CN117677460A

CN117677460A - Laser processing method, optical sheet manufacturing method, and laser processing apparatus

Info

Publication number: CN117677460A
Application number: CN202280051459.7A
Authority: CN
Inventors: 若山峻哉; 松尾直之
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2021-09-30
Filing date: 2022-09-07
Publication date: 2024-03-08
Also published as: KR20240066243A; TW202320952A; WO2023053879A1

Abstract

A laser processing method comprising the steps of: while conveying the long sheet (10) in a first direction which is a longitudinal direction, a Laser Beam (LB) is scanned by a polygon scanner (40) in a second direction intersecting the first direction, thereby forming a two-dimensional pattern on the sheet (10).

Description

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

Technical Field

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

Background

In recent years, a laser processing method has been attracting attention as a method for efficiently processing an elongated sheet (e.g., film, paper, or cloth) while conveying the sheet. For example, patent document 1 discloses a laser processing method for processing a sheet by performing two-dimensional scanning of laser light using a galvanometer scanner while conveying the sheet in a so-called roll-to-roll system in which rolls of the sheet are unwound and wound. The galvanometer scanner can deflect the laser beam by using two plate-shaped galvanometer mirrors having rotation axes that are not parallel to each other, and perform two-dimensional scanning of the laser beam.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open publication 2016-107288

Disclosure of Invention

Problems to be solved by the invention

The galvanometer scanner can perform two-dimensional scanning, and has high processing freedom. On the other hand, the scanning speed of the galvanometer scanner is not so high, and is about 10m/s at maximum. The scanning range of the galvanometer scanner is not so wide, below 100mm. From the viewpoint of efficiently processing an elongated sheet while conveying the sheet, a laser processing method is expected to replace a galvanometer scanner having a low scanning speed and a narrow scanning range.

The present invention aims to provide a laser processing method and a laser processing device for efficiently performing laser processing while conveying an elongated sheet, and a method for manufacturing an optical sheet using the laser processing method.

Technical scheme for solving problems

According to an embodiment of the present invention, a solution described in the following items is provided.

[ item 1]

A laser processing method comprising the steps of:

while conveying an elongated sheet in a first direction which is a longitudinal direction, a laser beam is scanned by a polygon scanner in a second direction intersecting the first direction, thereby forming a two-dimensional pattern on the sheet.

[ item 2]

The laser processing method according to item 1, wherein,

in the step of forming the two-dimensional pattern on the sheet, a conveying speed of the sheet is determined based on the number of scanning lines per 1 second of the polygon scanner and a distance between scanning lines adjacent in the first direction of a predetermined two-dimensional pattern formed on the sheet.

[ item 3]

The laser processing method according to item 1 or 2, wherein,

the sheet has a portion and at least one other portion that is present with the portion along the second direction,

the step of forming the two-dimensional pattern on the sheet includes:

deflecting the laser light toward the portion and scanning the laser light along the second direction using the polygon scanner;

at least one other laser light is deflected toward the at least one other portion using at least one other polygon scanner that is present with the polygon scanner along the second direction and scanned along the second direction, thereby forming the two-dimensional pattern on the sheet.

[ 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 includes: intermittently emitting the laser light, and scanning the laser light in the second direction using the polygon scanner, thereby forming a plurality of processing regions distributed in a dot shape on the sheet,

the plurality of processing regions each have an average diameter of 10 μm or more and 500 μm or less,

the distance between centers of two closest processing regions among the plurality of processing regions is 10 μm or more and 500 μm or less.

[ item 5]

The laser processing method according to any one of items 1 to 4, wherein,

the sheet has a moving speed of 0.5m/min or more and 10m/min or less.

[ item 6]

The laser processing method according to any one of items 1 to 5, wherein,

the length of the sheet in the second direction is 100mm or more.

[ item 7]

A method for manufacturing an optical sheet includes the steps of:

while conveying an elongated sheet in a first longitudinal direction, a laser beam intermittently emitted is scanned in a second direction intersecting the first direction by a polygon scanner, thereby forming a first region and a plurality of second regions each surrounded by the first region and distributed in a dot shape on the sheet, the elongated sheet being capable of forming a portion having a refractive index different from a surrounding refractive index by light irradiation,

The refractive index of each of the plurality of second regions is different from the refractive index of the first region.

[ item 8]

The method for producing an optical sheet according to item 7, wherein,

the average diameter of each of the plurality of second regions is 10 μm or more and 500 μm or less,

the distance between centers of two nearest second regions in the plurality of second regions is 10 μm or more and 500 μm or less.

[ item 9]

The method for producing an optical sheet according to item 7 or 8, wherein,

the sheet has a moving speed of 0.5m/min or more and 10m/min or less.

[ item 10]

The method for producing an optical sheet according to item 7 or 8, wherein,

the sheet is an optical laminate sheet having a porous layer and a resin composition layer, the porous layer having a porous structure, the resin composition layer being laminated on the porous layer and containing a resin composition that melts upon irradiation of the laser beam, 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 includes: deflecting the laser light toward the resin composition layer of the optical laminate using the polygon scanner, and scanning the laser light in the second direction,

The first region is a region having the porous structure in the porous layer of the optical laminate,

the plurality of second regions are regions in which voids of the porous structure are at least partially filled with the resin composition melted by the irradiation of the laser beam.

[ item 11]

A laser processing apparatus includes a conveyor, a laser light source, a polygon scanner, and a control device,

in the case of the control device being provided with a control unit,

causing the conveyor to convey a long sheet in a long side direction, i.e., a first direction;

causing the laser light source to emit laser light;

causing the polygon scanner to deflect the laser light toward the sheet and scan the laser light in a second direction intersecting the first direction,

thereby forming a two-dimensional pattern on the sheet.

[ item 12]

The laser processing apparatus according to item 11, wherein,

the control device determines a conveying speed of the sheet based on the number of scanning lines per 1 second of the polygon scanner and a distance between scanning lines adjacent in the first direction formed in a predetermined two-dimensional pattern of the sheet.

[ item 13]

The laser processing apparatus according to item 11 or 12, wherein,

At least one other laser light source and at least one other polygon scanner present along the second direction together with the polygon scanner,

in the case of the control device being provided with a control unit,

causing the polygon scanner to deflect the laser light toward the certain portion of the sheet 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 light;

causing 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 and to scan the at least one other laser light along the second direction,

thereby forming the two-dimensional pattern on the sheet.

[ item 14]

The laser processing apparatus according to any one of items 11 to 13, wherein,

in the case of the control device being provided with a control unit,

intermittently emitting the laser from the laser source;

causing the polygon scanner to deflect the laser light toward the sheet and scan the laser light along the second direction,

Whereby a plurality of processing areas are formed in a punctiform distribution on the sheet,

[ item 15]

The laser processing apparatus according to any one of items 11 to 14, wherein,

the sheet has a moving speed of 0.5m/min or more and 50m/s or less.

Effects of the invention

According to an embodiment of the present invention, there are provided a laser processing method and a laser processing apparatus for efficiently performing laser processing while conveying an elongated sheet, and a method for manufacturing an optical sheet using the laser processing method.

Drawings

Fig. 1 is a schematic perspective view of a laser processing apparatus according to an embodiment of the present invention.

Fig. 2A shows a schematic front view showing a case where the polygon scanner deflects laser light toward a sheet.

Fig. 2B shows a schematic front view showing a case where the polygon scanner deflects laser light toward a sheet.

Fig. 2C shows a schematic front view showing a case where the polygon scanner deflects laser light toward a sheet.

Fig. 3A shows a bitmap image of an example of a predetermined two-dimensional pattern formed on a part of a sheet.

Fig. 3B shows a schematic plan view of an example of a two-dimensional pattern actually formed on a part of a sheet.

Fig. 4A shows a bitmap image of another example of a predetermined two-dimensional pattern formed on a part of a sheet.

Fig. 4B shows a schematic top view of another example of a two-dimensional pattern actually formed on a portion of a sheet.

Fig. 5 is a schematic diagram showing a case where a part of a layer is removed by laser light.

Fig. 6 is a schematic perspective view of a laser processing apparatus according to another embodiment of the present invention.

