Laser processing method, method for producing optical sheet, and laser processing device

Abstract

This laser processing method includes a step for scanning a laser beam (LB) along a second direction intersecting a first direction, which is a longitudinal direction, using a polygon scanner (40) while transporting a long and narrow sheet member (10) in the first direction, thereby forming a two-dimensional pattern on the sheet member (10).

Description

Laser processing method, optical sheet manufacturing method and laser processing device

[0001] The present invention relates to a laser processing method, a method for manufacturing an optical sheet, and a laser processing apparatus.

[0002] In recent years, laser processing methods have attracted attention as a method for efficiently processing long sheet materials (e.g., film, paper, or cloth) while they are being transported. For example, Patent Document 1 discloses a laser processing method in which a sheet material is processed by two-dimensionally scanning a laser beam using a galvanometer scanner while the sheet material is being transported by unwinding and rewinding a roll of the sheet material, a so-called roll-to-roll method. The galvanometer scanner deflects the laser beam using two plate-shaped galvanometer mirrors having non-parallel rotation axes, thereby enabling the laser beam to be scanned two-dimensionally.

[0003] JP 2016-107288 A

[0004] Galvano scanners are capable of two-dimensional scanning and offer a high degree of processing flexibility. However, the scanning speed of galvano scanners is not very high, at most about 10 m / s. The scanning range of galvano scanners is not very wide, less than 100 mm. From the perspective of efficiently processing long sheet materials while they are being transported, a laser processing method that can replace the galvano scanner, which has a low scanning speed and a narrow scanning range, is desired.

[0005] An object of the present invention is to provide a laser processing method and laser processing apparatus for efficiently laser processing a long sheet material while conveying it, and a method for manufacturing an optical sheet using the laser processing method.

[0006] According to an embodiment of the present invention, the following solutions are provided:

[0007] [Item 1] A laser processing method including a step of forming a two-dimensional pattern on a long sheet material by using a polygon scanner to scan a laser beam along a second direction intersecting the first direction while transporting the long sheet material in a first direction that is a longitudinal direction of the sheet material.

[0008] [Item 2] The laser processing method according to Item 1, wherein the step of forming the two-dimensional pattern on the sheet material determines a conveying speed of the sheet material based on the number of scanning lines per second of the polygon scanner and a distance between adjacent scanning lines in the first direction of the two-dimensional pattern to be formed on the sheet material.

[0009] [Item 3] The laser processing method according to item 1 or 2, wherein the sheet material has a certain portion and at least one other portion located together with the certain portion along the second direction, and the step of forming the two-dimensional pattern on the sheet material includes: deflecting the laser light toward the certain portion using the polygon scanner and scanning the laser light along the second direction; and deflecting at least one other laser light toward the at least one other portion using at least one other polygon scanner located together with the polygon scanner along the second direction, thereby forming the two-dimensional pattern on the sheet material.

[0010] [Item 4] The laser processing method according to any one of Items 1 to 3, wherein the step of forming the two-dimensional pattern on the sheet material includes intermittently emitting the laser light and scanning the laser light along the second direction using the polygon scanner to form a plurality of processing areas distributed in a dot pattern on the sheet material, wherein an average diameter of each of the plurality of processing areas is 10 μm or more and 500 μm or less, and a center-to-center distance between two nearest processing areas of the plurality of processing areas is 10 μm or more and 500 μm or less.

[0011] [Item 5] The laser processing method according to any one of Items 1 to 4, wherein the moving speed of the sheet material is 0.5 m / min or more and 10 m / min or less.

[0012] [Item 6] The laser processing method according to any one of Items 1 to 5, wherein the length of the sheet material in the second direction is 100 mm or more.

[0013] [Item 7] A method for manufacturing an optical sheet, comprising the steps of: transporting a long sheet material, which is capable of forming a portion having a refractive index different from that of its surroundings by light irradiation, in a first direction that is the longitudinal direction; and scanning the sheet material with intermittently emitted laser light along a second direction that intersects with the first direction, using a polygon scanner, thereby forming a first region and a plurality of second regions that are distributed in a dot pattern and each surrounded by the first region, in the sheet material; wherein the refractive index of each of the plurality of second regions is different from the refractive index of the first region.

[0014] [Item 8] The method for manufacturing an optical sheet according to Item 7, wherein an average diameter of each of the plurality of second regions is 10 μm or more and 500 μm or less, and a center-to-center distance between two nearest second regions among the plurality of second regions is 10 μm or more and 500 μm or less.

[0015] [Item 9] The method for manufacturing an optical sheet according to Item 7 or 8, wherein the moving speed of the sheet material is 0.5 m / min or more and 10 m / min or less.

[0016] [Item 10] The method for manufacturing an optical sheet according to Item 7 or 8, wherein the sheet material is an optical laminate sheet having a porous layer having a porous structure and a resin composition layer laminated on the porous layer and containing a resin composition that is melted by the irradiation of the laser light, and the resin composition layer is located closer to the polygon scanner than the porous layer, and the step of forming the first region and the plurality of second regions on the sheet material includes using the polygon scanner to deflect the laser light onto the resin composition layer of the optical laminate sheet and scan the laser light along the second direction, and the first region is a region that has the porous structure in the porous layer of the optical laminate sheet, and each of the plurality of second regions is a region where voids in the porous structure are at least partially filled with the resin composition that has been melted by the irradiation of the laser light.

[0017] [Item 11] A laser processing apparatus comprising a conveyor, a laser light source, a polygon scanner, and a control device, wherein the control device causes the conveyor to convey a long sheet material in a first direction that is a longitudinal direction, causes the laser light source to emit laser light, and causes the polygon scanner to deflect the laser light toward the sheet material and scan the laser light along a second direction that intersects with the first direction, thereby forming a two-dimensional pattern on the sheet material.

[0018] [Item 12] The laser processing device according to Item 11, wherein the control device determines a conveying speed of the sheet material based on the number of scanning lines per second of the polygon scanner and the distance between adjacent scanning lines in the first direction of a two-dimensional pattern to be formed on the sheet material.

[0019] [Item 13] The laser processing apparatus according to item 11 or 12, further comprising at least one other laser light source and at least one other polygon scanner positioned along the second direction together with the polygon scanner, wherein the sheet material has a certain portion and at least one other portion positioned along the second direction together with the certain portion, and wherein the control device: causes the polygon scanner to deflect the laser light toward the certain portion of the sheet material and scan the laser light along the second direction; causes the at least one other laser light source to emit at least one other laser light; and causes the at least one other polygon scanner to deflect the at least one other laser light toward the at least one other portion of the sheet material and scan the at least one other laser light along the second direction, thereby forming the two-dimensional pattern on the sheet material.

[0020] [Item 14] The control device causes the laser light source to intermittently emit the laser light, causes the polygon scanner to deflect the laser light toward the sheet material, and causes the laser light to scan along the second direction, thereby forming a plurality of processing areas distributed in a dot pattern on the sheet material, wherein an average diameter of each of the plurality of processing areas is 10 μm or more and 500 μm or less, and a center-to-center distance between two nearest processing areas of the plurality of processing areas is 10 μm or more and 500 μm or less.

[0021] [Item 15] The laser processing device according to any one of Items 11 to 14, wherein the moving speed of the sheet material is 0.5 m / min or more and 50 m / s or less.

[0022] According to the embodiments of the present invention, there are provided a laser processing method and a laser processing apparatus for efficiently laser processing a long sheet material while conveying the sheet material, and a method for manufacturing an optical sheet using the laser processing method.

[0023] 8A is a schematic perspective view of a laser processing apparatus according to an embodiment of the present invention. FIG. 8B is a schematic front view showing how a polygon scanner deflects laser light toward a sheet material. FIG. 8C is a schematic front view showing how a polygon scanner deflects laser light toward a sheet material. FIG. 8D is a schematic front view showing how a polygon scanner deflects laser light toward a sheet material. FIG. 8E is a schematic view showing how a polygon scanner deflects laser light toward a sheet material. FIG. 8F is a bitmap image of an example of a two-dimensional pattern to be formed on a portion of the sheet material. FIG. 8G is a schematic plan view of an example of a two-dimensional pattern actually formed on a portion of the sheet material. FIG. 8H is a bitmap image of another example of a two-dimensional pattern to be formed on a portion of the sheet material. FIG. 8I is a schematic plan view of another example of a two-dimensional pattern actually formed on a portion of the sheet material. FIG. 8I is a schematic view showing how a portion of a layer is removed by laser light. FIG. 8H is a schematic perspective view of a laser processing apparatus according to another embodiment of the present invention. FIG. 8I is a schematic cross-sectional view of an optical laminated sheet. FIG. 8I is a schematic cross-sectional view of an optical sheet manufactured by irradiating an optical laminated sheet with laser light. FIG. 8I is a schematic plan view of the porous layer shown in FIG. 8A. FIG. 8I is a schematic cross-sectional view of a first light distribution element. 13B shows a schematic cross-sectional view of a second light distributing element. 13C shows a flowchart of one cycle of steps in a method for manufacturing an optical sheet according to Example 1. 13D shows a flowchart of one cycle of steps in a method for manufacturing an optical sheet according to Example 2. 13E shows a flowchart of one cycle of steps in a method for manufacturing an optical sheet according to Example 3. 13F shows a flowchart of one cycle of steps in a method for manufacturing an optical sheet according to Comparative Example 1. 13G shows a flowchart of one cycle of steps in a method for manufacturing an optical sheet according to Comparative Example 2. 13H shows a flowchart of one cycle of steps in a method for manufacturing an optical sheet according to Comparative Example 3. 13I shows a cross-sectional SEM image of the optical sheet obtained in Example 1. 13I shows a schematic diagram of the configuration of a light distributing element sample used to evaluate the light extraction effect. 13I shows a plan view of a part of the manufactured unevenly shaped film as seen from the uneven surface side. 13I shows a cross-sectional view of the unevenly shaped film shown in FIG. 13A along 13B-13B'.

