JP2023020932A - Surface treatment method, manufacturing method for article, surface treatment device, and article - Google Patents

Abstract

To provide a method for manufacturing a LIPSS, exhibiting a high quality structural color, over a large area with relatively high productivity.SOLUTION: A surface treatment method in which a first region and a second region arranged in that order along a first direction and adjacent to each other are set on a base-material surface, a plurality of scanning paths parallel to one another extending along the first direction are set in each of the first region and the second region, and a pulse laser is emitted to the base-material surface, is characterized in that, after each of the plurality of scanning paths set in the first region are sequentially scanned while an emitting position of the pulse laser is moved in the first direction, each of the plurality of scanning paths set in the second region is sequentially scanned while the emitting position of the pulse laser is moved in the first direction.SELECTED DRAWING: Figure 7

Description

TECHNICAL FIELD The present invention relates to a method for creating a fine periodic structure on the surface of an article using a laser.

For example, the rainbow colors seen when a CD or DVD is held up to light are caused by interference, diffraction, and refraction due to fine periodic structures of about the wavelength of light, and are called structural colors. Structural colors are used for purposes such as decoration and anti-counterfeiting purposes, as they can achieve directional luster that cannot be achieved by printing or the like.
Structural color is known to be obtained by forming a fine periodic structure (diffractive periodic structure) on the surface of a substrate using laser processing. A fine periodic structure formed by laser processing is called LIPSS (Laser Induced Periodic Surface Structure).

In Patent Document 1, a base material is irradiated with a laser that is uniaxial and near the processing threshold, and the irradiated part is scanned while overlapping to ablate the interference part of the incident light and the scattered light along the base material surface. A method for self-organizing fine periodic structures is described.

WO2004/035255

For example, when a structural color is used for the purpose of decoration or anti-counterfeiting purposes, there are many requests to apply the structural color to a relatively large area in order to enhance the visual effect.
When forming a fine periodic structure (LIPSS) by laser processing in order to impart a structural color, the pitch of the periodic structure changes depending on the irradiation conditions such as the angle of incidence when the laser beam is applied to the base material. It has been known. If the pitch changes or is disturbed, the appearance of the structural color changes, so in order to impart a highly uniform structural color, it is necessary to suppress the variation in the angle at which the laser is incident within the area where the LIPSS is provided. There is a need.

On the other hand, in order to perform laser processing at high speed, instead of mechanically moving the laser light source relative to the workpiece, an optical scanning mechanism such as a galvanomirror is used to deflect the laser beam for scanning. It is common to If the angle of optically deflected scanning is increased, the processing range can be widened, and high-speed processing becomes possible.
Therefore, there has been a demand for a method for producing LIPSS exhibiting a high-quality structural color over a large surface area of an article with relatively high productivity.

In a first aspect of the present invention, a first region and a second region are set adjacent to each other in this order along a first direction on the surface of a substrate, and each of the first region and the second region , in the surface treatment method of setting a plurality of parallel scanning paths extending along the first direction and irradiating the surface of the base material with a pulsed laser, each of the plurality of scanning paths set in the first region are sequentially scanned while moving the irradiation position of the pulse laser in the first direction, and then each of the plurality of scanning paths set in the second region is scanned by moving the irradiation position of the pulse laser to the first direction. This surface treatment method is characterized in that scanning is performed sequentially while moving in a direction.

A second aspect of the present invention includes a deflection unit for optically deflecting and scanning a laser beam output from a laser light source, a moving mechanism for mechanically changing the relative position between the deflection unit and a workpiece, and the deflection unit. and a control unit that controls the movement mechanism, the control unit including a first area and a second area that are set on the surface of the workpiece and are arranged adjacent to each other in this order along a first direction; and a plurality of mutually parallel scanning paths extending along the first direction, which are set in each of the first region and the second region. After sequentially scanning each of the plurality of scanning paths set in the first region while moving in the first direction, the moving mechanism changes the relative positions of the deflection unit and the work in the first direction. Further, the deflecting unit sequentially scans each of the plurality of scanning paths set in the second area while moving the irradiation position of the laser light in the first direction. , is a surface treatment apparatus characterized by:

In a third aspect of the present invention, each of the first region and the second region adjacent in the first direction on the surface of the substrate has a plurality of mutually parallel protrusions extending along the first direction. A periodic structure is provided, and the periodic structure formed inside the first region and the periodic structure formed inside the second region are substantially the same periodic structure, and the first region and the boundary portion of the second region, an end portion of each of the plurality of protrusions formed in the first region and an end portion of each of the plurality of protrusions formed in the second region and the shape of the protrusion at each end of the plurality of protrusions formed in the first region is different from the shape of the protrusion inside the first region, and is different from the shape of the protrusion in the second region. The shape of the protrusions at each end of the plurality of protrusions formed in the second region is different from the shape of the protrusions inside the second region.

According to the present invention, LIPSS exhibiting a high-quality structural color can be produced over a large surface area of an article with relatively high productivity.

