Method for producing marked product

Abstract

A method for producing a marked product comprises: transporting an object along a transport path; disposing a beam-forming mechanism between a laser oscillator and the transport path, the beam-forming mechanism forming a regular intensity distribution of laser light emitted from the laser oscillator by branching the laser light according to a prescribed pattern or blocking some of the laser light according to a prescribed pattern; disposing a mask member between the laser oscillator and the transport path, the mask member having formed thereon a transmission pattern corresponding to the design of a marking to be applied to the object; and generating laser light from the laser oscillator and irradiating the object being transported with the laser light that has passed through the beam-forming mechanism and the mask member. The travel direction of the laser light emitted from the beam-forming mechanism is one direction and is the same as the travel direction of the laser light incident on the beam-forming mechanism.

Description

How to produce marked products

[0001] The present disclosure relates to a method for producing marked products.

[0002] Patent Document 1 discloses a laser marking device. The laser marking device in Patent Document 1 uses the same scanning means and lens to scan and process the surface of an object with multiple lasers. The scanning means has a first scanning means that scans in a first direction and a second scanning means that scans in a direction approximately perpendicular to the first direction, and the first scanning means is located in the optical path where the optical paths of the multiple lasers converge. The object is controlled to move in the same direction as one of the scanning means.

[0003] Japanese Patent Application Laid-Open No. 2023-025326

[0004] In the laser marking device of Patent Document 1, an object whose movement is controlled in one direction is divided into multiple drawing areas, and multiple laser light sources are assigned to these areas. According to Patent Document 1, productivity is improved by reducing the drawing area per beam in this way. However, in a method of forming dots on an object surface while scanning the laser light, it is necessary to reduce the object movement speed in accordance with the dot drawing speed. For this reason, further improvement in the processing speed of laser marking is desired.

[0005] The present disclosure aims to provide a method for producing marked products with improved processing speed.

[0006] A method for producing a marked product according to a first aspect of the present disclosure includes transporting an object along a transport path, disposing a beam shaping mechanism between a laser oscillator and the transport path that branches laser light generated from the laser oscillator according to a predetermined pattern or blocks part of the laser light according to a predetermined pattern, thereby forming a regular intensity distribution of the laser light, disposing a mask member between the laser oscillator and the transport path on which a design pattern that transmits or blocks the laser light is formed corresponding to the design of the marking to be made on the object, and generating laser light from the laser oscillator and irradiating the object being transported with the laser light that has passed through the beam shaping mechanism and the mask member. The traveling direction of the laser light emitted from the beam shaping mechanism is unidirectional, which is the same as the traveling direction of the laser light incident on the beam shaping mechanism.

[0007] A method for producing a marked product according to a second aspect of the present disclosure is the method for producing a marked product according to the first aspect, in which the laser oscillator is an excimer laser oscillator, a UV laser oscillator, a CO2 laser oscillator, or a YAG laser oscillator.

[0008] A method for producing a marked product according to a third aspect of the present disclosure is a method for producing a marked product according to the first or second aspect, wherein the beam shaping mechanism is an optical element made of a material that transmits laser light and has a regular pattern consisting of flat portions that transmit laser light and curved portions adjacent to the flat portions that branch the laser light to the adjacent flat portions.

[0009] A method for producing a marked product according to a fourth aspect of the present disclosure is a method for producing a marked product according to any one of the first to third aspects, in which the beam shaping mechanism is a photomask having a regular pattern consisting of shielding areas that block laser light and transparent areas that transmit laser light.

[0010] A method for producing a marked product according to a fifth aspect of the present disclosure is a method for producing a marked product according to any one of the first to fourth aspects, wherein the beam shaping mechanism is a member on which a regular pattern is formed, the pattern consisting of a shielding area that blocks the laser light and a transparent area that transmits the laser light, and the shielding area is formed by a highly reflective mirror.

[0011] A method for producing a marked product according to a sixth aspect of the present disclosure is a method for producing a marked product according to any one of the first to fifth aspects, wherein the mask member is a photomask on which the design pattern is formed, the photomask comprising a shielding area that blocks the laser light and a transparent area that transmits the laser light.

[0012] A method for producing a marked product according to a seventh aspect of the present disclosure is a method for producing a marked product according to any one of the first to sixth aspects, wherein the mask member is a member on which the design pattern is formed, the mask member consisting of a shielding area that blocks the laser light and a transparent area that transmits the laser light, and the shielding area is formed by a highly reflective mirror.

[0013] A method for producing a marked product according to an eighth aspect of the present disclosure is a method for producing a marked product according to any one of the first to seventh aspects, in which the beam shaping mechanism and the mask member are integrally configured.

[0014] A method for producing a marked product according to a ninth aspect of the present disclosure is a method for producing a marked product according to any one of the first to eighth aspects, wherein the object comprises a resin container body including a bottom portion, a side portion extending upward from the outer peripheral edge of the bottom portion, a mouth portion defining an upper opening, and a shoulder portion continuous with the side portion and the mouth portion, and a recessed portion is formed in at least one of the bottom portion, side portion, and shoulder portion, and irradiating the object being transported with laser light that has passed through the beam shaping mechanism and the mask member includes irradiating the laser light onto the inner surface of the recessed portion.

[0015] A method for producing a marked product according to a tenth aspect of the present disclosure is a method for producing a marked product according to any one of the first to ninth aspects, in which the recessed portion is formed in the side surface portion.

[0016] A method for producing a marked product according to an eleventh aspect of the present disclosure is a method for producing a marked product according to any one of the first to tenth aspects, wherein the recessed portion extends around the entire circumference of the side portion.

[0017] A method for producing a marked product according to a twelfth aspect of the present disclosure is a method for producing a marked product according to any one of the first to eleventh aspects, wherein the recessed portion extends from the outer peripheral edge of the bottom portion to the upper end of the side portion.

[0018] A method for producing a marked product according to a thirteenth aspect of the present disclosure is a method for producing a marked product according to any one of the first to twelfth aspects, wherein the inner surface of the recessed portion forms a flat surface facing the external space of the container body at the innermost position, and irradiating the inner surface of the recessed portion with the laser light includes irradiating the laser light onto the flat surface.

[0019] A method for producing a marked product according to a fourteenth aspect of the present disclosure is a method for producing a marked product according to any one of the first to thirteenth aspects, wherein the object comprises a resin container body including a bottom portion, a side portion extending upward from the outer peripheral edge of the bottom portion, a mouth portion defining an upper opening, and a shoulder portion continuous with the side portion and the mouth portion, and at least one of the bottom portion, side portion, and shoulder portion has a protrusion formed thereon that protrudes from the outer surface, and irradiating the object being transported with laser light that has passed through the beam shaping mechanism and the mask member includes irradiating the laser light near the protrusion.

[0020] A marked product according to a fifteenth aspect of the present disclosure comprises a resin container body including a bottom portion, a side portion extending upward from the outer peripheral edge of the bottom portion, a mouth portion defining an upper opening, and a shoulder portion continuous with the side portion and the mouth portion, and at least one of the bottom portion, side portion, and shoulder portion is formed with a marking area including a collection of multiple recesses or a collection of multiple protrusions formed on the outer surface, the marking area displaying a predetermined design, and a recessed portion, and the marking area is formed on the inner surface of the recessed portion.