[0024] Hereinafter, a laser processing method, a laser processing apparatus, and a method for manufacturing an optical sheet according to embodiments of the present invention will be described with reference to the drawings. The laser processing apparatus according to the embodiments of the present invention is not limited to the following examples.

[0025] (Embodiment) [Laser Processing Apparatus] First, referring to Fig. 1, an example of the configuration of a laser processing apparatus according to an embodiment of the present invention will be described. Fig. 1 shows a schematic perspective view of a laser processing apparatus 100 according to an embodiment of the present invention. For reference, the drawing shows a schematic representation of an X-axis, a Y-axis, and a Z-axis that are orthogonal to each other. The direction of the X-axis arrow is referred to as the +X direction, and the opposite direction is referred to as the -X direction. When there is no need to distinguish between the ±X directions, they are simply referred to as the X direction. The same applies to the Y-axis and Z-axis.

[0026] The laser processing apparatus 100 shown in Fig. 1 includes a conveyor 20 that conveys a long sheet material 10 in the +X direction, which is the longitudinal direction, a laser light source 30 that emits a laser beam LB, a polygon scanner 40 that deflects the laser beam LB and scans the laser beam LB along the +Y direction, and a control device 50 that controls the operations of the conveyor 20, the laser light source 30, and the polygon scanner 40. The white arrows D1 and D2 shown in Fig. 1 represent the movement direction of the sheet material 10 and the scanning direction of the polygon scanner 40, respectively. The dotted lines shown in Fig. 1 represent control signals sent from the control device 50.

[0027] According to the laser processing apparatus 100 of this embodiment, a two-dimensional pattern can be efficiently formed on the sheet material 10 by scanning the laser beam LB in the +Y direction using the polygon scanner 40 capable of high-speed scanning while transporting the sheet material 10 in the +X direction. Each component will be described below.

[0028] <Sheet Material 10> The sheet material 10 may be, for example, a film, paper, or cloth. The film may be, for example, a single-layer film or a laminated film having multiple films. The laminated film may have, in addition to multiple films, an adhesive layer that bonds the two closest plastic layers together, or may have at least one conductive inorganic film selected from ITO, Ag, Au, and Cu on its surface. The film may be, for example, a polarizing film or a retardation film used in a display. The size of the sheet material 10 in the Y direction may be, for example, 100 mm or more and 300 mm or less. When using a polygon scanner 40, unlike a galvanometer scanner, the size of the sheet material 10 in the Y direction can be 100 mm or more.

[0029] <Conveyor 20> The conveyor 20 includes an unwinding roller 22a, a winding roller 22b, two conveying rollers 24, and an unwinding motor 26a and a winding motor 26b. The unwinding motor 26a and the winding motor 26b rotate the unwinding roller 22a and the winding roller 22b in the same direction. The unwinding roller 22a unwinds the unprocessed sheet material 10 from the roll, and the winding roller 22b winds the processed sheet material 10. The two conveying rollers 24 are spaced apart in the X direction and support the moving sheet material 10. By unwinding and winding the sheet material 10 via the two conveying rollers 24, the sheet material 10 can be conveyed in the +X direction while maintaining it parallel to the XY plane. By setting the rotational speed of the winding roller 22b slightly higher than that of the unwinding roller 22a, tension is applied to the sheet material 10, thereby suppressing sagging of the sheet material 10.

[0030] By continuously rotating the unwind roller 22a and the take-up roller 22b, the sheet material 10 can be continuously transported. Continuous transport of the sheet material 10 allows for more efficient laser processing of the sheet material 10 than intermittent transport, in which the transport of the sheet material is stopped and resumed after each processing, or single-sheet transport, in which individual sheets of sheet material are transported one by one. Intermittent transport includes a process of vacuum-adsorbing the sheet material to the stage before processing and releasing the vacuum after processing. Single-sheet transport also includes a process of placing one of the individual sheets on the stage, vacuum-adsorbing it, releasing the vacuum after processing, and recovering it. The transport speed of the sheet material 10 in continuous transport can be, for example, 0.5 m / min or more and 10 m / min or less. The transport speed of the sheet material 10 can be increased with the high-speed scanning of the polygon scanner 40. However, in this embodiment, it is sufficient that the sheet material 10 is transported during laser processing, and therefore the transport of the sheet material 10 may be temporarily stopped before and / or after laser processing.

[0031] In the example shown in Figure 1, the sheet material 10 is transported using a roll-to-roll method, but the sheet material 10 may also be transported by placing a long sheet material 10 that is not in a roll shape on a stage and moving the stage in the +X direction.

[0032] <Laser Light Source 30> The laser light source 30 is a laser light source capable of continuously or intermittently emitting ultraviolet, visible, or infrared laser light LB. In the example shown in FIG. 1 , the laser light source 30 is disposed outside the polygon scanner 40, but it may also be built into the polygon scanner 40. The wavelength of the laser light LB is suitable for processing the sheet material 10. The laser light LB may be, for example, 150 nm or more and 11,000 nm or less, and preferably 250 nm or more and 2,000 nm or less. When the sheet material 10 contains a material that absorbs infrared light, the wavelength of the laser light LB may be, for example, 900 nm or more and 1,500 nm or less, and preferably 900 nm or more and 1,200 nm or less.

[0033] The spatial intensity distribution of the laser beam LB preferably has a Gaussian distribution or a top-hat distribution, but is not limited to this. The beam shape may be circular or rectangular. The beam may be focused using a focusing optical system such as an objective lens. When the beam shape is circular, the focal diameter (spot diameter) is preferably, for example, in the range of 10 μm to 150 μm, and more preferably in the range of 30 μm to 100 μm. By setting the focal diameter to 10 μm or more, a sufficient depth of focus can be obtained, thereby stabilizing the process. Furthermore, by setting the focal diameter to 150 μm or less, a decrease in energy density can be suppressed, and the formation of a desired pattern can be promoted. Furthermore, in the case of pulsed laser beams, increasing the number of pulses that can be emitted per unit time increases the number of patterns that can be formed per unit time, leading to improved productivity.

[0034] From the viewpoint of forming a pattern in a short time, the laser light LB is preferably a pulsed laser light that is emitted intermittently, and preferably a laser light having a pulse width on the order of nanoseconds to microseconds. If the pulse width is too short, heat generation may not occur, but if the pulse width is within the above range, a photochemical reaction occurs that generates heat, so that sufficient energy injection time can be achieved to form the desired pattern. Furthermore, if the pulse width is within this range, the formation of one pattern can be completed in a short time, which is preferable from the viewpoint of productivity.

[0035] The repetition frequency of the pulsed laser light is not particularly limited, but from the viewpoint of productivity, the higher the repetition frequency, the better, and can be adjusted appropriately within the range of 10 kHz to 5,000 kHz.

[0036] The types of laser oscillators that satisfy the above requirements include YAG laser devices, YLF laser devices, and YVO ４ Examples of the laser device include, but are not limited to, a laser device, a fiber laser device, and a semiconductor laser device.

[0037] The irradiation conditions of the laser beam LB can be set to any appropriate conditions, but the energy density is preferably 1 J / cm ２ More than 20J / cm ２It is preferable that the energy density is within this range, which is sufficient to form a desired pattern and also suppresses evaporation and thermal decomposition of the irradiated material. The energy density is calculated using the following formula: Energy density [J / cm ２ ] = pulse energy [J] / focused spot area [cm ２ ] (Note that pulse energy [J] = power [W] / repetition frequency [kHz].)

[0038] <Polygon Scanner 40> The polygon scanner 40 includes a rotatable polygon mirror 42, a convex mirror 44a, a concave mirror 44b, and a housing 46 that houses these components. In FIG. 1, for ease of explanation, the housing 46 is depicted by a dashed line as if it were transparent. The convex mirror 44a is located on the −Z side of the polygon mirror 42. The concave mirror 44b is located on the +X side of the polygon mirror 42 and the convex mirror 44a, and is positioned lower than the polygon mirror 42 and higher than the convex mirror 44a. The housing 46 has a front surface positioned on the +X side, a back surface positioned on the −X side, two side surfaces positioned on the ±Y sides, and a top surface positioned on the +Z side, but does not have a bottom surface positioned on the −Z side. The housing 46 has an opening 46o on the side facing the +Y side that allows the laser light LB emitted from the laser light source 30 to pass through. The opening may be located on the front, back, or top surface instead of the side surface. In this case, the laser light LB passing through the opening is deflected toward the polygon mirror 42 by, for example, a plate-shaped mirror provided inside the polygon scanner 40 .