FIG. 2 is a schematic diagram showing a laser head portion provided in the laser processing apparatus according to the embodiment; The schematic diagram which shows the structure of the laser processing apparatus which concerns on embodiment. A photograph of an enlarged fine periodic structure taken from the direction of plan view. FIG. 4 is a diagram schematically showing a cross section of the fine periodic structure cut along the Y direction; (a) A schematic diagram for explaining a scanning method to be used as a reference. (b) A plan view schematically showing a history of laser pulse irradiation by a scanning method that serves as a reference. (a) A schematic diagram for explaining a scanning method according to an embodiment. (b) A plan view schematically showing a history of laser pulse irradiation by the scanning method according to the embodiment. (a) A schematic plan view for explaining a procedure for setting a plurality of patches to form a fine periodic structure in Embodiment 1. FIG. (b) A plan view schematically showing a history of laser pulse irradiation in the first embodiment. (a) A schematic plan view for explaining a procedure for setting a plurality of patches to form a fine periodic structure in the reference embodiment. (b) A plan view schematically showing a history of laser pulse irradiation in the reference embodiment. FIG. 7B is an enlarged view schematically showing a mode (pattern) of overlapping irradiation spots by enlarging the small area 22 shown in FIG. 7A. (a) A schematic plan view for explaining a procedure for setting a plurality of patches to form a fine periodic structure in the second embodiment. (b) A plan view schematically showing a history of laser pulse irradiation in the second embodiment. (a) The figure which shows the form of the patch 10A based on Embodiment 2. FIG. (b) The figure which shows the form of the patch 10B based on Embodiment 2. FIG. (c) The figure which shows the form of the patch 10C which concerns on Embodiment 2. FIG. The schematic diagram which planarly viewed the molding surface of the molding die which concerns on an Example. The photograph which image|photographed the molding surface of the molding die which concerns on an Example. (a) A diagram showing an embodiment in which only triangular patches are arranged. (b) A diagram showing an embodiment in which only hexagonal patches are arranged. A microscopic photograph of a resin molded product to which LIPSS on the molding surface of the mold is transferred. Enlarged view of the LIPSS-transferred patch. The figure which shows the result of having carried out FFT processing of the data measured by AFM.

A surface treatment method, a surface treatment apparatus, and the like according to embodiments of the present invention will be described with reference to the drawings. The embodiments and examples shown below are examples, and for example, detailed configurations can be modified appropriately by those skilled in the art without departing from the scope of the present invention.
It should be noted that in the drawings referred to in the following description of the embodiments and examples, elements indicated with the same reference numbers have the same functions unless otherwise specified.

In the following description, for example, the X plus direction indicates the same direction as the X-axis arrow in the illustrated coordinate system, and the X minus direction indicates the X axis in the illustrated coordinate system. The direction indicated by the arrow is 180 degrees opposite. Moreover, when simply describing the X direction, it means the direction parallel to the X axis regardless of whether it is different from the direction indicated by the X axis arrow in the drawing. The same applies to directions other than X.

(laser processing equipment)
FIG. 1 is a schematic diagram showing a laser head portion provided in a laser processing apparatus used for forming LIPSS. A laser beam output from a laser oscillator 17 inside a laser head 16 is reflected in a predetermined direction by a galvanomirror 18 (deflecting portion), passes through a condenser lens 19, and is shaped into a beam. 11 (workpiece) is irradiated. At this time, by moving the galvanomirror 18, the laser irradiation position on the workpiece 11 can be changed two-dimensionally for scanning. Reference numeral 10 in the drawing denotes a region (range) that can be processed by deflecting and scanning the laser beam with an optical scanning means (galvanomirror 18), and is called a patch. The size of the patch 10 may be set so as to match the limit of the movable range of the galvanomirror 18 . However, in that case, the difference in the incident angle of the laser beam between the central portion and the peripheral portion of the workpiece 11 becomes too large, and the structural color when the LIPSS is formed becomes unacceptably uneven in appearance. It is possible. Therefore, even if the size of the patch 10 is smaller than the mechanical movable limit, it is preferable to set the size so that the non-uniformity of the structural color within the patch is within an allowable range.

If the LIPSS is to be formed on the workpiece 11 (work) because the area is too large to be covered by one patch 10, a plurality of adjacent patches are set to cover the entire area to be processed. It is preferable to set the size of the patch 10 so that the difference in the incident angle of the laser light does not become too large near the boundary between adjacent patches and the difference in structural color does not exceed the visually permissible range.

The mechanism (deflector) for optically deflecting and scanning the laser beam is not limited to this example, and a mechanism such as a polygon mirror that continuously deflects in one direction at high speed may be used.

FIG. 2 is a schematic diagram showing the configuration of a laser processing apparatus having the laser head 16 described above. A laser processing apparatus 51 includes a laser head 16 capable of irradiating a laser beam 52 for processing, and a processing stage 55 on which a workpiece 11 can be placed. The laser processing device 51 also includes an X-axis movement mechanism, a Y-axis movement mechanism, and a Z-axis movement mechanism, and is configured to be able to change the relative position between the laser head 16 and the workpiece 11. . The laser head 16 , the X-axis movement mechanism, the Y-axis movement mechanism, and the Z-axis movement mechanism are controlled by the controller 100 .

The control unit 100 is a computer that controls the operation of each unit of the laser processing device 51, and includes a CPU, a memory, an I/O control unit, and the like. An output device such as a display may be provided. The memory in the control unit 100 stores a control program for manufacturing a periodic structure of fine unevenness (a fine periodic structure (nano periodic structure)) and information related to settings of patches and scanning methods. Such information may be input by the user from an input device, may be input from an external computer or storage device via a network via the I/O control unit, or may be input from a portable memory such as a USB memory. You can enter by wearing it.

In addition, although not shown, the laser processing apparatus 51 includes a quarter-wave plate for adjusting the polarization direction of the laser beam that irradiates the workpiece 11 (work). It is held between the condenser lens 19 and the workpiece 11 so as to be rotatable around the optical axis. In this embodiment, the angle of the rotation direction of the quarter-wave plate is adjusted so that the deflection direction of the laser beam that irradiates the workpiece 11 is orthogonal to the direction of the scanning line SC (X direction), which will be described later. It is possible. By performing such adjustment, it is possible to form a good-shaped LIPSS structure in which the longitudinal direction of each groove is aligned along the direction of the scanning line SC, and impart a high-quality structural color to the surface of the workpiece 11. becomes possible.

The laser light output from the laser head 16 is focused on the irradiation position on the workpiece 11 . An optical element (not shown) may be further provided between the laser head 16 and the workpiece 11 to shape and converge the beam. As one method of controlling the irradiation energy density of the laser so as to be close to the processing threshold of the workpiece 11, the positional relationship is adjusted so that the irradiation is performed at an off-focus position shifted by a certain distance from the focal position. good too.