[0021] A marked product according to a sixteenth aspect of the present disclosure is the marked product according to the fifteenth aspect, wherein the marking area and the recessed portion are formed on the side surface.

[0022] A marked product according to a seventeenth aspect of the present disclosure is the marked product according to the fifteenth or sixteenth aspect, wherein the recessed portion extends around the entire periphery of the side portion.

[0023] A marked product according to an eighteenth aspect of the present disclosure is a marked product according to any one of the fifteenth to seventeenth aspects, wherein the recessed portion extends from the outer peripheral edge of the bottom portion to the upper end of the side portion.

[0024] A marked product according to a 19th aspect of the present disclosure comprises a resin container body including a bottom portion, a side portion extending upward from the outer peripheral edge of the bottom portion, a mouth portion defining an upper opening, and a shoulder portion continuous with the side portion and the mouth portion, and at least one of the bottom portion, side portion, and shoulder portion is provided with a marking area including a collection of multiple recesses or multiple protrusions formed on the outer surface, the marking area displaying a predetermined design, and a protrusion protruding outward from the marking area near the marking area.

[0025] The present disclosure provides a method for producing marked products with increased processing speed.

[0026] 1 is a diagram illustrating a method for producing a marked product according to an embodiment. A diagram illustrating an example configuration of a beam shaping mechanism. A diagram illustrating another example configuration of a beam shaping mechanism. A plan view illustrating yet another example configuration of a beam shaping mechanism. A plan view illustrating an example configuration of a mask member. A flowchart illustrating an example flow of a method for producing a marked product. A diagram illustrating a first example configuration of an object and a marked product. A diagram illustrating a second example configuration of an object and a marked product. A diagram illustrating a third example configuration of an object and a marked product. A diagram illustrating a fourth example configuration of an object and a marked product. A diagram illustrating a fifth example configuration of an object and a marked product. A diagram illustrating the behavior of incident laser light in a beam shaping mechanism. A diagram illustrating the behavior of incident laser light in another beam shaping mechanism. A diagram illustrating the behavior of incident laser light in yet another beam shaping mechanism. A diagram illustrating a photomask pattern according to a modified example. A diagram illustrating a photomask pattern according to another modified example. A diagram illustrating a photomask pattern according to yet another modified example. A diagram illustrating a photomask pattern according to yet another modified example. A diagram illustrating the configuration of a marking device for performing a production method according to an example. A diagram illustrating the configuration of a marking device for performing a production method according to a comparative example. An image of a mask member used in the experiment. A microscope image of a marking created in the experiment. A microscope image of a marking created using a beam shaping mechanism according to an embodiment. A microscope image of a marking created using a beam shaping mechanism according to an embodiment. A microscope image of a marking created using a beam shaping mechanism according to an embodiment. A microscope image of a marking created using a beam shaping mechanism according to an embodiment.

[0027] Hereinafter, a method for producing a marked product according to an embodiment of the present disclosure will be described with reference to the drawings.

[0028] 1 is a diagram illustrating a method for producing marked products, including a laser marking method according to an embodiment of the present disclosure (hereinafter also simply referred to as the "marking method"). The marking method according to this embodiment reduces the processing time required for each marking compared to conventional marking methods. Therefore, the method can be particularly preferably applied to a conveyance line where multiple objects are continuously conveyed, enabling efficient production of marked products.

[0029] The objects to be marked are not particularly limited, and examples thereof include resin products, metal products, electronic components (e.g., circuit elements sealed in resin), edible products, glass products, ceramic products, wood products, leather products, paper products, textile products, rubber products, and packaging materials (e.g., plastic films). The surface of the object may be made of any material, but preferably has a property that changes color and gloss upon irradiation with laser light to the extent that the marked design becomes visible. However, the object may be pre-colored in the marking area to be marked, and processed to enhance the visibility of the marked design by removing the color, or the area may be colored after marking. Furthermore, the object may be made of a material containing a component that changes color upon irradiation with laser light. A typical example of a resin product is a PET bottle. Typical examples of edible products include tablets (sugar-coated tablets, plain tablets, coated tablets, etc.) and capsules.

[0030] The marking design to be applied to an object is not particularly limited, and may include, for example, letters, designs, one-dimensional information codes such as barcodes, or two-dimensional information codes such as QR Codes (registered trademark).

[0031] The following describes an example of a method for marking a design, including a barcode, on the side of the container body of a PET bottle 1. The PET bottle 1 includes, but is not limited to, a transparent container body made of polyethylene terephthalate and a thermoplastic resin cap attached to the top opening of the container body. The PET bottles 1 are loaded in a line on a conveyor line (conveyor path) 10, such as a belt conveyor, and move continuously in a predetermined direction along the conveyor line 10. The conveyor line 10 is configured to convey, for example, approximately 600 to 1,000 PET bottles 1 per minute.

[0032] A marking device 2 for carrying out the method for producing marked products according to this embodiment is installed to the side of the conveying line 10. The marking device 2 is a device that uses laser light to mark a predetermined design on the side of a PET bottle 1 that passes through a predetermined position, and is equipped with a laser oscillator 20, a field lens 21, a beam shaping mechanism 22, a mask member 23, and a projection lens 24. The conveying line 10 and the marking device 2 constitute a production system for producing marked products.

[0033] The laser oscillator 20 is a device that generates laser light. Generally, laser light is highly directional, and it can be said that the laser light generated from the laser oscillator 20 travels in a uniform direction. The laser oscillator 20 is not particularly limited, and any of an excimer laser oscillator, a UV laser oscillator, a CO2 laser oscillator, and a YAG laser oscillator can be used. When the object is a PET bottle 1, an excimer laser oscillator is preferable as the laser oscillator 20. According to the inventors' studies, when the wavelength of the laser light is approximately 193 nm to 315 nm, the transmittance through a transparent polyethylene terephthalate plate with a thickness of approximately 0.2 mm is approximately 0%T to 0.07%T, which indicates high absorbance through polyethylene terephthalate. In contrast, when the wavelength of the laser light is 355.5 nm, the transmittance through the same polyethylene terephthalate plate is approximately 75%T, which indicates relatively low absorbance through polyethylene terephthalate. The polyethylene terephthalate plate is a sample cut out from an existing PET bottle, but the transmittance of the laser light is not thought to depend on the thickness of the sample. An excimer laser is a laser that uses a mixed gas of rare gases, halogens, etc., and has typical wavelengths of 193 nm, 248 nm, 308 nm, and 351 nm, making it suitable for marking PET bottles 1. The wavelength of the laser pulse from the laser oscillator 20 (excimer laser oscillator) according to this embodiment is 308 nm.

[0034] In this way, the laser oscillator 20 can be selected to generate laser light of an appropriate wavelength depending on the object to be marked.

[0035] Furthermore, the irradiation time per shot of various laser oscillators is, for example, approximately 27 nanoseconds for an excimer laser oscillator, approximately 100 nanoseconds for a TEA-CO2 laser oscillator, and approximately 50 nanoseconds for a nanosecond solid-state UV laser oscillator. Thus, excimer laser oscillators are preferred from the perspective of their short irradiation time per shot. The repetition frequency of the laser oscillator 20 can be adjusted appropriately depending on the conveyance speed of the objects to be marked. For example, marking 1,000 PET bottles 1 per minute requires 17 shots per second. In this case, setting the frequency of the laser oscillator 20, which has a higher repetition frequency, to 17 Hz allows for continuous marking of objects moving on the conveyance line 10. The speed of the conveyed objects, not limited to PET bottles 1, can be, for example, 1 m / s to 2 m / s.