[0039] The polygon scanner 40 deflects the laser beam LB toward the sheet material 10 by reflecting it off the polygon mirror 42, the convex mirror 44a, and the concave mirror 44b in that order, and repeatedly scans the laser beam LB along the +Y direction. In the example shown in FIG. 1 , the scanning direction D2 of the polygon scanner 40 is perpendicular to the moving direction D1 of the sheet material 10, but the two directions do not need to be perpendicular to each other as long as they intersect. In this specification, the moving direction D1 of the sheet material 10 is also referred to as the "first direction," and the scanning direction D2 of the polygon scanner 40 is also referred to as the "second direction." The scanning operation of the polygon scanner 40 will be described in detail later.

[0040] The scanning speed at which the polygon scanner 40 scans the laser beam LB on the surface of the sheet material 10 in the +Y direction may be, for example, 25 m / s to 200 m / s. The scanning range of the polygon scanner 40 may be, for example, 10 mm to 500 mm.

[0041] The scanning speed of the galvanometer scanner is at most about 10 m / s, and the scanning range of the galvanometer scanner is less than 100 mm. Therefore, the polygon scanner 40 can perform laser processing on the sheet material 10 more efficiently while transporting the sheet material 10 than the galvanometer scanner.

[0042] <Control device 50> The control device 50 controls the conveyor 20, the laser light source 30, and the polygon scanner 40 as follows: (1) The control device 50 causes the conveyor 20 to convey the sheet material 10 in the +X direction. (2) The control device 50 causes the laser light source 30 to emit the laser light LB. (3) The control device 50 causes the polygon scanner 40 to deflect the laser light LB and scan the laser light LB along the +Y direction.

[0043] The control device 50 forms a two-dimensional pattern on the sheet material 10 through control operations (1) to (3).

[0044] In control operation (1), the control device 50 controls the rotation of the unwinding motor 26a and the winding motor 26b in the conveyor 20 to adjust the conveying speed of the sheet material 10. A rotary encoder (not shown) is attached to one of the two conveying rollers 24. The rotary encoder measures the rotation speed, rotation position, and rotation angle of the conveying roller 24 and sends a signal of the measurement results to the control device 50. The control device 50 calculates the conveying speed of the sheet material 10 based on the signal sent from the rotary encoder. In control operation (2), the control device 50 controls the laser light source 30 to adjust the emission timing for continuously or intermittently emitting the laser light LB and the output power of the laser light LB. In control operation (3), the control device 50 controls the rotation of the polygon mirror 42 to adjust the scanning speed of the polygon scanner 40.

[0045] In the example shown in FIG. 1 , the control device 50 is a laptop-type personal computer, but it may also be a desktop-type personal computer. The control device 50 does not have to be a single control device. The control device 50 may be divided into a control device that controls the operation of two of the conveyor 20, the laser light source 30, and the polygon scanner 40, and a control device that controls the remaining operations. Alternatively, the control device 50 may be divided into a control device that controls the operation of the conveyor 20, a control device that controls the operation of the laser light source 30, and a control device that controls the operation of the polygon scanner 40. The control device 50 may be located in a remote location away from the conveyor 20, the laser light source 30, and the polygon scanner 40, and may send control signals to the conveyor 20, the laser light source 30, and the polygon scanner 40 via a communication network.

[0046] Next, the scanning operation of the polygon scanner 40 will be described with reference to Figures 2A to 2C. Figures 2A to 2C are schematic front views showing how the polygon scanner 40 deflects the laser beam LB toward the sheet material 10. The housing 46 is omitted from Figures 2A to 2C. Time passes in the order shown in Figures 2A to 2C. The polygon mirror 42 is a regular octagonal prism with reflective surfaces on its side faces. The polygon mirror 42 is not limited to a regular octagonal prism, but may be a cylinder with any polygonal base. The polygon mirror 42 rotates counterclockwise around an axis parallel to the X direction as viewed from the +X direction. The polygon mirror 42 reflects the laser beam LB toward a convex mirror 44a at a reflective surface 42s. The convex mirror 44a is positioned to receive the laser beam LB reflected by the polygon mirror 42 and reflect it toward a concave mirror 44b. The concave mirror 44 b is disposed at a position where it receives the laser beam LB reflected by the convex mirror 44 a and reflects it toward the sheet material 10 .

[0047] 2A to 2C, the polygon mirror 42 reflects the laser beam LB in different directions as it rotates. The convex mirror 44a and the concave mirror 44b allow the laser beam LB to be perpendicularly incident on the sheet material 10, regardless of the direction of the laser beam LB reflected by the polygon mirror 42. As a result, the laser beam LB is prevented from being incident obliquely on the sheet material 10, and the sheet material 10 can be processed with the laser beam LB with high precision.

[0048] As shown in Figures 2A to 2C, polygon scanner 40 scans laser beam LB along the +Y direction. After a further time has passed since the example shown in Figure 2C, polygon mirror 42 reflects laser beam LB again from a reflective surface on the reverse rotation direction side adjacent to reflective surface 42s, as shown in Figures 2A to 2C. In this way, polygon scanner 40 repeatedly scans laser beam LB along the +Y direction.

[0049] The polygon scanner 40 can perform one-dimensional scanning simply by continuing to rotate the polygon mirror 42 in the same direction. In contrast, the galvanometer scanner requires adjusting the rotation angles of the two galvanometer mirrors to perform two-dimensional scanning. The polygon scanner 40 can achieve high-speed scanning with a simpler configuration than the galvanometer scanner.

[0050] Next, with reference to Figures 3A and 3B, an example of a two-dimensional pattern formed on the sheet material 10 by the laser processing apparatus 100 according to this embodiment will be described. The two-dimensional pattern to be formed on the sheet material 10 is represented, for example, as a bitmap image. Figure 3A shows a bitmap image of an example of a two-dimensional pattern to be formed on a portion of the sheet material 10. In the example shown in Figure 3A, the two-dimensional pattern to be formed is represented by a plurality of hatched areas in an area divided into 12 rows and 12 columns. Each hatched area is an irradiation area to be irradiated with laser light LB. The laser light LB is pulsed laser light.

[0051] FIG. 3B shows a schematic plan view of an example of a two-dimensional pattern actually formed on a portion of the sheet material 10. As shown in FIG. 3B, the two-dimensional pattern formed on the sheet material 10 has a plurality of dot-shaped processed regions 10a formed by irradiation with laser light LB. The processed regions 10a may be, for example, portions whose refractive index differs from that of the surrounding area, recesses, or through-holes. The shape of the two-dimensional pattern formed on the sheet material 10 is determined by the distribution of the plurality of dot-shaped processed regions 10a. In the example shown in FIG. 3B, a square is determined by the distribution of 16 processed regions 10a in 4 rows and 4 columns, and a triangle is determined by the distribution of 10 processed regions 10a.

[0052] The average diameter of each of the plurality of processed regions 10a may be, for example, 10 μm or more and 500 μm or less. The center-to-center distance between the two closest processed regions among the plurality of processed regions 10a may be, for example, 10 μm or more and 500 μm or less. A highly precise two-dimensional pattern can be formed by distributing the plurality of processed regions 10a in this manner.

[0053] In another example of laser processing, not all processing areas 10a need to be discretely distributed, and at least some of the processing areas 10a may partially overlap. Next, an example of such processing areas 10a will be described with reference to FIGS. 4A and 4B. FIG. 4A shows a bitmap image of another example of a two-dimensional pattern to be formed on a portion of the sheet material 10. In the example shown in FIG. 4A, the two-dimensional pattern to be formed forms a closed circuit. FIG. 4B shows a schematic plan view of another example of a two-dimensional pattern actually formed on a portion of the sheet material 10. Each processing area 10a shown in FIG. 4B is a through hole. The top, bottom, left, and right portions of each processing area 10a shown in FIG. 4B extend beyond the corresponding irradiation area shown in FIG. 4A. Because the dot size of each adjacent processing area 10a is larger than the center-to-center distance between adjacent processing areas 10a, adjacent processing areas 10a partially overlap each other. The sheet material 10 shown in Figure 4B has a cutout portion 10A surrounded by multiple processing areas 10a and a peripheral portion 10B located around the multiple processing areas 10a. The multiple processing areas 10a form a closed path, which allows the cutout portion 10A and the peripheral portion 10B to be separated from each other. The shape of the cutout portion 10A is determined by the distribution of the multiple processing areas 10a. In this manner, a portion of any shape can be cut out from the sheet material 10.

[0054] In this specification, "multiple processing areas 10a distributed in a dot pattern" means not only a case where multiple dot-shaped processing areas 10a are distributed discretely without overlapping each other, but also a case where at least some (partial or all) of the multiple dot-shaped processing areas 10a are distributed so as to partially overlap each other.

[0055] As another example of laser processing, a portion of a layer in a laminated structure may be removed using laser light LB. Next, an example of such laser processing will be described with reference to FIG. 5 . FIG. 5 shows a schematic diagram illustrating the removal of a portion of a layer using laser light LB. Time passes in the order of the examples shown in the upper, middle, and lower diagrams. The sheet material 10 shown in FIG. 5 has a laminated structure of a lower layer 10C1 and an upper layer 10C2. By repeatedly scanning the laser light LB along the +Y direction using a polygon scanner 40, portions of the upper layer 10C2 are repeatedly removed in a linear pattern. As a result, multiple grooves spaced apart in the X direction are formed in the upper layer 10C2. In forming the grooves, the laser light LB may be emitted intermittently or continuously. For example, by intermittently emitting the laser light LB toward the upper layer 10C2 and scanning the laser light LB in the +Y direction, multiple dot-shaped processing regions that partially overlap each other may be formed in the upper layer 10C2. Alternatively, a linear processed region may be formed in upper layer 10C2 by continuously emitting laser beam LB toward upper layer 10C2 and scanning laser beam LB in the +Y direction.