As already described, the laser head 16 incorporates a two-axis galvanometer scanner and an fθ lens, and by driving the galvanometer mirror 18, the irradiation position can be moved at high speed. Since scanning by the galvano mirror 18 can be performed at a higher speed than stage driving by the X-axis moving mechanism and the Y-axis moving mechanism, the inside of one patch is scanned using the galvano mirror 18, and the patch is switched by the moving mechanism. Move the stage.

As a laser light source for laser processing, a pulse laser that repeatedly irradiates short pulses can be preferably used. Various lasers such as picosecond and nanosecond pulse lasers such as CO ₂ laser and YAG laser can be used, and for example, a titanium sapphire laser can be preferably used. The titanium sapphire laser is an ultrashort pulse so-called femtosecond laser, and has output specifications such as a pulse width of 120 fs, a center wavelength of 800 nm, a repetition frequency of 1 kHz, and an energy of 0.25 μJ to 400 μJ per pulse.

(Laser scanning method within one patch)
FIG. 3 shows a photograph of the periodic structure (fine periodic structure) according to the present embodiment, which is enlarged from a plane view. It can be seen that there is a structure in which fine grooves are arranged in parallel along the X direction (first direction). FIG. 4 is a diagram schematically showing a cross section of the fine periodic structure cut along the Y direction (second direction). , the microgrooves (or microprotrusions) have a depth (or height) indicated by 13 . A typical LIPSS has a pitch 12 of 1 μm and a depth (or height) 13 of about 0.5 μm to 0.7 μm.

In order to form fine grooves extending in the X direction in the patch, while irradiating the workpiece 11 with the pulsed laser at a predetermined repetition frequency, the pulsed laser is irradiated so that the irradiation regions of each pulse partially overlap each other. is scanned in the X direction (first direction) to form fine grooves. The polarization direction of the laser light that irradiates the workpiece 11 is adjusted so as to be orthogonal to the direction (X direction) of the scanning line SC, which will be described later. The repetition frequency, scanning speed, irradiation beam diameter, etc. of the pulse laser are adjusted so that conditions suitable for forming LIPSS, that is, the irradiation energy density with respect to the substrate, are close to the processing threshold. By irradiating with an appropriate energy density, a fine periodic structure is formed in a self-organizing manner by ablation of the interference portion between the incident light and the scattered light along the substrate surface. By irradiating a laser along one scanning line, a fine periodic structure consisting of a plurality of fine grooves (or fine protrusions) can be formed along the scanning line.
In order to arrange the fine grooves extending in the X direction in the Y direction over a certain width, it is necessary to scan the laser in the X direction multiple times. In order to scan the laser in the X direction, there are a method of moving the irradiation position in the X plus direction in time series and a method of moving in the X minus direction in time series.

FIGS. 5(a) and 6(a) are schematic diagrams for explaining two methods of laser scanning. In order to simplify the explanation, nine scanning lines are set in the patch 10 here. It is assumed that a large number of fine grooves are formed by In a plan view of the patch 10, the scanning order of nine scanning lines SC (scanning paths) scanned with laser light is indicated by circled numerals 1 to 9, and the irradiation position is moved for each scanning line SC. Directions are indicated by arrows.

FIGS. 5(b) and 6(b) schematically show irradiation histories when laser pulses are irradiated corresponding to the scanning methods of FIGS. 5(a) and 6(a), respectively. It is a top view. The shape of the irradiation spot LS of the pulse laser is typically shown as a circle, and the new irradiation spot is superimposed on the old irradiation spot in chronological order. Therefore, in a region where the old pulse and the new pulse overlap and are irradiated, the irradiation shape of the old pulse is hidden by the irradiation shape of the new pulse and cannot be seen.

As shown in FIG. 5A, by adopting so-called raster scanning in which the scanning line is scanned in the order of circled numerals 1 to 9 while the beam movement is alternately switched between the X plus direction and the X minus direction, scanning can be performed. There is no need to return the galvo scanner to the same starting point in the X direction for each line. Therefore, the time required for processing can be shortened. On the other hand, as shown in FIG. 6A, when all the scanning lines indicated by circled numerals 1 to 9 are irradiated while moving the beam in the X plus direction, the scanning line (scanning path) is Since it is necessary to return the irradiation position to the starting point in the X direction each time the switching is performed, the time required for processing becomes longer than in FIG.

Here, looking at the irradiation history of the pulse, as is clear from a comparison of FIG. 5B and FIG. It can be seen that the uniformity is higher in the latter, whereas it is not uniform. As described above, LIPSS irradiates a laser with an intensity near the processing threshold, scans the irradiated area while overlapping it, and ablates the interference portion of the incident light and the scattered light along the substrate surface, thereby forming a self-organized structure. It forms a fine periodic structure in the For this reason, if the irradiation spots LS are unevenly overlapped, it is not possible to substantially uniformly impart a structural color with excellent appearance quality to the patch 10 .

Therefore, in the embodiment of the present invention, as shown in FIG. 6A, the laser is scanned so that the irradiation spot moves in the same direction for all scanning lines within one patch.

Furthermore, when setting a plurality of patches and forming a fine periodic structure in each patch, the direction of the scanning lines should be parallel to each other in order to prevent the structural colors of the patches from becoming different. set to be Further, scanning is performed so that the irradiation spot moves in the same direction on any scanning line of any patch. Then, a substantially homogeneous structural color is imparted within any patch.
A procedure for forming a fine periodic structure by setting a plurality of patches in order to impart a structural color to a relatively large area of the outer surface of the workpiece will be described below.

[Embodiment 1]
FIG. 7(a) is a schematic plan view for explaining the procedure for forming a fine periodic structure in order to impart a structural color to a relatively large area of the outer surface of the workpiece. In this embodiment, a structural color is imparted to the outer surface region 21 of the workpiece 11 (workpiece). Since the area 21 is too large to be covered by a single patch, in this embodiment, nine square patches 10 are set and arranged adjacent to each other in a 3×3 matrix. Note that the shape of the patch 10 may be a rectangle with sides of unequal lengths instead of a square.

In any patch 10, as described with reference to FIG. 6A, the scanning line SC (not shown) of the laser beam is set parallel to the X direction, and the irradiation spot is The laser beam is scanned such that the moving direction is the X plus direction (first direction).