Fig. 7 shows a schematic cross-sectional view of an optical laminate.

Fig. 8A is a schematic cross-sectional view of an optical sheet manufactured by irradiating an optical laminate with laser light.

Fig. 8B is a schematic plan view of the porous layer shown in fig. 8A.

Fig. 9A shows a schematic cross-sectional view of the first light distribution element.

Fig. 9B shows a schematic cross-sectional view of the second light distribution element.

Fig. 10A is a flowchart showing a process of one cycle in the method for manufacturing an optical sheet of example 1.

Fig. 10B is a flowchart showing a process of one cycle in the method for manufacturing an optical sheet of example 2.

Fig. 10C is a flowchart showing a process of one cycle in the method for manufacturing an optical sheet of example 3.

Fig. 10D is a flowchart showing a process of one cycle in the method for producing an optical sheet of comparative example 1.

Fig. 10E is a flowchart showing a process of one cycle in the method for manufacturing an optical sheet of comparative example 2.

Fig. 10F is a flowchart showing a process of one cycle in the method for producing an optical sheet of comparative example 3.

Fig. 11 shows a cross-sectional SEM image of the optical sheet obtained in example 1.

Fig. 12 schematically shows a structure of a light distribution element sample for evaluating the light extraction effect.

Fig. 13A is a plan view of a part of the produced concave-convex shaped film as viewed from the concave-convex surface side.

Fig. 13B shows a cross-sectional view of the concave-convex shaped film 13B-13B' shown in fig. 13A.

Detailed Description

A laser processing method, a laser processing apparatus, and a method for manufacturing an optical sheet according to an embodiment of the present invention will be described below with reference to the accompanying drawings. The laser processing apparatus according to the embodiment of the present invention is not limited to the apparatus exemplified below.

(embodiment)

[ laser processing device ]

First, a configuration example of a laser processing apparatus according to an embodiment of the present invention will be described with reference to fig. 1. Fig. 1 is a schematic perspective view of a laser processing apparatus 100 according to an embodiment of the present invention. In the drawings, for reference, X-axis, Y-axis, and Z-axis are schematically shown as being orthogonal to each other. The direction of the arrow on the X axis is referred to as the +x direction, and the opposite direction is referred to as the-X direction. In the case of not distinguishing + -X direction, it is simply called X direction. The same applies to the Y-axis and the Z-axis.

The laser processing apparatus 100 shown in fig. 1 includes a conveyor 20 that conveys the long sheet 10 in the longitudinal direction, that is, in the +x direction, a laser light source 30 that emits laser light LB, a polygon scanner 40 that deflects the laser light LB and scans the laser light LB along +y, and a control device 50 that controls operations of the conveyor 20, the laser light source 30, and the polygon scanner 40. White outline arrows D1 and D2 shown in fig. 1 indicate the moving direction of the sheet 10 and the scanning direction of the polygon scanner 40, respectively. The dashed lines shown in fig. 1 represent control signals transmitted from the control device 50.

According to the laser processing apparatus 100 of the present embodiment, the laser beam LB is scanned in the +y direction by using the polygon scanner 40 capable of scanning at high speed while the sheet 10 is conveyed in the +x direction, whereby a two-dimensional pattern can be efficiently formed on the sheet 10. The following describes each component.

< sheet 10>

The sheet 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 a plurality of films. The laminated film may have an adhesive layer for bonding two closest plastics together, or may have an inorganic film having at least one conductivity selected from ITO, ag, au and Cu on the surface, for example, in addition to the plurality of films. The film may be, for example, a polarizing film or a retardation film for a display. The dimension of the sheet 10 in the Y direction may be, for example, 100mm or more and 300mm or less. In the case of using the polygon scanner 40, the size of the sheet 10 in the Y direction can be set to 100mm or more, unlike the galvanometer scanner.

< conveyor 20>

The conveyor 20 includes a take-up roller 22a and a take-up roller 22b, two conveying rollers 24, and a take-up motor 26a and a take-up motor 26b. The unwinding motor 26a and the winding motor 26b rotate the unwinding roller 22a and the winding roller 22b in the same rotation direction. The roll-out roller 22a rolls out the sheet 10 before processing from the roll, and the roll-up roller 22b rolls up the sheet 10 after processing. The two conveying rollers 24 exist apart in the X direction, supporting the sheet 10 in motion. By winding and unwinding the sheet 10 by the two conveying rollers 24, the sheet 10 can be conveyed in the +x direction while keeping the sheet 10 parallel to the XY plane. By setting the rotation speed of the take-up roller 22b slightly higher than the rotation speed of the take-out roller 22a, tension is applied to the sheet 10, and thus, loosening of the sheet 10 can be suppressed.

By continuing the rotation of the take-up roller 22a and the take-up roller 22b, the sheet 10 can be continuously conveyed. By continuously conveying the sheet 10, laser processing can be performed efficiently, as compared with intermittent conveyance in which conveyance of the sheet is stopped every time processing and then restarted after processing, and sheet-by-sheet conveyance in which individual sheets are conveyed one by one. Intermittent conveyance also includes a step of vacuum-adsorbing the sheet before processing to a stage and releasing vacuum adsorption after processing. The sheet-by-sheet conveyance also includes a step of vacuum-adsorbing and recovering a single paper-like sheet by placing the sheet on a stage and removing the vacuum-adsorbing after processing. The conveyance speed of the sheet 10 during continuous conveyance may be, for example, 0.5m/min or more and 10m/min or less. Along with the high-speed scanning by the polygon scanner 40, the conveying speed of the sheet 10 can be increased. However, in the present embodiment, the sheet 10 may be conveyed during laser processing, and therefore, the conveyance of the sheet 10 may be temporarily stopped before and/or after laser processing.

In the example shown in fig. 1, the sheet 10 is conveyed by the roll-to-roll system, but the sheet 10 may be conveyed by placing a long sheet 10 that is not in a roll shape on a stage and moving the stage in the +x direction.

< laser light Source 30>

The laser light source 30 is a laser light source capable of continuously or intermittently emitting laser light LB of ultraviolet, visible or infrared light. In the example shown in fig. 1, the laser light source 30 is disposed outside the polygon scanner 40, but may be incorporated in the polygon scanner 40. The wavelength of the laser beam LB is a wavelength suitable for processing the sheet 10. The laser beam LB may be, for example, 150nm to 11000nm, preferably 250nm to 2000 nm. When the sheet 10 contains a material that absorbs infrared rays, the wavelength of the laser beam LB may be, for example, 900nm to 1500nm, and preferably 900nm to 1200 nm.

The spatial intensity distribution of the laser beam LB preferably has a gaussian distribution or a flat-top distribution, but is not limited thereto. The beam shape may be circular or rectangular. Condensing may be performed by using a condensing optical system such as an objective lens. When the beam shape is circular, the focal diameter (spot diameter) is preferably in the range of, for example, 10 μm to 150 μm, more preferably 30 μm to 100 μm. By setting the focal diameter to 10 μm or more, a sufficient focal depth can be obtained, and process stabilization can be achieved. Further, by setting the focal diameter to 150 μm or less, a reduction in energy density can be suppressed, and desired pattern formation can be promoted. In addition, in the case of a pulsed laser, since the number of patterns that can be formed per unit time is increased by increasing the number of pulses that can be emitted per unit time, improvement in productivity is achieved.

From the viewpoint of patterning in a short time, the laser beam LB is preferably a pulse laser beam emitted intermittently, and preferably a laser beam having a pulse width of the order of nanoseconds to microseconds. If the pulse width is too short, heat generation may not be involved, but if the pulse width is in the above range, photochemical reaction involving heat generation occurs, and thus the energy injection time is sufficient, and a desired pattern formation can be achieved. In addition, 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.

The repetition rate of the pulse laser is not particularly limited, but from the viewpoint of productivity, the higher the repetition rate is, the more preferably the repetition rate is, and the more preferably the repetition rate is adjusted within a range of 10kHz to 5,000 kHz.

Examples of the type of laser oscillator satisfying the above requirements include a YAG laser device, a YLF laser device, and YVO ₄ Laser devices, fiber laser devices, semiconductor laser devices, and the like, but are not limited thereto.