[0056] The upper layer 10C2 is made of, for example, Cr, Cu, Ti, Ag, Ni—Cr alloy, SUS, Cu—Zn alloy, ITO, SiO ２ , TiO ２ and ZnO. The lower layer 10C1 may be formed from a material on which such a material can be formed.

[0057] The control device 50 that forms a two-dimensional pattern on the sheet material 10 executes the following steps (A) to (D) before the above control operations (1) to (3): (A) Determine the number of scanning lines per second of the polygon scanner 40; (B) Determine the two-dimensional pattern to be formed; (C) Determine the emission timing of the laser light LB based on the two-dimensional pattern to be formed; (D) Determine the conveying speed of the sheet material 10 based on the number of scanning lines per second and the distance between adjacent scanning lines in the X direction of the two-dimensional pattern to be formed.

[0058] For example, if the number of scan lines per second is 224 lines / s and the distance between adjacent scan lines in the X direction is 150 μm / line, the conveying speed of the sheet material 10 is 224 lines / s × 150 μm / line = 0.034 m / s = 2.04 m / min.

[0059] The control device 50 executes the above control operation (1) at the conveying speed of the sheet material 10 determined by procedure (D), executes the above control operation (2) at the emission timing determined by procedure (C), and executes the above control operation (3) at the number of scanning lines per second determined by procedure (A).

[0060] Next, with reference to FIG. 6 , an example configuration of a laser processing apparatus according to another embodiment of the present invention will be described. Here, differences from the laser processing apparatus according to the above-described embodiment will be mainly described. The upper limit of the size of the sheet material 10 in the Y direction can be further increased by arranging multiple polygon scanners 40 in parallel in the Y direction. FIG. 6 is a schematic perspective view of a laser processing apparatus 110 according to another embodiment of the present invention. In FIG. 6 , control signals sent by the control device 50 are omitted. The laser processing apparatus 110 shown in FIG. 6 differs from the laser processing apparatus 100 shown in FIG. 1 in that the sheet material 10 and the conveyor 20 are larger in the Y direction and the laser processing apparatus 110 includes two laser light sources 30-1 and 30-2 and two polygon scanners 40-1 and 40-2. The laser light source 30-2 is located along the +Y direction together with the laser light source 30-1, and the polygon scanner 40-2 is located along the +Y direction together with the polygon scanner 40-1.

[0061] The laser processing apparatus 110 may include, in addition to a certain laser light source such as laser light source 30-1, at least one other laser light source such as laser light source 30-2, and may include, in addition to a certain polygon scanner such as polygon scanner 40-1, at least one other polygon scanner such as polygon scanner 40-2. The number of laser light sources and the number of polygon scanners may each be three or more. In this specification, the laser light emitted from the certain laser light source is also referred to as "certain laser light," and the laser light emitted from the at least one other laser light source is also referred to as "at least one other laser light."

[0062] The sheet material 10 shown in FIG. 6 has a first portion 10-1 and a second portion 10-2 located along the +Y direction together with the first portion 10-1. The dashed-dotted line in FIG. 6 represents the boundary between the first portion 10-1 and the second portion 10-2. In the example shown in FIG. 6, the first portion 10-1 and the second portion 10-2 have the same width in the Y direction, but one of the first portion 10-1 and the second portion 10-2 may be wider than the other. The sheet material 10 may have one portion such as the first portion 10-1 and at least one other portion such as the second portion 10-2. The number of portions located along the +Y direction in the sheet material 10 may be three or more.

[0063] Each of the two laser light sources 30-1 and 30-2 shown in FIG. 6 has the same configuration as the laser light source 30 shown in FIG. 1. The polygon scanner 40-1 shown in FIG. 6 has a mirror 46-1, and the polygon scanner 40-2 shown in FIG. 6 has a mirror 46-2. With the exception of the two mirrors 46-1 and 46-2, each of the two polygon scanners 40-1 and 40-2 shown in FIG. 6 has the same configuration as the polygon scanner 40 shown in FIG. 1. In the example shown in FIG. 6, the two laser light sources 30-1 and 30-2 are disposed on the back side of the two polygon scanners 40-1 and 40-2, respectively. Laser beams LB1 and LB2 emitted from the laser light sources 30-1 and 30-2 pass through openings (not shown) and are deflected by the mirrors 46-1 and 46-2 toward the polygon mirrors. It is also possible to split a high-power laser beam emitted from one laser light source and make it incident on two polygon scanners 40-1 and 40-2.

[0064] The control operation of the control device 50, which performs laser processing using the two laser light sources 30-1 and 30-2 and the two polygon scanners 40-1 and 40-2 while transporting the sheet material 10, is as follows: (1) The transporter 20 transports the sheet material 10 in the +X direction. (2) The laser light source 30-1 emits laser light LB1. (3) The polygon scanner 40-1 deflects the laser light LB1 toward the first portion 10-1 and causes the laser light LB1 to scan along the +Y direction. (4) The laser light source 30-2 emits laser light LB2. (5) The polygon scanner 40-2 deflects the laser light LB2 toward the second portion 10-2 and causes the laser light LB2 to scan along the +Y direction.

[0065] The number of scanning lines per second of the polygon scanners 40-1 and 40-2, the emission timing of the laser beams LB1 and LB2, and the conveying speed of the sheet material 10 are as explained in the above procedures (A) to (D).

[0066] The control device 50 forms a two-dimensional pattern on the sheet material 10 through such control operations. Control operations (2) and (3) are synchronized with control operations (4) and (5) so that the planned two-dimensional pattern can be formed on the sheet material 10. The laser processing device 110 according to this embodiment can further increase the upper limit of the size of the sheet material 10 in the Y direction. When two polygon scanners 40-1 and 40-2 are used, the upper limit of the size of the sheet material 10 in the Y direction can be, for example, 600 mm. The upper limit of the size of the sheet material 10 in the Y direction can be further increased by increasing the number of polygon scanners arranged in parallel in the Y direction. By arranging multiple polygon scanners in parallel, a wider sheet material 10 can be laser processed at once, thereby improving productivity.

[0067] [Laser Processing Method] The laser processing apparatus 100 according to the embodiment of the present invention described above can realize the following laser processing method. The laser processing method according to the embodiment of the present invention includes a step of forming a two-dimensional pattern on the sheet material 10 by scanning the sheet material 10 with laser light LB along the +Y direction using the polygon scanner 40 while transporting the sheet material 10 in the +X direction. When the two-dimensional pattern is determined by a distribution of a plurality of dot-shaped processing regions 10a, the step of forming the two-dimensional pattern on the sheet material 10 includes intermittently emitting the laser light LB and scanning the laser light LB along the +Y direction to form a plurality of dot-shaped processing regions on the sheet material 10.

[0068] Furthermore, the laser processing apparatus 110 according to the above-described other embodiment of the present invention can realize the following laser processing method. The laser processing method according to the other embodiment of the present invention includes the steps of: using a polygon scanner 40-1 to deflect laser light LB1 onto a first portion 10-1 of the sheet material 10 and scanning the laser light LB1 along the +Y direction while transporting the sheet material 10 in the +X direction; and using a polygon scanner 40-2 to deflect laser light LB2 onto a second portion 10-2 of the sheet material 10 and scanning the laser light LB2 along the +Y direction, thereby forming a two-dimensional pattern on the sheet material 10.

[0069] [Method for Manufacturing an Optical Sheet] A method for manufacturing an optical sheet using the above-described laser processing method is described below. The sheet material 10 is a sheet material capable of forming a portion whose refractive index differs from that of the surrounding area by light irradiation. The method for manufacturing an optical sheet includes a step of using a polygon scanner 40 to scan intermittently emitted laser light LB along the +Y direction while transporting the sheet material 10 in the +X direction, thereby forming a first region and a plurality of second regions in a dot pattern, each surrounded by a first region. The refractive index of each of the plurality of second regions is different from that of the first region. The average diameter of each of the plurality of second regions is 10 μm or more and 500 μm or less, and the center-to-center distance between the two closest second regions among the plurality of second regions is 10 μm or more and 500 μm or less. This method for manufacturing an optical sheet can, for example, produce an optical sheet with functionality such as efficiently extracting light propagating through a light guide layer to the outside or efficiently diffusing light incident on the optical sheet.