[0036] The field lens 21 is an optical component disposed between the laser oscillator 20 and the beam shaping mechanism 22. The field lens 21 further aligns the direction of travel of the laser light generated by the laser oscillator 20 and adjusts the size of the laser beam emitted from the field lens 21. In the example of FIG. 1 , the laser light is aligned so as to be parallel to the optical axis of the projection lens 24 (described later), and the laser beam formed by the aligned laser light is adjusted to have a size of 60 mm × 20 mm. For example, when the magnification of the projection lens 24 is 2x, the size of the marking formed on the side of the PET bottle 1 will be 30 mm × 10 mm.

[0037] The beam shaping mechanism 22 forms a regular path through which the laser light generated by the laser oscillator 20 (including the laser beam emitted from the field lens 21) passes. Specifically, the beam shaping mechanism 22 branches the laser light according to a predetermined pattern or blocks a portion of the laser light according to a predetermined pattern, thereby forming a regular intensity distribution of the laser light. As a result, the laser beam passing through the beam shaping mechanism 22 forms a plurality of laser beams that are parallel to the optical axis of the projection lens 24 (described later) and arranged two-dimensionally in a plane perpendicular to the traveling direction of the laser light. Examples of the beam shaping mechanism 22 that branches the laser light according to a predetermined pattern include optical members 22A and 22B shown in FIGS. 2A and 2B. Examples of the beam shaping mechanism 22 that blocks a portion of the laser light according to a predetermined pattern include a photomask 22C shown in FIG. 2C. The direction of travel of the laser light (multiple laser beams) emitted from the beam shaping mechanism 22 is the same as the direction of travel of the laser light incident on the beam shaping mechanism 22, and can be said to be unidirectional, just like the direction of travel of the laser light incident on the beam shaping mechanism 22.

[0038] The optical members 22A and 22B are each rectangular flat plates in plan view and are made of a transparent inorganic material that transmits laser light. Examples of such inorganic materials include silicon dioxide (quartz, glass), inorganic glass other than silicon dioxide, and the like. The optical members 22A and 22B each include pattern regions 220A and 220B, in which a predetermined regular pattern is formed. Note that the surfaces of the optical members 22A and 22B on which the pattern regions 220A and 220B are formed are the laser light incident surfaces, and the flat surfaces on which the pattern regions 220A and 220B are not formed are the laser light exit surfaces.

[0039] The pattern region 220A has a regular pattern consisting of multiple flat portions 2200A and multiple curved portions 2201A adjacent to each flat portion 2200A (note that only representative portions are labeled). The flat portions 2200A form flat surfaces that are square in plan view and are continuous with the curved portions 2201A at their peripheries. The curved portions 2201A are curved portions that are continuous with the peripheries of the two flat portions 2200A and have a semicircular shape in side view. The curved portions 2201A are recessed relative to the flat portions 2200A, and the thickness of the optical element 22A is greatest at the flat portions 2200A and smallest midway between the two adjacent flat portions 2200A (at the vertices of the semicircles formed by the curved portions 2201A). Each flat portion 2200A transmits the laser light incident on the optical element 22A directly. On the other hand, each curved surface portion 2201A refracts the laser light incident on the optical element 22A to form regularly arranged regions that do not transmit the laser light (see FIG. 10A). That is, each curved surface portion 2201A branches the laser light incident on the optical element 22A to the adjacent flat portion 2200A. As a result, the laser light incident on the optical element 22A is shaped into multiple laser beams corresponding to the flat portions 2200A.

[0040] The pattern region 220B has a regular pattern consisting of a plurality of flat portions 2200B and 2201B and a plurality of curved portions 2202B adjacent to the flat portions 2200B and 2201B (note that only representative portions are labeled with reference numerals). The flat portions 2200B have a square shape in a plan view and are continuous with the curved portions 2202B at their peripheries. The flat portions 2201B also have a square shape in a plan view and are continuous with the curved portions 2202B at their peripheries. However, the flat portions 2201B are recessed relative to the flat portions 2200B, and the thickness of the optical element 22B is greatest at the flat portions 2200B and smallest at the flat portions 2201B. The curved portions 2202B are curved portions that are continuous with the peripheries of the flat portions 2200B and 2201B and are quadrant-shaped in a cross-sectional view. Each of the flat portions 2200B and 2201B transmits the laser light incident on the optical element 22B as is. On the other hand, each of the curved portions 2202B refracts the laser light incident on the optical element 22B to form regularly arranged regions that do not transmit the laser light (see FIG. 10B ). In other words, each of the curved portions 2202B branches the laser light incident on the optical element 22B to the adjacent flat portion 2201B. As a result, the laser light incident on the optical element 22B is shaped into multiple laser beams corresponding to the flat portions 2200B and 2201B.

[0041] The thickness of the optical members 22A and 22B can be, for example, 1.5 mm. The lengths of one side of the flat portion 2200A of the optical member 22A, the flat portion 2200B of the optical member 22B, and the flat portion 2201B can be designed appropriately depending on the magnification of the projection lens 24 (described later), and can be, for example, 10 μm to 300 μm. Similarly, the radii of the arcs described by the curved surface portions 2201A of the optical member 22A and the curved surface portions 2202B of the optical member 22B can be designed appropriately, and can be, for example, 1 μm to 100 μm. The radius of the arcs described by the curved surface portions 2202B is equal to the difference in elevation between the flat portions 2200B and 2201B. In addition, in optical member 22A, the distance between the centers of adjacent flat portions 2200A can be, for example, 10 μm to 100 μm, and in optical member 22ZB, the distance between the centers of adjacent flat portions 2200B and 2201B can be, for example, 15 μm to 150 μm. The number of laser beams formed by optical members 22A and 22B is not particularly limited, but can be 10,000 to 15,000 when laser marks are formed at 30 μm intervals in an area of ​​30 mm × 13 mm on the surface of PET bottle 1.

[0042] The photomask 22C is a rectangular plate-like member in a planar view and has a surface 220C, which is the laser light incident surface. The photomask 22C is positioned so that the surface 220 shown in FIG. 2C is perpendicular to the laser light propagation direction. A plurality of regularly arranged square-shaped transmission regions 221 and shielding regions 222 are formed on the surface 220C. The transmission regions 221 each transmit the laser light. The shielding regions 222 shield the laser light, allowing little or no transmission. As a result, the photomask 22C as a whole forms a regular path for the laser light. In other words, the intensity distribution of the laser light on the surface perpendicular to the laser light propagation direction forms a regular pattern. Such a photomask 22C can be formed, for example, by laminating a chromium film in a predetermined pattern on one side of a synthetic quartz substrate. In other words, the transmission regions 221 can be formed in a portion of the substrate where no chromium film is laminated, and the shielding regions 222 can each be formed with a chromium film.