The irradiation conditions of the laser beam LB may be set to any appropriate conditions, but it is preferable that the energy density is 1J/cm ² Above and 20J/cm ² The following is given. The energy density within this range is sufficient for forming a desired pattern, and the irradiation target can be suppressed Evaporating or thermally decomposing. The energy density is calculated according to the following formula.

Energy Density [ J/cm ] ² ]Pulse energy [ J ]]Area of focal point [ cm ] ² ](pulse energy [ J ]]=power [ W]Repetition frequency [ kHz]。)

< 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 accommodates these components. In fig. 1, for ease of explanation, the housing 46 is transparent and indicated by a broken line. The convex mirror 44a is located on the-Z direction side of the polygon mirror 42. The concave mirror 44b is located on the +x direction side of the polygon mirror 42 and the convex mirror 44a, and is located lower than the polygon mirror 42 and higher than the convex mirror 44 a. The housing 46 has a front surface on the +x direction side, a rear surface on the-X direction side, two side surfaces on the ±y direction side, and an upper surface on the +z direction side, but does not have a lower surface on the-Z direction side. The side surface of the housing 46 on the +y direction side has an opening 46o through which the laser beam LB emitted from the laser light source 30 passes. The opening may be provided on the front surface, the rear surface, or the upper surface, instead of the side surface. In this case, the laser beam LB passing through the opening is reflected by, for example, a plate-shaped mirror provided inside the polygon scanner 40 and deflected toward the polygon mirror 42.

The polygon scanner 40 sequentially reflects the laser beam LB in the order of the polygon mirror 42, the convex mirror 44a, and the concave mirror 44b, deflects the laser beam LB toward the sheet 10, and repeatedly scans the laser beam LB in the +y direction. In the example shown in fig. 1, the scanning direction D2 of the polygon scanner 40 is orthogonal to the moving direction D1 of the sheet 10, but the two need not be orthogonal to each other, and may be intersecting. In this specification, the moving direction D1 of the sheet 10 is also referred to as a "first direction", and the scanning direction D2 of the polygon scanner 40 is also referred to as a "second direction". Details of the scanning operation of the polygon scanner 40 will be described later.

The scanning speed of the polygon scanner 40 for scanning the laser beam LB in the +y direction on the surface of the sheet 10 may be, for example, 25m/s or more and 200m/s. The scanning range of the polygon scanner 40 may be, for example, 10mm or more and 500mm or less.

The scanning speed of the galvanometer scanner is at most about 10m/s, and the scanning range of the galvanometer scanner is lower than 100mm. Therefore, the polygon scanner 40 can efficiently perform laser processing while conveying the sheet 10, compared to a galvanometer scanner.

< 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 conveyor 20 is caused to convey the sheet 10 in the +x direction.

(2) The laser light source 30 emits the laser beam LB.

(3) The polygon scanner 40 is caused to deflect the laser light LB and scan the laser light LB along +y.

The control device 50 forms a two-dimensional pattern on the sheet 10 by controlling the operations (1) to (3).

In the control operation (1), the control device 50 controls the rotation of the winding-out motor 26a and the winding-up motor 26b in the conveyor 20, and adjusts the conveying speed of the sheet 10. A rotary encoder, not shown, is mounted on one of the two conveying rollers 24. The rotary encoder measures the rotational speed, rotational position, and rotational angle of the conveying roller 24, and sends a signal of the measurement result to the control device 50. The control device 50 calculates the conveying speed of the sheet 10 based on the signal sent from the rotary encoder. In the control operation (2), the control device 50 controls the laser light source 30 and adjusts the emission timing of the laser beam LB and the output of the laser beam LB continuously or intermittently. In the control operation (3), the control device 50 controls the rotation of the polygon mirror 42 and adjusts the scanning speed of the polygon scanner 40.

In the example shown in fig. 1, the control device 50 is a notebook-type personal computer, but may be a desk-top personal computer. The control device 50 need not be a single control device. The control device 50 may be divided into a control device that controls two operations 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 disposed at a location remote from the conveyor 20, the laser light source 30, and the polygon scanner 40, and may transmit control signals to the conveyor 20, the laser light source 30, and the polygon scanner 40 via a communication network.

Next, a scanning operation of the polygon scanner 40 will be described with reference to fig. 2A to 2C. Fig. 2A to 2C are schematic front views showing a case where the polygon scanner 40 deflects the laser beam LB toward the sheet 10. However, in fig. 2A to 2C, the housing 46 is omitted. The time passes in the order of the example shown in fig. 2A to 2C. The polygon mirror 42 is a regular eight-prism having a reflecting surface on a side surface. The polygon mirror 42 is not limited to a regular eight-sided prism, and may be any column having a polygon as a bottom surface. The polygon mirror 42 rotates in a counterclockwise direction when viewed from the +x direction side with an axis parallel to the X direction as a rotation axis. The polygon mirror 42 reflects the laser beam LB toward the convex mirror 44a by a certain reflection surface 42 s. The convex mirror 44a is disposed at a position to receive the laser beam LB reflected by the polygon mirror 42 and reflect the laser beam LB toward the concave mirror 44 b. The concave mirror 44b is disposed at a position to receive the laser beam LB reflected by the convex mirror 44a and reflect the laser beam LB toward the sheet 10.

As shown in fig. 2A to 2C, the polygon mirror 42 rotates to reflect the laser beam LB in different directions. The convex mirror 44a and the concave mirror 44b can make the laser beam LB vertically incident on the sheet 10 regardless of the direction of the laser beam LB reflected by the polygon mirror 42. As a result, the incidence of the laser beam LB to the sheet 10 is suppressed, and the sheet 10 can be processed with high precision by the laser beam LB.

As shown in fig. 2A to 2C, the polygon scanner 40 scans the laser beam LB in the +y direction. When a further time passes from the example shown in fig. 2C, the polygon mirror 42 reflects the laser beam LB again as shown in fig. 2A to 2C by the reflection surface on the reverse side adjacent to the reflection surface 42 s. Thus, the polygon scanner 40 repeatedly scans the laser beam LB in the +y direction.

In the polygon scanner 40, one-dimensional scanning can be achieved by simply continuing to rotate the polygon mirror 42 in the same rotational direction. In contrast, in the galvanometer scanner, it is necessary to perform two-dimensional scanning by adjusting the rotation angles of the two galvanometer mirrors. In the polygon scanner 40, high-speed scanning can be achieved by a simpler structure than electric scanning.

Next, an example of a two-dimensional pattern formed on the sheet 10 by the laser processing apparatus 100 according to the present embodiment will be described with reference to fig. 3A and 3B. The predetermined two-dimensional pattern formed on the sheet 10 is represented as a bitmap image, for example. Fig. 3A shows a bitmap image of an example of a predetermined two-dimensional pattern formed on a part of the sheet 10. In the example shown in fig. 3A, the predetermined two-dimensional pattern 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 irradiated with the laser beam LB. The laser beam LB is a pulse laser beam.

Fig. 3B shows a schematic plan view of an example of a two-dimensional pattern actually formed on a part of the sheet 10. As shown in fig. 3B, the two-dimensional pattern formed on the sheet 10 has a plurality of spot-shaped processing regions 10a formed by irradiation of the laser beam LB. The processing region 10a may be, for example, a portion having a refractive index different from that of the surrounding region, a recess, or a through hole. The shape of the two-dimensional pattern formed on the sheet 10 is determined according to the distribution of the plurality of spot-shaped processing regions 10a. In the example shown in fig. 3B, a square is determined from the distribution of 16 processing regions 10a of 4 rows and 4 columns, and a triangle is determined from the distribution of 10 processing regions 10a.

The average diameter of each of the plurality of processing regions 10a may be, for example, 10 μm or more and 500 μm or less. The distance between centers of two closest machining regions among the plurality of machining regions 10a may be, for example, 10 μm or more and 500 μm or less. A high-definition two-dimensional pattern can be formed by the distribution of the plurality of processing regions 10a.

