having an inner lower concave portion 421 is formed on the lower surface 22 of the resin film 20 . be done. That is, by irradiating the upper surface 21 of the resin film 20 with the laser beam 121 once, the upper convex portion 41 and the lower convex portion 42 can be formed at the same time. In addition, since the fluidized resin material of the upper and lower concave portions 411 and 421 can be moved toward the outer peripheral side, the height of the upper and lower convex portions 41 and 42 can be obtained efficiently.

At this time, since the upper surface 21 of the resin film 20 is irradiated with the laser beam 121, the lower convex portion 42 is arranged inside the upper convex portion 41, and the height _H2 of the lower convex portion 42 is the upper side. It is lower than the height H ₁ of the convex portion 41 (H ₂ <H ₁ ). Since the upper and lower protrusions 41 and 42 are simultaneously formed by laser irradiation, the lower protrusion 42 and the upper protrusion 41 are arranged concentrically. That is, since the upper convex portion 41 and the lower convex portion 42 are simultaneously formed by one laser irradiation, the positional relationship between the upper convex portion 41 and the lower convex portion 42 in plan view is defined with high accuracy.

Specific examples of the laser beam 121 include excimer lasers such as ArF excimer laser, KrF excimer laser, and XeCl excimer laser; solid-state lasers such as YAG laser, YLF laser, YVO ₄ laser, and titanium sapphire laser; A fiber laser, a carbon dioxide laser, or the like can be used. It is preferable to use a carbon dioxide gas laser as the laser beam 121 from the viewpoint of improving productivity by high output.

Further, the irradiation output of the laser light 121 by the laser irradiation device 120 is preferably 3W to 30W. Furthermore, the irradiation pulse of the laser light 121 by the laser irradiation device 120 is preferably 5 kHz to 20 kHz.

Then, the resin film 20 with the knurling portions 31 and 32 formed thereon is conveyed in its longitudinal direction and is wound while being pressed by the touch roll 110 . A near roll that does not press the resin film 20 may be used instead of the touch roll 110 or in addition to the touch roll 110 . Alternatively, the resin film 20 may be wound without using the touch roll 110 and the near roll.

At this time, as shown in FIG. 6B, in the film roll 1' of the comparative example which does not have the lower convex portion, the tension and the pressing force of the touch roll are applied when the resin film 20' is wound. If it fluctuates and becomes stronger, the upper convex portion 41' may be crushed and the predetermined height cannot be maintained, and the resin films 20' may come into contact with each other to generate a gauge band.

On the other hand, in this embodiment, as shown in FIG. Side protrusions 42 are formed, and many contacts are interposed between the wound resin films. Therefore, even if the tension or the pressing force of the touch roll 110 fluctuates and becomes stronger when the resin film 20 is wound, the upper and lower protrusions 41 and 42 are crushed and lowered. can be suppressed, the occurrence of winding defects in the film roll 1 can be suppressed.

Furthermore, in the present embodiment, in plan view, the lower convex portion 42 is arranged inside the upper convex portion 41, and the lower convex portion 42 is arranged concentrically with the upper convex portion 41. , a lower convex portion 42 is arranged on the back side of the upper convex portion 41 so as to overlap with the upper convex portion 41 . Therefore, when the resin film 20 is wound, the tension and the pressing force of the touch roll 110 fluctuate and become stronger, and even if the upper protrusions 41 are pushed in, the lower protrusions 42 will not be able to withstand the pushing. Since the upper and lower protrusions 41 and 42 are resisted, it is possible to further prevent the upper and lower protrusions 41 and 42 from being crushed and lowered.

It should be noted that the embodiments described above are described to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above embodiments is meant to include all design changes and equivalents that fall within the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1... Film winding body 10... Winding core 20... Resin film 21... Upper surface 22... Lower surface 31, 32... Knurling part 40... Unit knurl 41... Upper convex part
411... Upper concave portion 42... Lower convex portion
421 Lower concave portion 45 Unit knurl row 110 Touch roll 120 Laser irradiation device 121 Laser beam 122 Spot 123 Scanning path

Claims (7)

A film roll comprising a wound resin film,
The resin film has knurling portions at both ends in the width direction of the resin film,
The knurling portion includes a plurality of unit knurls regularly arranged at intervals,
Each said unit nar is
a circumferential first protrusion formed on the upper surface of the resin film and protruding upward;
a circumferential second protrusion formed on the lower surface of the resin film and protruding downward;
The film roll body in which the second convex portion is arranged inside the first convex portion and concentrically with the first convex portion in a plan view. The film roll according to claim 1,
The film roll body, wherein the second protrusion has a height lower than the height of the first protrusion. The film roll according to claim 1 or 2,
The first convex portion forms a single circular shape on the upper surface of the resin film,
The second convex portion is a film roll having a single circular shape on the lower surface of the resin film. The film roll according to any one of claims 1 to 3,
The thickness of the resin film is 20 μm to 50 μm,
The knurling portion is arranged within a range of 2 mm to 30 mm from the edge of the resin film,
The number density of unit knurls in the knurling portion is 8/cm ² to 100/cm ² ,
the diameter of the first protrusion is greater than 40 μm and equal to or less than 1500 μm;
The diameter of the second protrusion is 40 μm or more and less than 1500 μm,
The height of the first protrusion is 4 μm to 6 μm,
The standard deviation of the height of the first convex portion is 3 μm or less,
The height of the second protrusion is 2 μm to 4 μm,
The film roll, wherein the standard deviation of the height of the second protrusions is 2 μm or less. A method for producing a film roll according to any one of claims 1 to 4,
a first step of forming the knurling portions at both ends in the width direction of the resin film;
and a second step of winding the resin film,
The first step includes irradiating the resin film with a laser beam and scanning the laser beam along a circumferential scanning path to form the unit knurls. Method. A method for manufacturing a film roll according to claim 5,
A method for manufacturing a film roll, wherein the spot diameter of the laser beam is equal to or larger than the diameter of the scanning path. The method for manufacturing the film roll according to claim 5 or 6,
The irradiation output of the laser light is 3 W to 30 W,
The irradiation pulse of the laser light is 5 kHz to 20 kHz,
The spot diameter of the laser beam is 20 μm to 1000 μm,
The scanning speed of the laser beam is 500 mm/sec to 10000 mm/sec,
A method for producing a film roll, wherein the scanning path of the laser beam has a diameter of 20 μm to 500 μm.

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