[0043] The size of each transmission region 221C is formed so that the size of the laser light passing through it is sufficiently small relative to the minimum size of the slits 231 in the mask member 23, which will be described later. For example, the mask member 23, which will be described later, has multiple slits 231 formed therein. In this embodiment, the narrowest slit among these slits has a width of 0.25 mm. The number of laser beams passing through the slits is preferably 10 or more rows, more preferably 20 or more rows, and even more preferably 30 or more rows, in the width direction of the slits. Although this depends on the magnification of the projection lens 24, forming the laser light paths at the above-described density relative to the size of the slits 231 improves the optical readability of the barcode formed on the PET bottle 1. Note that the minimum width of the slits 231 and the preferred range of the number of rows (density) of laser beams relative to the size of the slits 231 are merely examples in the above embodiment and may vary depending on the marking design and the object to be marked.

[0044] The photomask 22C is not limited to the above example, and the transmitting region 221 and the blocking region 222 can be formed using other materials and in other patterns. Furthermore, the photomask 22C is an example of a beam shaping mechanism 22 that blocks a portion of the incident laser light and forms a regular path for the laser light as a whole, and therefore such a beam shaping mechanism 22 is not limited to a photomask. Here, "blocking a portion of the laser light" includes absorbing a portion of the laser light and reflecting a portion of the laser light to prevent it from passing through to the conveying line 10.

[0045] Another example of the beam shaping mechanism 22 is a component in which the shielding region 222 in the photomask 22C is formed of a high-reflection mirror. Examples of high-reflection mirrors include dielectric multilayer mirrors and metal mirrors. Dielectric multilayer mirrors are reflective components formed by alternating high-refractive-index dielectric films and low-refractive-index dielectric films, exhibiting high reflectivity at a predetermined wavelength. Metal mirrors are reflective components that reflect light by a metal coating on their surface, such as aluminum mirrors, silver mirrors, and gold mirrors. Among these, aluminum mirrors are preferred. For example, the beam shaping mechanism 22 may be a component obtained by forming a regular pattern of multiple through-holes (as the multiple transmission regions 221) or multiple transmission holes made of a material that transmits laser light in the high-reflection mirror. Alternatively, the beam shaping mechanism 22 may be a component obtained by laminating the high-reflection mirror as the shielding region 222 on one side of a substrate that transmits laser light.

[0046] The mask member 23 according to this embodiment is disposed between the beam shaping mechanism 22 and the projection lens 24 or the object. FIG. 3 illustrates an example of the mask member 23. The mask member 23 in FIG. 3 is a plate-like member having a rectangular shape in a plan view and a design pattern 230 corresponding to the marking design. The mask member 23 is formed of, for example, metal and has a thickness that prevents laser light from passing through. In the example shown in FIG. 3 , the design pattern 230 corresponding to the barcode is formed by multiple transparent regions indicated in black. Each of these transparent regions is formed by a rectangular or linear slit 231 penetrating the mask member 23, allowing incident laser light to pass through. As described above, the minimum size of the slit 231 is sufficiently larger than the cross-sectional area of ​​each incident laser beam, and the multiple laser beams emitted from the beam shaping mechanism 22 pass through the slit 231 as multiple laser beams. The mask member 23 according to this embodiment is disposed so that the surface shown in FIG. 3 faces the exit surface of the beam shaping mechanism 22. The mask member 23 may be arranged so as to be in contact with the beam shaping mechanism 22 or may be arranged at a distance from the beam shaping mechanism 22 .

[0047] The projection lens 24 is an optical system component placed between the mask member 23 and the object. The projection lens 24 converges the multiple laser beams emitted from the mask member 23 onto a predetermined area on the side of the PET bottle 1. In the example of FIG. 1 , the projection lens 24 converges the multiple laser beams onto an area measuring 30 mm in length and 10 mm in width on the side of the PET bottle 1. The energy density of the multiple laser beams that reach the side of the PET bottle 1 is 200 mJ / cm. 2 It is preferable that the dose is 400 mJ / cm or more. 2 More preferably, it is 500 mJ / cm or more. 2 More preferably, it is 600 mJ / cm or more. 2It is particularly preferable that the above range is satisfied. However, this range is an example of marking a barcode on a PET bottle 1 using an excimer laser oscillator, and may vary depending on the type of laser, the marking design, and the object to be marked. Each laser beam that reaches the side of the PET bottle 1 eliminates the polyethylene terephthalate on the side of the PET bottle 1, forming fine irregularities on the surface. The areas where the irregularities are formed lose their transparency and turn white due to the diffusion of visible light. This forms a marking area M on the side of the PET bottle 1, displaying the marking design according to the reduced design pattern 230.

[0048] The minute irregularities are irregularities that form a regular pattern and are formed from a plurality of recesses formed corresponding to the flat portions 2200A, 2200B, and 2201B of the beam shaping mechanism 22 or the transmissive region 221, and protrusions surrounding each of the recesses. These irregularities have a size and height difference at the micro level. From the viewpoint of improving the visibility of the marking design, it is preferable that the number of recesses formed per unit area is as large as possible.

[0049] 4 is a flowchart showing an example of the flow of each step when carrying out the above-described method for producing marked products.

[0050] First, a mask member 23 is prepared on which a design pattern 230 corresponding to the desired marking design is formed (step S1). The size of the design pattern 230 does not need to match the actual size of the marking to be formed on the object, and can be set to a size that takes into account reduction by the projection lens 24.

[0051] Next, the beam shaping mechanism 22 and the mask member 23 are arranged in this order between the laser oscillator 20 and the conveying line 10, more specifically, between the field lens 21 and the projection lens 24 (step S2). Note that the laser oscillator 20, field lens 21, beam shaping mechanism 22, mask member 23, and projection lens 24 do not necessarily need to be arranged in a straight line, and the order in which these components are arranged refers to the order in which the laser light generated by the laser oscillator 20 passes through them. The conveying line 10 is preferably arranged so that the traveling direction of the laser light generated by the laser oscillator 20 and passed through the beam shaping mechanism 22 and mask member 23 is perpendicular to the area on the conveying line 10 that will become the marking area M of the PET bottle 1.

[0052] Next, the conveyance line 10 starts conveying the plurality of PET bottles 1 (step S3). The conveyance speed may be constant. The frequency of the laser oscillator 20 can be appropriately set in accordance with the conveyance speed.

[0053] Next, marking by the marking device 2 is initiated (step S4). That is, the laser oscillator 20 begins irradiating the PET bottle 1 with laser light while it is being transported. Marking begins, for example, when the PET bottle 1 first passes in front of the projection lens 24. The production system according to this embodiment is equipped with an object detection sensor (not shown). The object detection sensor is configured to output a detection signal to a controller (not shown) that controls the operation of the marking device 2 upon detecting that each PET bottle 1 has approached the projection lens 24. Based on the detection signal, the controller controls the timing at which the laser oscillator 20 irradiates each PET bottle 1 with laser light. The object detection sensor is not particularly limited, and any type of sensor, such as a photoelectric sensor, laser sensor, ultrasonic sensor, or image sensor, can be used. Furthermore, the location at which the object detection sensor is installed is also not particularly limited.

[0054] Thereafter, one shot of laser light is repeatedly applied in the same manner to each of the PET bottles 1 that successively pass in front of the projection lens 24. This repetitive marking process stops if a certain period of time continues in which no new PET bottles 1 are detected by the object detection sensor, for example, because the conveying line 10 has stopped or there are no more PET bottles 1 passing in front of the projection lens 24 on the conveying line 10.