[0070] The sheet material 10 may include, for example, a photochromic material. Alternatively, the sheet material 10 may be an optical laminate sheet capable of forming a portion whose refractive index differs from that of the surrounding area upon irradiation with light, as described below. Next, an example of the configuration of such an optical laminate sheet will be described with reference to FIG. 7 . FIG. 7 shows a schematic cross-sectional view of an optical laminate sheet 10SS. The optical laminate sheet 10SS shown in FIG. 7 includes a porous layer 12 having a porous structure and a resin composition layer 14 laminated on the porous layer 12 and containing a resin composition that melts upon irradiation with laser light LB. The resin composition layer 14 is located closer to the polygon scanner 40 than the porous layer 12. When the wavelength of the laser light LB is greater than 800 nm and less than or equal to 2000 nm, the transmittance of the resin composition layer 14 to the laser light LB is 5% or greater and 85% or less. The optical laminate sheet 10SS further includes a substrate layer 16 supporting the porous layer 12 and a release sheet (separator) 18 disposed on the resin composition layer 14 opposite the porous layer 12. The substrate layer 16 and / or the release sheet 18 may be omitted.

[0071] The porous layer 12 may be formed of, for example, a porous silica material. The porosity of the porous silica material is greater than 0% and less than 100%. In order to obtain a low refractive index, the porosity is preferably 40% or more, more preferably 50% or more, and even more preferably 55% or more. There is no particular upper limit to the porosity, but from the viewpoint of strength, it is preferably 95% or less, and more preferably 85% or less.

[0072] The refractive index of silica (the matrix portion of the porous silica material) is preferably, for example, 1.41 or more and 1.43 or less. The resin composition layer 14 can be formed from various resin compositions. The refractive index of general resins is generally 1.45 or more and 1.70 or less. The resin composition may contain a photocurable resin.

[0073] The resin composition layer 14 absorbs the laser beam LB and can be efficiently heated by irradiation with the laser beam LB. As a result, the resin composition in the region of the resin composition layer 14 irradiated with the laser beam LB is melted, and the resin composition is selectively filled into the voids of the porous structure of the porous layer 12. The refractive index of the region where the voids of the porous structure are filled with the resin composition becomes higher than the refractive index of the surrounding region having the porous structure.

[0074] The method of irradiating the resin composition layer 14 with laser light LB and heating it by absorption of the laser light LB makes it possible to efficiently form a relatively finer pattern than conventional methods. The transmittance of the resin composition layer 14 to the laser light LB is more preferably 70% or less, and even more preferably 65% ​​or less.

[0075] Generally, organic substances absorb infrared light, so that infrared spectroscopy is used to identify them. The wavelength range (fingerprint region) of infrared light used to identify organic substances is 400 cm in wavenumber. －１ ~4000cm －１ In general, organic materials hardly absorb infrared rays with wavelengths of 2 μm (20,000 nm) or less. Organic materials that absorb infrared rays are sometimes called infrared absorbing dyes.

[0076] The resin composition of the resin composition layer 14 includes, for example, a resin composition that hardly absorbs the laser light LB and a coloring material that absorbs the laser light LB. The coloring material may include a dye (or pigment). Note that the dye (or pigment) refers to a coloring material that is soluble in a solvent (e.g., water or alcohol), and the pigment refers to a coloring material that is insoluble or poorly soluble in a solvent. Note that an atomic group that absorbs the first light may be chemically introduced (i.e., by chemical bonding) into the resin itself contained in the resin composition.

[0077] 8A and 8B , an example of an optical sheet manufactured using the laser processing method according to the present embodiment will be described. In the manufacturing method of the optical sheet, the step of forming the first region and the plurality of second regions in the sheet material 10 includes using a polygon scanner 40 to deflect a laser beam LB onto the resin composition layer 14 of the optical laminated sheet 10SS and scan the laser beam LB along the +Y direction.

[0078] FIG. 8A shows a schematic cross-sectional view of an optical sheet 10S manufactured by irradiating an optical laminate sheet 10SS with laser light LB. FIG. 8B shows a schematic plan view of the porous layer 12 shown in FIG. 8A. The optical sheet 10S shown in FIG. 8A differs from the optical laminate sheet 10SS shown in FIG. 7 in that, as shown in FIG. 8B, the porous layer 12 includes a first region 12a and a plurality of second regions 12b, each surrounded by the first region 12a and distributed in a dot pattern. The first region 12a is a region having a porous structure in the porous layer 12. Each of the plurality of second regions 12b is a region in which the voids in the porous structure are at least partially filled with a resin composition melted by irradiation with laser light LB. The refractive index of the second region 12b is higher than that of the first region 12a.

[0079] If the refractive index of the first region 12a is n1, the refractive index of the second region 12b is n2, and the refractive index of the resin composition layer 14 is n3, then n1 < n2 and n1 < n3 are satisfied. In this case, for example, the relationship n2 < n3 is satisfied. n1 may be, for example, 1.30 or less, n2 may be, for example, 1.43 or more, and n3 may be, for example, 1.45 or more. The refractive index n2 of the second region 12b can be controlled by adjusting the porosity of the porous structure contained in the porous layer 12 and the refractive index n3 of the resin composition contained in the resin composition layer 14. |n2 - n3| is preferably 0.1 or less. Total internal reflection at the interface between the resin composition layer 14 and the second region 12b of the porous layer 12 can be suppressed.

[0080] Next, application examples of the porous layer 12 and resin composition layer 14 included in the optical sheet 10S will be described with reference to Figures 9A and 9B. A light distributing element can be manufactured by laminating the optical sheet 10S on a dielectric layer, peeling off the release sheet 18, and providing a base layer on the resin composition layer 14. The refractive index of the dielectric layer is approximately equal to the refractive index of the base layer 16 in the optical sheet 10S. The dielectric layer and base layer 16 function as the light guide layer 11. Figures 9A and 9B show schematic cross-sectional views of the first light distributing element 10D1 and the second light distributing element 10D2, respectively.

[0081] The first light distribution element 10D1 shown in FIG. 9A has a laminated structure in which a light guide layer 11, a porous layer 12, a resin composition layer 14, and a base layer 13 are laminated in this order. The porous layer 12 and the resin composition layer 14 shown in FIG. 9A are also collectively referred to as an "optical layer 10Sa." Light incident from the light-receiving end surface (not shown) of the light guide layer 11 is totally internally reflected at the interface between the light guide layer 11 and the first region 12a of the porous layer 12 and the interface between the light guide layer 11 and air, and propagates through the light guide layer 11 in the X direction (guided light L Ｐ A portion of the light incident on the light guide layer 11 is incident on the interface between the light guide layer 11 and the second region 12b of the porous layer 12, passes through the resin composition layer 14 and the substrate layer 13 without being totally internally reflected, and is emitted from the first light distribution element 10D1 (emitted light L ＥIn other words, a portion of the light incident on the light guide layer 11 is optically coupled (extracted) by the optical layer 10Sa to the base layer 13 and emitted in the Z direction. Of course, the propagation direction of the light varies (distributes) from the X direction, and the emission direction of the light also varies (distributes) from the Z direction.

[0082] The second light distributing element 10D2 shown in FIG. 9B differs from the first light distributing element 10D1 shown in FIG. 9A in that the arrangements of the porous layer 12 and the resin composition layer 14 are reversed. The porous layer 12 and the resin composition layer 14 shown in FIG. 9B are also collectively referred to as the "optical layer 10Sb." Light incident from the light-receiving end surface (not shown) of the light guide layer 11 is totally internally reflected at the interface between the resin composition layer 14 and the first region 12a of the porous layer 12 and the interface between the light guide layer 11 and air, and propagates through the light guide layer 11 in the X direction (guided light L Ｐ A portion of the light incident on the light guide layer 11 is incident on the interface between the resin composition layer 14 and the second region 12b of the porous layer 12, passes through the resin composition layer 14 and the base material layer 13 without being totally internally reflected, and is emitted from the second light distribution element 10D2 (emitted light L Ｅ In other words, part of the light incident on the light guide layer 11 is optically coupled to the base layer 13 by the optical layer 10Sb and emitted in the Z direction.

[0083] The light distribution (emission intensity distribution, emission angle distribution, etc.) of light extracted from the light guide layer 11 (optically coupled with the substrate layer 13) by the porous layer 12 can be controlled by adjusting the arrangement of the first region 12a and the second region 12b in the layer plane (parallel to the XY plane) of the porous layer 12. The arrangement of the first region 12a and the second region 12b in the porous layer 12 is designed appropriately according to the required light distribution.

[0084] Details of the optical laminated sheet 10SS, the optical sheet 10S, and the light distribution elements 10D1 and D2 are described, for example, in Japanese Patent Application No. 2020-163478 (filing date: September 29, 2020) filed by the applicant of the present application. The entire disclosure of Japanese Patent Application No. 2020-163478 is incorporated herein by reference.

[0085] Hereinafter, the embodiments of the present invention will be described in detail with reference to examples, but the embodiments of the present invention are not limited to these examples.

[0086] In Examples 1 to 3 and Comparative Examples 1 to 3 described below, an optical laminate sheet having a configuration similar to that of the optical laminate sheet 10SS shown in Fig. 7 was laser processed to produce an optical sheet having a configuration similar to that of the optical sheet 10S shown in Fig. 8A. Examples 1 to 3 and Comparative Examples 1 to 3 differ in the laser processing method for the optical laminate sheet.