In this embodiment, nine patches are sequentially selected according to the numerical order shown in the patches in FIG. 7A, and laser light is irradiated to form LIPSS. If the horizontal direction (X direction) of the matrix arrangement of patches is defined as rows and the vertical direction (Y direction) is defined as columns, after sequentially processing patches arranged in one row, patches in another row adjacent to the row are sequentially processed. be processed.

The order of selecting scanning lines in each patch is along the Y direction as shown in FIG. 6(a). The direction in which the rows of patches are selected in the patch matrix arrangement is the Y direction, which is the same as the direction in which the scanning lines are selected in each patch.
For example, looking at the bottom row, patches are processed according to the numerical order of 1, 2, and 3 shown in the figure, then moving to the adjacent row in the Y plus direction, patches are processed according to the numerical order of 4, 5, and 6. being processed. In this embodiment, as shown in the figure, adjacent patches in any row in the matrix are processed in order along the X plus direction (first direction). That is, the direction (X plus direction) in which the patches are processed coincides with the direction (X plus direction) in which the irradiation spot moves in each scanning line (scanning path).

In relation to the description in the scope of claims, for example, in FIG. You can also call it 3 regions. At that time, of the two sides parallel to the X direction of the first region, the side that contacts the third region is called the first side, and the first side of the two sides parallel to the X direction of the third region A side that abuts the region may be called a second side.

Here, for comparison, a reference embodiment in which the patch processing order is set by a method different from that of the embodiment will be described with reference to FIG. In the reference embodiment shown in FIG. 8(a), as in the embodiment, nine square patches 10 are arranged adjacent to each other in a 3×3 matrix, and nine square patches 10 are arranged according to the numerical order shown in the patch. are sequentially selected and irradiated with a laser to form a LIPSS. In this reference embodiment, as shown in the drawing, adjacent patches are processed in order along the X minus direction in any row. That is, the direction in which patches are processed (minus X direction) is opposite to the direction in which the irradiation spot moves in each scanning line (plus direction X).

FIG. 7(b) is a plan view schematically showing a history of laser pulse irradiation corresponding to the scanning method of the embodiment shown in FIG. 7(a). FIG. 8(b) is a plan view schematically showing a history of laser pulse irradiation corresponding to the scanning method of the reference embodiment shown in FIG. 8(a). As in FIGS. 5(b) and 6(b) already described, the new irradiation spots are overwritten on the old irradiation spots chronologically. In other words, in a region where the old pulse and the new pulse overlap and are irradiated, the irradiation shape of the old pulse is hidden by the irradiation shape of the new pulse and cannot be seen.

As is clear from comparing FIG. 7(b) and FIG. 8(b), the aspect (pattern) of how the irradiation spots LS overlap at the boundary between the patches (the end of the scanning line) is greater than that of the former. It can be seen that the irregularity is greater in . LIPSS irradiates a laser with an intensity near the processing threshold, scans while overlapping the irradiated part, and ablate the interference part of the incident light and the scattered light along the base material surface to form a fine periodic structure in a self-organizing manner. to form Therefore, if there is a portion where the overlapping pattern of the irradiation spots LS is different from the surroundings, the fine structure will be substantially different from the surroundings, resulting in a different appearance from the surrounding structural colors. That is, it becomes impossible to uniformly form a structural color having excellent appearance quality in the region 21 .

Specifically, in the case of the reference embodiment shown in FIG. 8B, at the boundary between patches aligned in the X direction and the boundary between patches aligned in the Y direction, the regularity of the overlapping of irradiation spots is lower than that of the surroundings. It can be seen that there is a large difference between For this reason, when the region 21 formed with the LIPSS is visually observed, the vertical and horizontal lines corresponding to the borders of the patches appear in a grid pattern in the rainbow structural color.

On the other hand, in the case of the embodiment shown in FIG. 7B, at the boundary between patches aligned in the Y direction (second direction), that is, at the boundary line portion parallel to the X axis (first direction), There is no disturbance in the regularity of how the irradiation spots overlap. In addition, at the boundary between the patches arranged in the X direction, that is, at the boundary line parallel to the Y axis, the regularity of the overlapping of the irradiation spots is slightly different from that of the surrounding area. Turbulence is small. FIG. 9 is an enlarged view schematically showing how the irradiation spots overlap (pattern) by enlarging the small area 22 shown in FIG. 7(a). In most areas of each patch, irradiation spot shapes schematically shown as LSA are regularly arranged. and illuminated spot shapes denoted as LSC are shown. The end of the patch in the X direction corresponds to the start point or end point of the laser irradiation along the scanning line.

LSB and LSC are patterns slightly different from LSA, but compared to the reference form shown in FIG. That is, substantially the same periodic structure is formed in the portion schematically indicated by the overlap of LSA, and the portions indicated by LSB and LSC have slightly different shapes, but the difference is minor.

As is clear from the above, in the reference embodiment, grid-like lines are conspicuous in the region exhibiting the structural color. , and the boundaries between the patches arranged in the X direction are inconspicuous. Therefore, when a plurality of patches are set and LIPSS is formed in a large area to impart a structural color, the vertical lines at the boundaries of the patches are almost conspicuous, and a highly uniform structural color is imparted to the entire area. be able to.

In Embodiment 1, the LIPSS was formed under the following conditions (1) to (5).
(1) A plurality of square or rectangular patches were set and arranged in a matrix.
(2) In any patch, a plurality of scanning lines are set parallel to the X direction within the patch.
(3) The laser beam was scanned so that the irradiation spot moved in the X plus direction in any scanning line. In one patch, the order of selecting the scanning lines to be irradiated with the laser light was the order along the Y plus direction.
(4) Assuming that the horizontal direction (X direction) of the matrix arrangement of patches is rows and the vertical direction (Y direction) is columns, patches arranged in one row are sequentially laser-processed, and then patches in another row are sequentially processed. are laser-processed (line-sequential processing). When the laser processing shifts from one row to another row, it shifts to another row adjacent to the one row in the Y plus direction. That is, the direction in which the scanning lines to be irradiated with the laser light are selected in one patch and the direction in which the rows of the patches are processed are arranged in the same direction (Y plus direction).
(5) In any row, adjacent patches were processed in order along the X plus direction. That is, the direction in which the patches are processed in one row and the direction in which the irradiation spot moves in each scanning line are set to be the same direction (X plus direction).