[0055] 5 to 9 are diagrams showing examples of an object to be laser marked and a marked product produced by applying laser marking to the object. The objects are PET bottles 11A to 11E, each having a transparent resin container body 114A to 114E. The container bodies 114A to 114E include bottom portions 110A to 110E, side portions 111A to 111E extending upward from the outer periphery of the bottom portions 110A to 110E, shoulder portions 112A to 112E, and mouth portions 113A to 113E. The mouth portions 113A to 113E define upper openings. The shoulder portions 112A to 112E are continuous with the upper ends of the side portions 111A to 111E and the lower ends of the mouth portions 113A to 113E, and form inclined or curved surfaces that are inclined relative to the vertical direction.

[0056] As shown in Figure 5, a recessed portion 115A extending along the entire periphery is formed in the side surface 111A of the PET bottle 11A. The recessed portion 115A is a portion of the side surface 111A that is recessed more inwardly into the container body 114A than the remaining portions of the side surface 111A. In other words, the side surface 111A defines the peripheral edges 1151A, 1152A and the bottom surface 1150A of the recessed portion 115A. The bottom surface 1150A is located at the innermost position of the inner surface of the recessed portion 115A and faces the exterior space of the container body 114A. For example, by laser marking the bottom surface 1150A of the recessed portion 115A of the PET bottle 11A using the above-described method for producing a marked product, a marked PET bottle 1A is obtained, with a marking area M formed on the bottom surface 1150A. In this case, in the above-described method for producing a marked product, irradiating the PET bottle 11A with a laser beam during transportation includes irradiating the bottom surface 1150A with the laser beam. The marking area M includes a collection of multiple recesses or multiple protrusions formed by laser marks, and displays a predetermined design. The minimum depth of the recesses 115A (the distance from the periphery 1151A or periphery 1152A to the bottom surface 1150A) is not particularly limited, and may be any depth such that the protrusions of the marking area M do not reach the periphery 1151A or periphery 1152A.

[0057] As shown in Figure 6, a recess 115B is formed in the side surface 111B of the PET bottle 11B, extending from the outer peripheral edge of the bottom surface 110B to the upper end of the side surface 111B (the boundary with the shoulder 112B). The recess 115B is a portion of the side surface 111B that is recessed more inwardly into the container body 114B than the other portions. In other words, the side surface 111B defines the peripheral edges 1151B, 1152B of the recess 115B and the bottom surface 1150B. The bottom surface 1150B faces the external space of the container body 114B and is the innermost surface of the recess 115B, and is preferably flat. For example, by applying laser marking to the bottom surface 1150B of a PET bottle 11B using the above-described method for producing a marked product, a PET bottle 1B is obtained as a marked product, with a marking area M formed on the bottom surface 1150B. In this case, in the above-described method for producing a marked product, irradiating the PET bottle 11B with laser light during transport includes irradiating the bottom surface 1150B with laser light. The marking area M comprises a collection of multiple recesses or multiple protrusions formed by laser marks, and displays a predetermined design. The minimum depth of the recesses 115B (the distance from the periphery 1151B or periphery 1152B to the bottom surface 1150B) is not particularly limited, and may be any depth such that the protrusions of the marking area M do not reach the periphery 1151B or periphery 1152B.

[0058] As shown in Figure 7, a recessed portion 115C is formed in the side surface 111C of the PET bottle 11C. The recessed portion 115C is a portion of the side surface 111C that is recessed more inwardly into the container body 114C than the other portions of the side surface 111C. In other words, the side surface 111C defines the periphery 1151C of the recessed portion 115C and the bottom surface 1150C. The bottom surface 1150C faces the external space of the container body 114C and is the innermost surface of the recessed portion 115C, and is preferably a flat surface. For example, by laser marking the bottom surface 1150C of the PET bottle 11C using the above-described method for producing a marked product, a marked PET bottle 1C is obtained, with a marking area M formed on the bottom surface 1150C. In this case, in the method for producing a marked product, irradiating the PET bottle 11C with laser light during transportation includes irradiating the bottom surface 1150C with laser light. Note that in FIG. 7, the PET bottle 11C is shown as viewed from the side of the recessed portion 115C, and the PET bottle 1C is shown as viewed from the front of the recessed portion 115C, with the recessed portion 115C being rectangular in front view. The marking area M includes a collection of multiple recesses or multiple protrusions formed by laser marks and displays a predetermined design. The minimum depth of the recessed portion 115C (the distance from the periphery 1151C to the bottom surface 1150C) is not particularly limited, as long as the protrusions of the marking area M do not reach the periphery 1151C.

[0059] As shown in FIG. 8 , the side surface 111D of the PET bottle 11D has a protrusion 115D that protrudes from its outer surface. The shape of the protrusion 115D is not particularly limited, as long as it protrudes outward from the container body 114D beyond the remaining surrounding areas. For example, by performing laser marking near the protrusion 115D of the PET bottle 11D using the above-described method for producing a marked product, a marked PET bottle 1D is obtained with a marking area M formed near the protrusion 115D. In this case, in the above-described method for producing a marked product, irradiating the PET bottle 11D with laser light during transport includes irradiating the PET bottle 11D with laser light near the protrusion 115D. Note that FIG. 8 shows the PET bottle 11D as viewed from the side of the protrusion 115D, and the PET bottle 1D as viewed from the front of the protrusion 115D. The marking area M is formed, for example, below the protrusion 115D. The maximum height of the protrusion 115D relative to the outer surface of the side surface portion 111D is not particularly limited as long as it protrudes outward beyond the convex portion of the marking region M. It is preferable that the marking region M be formed as close to the periphery of the protrusion 115D as possible.

[0060] As shown in Figure 9, the side surface 111E of the PET bottle 11E has multiple protrusions 115E protruding from its outer surface. The shape of each protrusion 115E is not particularly limited, as long as it protrudes outward from the container body 114D from the rest of the surrounding area. While Figure 9 shows six protrusions 115E arranged in a generally rectangular shape, the number and arrangement of the protrusions 115E are not particularly limited, as long as there are two or more protrusions 115E spaced apart at regular intervals. For example, by laser marking the area surrounded by the multiple protrusions 115E of the PET bottle 11E using the above-described method for producing a marked product, a PET bottle 1E is obtained as a marked product, with a marking area M formed in the area surrounded by the multiple protrusions 115E. In this case, in the method for producing a marked product, irradiating the PET bottle 11E with laser light during transportation includes irradiating the area surrounded by the plurality of protrusions 115E of the PET bottle 11E or the area between two protrusions 115E. The maximum height of each protrusion 115E based on the outer surface of the side surface 111E is not particularly limited, as long as it protrudes outward beyond the convex portion of the marking area M.