As another example of the laser processing, the entire processing region 10a may not be discretely distributed, and at least a part of the processing region 10a may be partially overlapped. Next, an example of such a processing region 10a will be described with reference to fig. 4A and 4B. Fig. 4A shows a bitmap image of another example of a predetermined two-dimensional pattern formed on a part of the sheet 10. In the example shown in fig. 4A, the predetermined two-dimensional pattern formed forms a closed circuit. Fig. 4B shows a schematic top view of another example of a two-dimensional pattern actually formed on a portion of the sheet 10. Each processing region 10a shown in fig. 4B is a through hole. The upper, lower, left, and right portions of each processing region 10a shown in fig. 4B bulge out from the corresponding irradiation region shown in fig. 4A. Because the respective dot sizes of the adjacent processing regions 10a are larger than the center-to-center distance of the adjacent processing regions 10a, the adjacent processing regions 10a partially overlap each other. The sheet 10 shown in fig. 4B has a cut-out portion 10A surrounded by a plurality of processing regions 10A, and a peripheral portion 10B located around the plurality of processing regions 10A. The cut-out portion 10A and the peripheral portion 10B can be separated from each other by a plurality of processing regions 10A forming a closed circuit. The shape of the cut-out portion 10A is determined according to the distribution of the plurality of processing regions 10A. As described above, an arbitrary shape portion can be cut out from the sheet 10.

In the present specification, the "plurality of processing regions 10a in a dot shape" is not only a case where the plurality of processing regions 10a in a pointed shape are not overlapped with each other but are distributed discretely, but also a case where at least a part (a part or all) of the plurality of processing regions 10a in a pointed shape are partially overlapped with each other.

As another example of the laser processing, a part of the layers of the laminated structure may be removed by the laser beam LB. Next, an example of such laser processing will be described with reference to fig. 5. Fig. 5 is a schematic diagram showing a case where a part of the layer is removed by the laser beam LB. Time passes in the order of the examples shown in the upper, central and lower figures. The sheet 10 shown in fig. 5 has a laminated structure of a lower layer 10C1 and an upper layer 10C 2. The laser beam LB is repeatedly scanned in the +y direction by the polygon scanner 40, and a part of the upper layer 10C2 is repeatedly removed in a linear shape. As a result, a plurality of grooves are formed in the upper layer 10C2 at intervals in the X direction. In the formation of the grooves, the laser beam LB may be intermittently or continuously emitted. For example, the laser beam LB may be intermittently emitted toward the upper layer 10C2, and the laser beam LB may be scanned in the +y direction, whereby a plurality of spot-shaped processing regions partially overlapping each other may be formed in the upper layer 10C 2. Alternatively, the laser beam LB may be continuously emitted toward the upper layer 10C2 and scanned in the +y direction, whereby a linear processing region may be formed in the upper layer 10C 2.

The upper layer 10C2 may be made of, for example, a material selected from the group consisting of 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 of a material capable of forming such a material on the upper surface.

The control device 50 for forming a two-dimensional pattern on the sheet 10 executes the following steps (a) to (D) before the control operations (1) to (3).

(A) The number of scan lines per 1 second of the polygon scanner 40 is determined.

(B) The predetermined two-dimensional pattern formed is determined.

(C) The emission timing of the laser beam LB is determined based on the formed predetermined two-dimensional pattern.

(D) The conveying speed of the sheet 10 is determined based on the number of scanning lines per 1 second and the distance between adjacent scanning lines in the X direction of the formed predetermined two-dimensional pattern.

For example, in the case where the number of scanning lines per 1 second is 224line/s and the distance between adjacent scanning lines in the X direction is 150 μm/line, the conveying speed of the sheet 10 is 224line/s×150 μm/line=0.034 m/s=2.04 m/min.

The control device 50 executes the control operation (1) at the conveyance speed of the sheet 10 determined in step (D), executes the control operation (2) at the ejection timing determined in step (C), and executes the control operation (3) for every 1 second of the scanning line number determined in step (a).

Next, a configuration example of a laser processing apparatus according to another embodiment of the present invention will be described with reference to fig. 6. Here, the differences from the laser processing apparatus of the above embodiment will be mainly described. The upper limit of the dimension of the sheet 10 in the Y direction can be further increased by disposing a plurality of polygon scanners 40 side by side 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, the control signal transmitted by the control device 50 is omitted. The laser processing apparatus 110 shown in fig. 6 is different from the laser processing apparatus 100 shown in fig. 1 in that the dimension in the Y direction of the sheet 10 and the conveyor 20 is large, and the laser processing apparatus 110 includes two laser light sources 30-1, 30-2 and two polygon scanners 40-1, 40-2. The laser light source 30-2 is present along the +y direction together with the laser light source 30-1, and the polygon scanner 40-2 is present along the +y direction together with the polygon scanner 40-1.

The laser processing device 110 may further include at least one other laser light source such as the laser light source 30-2 in addition to the laser light source 30-1, and may further include at least one other polygon scanner such as the polygon scanner 40-2 in addition to the polygon scanner 40-1. The number of laser light sources and the number of polygon scanners may be 3 or more, respectively. In the present specification, the laser beam emitted from the certain laser light source is also referred to as "certain laser beam", and the laser beam emitted from the at least one other laser light source is also referred to as "at least one other laser beam".

The sheet 10 shown in fig. 6 has a first portion 10-1 and a second portion 10-2 that exists along the +y direction together with the first portion 10-1. The dash-dot line shown in fig. 6 indicates the boundary of 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 have a width wider than the other. The sheet 10 may have a portion such as the first portion 10-1 and at least one other portion such as the second portion 10-2. The number of the plurality of portions present in the sheet 10 in the +y direction may be 3 or more.

The two laser light sources 30-1, 30-2 shown in fig. 6 each have the same configuration as the laser light source 30 shown in fig. 1. The polygon scanner 40-1 shown in fig. 6 includes a mirror 46-1, and the polygon scanner 40-2 shown in fig. 6 includes a mirror 46-2. The two polygon scanners 40-1 and 40-2 shown in fig. 6 each have the same structure as the polygon scanner 40 shown in fig. 1, except for the two reflecting mirrors 46-1 and 46-2. In the example shown in fig. 6, two laser light sources 30-1, 30-2 are arranged on the back sides of two polygon scanners 40-1, 40-2, respectively. The laser beams LB1 and LB2 emitted from the laser light sources 30-1 and 30-2 pass through openings, not shown, are reflected by the mirrors 46-1 and 46-2, and are deflected toward the polygon mirror. The high-output laser beam emitted from one laser light source may be branched and incident on the two polygon scanners 40-1 and 40-2.

The control operation of the control device 50 for performing laser processing by the two laser light sources 30-1, 30-2 and the two polygon scanners 40-1, 40-2 while conveying the sheet 10 is as follows.

(1) The conveyor 20 is caused to convey the sheet 10 in the +x direction.

(2) The laser light source 30-1 emits the laser beam LB1.

(3) The polygon scanner 40-1 is caused to deflect the laser light LB1 toward the first section 10-1 and to scan the laser light LB1 in the +y direction.

(4) The laser light source 30-2 emits the laser beam LB2.

(5) The polygon scanner 40-2 is caused to deflect the laser light LB2 toward the second section 10-2 and to scan the laser light LB2 in the +y direction.

The number of scanning lines per 1 second, the timing of emission of the laser beams LB1 and LB2, and the conveyance speed of the sheet 10 of the polygon scanners 40-1 and 40-2 are as described in the above steps (a) to (D).

The control device 50 forms a two-dimensional pattern on the sheet 10 by this control action. The control operations (2) and (3) and the control operations (4) and (5) are synchronized so that a predetermined two-dimensional pattern can be formed on the sheet 10. According to the laser processing apparatus 110 of the present embodiment, the upper limit of the dimension of the sheet 10 in the Y direction can be further increased. In the case of using two polygon scanners 40-1, 40-2, the upper limit of the dimension in the Y direction of the sheet 10 may be 600mm, for example. The upper limit of the size in the Y direction of the sheet 10 can be further increased by increasing the number of polygon scanners arranged side by side in the Y direction. Since the wider sheet 10 can be subjected to laser processing once by arranging a plurality of polygon scanners in parallel, productivity can be improved.