According to this embodiment, a microstructure (LIPSS) exhibiting a high-quality structural color can be manufactured over a large area with relatively high productivity. That is, it is possible to provide a method and a manufacturing apparatus for manufacturing an article having excellent structural color.

The LIPSS formation method according to the present embodiment can be carried out in a manner in which the surface of an article is directly laser-processed (surface treated) to impart a structural color to the article. Furthermore, instead of directly laser processing the article, the molding surface of the mold used for manufacturing the article can be surface-treated by laser processing. That is, it is also possible to form a fine periodic structure (concave and convex opposite to the fine periodic structure formed on the article) for imparting a structural color to the article on the molding surface of the mold by laser processing. can do. If the molding surface shape of the mold is transferred to a molding material (for example, a resin material) using a molding mold subjected to such a surface treatment, the boundary between patches when LIPSS is formed on the molding surface is inconspicuous. A high-quality structural color can be imparted to a molded product (for example, a resin molded product).

The LIPSS according to this embodiment can be formed on various articles such as anti-counterfeiting seals and various printer parts (for example, printer cartridges, printer drum covers, printer exterior parts). . That is, a high-quality structural color can be imparted to the substrate surface of these articles.

[Embodiment 2]
As a second embodiment, a method of setting a patch having a shape different from that of the first embodiment and performing laser processing when forming LIPSS will be described. In the description of the second embodiment, matters common to the description of the first embodiment will be simplified or omitted.
In Embodiment 1, the LIPSS was formed based on the conditions (1) to (5) described above, but in Embodiment 2, condition (1) is different from Embodiment 1, and (2) to (5) is the same as in the first embodiment.

FIG. 10(a) shows that, in Embodiment 2, a plurality of patches are set and a fine periodic structure is formed for each patch when imparting a structural color to a relatively large area of the outer surface of the workpiece. It is a typical plan view for explaining the procedure to go. In this embodiment, structural color is imparted to the region 21 of the outer surface of the workpiece 11 . In this embodiment, patches 10A, 10B, and 10C of three different shapes are set and arranged adjacent to each other in a 4×3 matrix to cover the area 21 . 11(a) is a schematic plan view for explaining the patch 10A, FIG. 11(b) is a schematic plan view for explaining the patch 10B, and FIG. 11(c) is a schematic plan view for explaining the patch 10C.

As shown in FIGS. 11(a) to 11(c), in any patch, the scanning line SC of the laser light is set parallel to the X direction as described in condition (2). . Then, the laser light is scanned so that the direction in which the irradiation spot moves is the X plus direction in any scanning line SC. Moreover, the order of selecting the scanning lines to be irradiated with the laser light within one patch is the order along the Y plus direction, as in FIG. 6A of the first embodiment.

11(a) to 11(c), the sides where the patches adjacent in the X direction (row direction) in FIG. 10(a) are in contact with each other are indicated by thick lines as sides CS. In the first embodiment, the sides where patches adjacent to each other in the X direction (row direction) abut are orthogonal to the X direction (row direction). They intersect obliquely (other than at 90 degrees) rather than orthogonally. The acute angle side (smaller angle) of the crossing angles is shown as α.

FIG. 10(b) is a schematic enlarged view showing an aspect (pattern) of how the irradiation spots overlap by enlarging the small region 32 shown in FIG. 10(a). In most areas of each patch, irradiation spot shapes schematically shown as LSA are regularly arranged. and LSC are shown. The end of the patch in the X direction corresponds to the start point or end point of the laser irradiation along the scanning line.

LSBs and LSCs have a slightly different pattern from LSAs, but in this embodiment, LSBs and LSCs are arranged obliquely along side CS, and the arrangement density is lower than that of Embodiment 1 shown in FIG. I understand. That is, since the placement density of the locations where the overlapping of the irradiation spots is disturbed at the boundary of the patches is small, when looking at the structural color imparted to the region 21, the boundary between the patches arranged in the X direction is lower than that in the first embodiment. becomes even more inconspicuous.

The smaller the crossing angle α, the more the LSBs and LSCs are dispersed in the X direction, so the boundaries between patches arranged in the X direction tend to become less conspicuous. Therefore, α is preferably set to 45 degrees or less, for example. However, the smaller the α, the smaller the area of one patch that can be optically scanned in the limited optical deflection range of the laser processing machine. Considering the balance between the effect of making the boundaries between patches inconspicuous in the region to which the structural color is imparted and the increase in the time required for manufacturing, it is desirable to set the size of α, which is 20 degrees or more and 70 degrees or less. is preferably set appropriately within the range of

According to this embodiment, a fine structure (LIPSS) exhibiting a high-quality structural color on the surface of an article can be manufactured over a large area with relatively high productivity. Further, as in Embodiment 1, the surface of an article is directly laser-processed to impart a structural color to the article. Aspects can also be implemented. If the molding surface shape is transferred to a molding material (for example, a resin material) using a molding die manufactured in such a manner, the boundary between patches when the molding surface of the mold is laser-processed is inconspicuous, and the resin is molded. A structural color can be imparted to the molded product.

An example of forming a LIPSS shape by performing laser processing on the surface of a molding die with the aim of imparting decorativeness to a resin molded product is shown. FIG. 12 is a schematic plan view of the molding surface of the molding die, which is the workpiece 11, and shows an example in which a LIPSS is formed in a ring-shaped region 21 having a circular outer edge and an elliptical inner edge. The figure also shows lines indicating the shape of the patch set by applying the idea of the second embodiment.