[0087] In Example 1, an optical laminate sheet continuously transported by a roll-to-roll method was laser processed using a single polygon scanner. In Example 2, an optical laminate sheet transported intermittently by a roll-to-roll method was laser processed using a single polygon scanner. In Example 3, an optical laminate sheet continuously transported by a roll-to-roll method was laser processed using two polygon scanners arranged in parallel. In Comparative Example 1, an optical laminate sheet intermittently transported by a roll-to-roll method was laser processed using a single galvanometer scanner. In Comparative Example 2, an optical laminate sheet continuously transported by a roll-to-roll method was laser processed using a single galvanometer scanner. In Comparative Example 3, an optical laminate sheet transported sheet by sheet was laser processed using a single polygon. Flowcharts of the optical sheet manufacturing methods according to Examples 1 to 3 and Comparative Examples 1 to 3 will be described with reference to FIGS. 10A to 10F, respectively, which will be described later.

[0088] In Examples 1 to 3 and Comparative Examples 1 to 3, the following operations were defined as one cycle, and the cycle time was calculated to evaluate the productivity of the optical sheet. The productivity of the optical sheet was defined as the length of the optical sheet produced per minute. In Examples 1 and 2 and Comparative Example 3, one cycle was defined as an operation of laser processing an area measuring 50 mm in the X direction and 310 mm in the Y direction using a single polygon scanner. In Example 3, one cycle was defined as an operation of laser processing an area measuring 50 mm in the X direction and 600 mm in the Y direction using two polygon scanners. In Comparative Examples 1 and 2, one cycle was defined as an operation of laser processing an area measuring 50 mm in the X direction and 50 mm in the Y direction using a single galvanometer scanner.

[0089] [Example 1] Fig. 10A shows a flowchart of one cycle of steps in a method for manufacturing an optical sheet according to Example 1. As shown in Fig. 10A, in one cycle, an optical laminate sheet was laser processed by a single polygon scanner while being continuously transported by a roll-to-roll method.

[0090] The method for producing the porous layer will be described later.

[0091] The resin composition layer had a laminated structure of a dye-free adhesive layer (resin composition layer) and a dye layer formed on the adhesive layer. A dye solution was prepared by adding 0.52 parts by mass of a dye-based dye CIR-RL (a phenylenediamine-based diimonium compound) manufactured by Nippon Carlit Co., Ltd. to 100 parts by mass of a solvent (MIBK).

[0092] One separator of the double-sided PSA A (PET separator / acrylic PSA A / PET separator, thickness 38 μm / 10 μm / 38 μm) prepared by the method described below was peeled off, and the dye solution was applied to the exposed surface of the acrylic PSA to obtain a dye layer. The transmittance of the laminate of the optical adhesive layer and the dye layer to laser light with a wavelength of 1060 nm was 28%.

[0093] In Example 2 and Comparative Examples 1 to 3, the same types of porous layer and resin composition layer as in Example 1 were used.

[0094] An optical sheet was produced by irradiating an optical laminate sheet with near-infrared nanosecond pulse fiber laser light under the following conditions: Laser oscillator: SPI redENERGY G4 Objective lens: f350 mm Polygon scanner: Next Scan Technology LSE310 Beam intensity distribution: Gaussian Spot size: φ55 μm Repetition frequency: 500 kHz Scan speed: 50 m / s Pattern pitch: 150 μm Power: 55 W Pulse energy: 110 μJ Energy density: 4.6 J / cm ２

[0095] Observation of a front image of the obtained optical sheet using an optical microscope confirmed that the second regions, each approximately circular and 30 μm in diameter, were formed with relatively high precision at a pitch of 150 μm. The formation of the second regions was also confirmed from a cross-sectional SEM image of the optical sheet. Figure 11 shows a cross-sectional SEM image of the optical sheet obtained in Example 1. As can be seen from the cross-sectional SEM image shown in Figure 11, almost no voids were observed in the second region of the porous layer formed by laser irradiation. In contrast, many fine voids (pores) were observed in the first region of the porous layer. Furthermore, the light extraction effect was also confirmed. Methods for evaluating the shape of the optical sheet using cross-sectional SEM images and confirming the light extraction effect will be described later.

[0096] In Example 1, since there was only one machining step in one cycle, the cycle time was equal to the machining time. The cycle time was 1.5 seconds of the machining time. The productivity was 2.02 m / min.

[0097] [Example 2] Figure 10B shows a flowchart of one cycle of the process for manufacturing an optical sheet according to Example 2. As shown in Figure 10B, in one cycle, an optical laminate sheet is fixed to a stage by vacuum suction while being stopped, and the optical laminate sheet is transported by a roll-to-roll method. Laser processing is performed using a single polygon scanner while the stage is moved at the same timing and transport speed. After processing, the movement of the stage and the transport of the optical laminate sheet are stopped, the suction fixation is released, and the stage is moved to its initial position before suction fixation. The stage movement distance in one cycle was 50 mm. By suction fixation to the stage, the optical laminate sheet can be prevented from floating or shifting from the stage during laser processing. As a result, the accuracy of laser processing can be improved.

[0098] An optical sheet was produced by irradiating an optical laminate sheet with near-infrared nanosecond pulse fiber laser light under the following conditions: Laser oscillator: SPI redENERGY G4 Objective lens: f350 mm Polygon scanner: Next Scan Technology LSE310 Beam intensity distribution: Gaussian Spot size: φ55 μm Repetition frequency: 500 kHz Scan speed: 100 m / s Pattern pitch: 150 μm Power: 86 W Pulse energy: 172 μJ Energy density: 7.2 J / cm ２

[0099] When a front image of the obtained optical sheet was observed with an optical microscope, it was confirmed that the second regions, which were approximately circular and had a diameter of 42 μm, were formed at a pitch of 150 μm with relatively high precision. The light extraction effect was also confirmed.

[0100] In Example 2, one cycle includes the steps of machining, suction clamping and release, and moving the stage to its initial position, so the cycle time is equal to the total time of these steps. The machining time was 1.5 seconds, the suction clamping and release time was 0.6 seconds, and the stage movement time to its initial position was 1 second, resulting in a cycle time of 3.1 seconds, the sum of these steps. Productivity was 0.97 m / min.

[0101] 10C shows a flowchart of one cycle of steps in the method for manufacturing an optical sheet according to Example 3. Example 3 was the same as Example 1, except that an optical laminate sheet having a larger size in the Y direction was laser processed using two polygon scanners.

[0102] When a front image of the obtained optical sheet was observed with an optical microscope, it was confirmed that the second regions, which were approximately circular and had a diameter of 30 μm, were formed at a pitch of 150 μm with relatively high precision. The light extraction effect was also confirmed.

[0103] In Example 3, since there was only one processing step in one cycle, the cycle time was equal to the processing time. The cycle time was 1.5 seconds of the processing time. The productivity was 2.02 m / min. The productivity was the same in Examples 1 and 3, even though the optical laminate sheet was larger in size in the Y direction.

[0104] 10D shows a flowchart of one cycle of steps in the method for manufacturing an optical sheet according to Comparative Example 1. As shown in Fig. 10D , in one cycle, the transport of the optical laminate sheet by the roll-to-roll method was stopped, the optical laminate sheet was fixed to a stage by vacuum suction, laser processing was performed by a single galvanometer scanner, the vacuum suction was released after processing, and transport of the optical laminate sheet by the roll-to-roll method was resumed.

[0105] An optical sheet was produced by irradiating an optical laminate sheet with near-infrared nanosecond pulse fiber laser light under the following conditions: Laser oscillator: JenLas fiber ns 20 manufactured by Jenoptik, Wavelength: 1064 nm, Objective lens: fθ lens (f82 mm), Galvanometer scanner: IntelliScan 14 manufactured by ScanLab, Beam intensity distribution: Gaussian, Spot size: φ60 μm, Repetition frequency: 12.5 kHz, Scan speed: 2500 mm / sec, Pattern pitch: 150 μm, Power: 5.6 W, Pulse energy: 448 μJ

[0106] When a front image of the obtained optical sheet was observed with an optical microscope, it was confirmed that the second regions, which were approximately circular and had a diameter of 50 μm, were formed at a pitch of 150 μm with relatively high precision. The light extraction effect was also confirmed.

[0107] In Comparative Example 1, one cycle included the steps of processing, suction clamping and release, and transport, so the cycle time was equal to the total time of these steps. The processing time was 60.0 seconds, the suction clamping and release time was 0.6 seconds, and the transport time was 1 second, resulting in a cycle time of 61.6 seconds, the sum of these. The productivity was 0.05 m / min.

[0108] [Comparative Example 2] Fig. 10E shows a flowchart of one cycle of steps in the method for manufacturing an optical sheet according to Comparative Example 2. As shown in Fig. 10E, in one cycle, the optical laminate sheet was laser processed by a single galvanometer scanner while being continuously transported by a roll-to-roll method.

[0109] An optical sheet was produced by irradiating an optical laminate sheet with near-infrared nanosecond pulse fiber laser light under the following conditions: Laser oscillator: JenLas fiber ns 20 manufactured by Jenoptik, Wavelength: 1064 nm, Objective lens: fθ lens (f82 mm), Galvanometer scanner: IntelliScan 14 manufactured by ScanLab, Beam intensity distribution: Gaussian, Spot size: φ60 μm, Repetition frequency: 12.5 kHz, Scan speed: 2500 mm / sec, Pattern pitch: 150 μm, Power: 4.5 W, Pulse energy: 360 μJ

[0110] When a front image of the obtained optical sheet was observed with an optical microscope, it was confirmed that the second regions, which were approximately circular and had a diameter of 70 μm, were formed at a pitch of 150 μm with relatively high precision. The light extraction effect was also confirmed.