[0061] <4. Features> (1) According to the method for producing marked products of the above embodiment, the beam shaping mechanism 22 can form multiple laser beams corresponding to the dot pattern formed when laser light is repeatedly irradiated along a predetermined scanning line. In other words, a desired marking can be applied to a single object with a single shot of laser light, making it easy to mark objects moving at high speed without slowing them down. Other methods for improving the speed of laser marking include installing multiple laser oscillators or splitting the laser beam onto multiple objects to simultaneously mark multiple objects. However, these methods have drawbacks, such as the increased size and cost of the equipment, and also have limitations in achieving a marking speed commensurate with the transport speed of objects on a typical transport line. In contrast, the method for producing marked products of the present embodiment has an irradiation time of approximately 10 to 30 nanoseconds per shot, making it easy to accommodate even high-speed object transport speeds. Furthermore, when the irradiation time for one shot is within the above range, the distance the object moves during laser light irradiation can be made sufficiently small compared to the dimensions of the regular uneven shape representing the marking design, thereby avoiding a situation in which the regular uneven shape is not properly formed on the object due to the influence of the conveying speed.

[0062] (2) According to the method for producing a marked product according to the above embodiment, the multiple laser beams that have passed through the beam shaping mechanism 22 are shaped into a desired design by the mask member 23. Therefore, by preparing a mask member 23 on which a design pattern corresponding to the desired design is formed, the marking design can be easily changed.

[0063] (3) According to the method for producing marked products of the above embodiment, multiple laser beams are converged by the projection lens 24, so marking can be performed according to the size of the object to be marked.

[0064] (4) Figures 10A-10C are diagrams illustrating the differences in the behavior of incident laser light, using the optical element 22A, optical element 22B, and photomask 22C according to the above-described embodiment as examples. As can be seen from Figures 10A and 10C, unlike the beam shaping mechanism 22, which has a shielding region made of a laser light-reflecting material, such as the photomask 22C, the optical element 22A forms a laser beam corresponding to a dot pattern by shaping the intensity distribution of the incident laser light according to a predetermined pattern. Therefore, compared to the photomask 22C, the incident laser light can be more effectively utilized for marking. Furthermore, while the material forming the shielding region of the photomask 22C may be deteriorated by reflecting the laser light, the flat portion 2200A and the curved portion 2201A of the optical element 22A are both made of a material that transmits laser light, so there is no risk of deterioration. The advantages of the optical element 22A described above also apply to the optical element 22B.

[0065] (5) As described above, the marking area M formed by irradiation with laser light has a fine uneven pattern including a collection of multiple minute recesses or a collection of multiple minute protrusions formed by removing material from the surface of an object. The fine uneven pattern is easily destroyed by contact with other objects. In particular, if the marked product is a PET bottle 1, the uneven pattern may be destroyed by contact with other objects during distribution, resulting in problems such as the barcode in the marking area M not being correctly read by a barcode reader. However, in the PET bottles 1A-1C, the marking area M is formed on the inner surface of the recessed portions 115A-115C, making it less likely to come into contact with other objects and less likely to destroy the uneven pattern in the marking area M. Furthermore, in the PET bottle 1D, the marking area M is formed near the protrusion 115D, which prevents the marking area M from coming into contact with other objects, making the uneven pattern in the marking area M less likely to be destroyed. In the PET bottle 1E, the marking area M is formed in an area surrounded by multiple protrusions 115E, which prevents the marking area M from coming into contact with other objects, and prevents the uneven pattern of the marking area M from being distorted. Therefore, the PET bottles 1A to 1E have the effect of maintaining the visibility of the design displayed in the marking area M and the readability of the information code using a code reader or the like.

[0066] (6) In PET bottle 11A, recess 115A extends along the entire circumference. This allows laser light to be irradiated onto bottom surface 1150A of recess 115A, regardless of the rotational position of PET bottle 11A relative to laser oscillator 20 during transport on conveyor line 10. Furthermore, bottom surfaces 1150B and 1150C of PET bottles 11B and 11C can be formed as flat surfaces. This eliminates the difference in focal length depending on the position at which the laser light is irradiated, regardless of the shape of side surfaces 111B and 111C, allowing for more accurate display of the design in marking area M. In PET bottles 11D and 11E, conveyor line 10 is configured to contact protrusions 115D and 115E at a predetermined position, allowing it to be used as a mechanism for automatically adjusting the rotational position of PET bottles 11D and 11E before passing through laser oscillator 20.

[0067] 5. Modifications Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention. For example, the following modifications are possible. Furthermore, the gist of the following modifications can be combined as appropriate.

[0068] (1) The field lens 21 and the projection lens 24 may each be composed of a single lens, or may each include multiple lenses.

[0069] (2) The photomask 22C is not limited to the one having the square-shaped transparent region 221 formed therein, as in the above embodiment. Examples of other patterns of the photomask 22C formed with transparent and shielding regions include the patterns shown in FIGS. 11A to 11D. FIG. 11A shows an example of a pattern combining a larger square-shaped transparent region 221a and a smaller square-shaped transparent region 221b. FIG. 11B shows an example of a pattern in which regular hexagonal transparent regions 221c are regularly arranged. FIG. 11C shows an example of a pattern in which a smaller square-shaped transparent region 221d is further arranged between two adjacent transparent regions 221a in the example of FIG. 11A, forming a continuous larger transparent region and a smaller transparent region 221b. FIG. 11D shows an example of a pattern in which square-shaped shielding regions 222a and 222b are formed inside and outside a square-shaped transparent region 221e, respectively. The above-described examples of the configuration of the pattern formed by the transmitting region and the blocking region can be applied not only to the photomask 22C but also to a member in which the blocking region is formed by a high-reflection mirror.

[0070] (3) The mask member 23 is not limited to having the slits 231 formed therein, as in the above embodiment. For example, similar to the photomask 22C, a chromium film may be laminated in a predetermined pattern on one side of a synthetic quartz substrate to form a shielding region that blocks laser light and a transparent region that transmits laser light. Alternatively, as described in the configuration example of the beam shaping mechanism 22, the mask member 23 may be formed of a member in which through-holes corresponding to the design pattern 230 are formed in a high-reflection mirror, or a transparent hole formed of a material that transmits laser light. Furthermore, the mask member 23 may be formed of a member in which a high-reflection mirror is laminated on one side of a laser-transmitting substrate. In this case, the portion of the substrate on which the high-reflection mirror is not laminated corresponds to the design pattern 230. However, the design pattern 230 corresponding to the marking design may be formed of the entire transparent region (or the entire slit) that transmits laser light, or the entire shielding region (or a portion without a slit) that blocks laser light. When the design pattern 230 is formed over the entire shielding area or in the area where no slits are formed, the unprocessed area on the object surface surrounded by the area where fine irregularities are formed becomes the marking design. From the viewpoint of durability and the ability to form the design pattern 230 with a higher degree of freedom, the mask member 23 is preferably one in which a chrome film is laminated on a base material, one in which a high-reflection mirror has through holes, or one in which a high-reflection mirror is laminated on a base material.