STAVAX was used as the material of the molding die. As a laser processing machine, LP400U (manufactured by GF Machining Solutions) was used. As a laser light source, an ultrashort pulse laser oscillator manufactured by AMPLITUDE SYSTEMS was used. The wavelength is 1030 nm. A pulse energy of 7.5 μJ per pulse and a lens focal length of about 170 mm were used, and the laser irradiation spot diameter was adjusted to 40 μm by adjusting the distance between the lens and the molding surface of the molding die. As a laser scanning method, a galvanomirror was used, the scanning speed was 500 mm/s, the scanning interval was 5 μm, and the irradiation frequency of the short pulse laser was 101 kHz. A square with a side of 40 mm was assumed to be an area that could be irradiated with a laser by optical scanning using a galvanomirror, and the shape of each patch was assumed to be within the area of the square.

A LIPSS was formed in the ring-shaped region 21 by scanning the laser by the scanning method described in the second embodiment. The formed LIPSS has a periodic structure whose cross section is schematically shown in FIG. height) 13 was 0.3 to 0.5 μm.

FIG. 13 is a photograph of the molding surface of the mold on which the LIPSS is formed. Although it is difficult to distinguish from the photograph, the ring-shaped region 21 exhibited a high-quality structural color with the naked eye, and almost no boundary line of the patch was visible in the region 21 .

When a resin molded product was created by injection molding using the mold, the resin molded product to which the LIPSS on the mold molding surface was transferred exhibited a high-quality structural color, and when the mold was laser processed, The boundary line of the patch was hardly visible to the naked eye.

FIG. 15 shows a microscopic photograph of a resin molded product to which LIPSS on the molding surface of the mold is transferred. The boundary line of the patch when the mold was laser-processed was hardly visible to the naked eye, but when observed with a microscope, the boundary portion of the patch onto which LIPSS was transferred was observed black.

FIG. 16 is an enlarged view of the LIPSS-transferred patch shown in FIG. 15, in which the first region and the second region are adjacent in the first direction, and the edge of the first region or the edge of the second region. 3 is an enlarged view of area A including a boundary portion which is a part; FIG. FIG. 17 shows the results of AFM observation of region B, which is part of the boundary that is the end of the first region or the end of the second region, and region C, which is part of the interior of the first region. is. A fine periodic structure having a plurality of mutually parallel protrusions extending along the first direction is formed in both the first region and the second region. In regions B and C, measurements are made by AFM at 16 locations at a pitch of 0.078125 μm in the direction intersecting the first direction and at 128 locations in eight rows at a pitch of 0.078125 μm in the first direction.

FIG. 17 shows the results of FFT (fast fourier transform) processing of the measured data. In the result of FFT (fast fourier transform) of the data measured by AFM, the value of the highest portion is taken as the height of the convex portion. It can be seen that the height of the projections inside the first region and inside the second region is 0.3 μm or more, and the height of the projections at the boundary is 0.25 μm or less. In other words, it was found that the periodic structure of the convex portion collapsed and the height became low at the boundary portion, so that it was visually recognized as black when observed with a microscope. It is assumed that the center line of the black boundary portion (the line connecting the centers of the portions where the height of the convex portion is 0.25 μm or less in the first direction) extends in a direction perpendicular to the first direction. , the boundary was visible with the naked eye. That is, it is preferable to incline so that the angle between the center line of the boundary and the first direction is 20° or more and 70° or less. As a result, the border becomes almost invisible to the naked eye. The shape of the patch (for example, the first area) to which the LIPSS is transferred may be triangular or quadrangular. Moreover, it may be hexagonal or polygonal. Furthermore, the shape may not be a polygon composed only of straight lines, and may be a shape including curved lines.

[Other embodiments]
The present invention is not limited to the embodiments and examples described above, and many modifications are possible within the technical concept of the present invention.

For example, in order to cover the entire region to be processed, a plurality of rectangular patches are set in the first embodiment, and triangular and parallelogram patches are set and arranged in the second embodiment. The arrangement method is not limited to this example. For example, only triangular patches may be arranged as shown in FIG. 14(a), or hexagonal patches may be used as shown in FIG. 14(b). In addition, polygonal patches different from the exemplified shape may be arranged in the region to be processed. Furthermore, the shape of the patch need not be a polygon composed only of straight lines, and may be a shape including a curve that intersects the scanning direction of the laser beam.

The present invention provides a program that implements one or more functions of the embodiments to a system or device via a network or storage medium, and one or more processors in the computer of the system or device reads and executes the program. But it is feasible. It can also be implemented by a circuit (for example, ASIC) that implements one or more functions.