[ 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 the steps of: while conveying the sheet 10 in the +x direction, the laser beam LB is scanned in the +y direction by using the polygon scanner 40, thereby forming a two-dimensional pattern on the sheet 10. When the two-dimensional pattern is determined based on the distribution of the plurality of spot-like processing regions 10a, the step of forming the two-dimensional pattern on the sheet 10 includes: the laser beam LB is intermittently emitted and scanned in the +y direction, whereby a plurality of processing regions distributed in a dot shape are formed on the sheet 10.

Further, the laser processing apparatus 110 according to the other embodiment of the present invention described above can realize the following laser processing method. The laser processing method according to another embodiment of the present invention includes the steps of: while conveying the sheet 10 in the +x direction, the laser beam LB1 is deflected toward the first portion 10-1 of the sheet 10 using the polygon scanner 40-1 and the laser beam LB1 is scanned in the +y direction, and the laser beam LB2 is deflected toward the second portion 10-2 of the sheet 10 using the polygon scanner 40-2 and the laser beam LB2 is scanned in the +y direction, thereby forming a two-dimensional pattern on the sheet 10.

[ method for producing optical sheet ]

Hereinafter, a method for manufacturing an optical sheet by the laser processing method will be described. The sheet 10 is a sheet in which a portion having a refractive index different from that of the surrounding portion can be formed by light irradiation. The method for manufacturing the optical sheet comprises the following steps: while conveying the sheet 10 in the +x direction, the laser beam LB intermittently emitted is scanned in the +y direction by the polygon scanner 40, whereby a first region and a plurality of second regions each surrounded by the first region and distributed in a dot shape are formed on the sheet 10. The refractive index of each of the plurality of second regions is different from the refractive index 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 distance between centers of two closest second regions among the plurality of second regions is 10 μm or more and 500 μm or less. By such a method for producing an optical sheet, for example, an optical sheet having a function of efficiently taking out light propagating in the light guide layer to the outside, efficiently diffusing light incident on the optical sheet, and the like can be produced.

The sheet 10 may, for example, comprise a photochromic material. Alternatively, the sheet 10 may be an optical laminate sheet which is described below and which can be irradiated with light to form a portion having a refractive index different from that of the surrounding portion. Next, a structural example of such an optical laminate will be described with reference to fig. 7. Fig. 7 shows a schematic cross-sectional view of optical laminate 10 SS. The optical laminate sheet 10SS shown in fig. 7 has a porous layer 12 and a resin composition layer 14, the porous layer 12 having a porous structure, the resin composition layer 14 being laminated on the porous layer 12 and containing a resin composition melted by irradiation of the laser beam 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 beam LB is more than 800nm and not more than 2000nm, the transmittance of the resin composition layer 14 with respect to the laser beam LB is 5% or more and 85% or less. The optical laminate 10SS further includes a base layer 16 for supporting the porous layer 12, and a release sheet (separator) 18 of the resin composition layer 14 disposed on the opposite side of the porous layer 12. The substrate layer 16 and/or the release sheet 18 may also be omitted.

The porous layer 12 may be formed of, for example, a silica porous body. The porosity of the silica porous body is more than 0% and less than 100%. In order to obtain a low refractive index, the void ratio is preferably 40% or more, more preferably 50% or more, and further preferably 55% or more. The upper limit of the void ratio is not particularly limited, but is preferably 95% or less, more preferably 85% or less, from the viewpoint of strength.

The refractive index of silica (matrix portion of silica porous body) is preferably 1.41 or more and 1.43 or less, for example. The resin composition layer 14 may be formed of various resin compositions. The refractive index of the general resin is approximately 1.45 to 1.70. The resin composition may also contain a photocurable resin.

The resin composition layer 14 absorbs the laser beam LB, and thus can be efficiently heated by irradiation with the laser beam LB. As a result, the resin composition in the region irradiated with the laser beam LB in the resin composition layer 14 melts, and the voids of the porous structure of the porous layer 12 are selectively filled with the resin composition. The refractive index of the region filled with the resin composition in the void of the porous structure is higher than the refractive index of the region having the porous structure located around the region.

The resin composition layer 14 can be efficiently patterned with higher definition than the conventional method in which the resin composition layer is irradiated with the laser beam LB and heated by absorption of the laser beam LB. The transmittance of the resin composition layer 14 with respect to the laser beam LB is more preferably 70% or less, and still more preferably 65% or less.

In general, an organic substance absorbs infrared rays so that infrared spectroscopy is used for identification thereof. The wavelength range (fingerprint region) of the infrared ray for the identification of organic matter was 400cm in terms of wavenumber ^－1 ～4000cm ^－1 The organic substance hardly absorbs infrared rays having a wavelength of 2 μm or less (20000 nm) in a wavelength of 2.5 μm to 25 μm. The infrared-absorbing organic substance may be referred to as an infrared-absorbing dye.

The resin composition provided in the resin composition layer 14 includes, for example, a resin composition that hardly absorbs the laser beam LB and a coloring material that absorbs the laser beam LB. The coloring material may contain a pigment (or dye), and the coloring material may also contain a pigment. The coloring matter (or dye) is a coloring material (coloring material) which is soluble in a solvent (e.g., water or ethanol), and the coloring matter is a coloring material which is insoluble or poorly soluble in a solvent. The radical that absorbs the first light may be chemically (i.e., by a chemical bond) introduced into the resin itself contained in the resin composition.

Next, an example of an optical sheet manufactured by the laser processing method according to the present embodiment will be described with reference to fig. 8A and 8B. The process for forming the first region and the plurality of second regions on the sheet 10 in the method for manufacturing an optical sheet includes: the laser beam LB is deflected toward the resin composition layer 14 of the optical laminate 10SS by using the polygon scanner 40, and scanned in the +y direction.

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

When 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, n1< n2 and n1< n3. At this time, for example, the relationship of 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 included in the porous layer 12 and the refractive index n3 of the resin composition included in the resin composition layer 14. The value of |n2 to n3| is preferably 0.1 or less. It is possible to suppress occurrence of total internal reflection at the interface of the resin composition layer 14 and the second region 12b of the porous layer 12.

Next, an application example of the porous layer 12 and the resin composition layer 14 included in the optical sheet 10S will be described with reference to fig. 9A and 9B. The optical sheet 10S is laminated on the dielectric layer, and the release sheet 18 is peeled off to provide a base layer on the resin composition layer 14, whereby a light distribution element can be manufactured. The refractive index of the dielectric layer is substantially equal to the refractive index of the base material layer 16 in the optical sheet 10S. The dielectric layer and the base material layer 16 function as the light guide layer 11. Fig. 9A and 9B are schematic cross-sectional views of the first light distribution element 10D1 and the second light distribution element 10D2, respectively.

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 material 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 "optical layer 10Sa". Light incident from a light receiving end surface (not shown) of the light guide layer 11 is totally reflected by 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 in the X direction in the light guide layer 11 (guided light L _P ). A part of the light incident into the light guide layer 11 enters the interface between the light guide layer 11 and the second region 12b of the porous layer 12, and is emitted from the first light distribution element 10D1 through the resin composition layer 14 and the base material layer 13 without total internal reflection (emitted light L _E ). In other words, a part of the light incident into the light guide layer 11 is optically coupled (extracted) to the base material layer 13 through the optical layer 10Sa and is emitted in the Z direction. Of course, the propagation direction of light is deviated from the X direction (distribution), and the emission direction of light is deviated from the Z direction (distribution).

The second light distribution element 10D2 shown in fig. 9B is different from the first light distribution element 10D1 shown in fig. 9A in that the arrangement of the porous layer 12 and the resin composition layer 14 is reversed. The porous layer 12 and the resin composition layer 14 shown in fig. 9B are also collectively referred to as "optical layer 10Sb". Light incident from a light receiving end surface (not shown) of the light guide layer 11 is totally reflected by 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 in the X direction in the light guide layer 11 (guided light L _P ). A part of the light incident into the light guide layer 11 enters the interface between the resin composition layer 14 and the second region 12b of the porous layer 12, and is emitted from the second light distribution element 10D2 through the resin composition layer 14 and the base material layer 13 without total internal reflection (emitted light L _E ). In other words, a part of the light incident into the light guide layer 11 is optically coupled to the base material layer 13 by the optical layer 10Sb and is emitted in the Z direction.