[0111] In Comparative Example 2, since there was only one machining step in one cycle, the cycle time was equal to the machining time. The cycle time was 60.0 seconds, which was the machining time. The productivity was 0.05 m / min.

[0112] [Comparative Example 3] Fig. 10F shows a flowchart of one cycle of steps in the optical sheet manufacturing method according to Comparative Example 3. As shown in Fig. 10F, in one cycle, one of the sheet-like optical laminate sheets was placed on a stage, fixed by vacuum suction, and laser processed by a single polygon scanner. After processing, the suction fixation was released, and the processed optical laminate sheet was collected.

[0113] Under the conditions described in Example 1, an optical laminate sheet was irradiated with near-infrared nanosecond pulse fiber laser light to produce an optical sheet.

[0114] When a front image of the obtained optical sheet was observed with an optical microscope, it was confirmed that the second regions, which were approximately circular and had a diameter of 30 μm, were formed at a pitch of 150 μm with relatively high precision. The light extraction effect was also confirmed.

[0115] In Comparative Example 3, one cycle included the steps of processing, suction fixation and release, and loading and recovery, so the cycle time was equal to the total time of these steps. The processing time was 1.5 seconds, the suction fixation and release time was 0.6 seconds, and the loading and recovery time was 60 seconds, resulting in a cycle time of 62.1 seconds, the sum of these. The productivity was 0.05 m / min.

[0116] Table 1 shows the flow, cycle time, and productivity of one cycle of the optical sheet manufacturing method according to the above-mentioned Examples and Comparative Examples.

[0117]

[0118] The optical sheet manufacturing methods according to Examples 1 and 3 had the highest productivity. This high productivity is due to the continuous conveyance by the roll-to-roll method and the high-speed scanning by the polygon scanner. The optical sheet manufacturing method according to Example 2 had the next highest productivity. Even though it includes processes of suction fixing and releasing the suction fixing of the optical laminate sheet and moving the stage to its initial position, the high-speed scanning by the polygon scanner made the productivity relatively high.

[0119] In contrast, the optical sheet manufacturing methods of Comparative Examples 1 and 2 had low productivity due to the long processing time using the galvanometer scanner. The optical sheet manufacturing method of Comparative Example 3 had low productivity due to the steps of fixing the optical laminate sheet by vacuum suction while transporting it one by one, releasing the suction fixation, and loading and recovery, even though high-speed scanning was performed using a polygon scanner.

[0120] From the above, it was found that productivity of optical sheets can be improved by continuous transport or transport with stops using a roll-to-roll method and high-speed scanning using a polygon scanner.

[0121] The porous layers used in the examples and comparative examples were prepared as follows.

[0122] [Preparation of Porous Layer] (1) Gelation of Silicon Compound 0.95 g of methyltrimethoxysilane (MTMS), a precursor of a gel-like silicon compound, was dissolved in 2.2 g of dimethyl sulfoxide (DMSO) to prepare a mixed solution A. 0.5 g of a 0.01 mol / L aqueous solution of oxalic acid was added to this mixed solution A, and the mixture was stirred at room temperature for 30 minutes to hydrolyze the MTMS, producing a mixed solution B containing tris(hydroxy)methylsilane.

[0123] To 5.5 g of DMSO, 0.38 g of 28% by mass aqueous ammonia and 0.2 g of pure water were added, and then the above-mentioned mixed solution B was further added and stirred at room temperature for 15 minutes to gel the tris(hydroxy)methylsilane, thereby obtaining mixed solution C containing a gel-like silicon compound (polymethylsilsesquioxane). (2) Aging Treatment Mixed solution C containing the gel-like silicon compound prepared as described above was incubated at 40 ° C for 20 hours to perform an aging treatment. (3) Crushing Treatment Next, the gel-like silicon compound aged as described above was crushed into granules of several mm to several cm in size using a spatula. Next, 40 g of isopropyl alcohol (IPA) was added to mixed solution C, gently stirred, and then allowed to stand at room temperature for 6 hours, and the solvent and catalyst in the gel were decanted. The same decantation treatment was performed three times to replace the solvent, obtaining mixed solution D. Next, the gel-like silicon compound in mixed solution D was crushed (high-pressure media-less crushing). The pulverization treatment (high-pressure media-less pulverization) was carried out using a homogenizer (manufactured by SMT Corporation, product name "UH-50"), in which 1.85 g of the gel-like compound in the mixed solution D and 1.15 g of IPA were weighed into a 5 cc screw bottle, and pulverization was carried out for 2 minutes under conditions of 50 W and 20 kHz.

[0124] This grinding process pulverized the gel-like silicon compound in Mixed Liquid D, thereby converting Mixed Liquid D' into a sol of the pulverized material. The volume average particle size, which indicates the particle size variation of the pulverized material contained in Mixed Liquid D', was measured using a dynamic light scattering Nanotrac particle size analyzer (manufactured by Nikkiso Co., Ltd., Model UPA-EX150) and found to be 0.50 to 0.70. Furthermore, to 0.75 g of this sol (Mixed Liquid C'), 0.062 g of a 1.5 wt% MEK (methyl ethyl ketone) solution of a photobase generator (product name WPBG266, Wako Pure Chemical Industries, Ltd.) and 0.036 g of a 5% MEK solution of bis(trimethoxysilyl)ethane were added to obtain a coating liquid for forming a porous layer (a liquid containing microporous particles). The coating liquid for forming a porous layer contains a porous silica material having silsesquioxane as its basic structure.

[0125] The coating solution was applied (coated) onto the surface of an acrylic resin film (thickness: 40 μm) prepared according to Production Example 1 of JP 2012-234163 A to form a coating film. The coating film was dried by treating at a temperature of 100°C for 1 minute, and then the dried coating film was irradiated with 300 mJ / cm using light with a wavelength of 360 nm. ２ The acrylic resin film was then irradiated with UV light at a light irradiation dose (energy) of 1.00 to obtain a laminate (acrylic film with a porous silica layer) in which a porous layer (a porous silica body formed by chemical bonding of microporous silica particles) was formed on the acrylic resin film. The refractive index of the porous layer was 1.15.

[0126] The acrylic adhesives and double-sided adhesive tapes used in the examples and comparative examples were prepared as follows.

[0127] [Preparation of Acrylic Pressure-Sensitive Adhesive Solution A and Fabrication of Double-Sided Pressure-Sensitive Adhesive Tape A] A four-neck flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser was charged with 91 parts by mass of butyl acrylate, 7 parts by mass of N-acryloylmorpholine, 3 parts by mass of acrylic acid, 0.3 parts by mass of 2-hydroxybutyl acrylate, 0.1 parts by mass of 2,2'-azobisisobutyronitrile as a polymerization initiator, and 200 parts by mass of ethyl acetate. Nitrogen gas was then introduced with gentle stirring to replace the atmosphere with nitrogen, and the liquid temperature in the flask was maintained at around 55°C while carrying out a polymerization reaction for 8 hours to prepare an acrylic polymer solution. The mass-average molecular weight of the acrylic polymer was 2,200,000.

[0128] Acrylic pressure-sensitive adhesive solution A was prepared by blending 0.25 parts by mass of dibenzoyl peroxide (1-minute half-life: 130°C) as a crosslinking agent, 0.15 parts of a polyisocyanate crosslinking agent consisting of a trimethylolpropane adduct of tolylene diisocyanate (Coronate L, manufactured by Tosoh Corporation), and 0.1 parts by mass of 3-glycidoxypropyltrimethoxysilane (KBM403, manufactured by Shin-Etsu Silicones Co., Ltd.) as a silane coupling agent with 100 parts by mass of the solids content of the obtained acrylic polymer solution.

[0129] Next, the acrylic pressure-sensitive adhesive solution A was applied to one side of a silicone-treated polyethylene terephthalate (PET) film (manufactured by Mitsubishi Chemical Corporation, thickness: 38 μm) so that the thickness of the pressure-sensitive adhesive layer after drying would be 10 μm, and the applied film was dried for 3 minutes at 150° C. The pressure-sensitive adhesive layer was then attached to the PET film with the silicone-treated surface facing the pressure-sensitive adhesive layer, thereby producing a double-sided pressure-sensitive adhesive tape.

[0130] [Measurement of refractive index] After forming a porous layer on an acrylic film, the film was cut to a size of 50 mm x 50 mm and attached to the surface of a glass plate (thickness: 3 mm) via a pressure-sensitive adhesive layer. The center of the back surface of the glass plate (diameter: approximately 20 mm) was filled with black marker to create a sample that was not reflective on the back surface of the glass plate. The sample was placed in an ellipsometer (VASE, manufactured by J.A. Woollam Japan) and the refractive index was measured at a wavelength of 500 nm and an incident angle of 50 degrees to 80 degrees.

[0131] [Measurement of light extraction effect] The separator of the optical element obtained in the following example was peeled off and attached to a 2 mm thick resin plate (Acrylite "EX001" manufactured by Mitsubishi Chemical Corporation), and a textured film was laminated on top of that via water (refractive index 1.33). LED light was incident from the edge of the resin plate, and the light extraction effect was evaluated visually. Figure 12 shows a schematic configuration of a light distribution element sample used to evaluate the light extraction effect. An optical layer 10Sb is disposed on a resin plate light guide layer 11, and a base layer 13 is disposed on the optical layer 10Sb. A textured film 15 is disposed on the base layer 13 via water, and the emitted light L Ｅ The distribution of was evaluated visually.