The embodiments described above include disclosure of the following items.
[Disclosure 1]
setting a first region and a second region adjacent to each other in this order along the first direction on the substrate surface;
setting a plurality of mutually parallel scanning paths extending along the first direction in each of the first region and the second region;
In the surface treatment method for irradiating the substrate surface with a pulse laser,
After sequentially scanning each of the plurality of scanning paths set in the first region while moving the irradiation position of the pulse laser in the first direction,
sequentially scanning each of the plurality of scanning paths set in the second region while moving the irradiation position of the pulse laser in the first direction;
A surface treatment method characterized by:
[Disclosure 2]
In the surface treatment method according to Disclosure 1,
setting a third region adjacent to and aligned with the first region along a second direction intersecting the first direction on the surface of the substrate;
setting a plurality of mutually parallel scanning paths extending along the first direction in the third region;
When scanning each of the plurality of scanning paths set in the first region while moving the irradiation position of the pulse laser in the first direction, scanning is performed in the order in which they are arranged along the second direction. After selecting a path and scanning all of the scan paths of the first area,
selecting a scanning path from among the plurality of scanning paths set in the third region in the order in which they are arranged in the second direction, and scanning while moving the irradiation position of the pulse laser in the first direction; scanning all of the scanning paths of the third region;
A surface treatment method characterized by:
[Disclosure 3]
In the surface treatment method according to Disclosure 1 or 2,
at least one of the first region and the second region is either a parallelogram, a polygon, or a shape with curved sides;
A surface treatment method characterized by:
[Disclosure 4]
In the surface treatment method according to Disclosure 2,
The first region has a first side parallel to the first direction,
the third region has a second side parallel to the first direction,
the first side and the second side are in contact;
A surface treatment method characterized by:
[Disclosure 5]
In the surface treatment method according to any one of Disclosures 1 to 4,
A polarization direction of the pulse laser with which the substrate surface is irradiated is orthogonal to the first direction,
A surface treatment method characterized by:
[Disclosure 6]
By the surface treatment method according to any one of Disclosures 1 to 5,
imparting a structural color to the substrate surface;
A surface treatment method characterized by:
[Disclosure 7]
In the surface treatment method according to any one of Disclosures 1 to 6,
The substrate surface is a molding surface of a molding die,
A surface treatment method characterized by:
[Disclosure 8]
A periodic structure is formed on the molding surface by the surface treatment method according to Disclosure 7, the shape of the molding surface is transferred to the molding material, and a structural color is imparted to the surface of the molding material.
A method for manufacturing an article characterized by:
[Disclosure 9]
A deflection section for optically deflecting and scanning a laser beam output from a laser light source, a movement mechanism for mechanically changing the relative position of the deflection section and a workpiece, and a control section for controlling the deflection section and the movement mechanism. , and
The control unit is set to each of a first region and a second region, which are set on the surface of the workpiece and are arranged adjacent to each other in this order along a first direction, and the first region and the second region. , a plurality of parallel scanning paths extending along the first direction,
After the deflection unit sequentially scans each of the plurality of scanning paths set in the first region while moving the irradiation position of the laser light in the first direction,
the moving mechanism changes the relative positions of the deflection unit and the workpiece in the first direction;
Further, the deflection unit sequentially scans each of the plurality of scanning paths set in the second region while moving the irradiation position of the laser light in the first direction.
A surface treatment apparatus characterized by:
[Disclosure 10]
In the surface treatment apparatus according to Disclosure 9,
The control unit includes a third region set on the surface of the workpiece and arranged adjacent to the first region along a second direction intersecting the first direction; a plurality of parallel scan paths extending along a direction;
The deflection unit selects a scanning path from among the plurality of scanning paths set in the first area in the order in which they are arranged along the second direction, and aligns the irradiation position of the laser light in the first direction. After scanning while moving and scanning all the scanning paths of the first area,
the moving mechanism changes the relative positions of the deflection unit and the work in the second direction;
Further, the deflection unit selects a scanning path from among the plurality of scanning paths set in the third area in the order in which they are arranged in the second direction, and aligns the irradiation position of the laser light in the first direction. Scan while moving, and control to scan all the scanning paths of the third region;
A surface treatment apparatus characterized by:
[Disclosure 11]
In the surface treatment apparatus according to Disclosure 9 or 10,
at least one of the first region and the second region is either a parallelogram, a polygon, or a shape with curved sides;
A surface treatment apparatus characterized by:
[Disclosure 12]
In the surface treatment apparatus according to Disclosure 10,
The first region has a first side parallel to the first direction,
the third region has a second side parallel to the first direction,
the first side and the second side are in contact;
A surface treatment apparatus characterized by:
[Disclosure 13]
In the surface treatment apparatus according to any one of Disclosures 9 to 12,
A mechanism for adjusting the polarization direction of the laser light is provided, and the polarization direction of the laser light irradiated to the surface of the work can be adjusted so as to be orthogonal to the first direction.
A surface treatment apparatus characterized by:
[Disclosure 14]
In the surface treatment apparatus according to any one of Disclosures 9 to 13,
The laser beam forms a structure exhibiting a structural color on the surface of the workpiece,
A surface treatment apparatus characterized by:
[Disclosure 15]
A periodic structure having a plurality of mutually parallel protrusions extending along the first direction is provided in each of the first region and the second region adjacent in the first direction on the surface of the substrate,
The periodic structure formed inside the first region and the periodic structure formed inside the second region are substantially the same periodic structure,
At the boundary between the first region and the second region, an end portion of each of the plurality of protrusions formed in the first region and each of the plurality of protrusions formed in the second region are provided. is formed at the end of
The shape of the protrusion at each end of the plurality of protrusions formed in the first region is different from the shape of the protrusion inside the first region, and the shape of the protrusion formed in the second region is different from the shape of the protrusion inside the first region. The shape of the protrusion at each end of the plurality of protrusions is different from the shape of the protrusion inside the second region,
An article characterized by
[Disclosure 16]
In the article of Disclosure 15,
The article according to claim 1, wherein the height of the protrusions at the boundary is 0.25 μm or less, and the plurality of protrusions formed in the first region are higher than the protrusions at the boundary.
[Disclosure 17]
In the article of Disclosure 15 or 16,
The article, wherein the angle formed by the center line of the boundary portion and the first direction is 20° or more and 70° or less.
[Disclosure 18]
In the article of any one of Disclosures 15-17,
At least one of the first region and the second region is either a parallelogram, a polygon, or a shape having curved sides,
An article characterized by
[Disclosure 19]
In the article of any one of Disclosures 15-18,
An article, wherein the base material is a base material for an anti-counterfeit seal.
[Disclosure 20]
In the article of any one of Disclosures 15-18,
The article, wherein the base material is a base material for printer parts.
[Disclosure 21]
In the article of any one of Disclosures 15-18,
An article, wherein the surface of the substrate is a molding surface of a mold.