[0071] (4) The above-described exemplary configurations of the beam shaping mechanism 22 (optical element 22A, optical element 22B, photomask 22C, a high-reflection mirror with through-holes or transmission holes formed therein, and a high-reflection mirror laminated on a substrate) and the mask member 23 (one with a slit 231, one with a chromium film laminated on a substrate, a high-reflection mirror with through-holes or transmission holes formed therein, and a high-reflection mirror laminated on a substrate) can be freely combined. The beam shaping mechanism 22 and the mask member 23 may also be integrally formed as a single component. More specifically, a regular pattern of a chromium film laminated on one side of a synthetic quartz substrate may serve both as a pattern for regularly dividing the laser light and as a design pattern. In another example, a regular pattern formed by a high-reflection mirror and through-holes or transmission holes, or a high-reflection mirror and a substrate, may serve both as a pattern for regularly dividing the laser light and as a design pattern. In other words, dividing the laser light by regular paths and transmitting the laser light in accordance with the design pattern 230 may be performed in the same layer. When the beam shaping mechanism 22 and the mask member 23 are configured as a single member, in the above-described method for producing a marked product, "arranging a beam shaping mechanism that forms a regular intensity distribution of the laser light" and "arranging a mask member on which a design pattern is formed" are performed simultaneously.

[0072] (5) The positional relationship between the beam shaping mechanism 22 and the mask member 23 is not limited to that described above. For example, the mask member 23 can be disposed between the projection lens 24 and the conveying line 10 (object). Furthermore, the mask member 23 can be disposed between the laser oscillator 20 and the beam shaping mechanism 22. However, from the viewpoint of forming the marking design on the object more clearly, it is preferable that the beam shaping mechanism 22 and the mask member 23 be disposed with as little space between them as possible or that they be configured as an integrated unit.

[0073] (6) The shapes of the PET bottle 1, PET bottles 11A-11E, and PET bottles 1A-1E may be modified as needed. For example, the side walls 111A-111E may be rectangular, and the shoulders 112A-112E may be horizontal. Furthermore, these may be primarily composed of a thermoplastic resin other than polyethylene terephthalate, and may be opaque, translucent, or colored. The recess 115A may be formed in the shoulder 112A rather than the side wall 111A. In other words, in the PET bottle 1A, the marking area M may be formed in the shoulder 112A. The bottom surface 1150A of the recess 115A may be formed as a flat surface. The recess 115B does not have to extend to the top of the side wall 111B, and may extend to the shoulder 112B. The recess 115B may be formed in the shoulder 112A. That is, in PET bottle 1B, marking area M may be formed on shoulder 112B. Bottom surface 1150B of recess 115B may be formed as a curved surface. Recess 115C may be formed on shoulder 112C or bottom surface 110C. That is, in PET bottle 1C, marking area M may be formed on shoulder 112C or bottom surface 110C. Bottom surface 1150C of recess 115C may be formed as a curved surface. The shape of recess 115C in a front view may also be modified as appropriate. Note that in recesses 115A-111C, marking area M only needs to be formed on the inner surface, and does not necessarily have to be formed on bottom surfaces 1150A-1150C. Protrusion 115D may be, for example, an endless ring, and marking area M may be formed within the area surrounded by protrusion 115D. Protrusion 115D may be formed on shoulder 112D or bottom 110D. That is, in PET bottle 1D, marking area M may be formed on shoulder 112D or bottom 110D. Protrusion 115E may be formed on shoulder 112E or bottom 110E. That is, in PET bottle 1E, marking area M may be formed on shoulder 112E or bottom 110E. At least two of recesses 115A-111C, protrusion 115D, and protrusion 115E may be formed on the same resin container.

[0074] (7) The order of steps S1 to S4 in the above flowchart can be changed as appropriate.

[0075] (8) The positional relationship between the conveying line 10 and the marking device 2 can be changed as appropriate. That is, the configuration of the production system is not limited to that of the above embodiment and can be changed as appropriate. For example, the marking device 2 may be configured to irradiate the object with laser light from above or below the conveying line 10. The orientation of the object when conveyed along the conveying line 10 is not particularly limited. For example, in the case of PET bottles 1, the orientation can be changed as appropriate, such as conveying the object with the side of the container body facing upward. The conveying line 10 is not limited to a belt conveyor that conveys objects, but may also be a conveyor that conveys objects with buckets or flights, a conveyor that conveys objects with a suspender, or the like. Furthermore, the object detection sensor described in the above embodiment may be omitted, and the timing of laser light irradiation and the timing of stopping the irradiation may be controlled by other means.

[0076] Examples of the present disclosure will be described below, but the present disclosure is not limited to the following examples.

[0077] 12 was prepared, and a barcode marking measuring 13 mm in length and 30 mm in width was formed on the surface of a sample 4 using each of the beam shaping mechanisms 35 according to Examples 1 to 4. In addition to the beam shaping mechanism 35, the marking device 3 was equipped with an excimer laser oscillator 30, a beam shaper 31, a beam homogenizer 32, a collimator lens 33, a field lens 34, a mask member 36, a projection lens 37, and a sample stage 38. The excimer laser oscillator 30 irradiated laser light with a wavelength of 308 nm for approximately 27 nanoseconds per shot, and the energy density of the laser beam that reached the surface of the sample 4 was 500 mJ / cm per shot. 2The beam shaper 31 and beam homogenizer 32 were constructed of known beam shapers and beam homogenizers, respectively, and were configured to flatten the laser beam generated by the excimer laser oscillator 30 and to homogenize the change in intensity distribution of the beam over time. As shown in FIG. 13, the mask member 36 was a metal plate with slits formed therein corresponding to the quiet zones and spaces of the barcode. The marking device 3 was configured to form a marking of the above size with one shot on the surface of the sample 4 placed on the sample stage 38. The sample 4 was a transparent polyethylene terephthalate plate measuring 100 mm long, 80 mm wide, and 1 mm thick.

[0078] The beam shaping mechanisms 35 according to Examples 1 and 2 were glass plates on which a pattern region 220A similar to the optical element 22A of the above embodiment was formed, but the lengths of one side of the flat portions 2200A were different from each other. The beam shaping mechanisms 35 according to Examples 3 and 4 were glass plates on which a pattern region 220B similar to the optical element 22B of the above embodiment was formed, but the lengths of one side of the flat portions 2200B and 2201B were different from each other. The following Table 1 shows the dimensions of each part of the pattern region according to Examples 1 to 4. The dimensional tolerance was set to ±0.15 μm.

[0079] 13 was prepared, and a barcode marking measuring 13 mm long x 30 mm wide was formed on the surface of another sample 4 (Comparative Example). The marking device 5 was equipped with a UV laser oscillator 50, an X-axis galvanometer scanner 51, a Y-axis galvanometer scanner 52, an Fθ lens 53, and a sample stage 54. The UV laser oscillator 50 emitted laser light with a wavelength of 355 nm under conditions of an output of 3 W and a frequency of 100 kHz, so that the irradiation diameter per shot on the surface of the sample 4 was 30 μm. The energy density of the laser beam reaching the surface of the sample 4 was 5.7 J / cm per shot. 2On the surface of the sample 4, markings were formed in the portions corresponding to the slits in the mask member 36 while controlling the X-axis galvano scanner 51 and the Y-axis galvano scanner 52 so that the laser marks formed by the irradiation of each shot would not overlap each other and would be formed at maximum density.

[0080] <Result 1> The entire markings formed using marking device 3 and the entire markings formed using marking device 5 were observed with the naked eye, and it was confirmed that the intended barcode design was formed using opaque white areas and transparent areas in both markings. Next, the time required to form a marking on sample 4 using marking device 3 and marking device 5 was compared. When marking device 3 was used, a marking was formed with one shot of laser irradiation (approximately 27 nanoseconds) regardless of the beam shaping mechanism 35 of Examples 1 to 4. In contrast, when marking device 5 was used, it took approximately 5.5 seconds to form a marking of the same size and design. This confirmed that using marking device 3 equipped with beam shaping mechanism 35 of Examples 1 to 4, a marking of a predetermined design can be formed sufficiently quickly on an object being transported at a constant speed.