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

Details of the optical laminate 10SS, the optical sheet 10S, and the light distribution elements 10D1 and D2 are described in, for example, japanese patent application No. 2020-163478 (application date: year 2020, month 29) filed by the applicant of the present application. The entire disclosure of Japanese patent application 2020-163478 is incorporated herein by reference.

Examples

Embodiments of the present invention will be specifically described below by way of examples, but the embodiments of the present invention are not limited by these examples.

In examples 1 to 3 and comparative examples 1 to 3 described below, optical sheets having the same structure as the optical sheet 10SS shown in fig. 7 were subjected to laser processing to produce optical sheets having the same structure as the optical sheet 10S shown in fig. 8A. In examples 1 to 3 and comparative examples 1 to 3, the laser processing method of the optical laminate sheet was different.

In example 1, a single polygon scanner was used to laser process optical laminates that were continuously transported in a roll-to-roll fashion. In example 2, an optical laminate sheet conveyed while being stopped by being interposed in a roll-to-roll manner was laser-processed using a single polygon scanner. In example 3, the optical laminate sheet continuously conveyed in a roll-to-roll manner was laser-processed using two polygon scanners arranged side by side. In comparative example 1, an optical laminate sheet intermittently conveyed in a roll-to-roll manner was laser-processed using a single galvanometer scanner. In comparative example 2, an optical laminate sheet continuously conveyed in a roll-to-roll manner was laser-processed using a single galvanometer scanner. In comparative example 3, a single polygon scanner was used to laser process the optical laminates transported sheet by sheet. Flowcharts of the methods for producing optical sheets of examples 1 to 3 and comparative examples 1 to 3 will be described with reference to fig. 10A to 10F described later.

In examples 1 to 3 and comparative examples 1 to 3, the cycle time was calculated using the following operation as one cycle, and productivity of the optical sheet was evaluated. The productivity of the optical sheet is defined according to the length of the optical sheet manufactured per minute. In examples 1 and 2 and comparative example 3, the operation of performing laser processing on a region having a dimension of 50mm in the X direction and a dimension of 310mm in the Y direction using a single polygon scanner was set as one cycle. In example 3, the operation of laser processing was performed in a region having a dimension of 50mm in the X direction and a dimension of 600mm in the Y direction using two polygon scanners as one cycle. In comparative examples 1 and 2, the operation of laser processing was performed in a region having a dimension of 50mm in the X direction and a dimension of 50mm in the Y direction using a single galvanometer scanner was set as one cycle.

Example 1

Fig. 10A is a flowchart showing a process of one cycle in the method for manufacturing an optical sheet of example 1. As shown in fig. 10A, the optical laminate is laser processed while being continuously transported in a roll-to-roll manner using a single polygon scanner in one cycle.

A method for producing the porous layer described later.

As the resin composition layer, a laminate structure of a pigment-free adhesive layer (resin composition layer) and a pigment layer formed on the adhesive layer is used. A dye-based pigment CIR-RL (phenylenediamine-based diimmonium compound) manufactured by Kabushiki Kaisha, japan Carlit was added in an amount of 0.52 parts by mass per 100 parts by mass of the solvent (MIBK) to prepare a pigment solution.

A separator of the double-sided adhesive A (PET separator/acrylic adhesive A/PET separator, thickness 38 μm/10 μm/38 μm) prepared by the method described later was peeled off, and the above pigment solution was applied to the exposed surface of the acrylic adhesive to obtain a pigment layer. The transmittance of the laminate of the optical adhesive layer and the pigment layer with respect to the laser light having a wavelength of 1060nm was 28%.

In example 2 and comparative examples 1 to 3, the same type of porous layer and resin composition layer as in example 1 were used.

The optical laminate was irradiated with a near infrared nanosecond pulse fiber laser under the following conditions to produce an optical sheet.

Laser oscillator: redENERGY 4 manufactured by SPI Co

An objective lens: f350mm

Polygon scanner: LSE310 manufactured by Next Scan Technology Co

Beam intensity distribution: gauss (Gauss)

Dot size:

repetition frequency: 500kHz

Scanning speed: 50 m/s

Pattern pitch: 150 μm

Power: 55W (55W)

Pulse energy: 110 mu J

Energy density: 4.6J/cm ²

By observing the front image of the obtained optical sheet with an optical microscope, it was confirmed that a second region having a substantially circular shape with a pitch of 150 μm and a diameter of 30 μm was formed with high definition. The formation of the second region was also confirmed from the cross-sectional SEM image of the optical sheet. Fig. 11 shows a cross-sectional SEM image of the optical sheet obtained in example 1. As is clear from the cross-sectional SEM image shown in fig. 11, voids are hardly visible in the second region formed by laser irradiation in the porous layer. In contrast, many fine voids (pores) were observed in the first region of the porous layer. And the light extraction effect can be confirmed. The method for evaluating the morphology of the optical sheet based on the cross-sectional SEM image and confirming the light extraction effect will be described later.

In example 1, since there is only a process of processing in one cycle, the cycle time is equal to the processing time. The cycle time was 1.5 seconds of the processing time. The productivity was 2.02m/min.

Example 2

Fig. 10B is a flowchart showing a process of one cycle in the method for manufacturing an optical sheet of example 2. As shown in fig. 10B, the optical laminate sheet during the conveyance stop is fixed to the stage by vacuum suction, the optical laminate sheet is conveyed in a roll-to-roll manner, laser processing is performed by a single polygon scanner while the stage is moved at the same timing and the same conveyance speed, and after the processing, the movement of the stage and the conveyance of the optical laminate sheet are stopped, and the suction fixation is released, so that the stage is moved to the initial position before the suction fixation. The distance of movement of the stage in one cycle is 50mm. By the suction-fixing to the stage, the optical laminate can be prevented from floating or shifting from the stage during laser processing. As a result, the accuracy of laser processing can be improved.

Laser oscillator: redENERGY 4 manufactured by SPI Co

An objective lens: f350mm

Polygon scanner: LSE310 manufactured by Next Scan Technology Co

Beam intensity distribution: gauss (Gauss)

Dot size:

repetition frequency: 500kHz

Scanning speed: 100 m/s

Pattern pitch: 150 μm

Power: 86W

Pulse energy: 172 mu J

Energy density: 7.2J/cm ²

By observing the front image of the obtained optical sheet with an optical microscope, it was confirmed that a second region having a substantially circular shape with a pitch of 150 μm and a diameter of 42 μm was formed with high definition. The light extraction effect can be confirmed.

In example 2, the steps of processing, suction fixing and releasing, and movement of the stage to the initial position are included in one cycle, and thus the cycle time is equal to the total time of these steps. The processing time was 1.5 seconds, the time for fixing and releasing the adsorption was 0.6 seconds, the movement time of the stage to the initial position was 1 second, and the cycle time was 3.1 seconds in total. The productivity was 0.97m/min.

Example 3

Fig. 10C is a flowchart showing a process of one cycle in the method for manufacturing an optical sheet of example 3. Example 3 is the same as example 1 except that the optical laminate having a large size in the Y direction is laser-processed by two polygon scanners.

By observing the front image of the obtained optical sheet with an optical microscope, it was confirmed that a second region having a substantially circular shape with a pitch of 150 μm and a diameter of 30 μm was formed with high definition. The light extraction effect can be confirmed.

In example 3, since there is only a process of processing in one cycle, the cycle time is equal to the processing time. The cycle time was 1.5 seconds of the processing time. The productivity was 2.02m/min. Even with the optical laminate sheet having a large dimension in the Y direction, productivity was the same in examples 1 and 3.

Comparative example 1

Fig. 10D is a flowchart showing a process of one cycle in the method for producing an optical sheet of comparative example 1. As shown in fig. 10D, the transport of the optical laminate sheet by the roll-to-roll method is stopped in one cycle, the optical laminate sheet is fixed to the stage by vacuum suction, laser processing is performed by a single galvanometer scanner, the vacuum suction is released after the processing, and the transport of the optical laminate sheet by the roll-to-roll method is restarted.