10, 10A, 10B, 10C patch/11 workpiece/12 pitch/13 depth (or height)/16 laser head/17 laser Oscillator/18 Galvanomirror/19 Collecting lens/21 Area/22 Small area/32 Small area/51 Laser processing device/52 Laser Light/55... Processing stage/100... Control part/CS... Side/LS... Irradiation spot/LSA, LSB, LSC... Irradiation spot shape/SC... Scanning line/α. .. the crossing angle between the side CS and the X direction

Claims (21)

setting a first region and a second region adjacent to each other in this order along the first direction on the substrate surface;
setting a plurality of mutually parallel scanning paths extending along the first direction in each of the first region and the second region;
In the surface treatment method for irradiating the substrate surface with a pulse laser,
After sequentially scanning each of the plurality of scanning paths set in the first region while moving the irradiation position of the pulse laser in the first direction,
sequentially scanning each of the plurality of scanning paths set in the second region while moving the irradiation position of the pulse laser in the first direction;
A surface treatment method characterized by: In the surface treatment method according to claim 1,
setting a third region adjacent to and aligned with the first region along a second direction intersecting the first direction on the surface of the substrate;
setting a plurality of mutually parallel scanning paths extending along the first direction in the third region;
When scanning each of the plurality of scanning paths set in the first region while moving the irradiation position of the pulse laser in the first direction, scanning is performed in the order in which they are arranged along the second direction. After selecting a path and scanning all of the scan paths of the first area,
selecting a scanning path from among the plurality of scanning paths set in the third region in the order in which they are arranged in the second direction, and scanning while moving the irradiation position of the pulse laser in the first direction; scanning all of the scanning paths of the third region;
A surface treatment method characterized by: In the surface treatment method according to claim 1 or 2,
at least one of the first region and the second region is either a parallelogram, a polygon, or a shape with curved sides;
A surface treatment method characterized by: In the surface treatment method according to claim 2,
The first region has a first side parallel to the first direction,
the third region has a second side parallel to the first direction,
the first side and the second side are in contact;
A surface treatment method characterized by: In the surface treatment method according to claim 1 or 2,
A polarization direction of the pulse laser with which the substrate surface is irradiated is orthogonal to the first direction,
A surface treatment method characterized by: By the surface treatment method according to claim 1 or 2,
imparting a structural color to the substrate surface;
A surface treatment method characterized by: In the surface treatment method according to claim 1 or 2,
The substrate surface is a molding surface of a molding die,
A surface treatment method characterized by: A periodic structure is formed on the molding surface by the surface treatment method according to claim 7, the shape of the molding surface is transferred to the molding material, and a structural color is imparted to the surface of the molding material.
A method for manufacturing an article characterized by: A deflection section for optically deflecting and scanning a laser beam output from a laser light source, a movement mechanism for mechanically changing the relative position of the deflection section and a workpiece, and a control section for controlling the deflection section and the movement mechanism. , and
The control unit is set to each of a first region and a second region, which are set on the surface of the workpiece and are arranged adjacent to each other in this order along a first direction, and the first region and the second region. , a plurality of parallel scanning paths extending along the first direction,
After the deflection unit sequentially scans each of the plurality of scanning paths set in the first region while moving the irradiation position of the laser light in the first direction,
the moving mechanism changes the relative positions of the deflection unit and the workpiece in the first direction;
Further, the deflection unit sequentially scans each of the plurality of scanning paths set in the second region while moving the irradiation position of the laser light in the first direction.
A surface treatment apparatus characterized by: In the surface treatment apparatus according to claim 9,
The control unit includes a third region set on the surface of the workpiece and arranged adjacent to the first region along a second direction intersecting the first direction; a plurality of parallel scan paths extending along a direction;
The deflection unit selects a scanning path from among the plurality of scanning paths set in the first area in the order in which they are arranged along the second direction, and aligns the irradiation position of the laser light in the first direction. After scanning while moving and scanning all the scanning paths of the first area,
the moving mechanism changes the relative positions of the deflection unit and the work in the second direction;
Further, the deflection unit selects a scanning path from among the plurality of scanning paths set in the third area in the order in which they are arranged in the second direction, and aligns the irradiation position of the laser light in the first direction. Scan while moving, and control to scan all the scanning paths of the third region;
A surface treatment apparatus characterized by: In the surface treatment apparatus according to claim 9 or 10,
at least one of the first region and the second region is either a parallelogram, a polygon, or a shape with curved sides;
A surface treatment apparatus characterized by: In the surface treatment apparatus according to claim 10,
The first region has a first side parallel to the first direction,
the third region has a second side parallel to the first direction,
the first side and the second side are in contact;
A surface treatment apparatus characterized by: In the surface treatment apparatus according to claim 9 or 10,
A mechanism for adjusting the polarization direction of the laser light is provided, and the polarization direction of the laser light irradiated to the surface of the work can be adjusted so as to be orthogonal to the first direction.
A surface treatment apparatus characterized by: In the surface treatment apparatus according to claim 9 or 10,
The laser beam forms a structure exhibiting a structural color on the surface of the workpiece,
A surface treatment apparatus characterized by: A periodic structure having a plurality of mutually parallel protrusions extending along the first direction is provided in each of the first region and the second region adjacent in the first direction on the surface of the substrate,
The periodic structure formed inside the first region and the periodic structure formed inside the second region are substantially the same periodic structure,
At the boundary between the first region and the second region, an end portion of each of the plurality of protrusions formed in the first region and each of the plurality of protrusions formed in the second region are provided. is formed at the end of
The shape of the protrusion at each end of the plurality of protrusions formed in the first region is different from the shape of the protrusion inside the first region, and the shape of the protrusion formed in the second region is different from the shape of the protrusion inside the first region. The shape of the protrusion at each end of the plurality of protrusions is different from the shape of the protrusion inside the second region,
An article characterized by 16. The article of claim 15, wherein
The article according to claim 1, wherein the height of the protrusions at the boundary is 0.25 μm or less, and the plurality of protrusions formed in the first region are higher than the protrusions at the boundary. An article according to claim 15 or 16,
The article, wherein the angle formed by the center line of the boundary portion and the first direction is 20° or more and 70° or less. An article according to claim 15 or 16,
At least one of the first region and the second region is either a parallelogram, a polygon, or a shape having curved sides,
An article characterized by An article according to claim 15 or 16,
An article, wherein the base material is a base material for an anti-counterfeit seal. An article according to claim 15 or 16,
The article, wherein the base material is a base material for printer parts. An article according to claim 15 or 16,
An article, wherein the surface of the substrate is a molding surface of a mold.

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