[0081] Furthermore, for the markings formed using the beam shaping mechanism 35 of Examples 1 to 4, the processing depth (μm) was measured using a 3D measuring laser microscope (OLS, manufactured by Olympus Corporation), and the reflection value (%) of the marked barcode was measured using a barcode verifier (STRATIX Laser Xminer). The results are shown in Table 2 below. The reflection value (%) indicates how much incident infrared light is reflected in each quiet zone and each space of the barcode. If the minimum value is 80% or higher, it can be said that there is no problem with reading by a barcode reader. The values ​​in Table 2 are the average values ​​for each quiet zone and each space. From Table 2, it was confirmed that although there were differences in processing depth between Examples 1 to 4, markings could be formed to a degree that did not interfere with reading as a barcode.

[0082] For reference, Fig. 15 shows an image captured by an electron microscope of a portion of a marking (a portion corresponding to a quiet zone of a barcode) formed using the marking device 3 equipped with the beam shaping mechanism 35 according to Example 1. As shown in Fig. 15, on the surface of the sample 4, a regular pattern is formed of areas where the laser light reaches and turns white, and areas where the laser light does not reach and remains transparent. This confirms that the beam shaping mechanism 35 has formed a regular intensity distribution of the laser light corresponding to the pattern formed by the flat and curved portions.

[0083] <Experiment 2> Markings were formed on the surface of sample 4 under the same conditions as in Experiment 1, except that the energy density of the laser light was changed (Examples 5 to 8). The energy density was set to the following conditions 1 to 4. Condition 1: 200 mJ / cm 2 Condition 2: 400mJ / cm 2 Condition 3: 600mJ / cm 2 Condition 4: 800mJ / cm 2 For each of the energy densities under conditions 1 to 4, the processing depth (μm) of the formed marking and the reflection value (%) of the marked barcode were measured in the same manner as in Experiment 1.

[0084] <Result 2> The results are shown in the following Table 3. For reference, images of markings formed at each energy density taken with an electron microscope are shown in Figures 16A to 16D.

[0085] From the results in Table 3, it was found that the higher the energy density, the deeper the processing depth. It was also found that the deeper the processing depth, the more likely protrusions are to be formed on the surface of Sample 4, as shown in Figures 16A to 16D. When more or larger protrusions are formed, the contrast between the white and transparent parts on the surface of Sample 4 tends to become stronger. In addition, the reflectance value was 0.01 at an energy density of 200 mJ / cm 2 However, it can be said that it is sufficiently high, 400 mJ / cm 2 It was confirmed that the value becomes higher when the value is above this level.

[0086] 1, 1A to 1E, 11A to 11E PET bottle 2 Marking device 10 Conveyor line 20 Laser oscillator 21 Field lens 22 Beam shaping mechanism 22A Optical member 22B Optical member 22C Photomask 23 Mask member 24 Projection lens 220 Surface 220A, 220B Pattern area 221, 221a to e Transmission area 222, 222a, 222b Shielding area 230 Design pattern 231 Slit 2200A Flat portion 2201A Curved portion 2200B, 2201B Flat portion 2202B Curved portion

Claims

1. A method for producing marked products comprising: transporting an object along a transport path; disposing, between a laser oscillator and the transport path, a beam shaping mechanism for branching a laser beam generated from the laser oscillator according to a predetermined pattern or for blocking a portion of the laser beam according to a predetermined pattern, thereby forming a regular intensity distribution of the laser beam; disposing, between the laser oscillator and the transport path, a mask member having a design pattern formed thereon for transmitting or blocking the laser beam corresponding to a marking design to be performed on the object; generating the laser beam from the laser oscillator, and irradiating the object being transported with the laser beam that has passed through the beam shaping mechanism and the mask member; wherein the traveling direction of the laser beam emitted from the beam shaping mechanism is unidirectional, which is the same as the traveling direction of the laser beam incident on the beam shaping mechanism.

2. The method for producing a marked product according to claim 1, wherein the laser oscillator is an excimer laser oscillator, a UV laser oscillator, a CO2 laser oscillator, or a YAG laser oscillator.

3. A method for producing a marked product according to claim 1 or 2, wherein the beam shaping mechanism is an optical element made of a material that transmits the laser light and has a regular pattern consisting of flat portions that transmit the laser light and curved portions adjacent to the flat portions that branch the laser light to the adjacent flat portions.

4. A method for producing a marked product according to claim 1 or 2, wherein the beam shaping mechanism is a photomask having a regular pattern consisting of blocking areas that block the laser light and transparent areas that transmit the laser light.

5. A method for producing a marked product as described in claim 1 or 2, wherein the beam shaping mechanism is a member on which a regular pattern is formed consisting of shielding areas that block the laser light and transparent areas that transmit the laser light, and the shielding areas are formed of a highly reflective mirror.

6. A method for producing a marked product as described in claim 1 or 2, wherein the mask member is a photomask on which the design pattern is formed, the photomask comprising a blocking area that blocks the laser light and a transparent area that transmits the laser light.

7. A method for producing a marked product as described in claim 1 or 2, wherein the mask member is a member on which the design pattern is formed, the design pattern consisting of a shielding area that blocks the laser light and a transparent area that transmits the laser light, and the shielding area is formed of a highly reflective mirror.

8. The method for producing a marked product according to claim 1 or 2, wherein the beam shaping mechanism and the mask member are integrally configured.

9. A method for producing a marked product as described in claim 1 or 2, wherein the object comprises a resin container body including a bottom portion, a side portion extending upward from the outer periphery of the bottom portion, a mouth portion defining an upper opening, and a shoulder portion continuous with the side portion and the mouth portion, and a recess is formed in at least one of the bottom portion, side portion, and shoulder portion, and irradiating the object being transported with laser light that has passed through the beam shaping mechanism and the mask member includes irradiating the laser light onto the inner surface of the recess portion.

10. The method for producing a marked product according to claim 9, wherein the recess is formed in the side surface.

11. The method for producing a marked product according to claim 9, wherein the recessed portion extends around the entire periphery of the side portion.

12. The method for producing a marked product according to claim 10, wherein the recessed portion extends from the outer peripheral edge of the bottom portion to the upper end of the side portion.

13. A method for producing a marked product as described in claim 9, wherein the inner surface of the recessed portion forms a flat surface facing the external space of the container body at its innermost position, and irradiating the inner surface of the recessed portion with the laser light includes irradiating the flat surface with the laser light.

14. A method for producing a marked product as described in claim 1 or 2, wherein the object comprises a resin container body including a bottom portion, a side portion extending upward from the outer periphery of the bottom portion, a mouth portion defining an upper opening, and a shoulder portion continuous with the side portion and the mouth portion, and at least one of the bottom portion, side portion and shoulder portion has a protrusion that protrudes from the outer surface, and irradiating the object being transported with laser light that has passed through the beam shaping mechanism and the mask member includes irradiating the laser light near the protrusion.

Images