Laser oscillator: jenlas fibers ns20 manufactured by Jenoptik Co., ltd

Wavelength: 1064nm

An objective lens: fθ lens (f 82 mm)

Galvo scanner: indelliscan 14 manufactured by ScanLab Co

Beam intensity distribution: gauss (Gauss)

Dot size:/>

repetition frequency: 12.5kHz

Scanning speed: 2500 mm/sec

Pattern pitch: 150 μm

Power: 5.6W

Pulse energy: 448 mu J

By observing the front image of the obtained optical sheet with an optical microscope, it was confirmed that a second region having a substantially circular shape with a pitch of 150 μm and a diameter of 50 μm was formed with high definition. The light extraction effect can be confirmed.

In comparative example 1, the cycle time is equal to the total time of the processing, adsorption fixing and releasing, and conveying steps. The processing time was 60.0 seconds, the time for adsorption fixation and release was 0.6 seconds, the transport time was 1 second, and the cycle time was 61.6 seconds in total. The productivity was 0.05m/min.

Comparative example 2

Fig. 10E is a flowchart showing a process of one cycle in the method for manufacturing an optical sheet of comparative example 2. As shown in fig. 10E, laser processing is performed by a single galvanometer scanner while continuously conveying the optical laminate in a roll-to-roll manner in one cycle.

Laser oscillator: jenlas fibers ns20 manufactured by Jenoptik Co., ltd

Wavelength: 1064nm

An objective lens: fθ lens (f 82 mm)

Galvo scanner: indelliscan 14 manufactured by ScanLab Co

Beam intensity distribution: gauss (Gauss)

Dot size:

repetition frequency: 12.5kHz

Scanning speed: 2500 mm/sec

Pattern pitch: 150 μm

Power: 4.5W

Pulse energy: 360 mu J

By observing the front image of the obtained optical sheet with an optical microscope, it was confirmed that a second region having a substantially circular shape with a pitch of 150 μm and a diameter of 70 μm was formed with high definition. The light extraction effect can be confirmed.

In comparative example 2, since there is only a process of processing in one cycle, the cycle time is equal to the processing time. The cycle time was 60.0 seconds of the processing time. The productivity was 0.05m/min.

Comparative example 3

Fig. 10F is a flowchart showing a process of one cycle in the method for producing an optical sheet of comparative example 3. As shown in fig. 10F, one single optical laminate sheet is placed on a stage and fixed by vacuum suction in one cycle, laser processing is performed by a single polygon scanner, the fixation is released after the processing, and the processed optical laminate sheet is recovered.

The optical laminate was irradiated with a near infrared nanosecond pulse fiber laser under the conditions described in example 1 to produce an optical sheet.

In comparative example 3, the cycle time is equal to the total time of the processing, adsorption fixing and removing, and mounting and collecting steps. The processing time was 1.5 seconds, the time for adsorption fixation and release was 0.6 seconds, the time for placement recovery was 60 seconds, and the cycle time was 62.1 seconds in total. The productivity was 0.05m/min.

Table 1 summarizes the flow, cycle time, and productivity of one cycle of the above-described methods for producing optical sheets of examples and comparative examples.

TABLE 1

The most productive is the method for manufacturing the optical sheets of examples 1 and 3. The productivity is high and low due to the continuous conveyance in the roll-to-roll system and the high-speed scanning by the polygon scanner. The production process of the optical sheet of example 2 is inferior in productivity. Even if there are steps of suction fixing and removal of suction fixing of the optical laminate and movement of the stage to the initial position, productivity is high due to high-speed scanning by the polygon scanner.

In contrast, in the manufacturing methods of the optical sheets of comparative examples 1 and 2, the processing time by the galvanometer scanner is long, so that the productivity is low. In the method for manufacturing the optical sheet of comparative example 3, even in the case of high-speed scanning by a polygon scanner, productivity is low because of the steps of fixing by vacuum suction, releasing the suction fixing, and mounting and collecting the optical laminate sheet by sheet conveyance.

As described above, it is clear that productivity of the optical sheet can be improved by continuous conveyance or conveyance with stoppage of inclusion by the roll-to-roll system, and high-speed scanning by the polygon scanner.

The porous layers used in the examples and comparative examples were produced as follows.

[ production of porous layer ]

(1) Gelation of silicon compounds

A mixture A was prepared by dissolving 0.95g of methyltrimethoxysilane (MTMS), which is a precursor of a gel-like silicon compound, in 2.2g of dimethyl sulfoxide (DMSO). To this mixed solution A, 0.5g of a 0.01mol/L aqueous oxalic acid solution was added, and the mixture was stirred at room temperature for 30 minutes, whereby MTMS was hydrolyzed to give a mixed solution B containing tris (hydroxy) methylsilane.

After adding 0.38g of 28 mass% aqueous ammonia and 0.2g of pure water to 5.5g of DMSO, the above-mentioned mixed solution B was additionally added, and the mixture was stirred at room temperature for 15 minutes, whereby gelation of tris (hydroxy) methylsilane was performed to obtain a mixed solution C containing a gel-like silicon compound (polymethylsilsesquioxane).

(2) Curing treatment

The gel-like silicon compound-containing mixed solution C prepared as described above was directly incubated at 40℃for 20 hours, and subjected to aging treatment.

(3) Crushing treatment

Then, the gel-like silicon compound which has been cured as described above is pulverized into particles having a size of several mm to several cm using a spatula. Next, 40g of isopropyl alcohol (IPA) was added to the mixed solution C and stirred gently, and then, the mixture was allowed to stand at room temperature for 6 hours, and the solvent and the catalyst in the gel were decanted. The solvent was replaced by three times of the same decantation treatment to obtain a mixed solution D. Next, the gel-like silicon compound in the mixed solution D is subjected to a pulverization treatment (high-pressure non-medium pulverization). In the pulverization treatment (high-pressure non-medium pulverization), 1.85g of the gel-like compound and 1.15g of IPA in the mixed solution D were weighed into a 5cc screw bottle using a homogenizer (trade name "UH-50" manufactured by SMT Co., ltd.) and pulverized under conditions of 50W and 20kHz for 2 minutes.

By this pulverization treatment, the gel-like silicon compound in the mixed solution D is pulverized, whereby the mixed solution D' becomes a sol solution of the pulverized product. The volume average particle diameter representing the particle size deviation of the pulverized product contained in the mixed solution D' was confirmed to be 0.50 to 0.70 by a dynamic light scattering Nanotrac particle size analyzer (model UPA-EX150, manufactured by Nikkin Co., ltd.). Further, a 1.5% by mass MEK (methyl ethyl ketone) solution of a photobase generator (and WPBG266, trade name) was added to 0.75g of the sol solution (mixed solution C') at a ratio of 0.062g, and a 5% by mass MEK solution of bis (trimethoxysilyl) ethane was added at a ratio of 0.036g, to obtain a porous layer-forming coating solution (fine pore particle-containing solution). The coating liquid for forming a porous layer contains a silica porous body having a silsesquioxane as a basic structure.

The surface of the acrylic resin film (thickness: 40 μm) prepared in production example 1 of Japanese patent application laid-open No. 2012-234163 was coated with the coating liquid to form a coating film. The above-mentioned coating film was treated at 100℃for 1 minute and dried, and then 300mJ/cm of light having a wavelength of 360nm was applied to the dried coating film ² Is carried out by irradiation of light (energy)UV irradiation, a laminate (an acrylic film with a silica porous layer) in which a porous layer (a silica porous body based on chemical bonds between silica fine pore particles) was formed on the acrylic resin film was obtained. The refractive index of the porous layer was 1.15.

The acrylic pressure-sensitive adhesive and the double-sided pressure-sensitive adhesive tape used in examples and comparative examples were produced as follows.