[0132] [Production of Textured Film] A textured film was produced according to the method described in JP-A-2013-524288. Specifically, the surface of a polymethyl methacrylate (PMMA) film was coated with lacquer (Finecure RM-64 manufactured by Sanyo Chemical Industries, Ltd.), an optical pattern was embossed on the film surface containing the lacquer, and then the lacquer was cured to produce the desired textured film. The total thickness of the textured film was 130 μm, and the haze was 0.8%.

[0133] FIG. 13A shows a plan view of a portion of the produced unevenly shaped film 15 as seen from the uneven surface side. FIG. 13B shows a 13B-13B' cross-sectional view of the unevenly shaped film shown in FIG. 13A. A plurality of recesses 15a having a triangular cross section with a length L of 80 μm, a width W of 14 μm, and a depth H of 10 μm were arranged at intervals of width E (155 μm) in the X-axis direction. Furthermore, such a pattern of recesses was arranged at intervals of width D (100 μm) in the Y-axis direction. The density of the recesses 15a on the surface of the unevenly shaped film was 3612 pieces / cm ２ 13B, θa and θb were both 41°, and the area ratio of the recesses 15a when the film was viewed in plan from the uneven surface side was 4.05%.

[0134] [Evaluation of Shape of Optical Sheet] In addition to observing the front image of the optical sheet obtained in the examples with an optical microscope, cross-sectional SEM images were obtained as follows.

[0135] Specifically, the separator was peeled off to expose the dye adhesive surface, and the adhesive surface was coated with Pt-Pd for 10 seconds using a Hitachi High-Technologies magnetron sputter (E-1030). Next, a protective film for FIB processing (formed by carbon deposition) was formed on the adhesive surface at room temperature using a FIB-SEM (Helios G4 UX) manufactured by FEI Japan. Furthermore, the sample was cooled to -160°C in the same device, and then, while cooled to -160°C, the main surface of the optical sheet was tilted 52° relative to the focused ion beam, subjected to FIB processing, and the cross section formed by FIB processing was observed using an SEM. FIB-SEM setting conditions: Acceleration voltage: FIB 30 kV, SEM 2 kV; Observed image: Backscattered electron image; Set temperature: -160°C

[0136] [Measurement of near-infrared transmittance of dye adhesive] With a PET separator (thickness 38 μm, refractive index 1.57) placed on one main surface, measurement light was incident on the dye adhesive surface, and the transmittance for the wavelength of the laser light used was measured. The near-infrared transmittance was measured using a Hitachi U-4100 spectrophotometer.

[0137] The laser processing method and laser processing apparatus according to the embodiment of the present invention can be used for laser processing of sheet material transported by a roll-to-roll method, for example. The optical sheet manufacturing method according to the embodiment of the present invention can be used for manufacturing optical sheets having functionality such as optical coupling.

[0138] 10: sheet material, 10-1: first portion, 10-2: second portion, 10a: processing area, 10A: cut-out portion, 10B: peripheral portion, 10C1: lower layer, 10C2: upper layer, 10D: light distribution element, 10S: optical sheet, 10Sa, 10Sb: optical layer, 10SS: optical laminated sheet, 11: light guide layer, 12: porous layer, 12a: first region, 12b: second region, 13: substrate layer, 14: resin composition layer, 15: unevenly shaped film, 16: substrate layer, 18: release sheet, 20: conveyor, 22a: unwinding roller, 22b: winding roller, 24: conveying roller, 26a: unwinding motor, 26b: winding motor, 30, 30-1, 30-2: laser light source, 40, 40-1, 40-2: polygon scanner, 42: polygon mirror, 44a: convex mirror, 44b: concave mirror, 46: housing, 46o: opening, 50: control device, 100, 110: laser processing device, D1: movement direction of sheet material, D2: scanning direction of polygon scanner, LB, LB1, LB2: light

Claims

1. A laser processing method including a step of forming a two-dimensional pattern on a long sheet material by using a polygon scanner to scan laser light along a second direction that intersects with a first direction, which is the longitudinal direction of the long sheet material.

2. 2. The laser processing method according to claim 1, wherein the step of forming the two-dimensional pattern on the sheet material determines a conveying speed of the sheet material based on the number of scanning lines per second of the polygon scanner and the distance between adjacent scanning lines in the first direction of the two-dimensional pattern to be formed on the sheet material.

3. the sheet material has a certain portion and at least one other portion positioned along the second direction together with the certain portion, The step of forming the two-dimensional pattern on the sheet material includes: deflecting the laser light toward the certain portion using the polygon scanner and scanning the laser light along the second direction; 3. The laser processing method according to claim 1, further comprising: using at least one other polygon scanner positioned along the second direction together with the polygon scanner, deflecting at least one other laser beam onto the at least one other portion, and scanning the at least one other laser beam along the second direction, thereby forming the two-dimensional pattern on the sheet material.

4. the step of forming the two-dimensional pattern on the sheet material includes intermittently emitting the laser light and scanning the laser light along the second direction using the polygon scanner to form a plurality of processed regions distributed in a dot pattern on the sheet material; The average diameter of each of the plurality of processed regions is 10 μm or more and 500 μm or less, 3. The laser processing method according to claim 1, wherein the center-to-center distance between two of the processing regions that are closest to each other is 10 [mu]m or more and 500 [mu]m or less.

5. 3. The laser processing method according to claim 1, wherein the conveying speed of the sheet material is 0.5 m / min or more and 10 m / min or less.

6. The laser processing method according to claim 1 or 2, wherein the length of the sheet material in the second direction is 100 mm or more.

7. The method includes a step of conveying a long sheet material, which is capable of forming a portion having a refractive index different from that of the surrounding area by light irradiation, in a first direction that is a longitudinal direction, and scanning the sheet material with laser light that is intermittently emitted along a second direction that intersects with the first direction using a polygon scanner, thereby forming a first region and a plurality of second regions that are distributed in a dot pattern and each of which is surrounded by the first region, on the sheet material; A method for manufacturing an optical sheet, wherein the refractive index of each of the plurality of second regions is different from the refractive index of the first region.

8. an average diameter of each of the plurality of second regions is 10 μm or more and 500 μm or less; The method for manufacturing an optical sheet according to claim 7 , wherein the center-to-center distance between two nearest second regions of the plurality of second regions is 10 μm or more and 500 μm or less.

9. The method for manufacturing an optical sheet according to claim 7 or 8, wherein the conveying speed of the sheet material is 0.5 m / min or more and 10 m / min or less.

10. the sheet material is an optical laminated sheet having a porous layer having a porous structure and a resin composition layer laminated on the porous layer and containing a resin composition that is melted by irradiation with the laser light, the resin composition layer being located closer to the polygon scanner than the porous layer; the step of forming the first region and the plurality of second regions on the sheet material includes deflecting the laser light onto the resin composition layer of the optical laminated sheet using the polygon scanner and scanning the laser light along the second direction; the first region is a region having the porous structure in the porous layer of the optical laminated sheet, 9. The method for manufacturing an optical sheet according to claim 7, wherein each of the plurality of second regions is a region in which voids in the porous structure are at least partially filled with the resin composition melted by irradiation with the laser light.

11. Equipped with a conveyor, a laser light source, a polygon scanner and a control device, The control device The conveyor conveys the long sheet material in a first direction, which is a longitudinal direction; causing the laser light source to emit laser light; The polygon scanner deflects the laser light toward the sheet material and scans the laser light along a second direction intersecting the first direction, A laser processing device that forms a two-dimensional pattern on the sheet material.

12. 12. The laser processing apparatus according to claim 11, wherein the control device determines the conveying speed of the sheet material based on the number of scanning lines per second of the polygon scanner and the distance between adjacent scanning lines in the first direction of the two-dimensional pattern to be formed on the sheet material.

13. further comprising at least one other laser light source and at least one other polygon scanner positioned along the second direction together with the polygon scanner; the sheet material has a certain portion and at least one other portion positioned along the second direction together with the certain portion, The control device causing the polygon scanner to deflect the laser light toward the certain portion of the sheet material and scan the laser light along the second direction; causing the at least one other laser light source to emit at least one other laser beam; causing the at least one other polygon scanner to deflect the at least one other laser beam toward the at least one other portion of the sheet material and scan the at least one other laser beam along the second direction; The laser processing device according to claim 11 or 12, wherein the two-dimensional pattern is formed on the sheet material.

14. The control device causing the laser light source to intermittently emit the laser light; The polygon scanner deflects the laser light toward the sheet material and scans the laser light along the second direction, forming a plurality of processed areas distributed in a dot pattern on the sheet material; The average diameter of each of the plurality of processed regions is 10 μm or more and 500 μm or less, 13. The laser processing device according to claim 11, wherein the center-to-center distance between two of the processing regions closest to each other is 10 [mu]m or more and 500 [mu]m or less.

15. 13. The laser processing device according to claim 11, wherein the conveying speed of the sheet material is 0.5 m / min or more and 10 m / min or less.