Preparation of acrylic pressure-sensitive adhesive solution A and production of double-sided pressure-sensitive adhesive tape A

A four-necked flask equipped with a stirring blade, a thermometer, a nitrogen inlet pipe, and a cooler 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-hydroxy butyl acrylate, 0.1 parts by mass of 2,2' -azobisisobutyronitrile as a polymerization initiator, and 200 parts by mass of ethyl acetate, and nitrogen was introduced while being slowly stirred to perform nitrogen substitution, and then the polymerization was carried out for 8 hours while maintaining the liquid temperature in the flask at about 55 ℃. The mass average molecular weight of the acrylic polymer was 220 ten thousand.

An acrylic pressure-sensitive adhesive solution A was prepared by mixing 100 parts by mass of the solid content of the obtained acrylic polymer solution with 0.25 part by mass of dibenzoyl peroxide (half-life at 1 minute: 130 ℃) as a crosslinking agent and 0.15 part by mass of a polyisocyanate-based crosslinking agent (manufactured by DONG Cao She, コ II, takara Shuzo L) composed of trimethylolpropane adduct of toluene diisocyanate, and 0.1 part by mass of 3-glycidoxypropyl trimethoxysilane (manufactured by Xintek silicon Co., ltd., KBM 403) as an organosilane coupling agent.

Next, the acrylic pressure-sensitive adhesive solution a was applied to one surface of a siliconized polyethylene terephthalate (PET) film (manufactured by mitsubishi chemical Co., ltd., thickness: 38 μm) so that the thickness of the dried pressure-sensitive adhesive layer was 10 μm, and dried at 150 ℃ for 3 minutes to form a pressure-sensitive adhesive layer. The siliconized surface of the PET film of the pressure-sensitive adhesive layer was bonded to the pressure-sensitive adhesive layer side to prepare a double-sided pressure-sensitive adhesive tape.

[ measurement of refractive index ]

After forming a porous layer on an acrylic film, the film was cut into a size of 50mm×50mm, and the porous layer was bonded to the surface of a glass plate (thickness: 3 mm) via a pressure-sensitive adhesive layer. A sample was prepared by applying a black ink pen to the center of the back surface of the glass plate (diameter: about 20 mm) to make the back surface of the glass plate non-reflective. The above-mentioned sample was placed on an ellipsometer (Vase, manufactured by J.A. Woollam Japan Co., ltd.) and the refractive index was measured at a wavelength of 500nm under the conditions of an incident angle of 50 degrees to 80 degrees.

[ measurement of light extraction Effect ]

The separator of the optical member obtained in the following example was peeled off and bonded to a resin plate having a thickness of 2mm (methacrylic resin "EX001" manufactured by mitsubishi chemical Co., ltd.), and a concave-convex forming film was laminated thereon via water (refractive index 1.33), and the effect of light extraction was evaluated visually by making LED light incident from the end of the resin plate. Fig. 12 schematically shows the structure of a light distribution element sample used for evaluation of the light extraction effect. An optical layer 10Sb is disposed on the resin sheet light guide layer 11, and a base material layer 13 is disposed on the optical layer 10 Sb. The emitted light L was visually evaluated by disposing the concave-convex shaping film 15 on the base material layer 13 via water _E Is a distribution of (a).

[ production of concave-convex shaped film ]

An uneven surface-formed film was produced according to the method described in Japanese patent application laid-open No. 2013-524288. Specifically, the surface of a polymethyl methacrylate (PMMA) film was coated with paint (triangulated industrial, RM-64), and the surface of the film containing the paint was embossed with an optical pattern, and then the paint was cured to produce a target textured film. The total thickness of the relief-forming film was 130. Mu.m, and the haze was 0.8%.

Fig. 13A is a plan view of a part of the produced concave-convex shaped film 15 as viewed from the concave-convex surface side. Fig. 13B is a cross-sectional view of the concave-convex shaped film 13B-13B' shown in fig. 13A. The plurality of triangular recesses 15a having a cross section with a length L of 80 μm, a width W of 14 μm, and a depth H of 10 μm are arranged at intervals of a width E (155 μm) in the X-axis direction. Further, the pattern of the concave portions is arranged at intervals of a width D (100 μm) in the Y-axis directionAnd (5) placing. The density of the concave portions 15a on the surface of the concave-convex shaping film was 3612 pieces/cm ² . In fig. 13B, θa and θb are each 41 °, and the occupied area ratio of the concave portion 15a when the film is viewed from the concave-convex surface side is 4.05%.

[ evaluation of morphology of optical sheet ]

The optical sheet obtained in examples was subjected to observation of a front image by an optical microscope, and cross-sectional SEM images were obtained as follows.

Specifically, the pigment-containing adhesive surface was exposed by peeling the separator by applying pt—pd for 10 seconds to the adhesive surface by magnetron sputtering (E-1030) manufactured by hitachi high technology corporation. Next, a protective film (formed by carbon deposition) for FIB milling was formed on the adhesive surface by FIB-SEM (Helios G4 UX) manufactured by FEI corporation of japan at normal temperature. Further, in the same apparatus, the sample was cooled to-160 ℃, and the main surface of the optical sheet was subjected to FIB milling while being inclined at 52 ° with respect to the focused ion beam in a state of being cooled to-160 ℃, and SEM observation of a cross section formed by FIB milling was performed.

FIB-SEM setup conditions

Acceleration voltage: FIB 30kV, SEM 2kV

Observing an image: reflective electronic image

Setting the temperature: -160 DEG C

[ near-infrared ray transmittance measurement of pigment Binder ]

In a state where a PET separator (thickness 38 μm, refractive index 1.57) was disposed on one main surface, measurement light was made incident from the pigment adhesive surface, and transmittance with respect to the wavelength of the laser light used was measured. As the near infrared transmittance, hitachi spectrophotometer U-4100 was used.

Industrial applicability

The laser processing method and the laser processing apparatus according to the embodiments of the present invention can be used for laser processing of a sheet conveyed in a roll-to-roll manner, for example. The method for manufacturing an optical sheet according to the embodiment of the present invention can be used for manufacturing an optical sheet having a function such as optical coupling property.

Description of the reference numerals

10 sheets

10-1 first part

10-2 second part

10a working 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 laminate

11 light guiding layer

12 porous layer

12a first region

12b second region

13 substrate layer

14 resin composition layer

15 concave-convex shaping film

16 substrate layer

18 stripping sheet

20 conveyor

22a roll-off roller

22b winding roller

24 conveying roller

26a roll-out 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 frame body

46o opening

50 control device

100. 110 laser processing device

D1 sheet movement direction

Scanning direction of D2 polygon scanner

LB, LB1, LB2 light

Claims

1. A laser processing method comprising the steps of:

2. The laser processing method according to claim 1, wherein,

3. The laser processing method according to claim 1 or 2, wherein,

the step of forming the two-dimensional pattern on the sheet includes:

4. The laser processing method according to claim 1 to 3, wherein,

5. The laser processing method according to claim 1 to 4, wherein,

the sheet is conveyed at a speed of 0.5m/min or more and 10m/min or less.

6. The laser processing method according to claim 1 to 5, wherein,

the length of the sheet in the second direction is 100mm or more.

7. A method for manufacturing an optical sheet includes the steps of:

8. The method for producing an optical sheet according to claim 7, wherein,

9. The method for producing an optical sheet according to claim 7 or 8, wherein,

the sheet is conveyed at a speed of 0.5m/min or more and 10m/min or less.

10. The method for producing an optical sheet according to claim 7 or 8, wherein,

11. A laser processing apparatus includes a conveyor, a laser light source, a polygon scanner, and a control device,

in the case of the control device being provided with a control unit,

causing the laser light source to emit laser light;

thereby forming a two-dimensional pattern on the sheet.

12. The laser processing apparatus as claimed in claim 11, wherein,

13. The laser processing apparatus as claimed in claim 11 or 12, wherein,

In the case of the control device being provided with a control unit,

thereby forming the two-dimensional pattern on the sheet.

14. The laser processing apparatus according to any one of claims 11 to 13, wherein,

in the case of the control device being provided with a control unit,

intermittently emitting the laser from the laser source;

15. The laser processing apparatus according to any one of claims 11 to 14, wherein,

the sheet is conveyed at a speed of 0.5m/min or more and 10m/min or less.