JP2012011688A - Method and apparatus for laser color marking - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for laser color marking which are suitable for the fixing of full colors while suppressing the deformation of a base material to be subjected to marking.SOLUTION: Ink containing a near-infrared light absorbent, an organic solvent into which at least the near-infrared light absorbent is dissolved and dye is applied onto the face to be subjected to marking in a resin processed product, the applied part in the ink is irradiated with a near-infrared laser beam to heat the near-infrared light absorbent, thus the dye is fixed to the face to be subjected to marking. For this purpose, the apparatus for laser color marking includes: an ink jet head 2 jetting the ink containing the near-infrared light absorbent and dye; and a near-infrared laser irradiation device for irradiating the applied part with the near-infrared laser beam so that the near-infrared light absorbent absorbs the near-infrared laser beam and is heated.

Description

  The present invention relates to a method and apparatus for marking multi-colored markings on the surface of a workpiece using laser light.

  2. Description of the Related Art Conventionally, a laser color marking method is widely known in which a surface of a workpiece is damaged or thermally deformed by laser light and permanent markings that cannot be erased are written in real time.

  However, this type of laser color marking method requires a large-sized laser irradiation device with a large output and an expensive galvano scanner or an XY stage, which makes the device expensive. In addition, this type of laser color marking method has a major limitation in that it can be written in a single color and cannot be multicolored.

  Therefore, in order to realize downsizing and simplification of the apparatus, for example, an infrared absorber is applied so as to form a predetermined pattern on the surface of the resin, and irradiation is performed so that the applied infrared absorber is fixed on the surface of the resin. Under the conditions, a method has been proposed in which a laser head irradiates a resin surface with a laser beam having a wavelength in the infrared region to fix an infrared absorber on the resin surface (Patent Document 1).

  However, when the infrared absorbing material is applied and fixed with a laser as described above, the infrared absorbing agent generates heat by absorbing the energy of the laser beam, and as a result, most of the infrared absorbing agent scatters on the substrate. It was difficult to develop color, and there was a bias in color development, from blue to green, and full color was impossible.

  As a technology relating to laser color marking that enables full colorization, a colorant-containing layer containing a colorant in a dispersed state is formed on the surface of a base material made of a thermoplastic material, and this colorant-containing layer has a predetermined marking. Irradiate laser light along the shape, soften the substrate of the portion irradiated with the laser light, and by mixing the colorant of the colorant-containing layer in the softened portion, the surface of the substrate A method of expressing a predetermined marking shape (Patent Document 2), or after putting a disperse dye on a cloth made of a thermoplastic synthetic resin, irradiating a laser beam in a selective absorption wavelength region of the thermoplastic synthetic fiber. For example, a dyeing method (Patent Document 3) is known in which an irradiated portion is heated to disperse and dye disperse dyes inside a fiber simultaneously with drying.

  However, since the marking methods disclosed in Patent Documents 1 to 3 are all based on heating the substrate with laser light, the substrate may be deformed.

  Therefore, by applying a sublimable dye or ink containing this to the object to be dyed (synthetic fibers, etc.) and irradiating the dyed object with laser light having a wavelength in the visible light range, the laser light is absorbed by the dye, not the object to be dyed. A coloring method has been proposed in which the substrate to be dyed is not damaged (Patent Document 4).

JP 2008-155232 A JP 2008-12869 A JP 59-106589 A JP 2006-249597 A

  However, a blue laser having a wavelength in the visible light region absorbs many dyes, but the output of the laser is as small as several hundred mW, and the marking process is limited in terms of speeding up and size increase. Further, a green laser having a wavelength in the visible light region can provide a large output, but a yellow dye has a small absorption in the green band (490 to 575 nm), is unsuitable for a yellow dye, and is not suitable for full-color fixing.

  The main object of the present invention is to provide a laser color marking method and apparatus suitable for full-color fixing while suppressing deformation of a substrate on which marking is performed.

  In order to achieve the above object, a laser color marking method according to the present invention includes a near-infrared absorber liquid, an organic solvent that dissolves at least the near-infrared absorber, and an ink containing a dye. Applying to the surface, and irradiating a near-infrared laser beam to the ink application portion, and heating the near-infrared absorber to fix the dye on the surface to be marked. And The ink preferably contains 0.3 to 3% by weight of the near infrared absorber. In addition, near infrared rays are electromagnetic waves with a wavelength range of 0.76 to 2.5 μm. In addition, the dye means a dye having the maximum absorption in the visible light region.

  In another embodiment, the laser color marking method according to the present invention includes a step of applying a dye ink to a surface to be marked of a resin processed product, and a near-infrared absorber in an organic solvent on the dye ink application portion. Applying the dissolved near-infrared absorbent solution, and irradiating the application part of the dye ink to which the near-infrared absorbent solution is applied with near-infrared laser light, and causing the near-infrared absorbent to generate heat Fixing the dye on the surface to be marked.

  In order to achieve the above object, a laser color marking device according to the present invention includes an inkjet head that ejects ink containing a near-infrared absorber and a dye, and the near-infrared absorber absorbs the near-infrared absorber. And a near-infrared laser irradiation device that irradiates near-infrared laser light for causing the agent to generate heat.

  In another form, the laser color marking device according to the present invention is an inkjet head that ejects a dye ink, an ejection device that ejects a near-infrared absorbent solution, and the near-infrared absorber that absorbs the near-infrared light. And a near-infrared laser irradiation device that irradiates near-infrared laser light for generating heat in the absorbent. In this case, it is preferable that the inkjet head and the ejection device are arranged in parallel.

  According to the present invention, since dye fixation (dyeing) occurs due to absorption heat generation of the near infrared absorber, there is no limitation on the dye, and full-color printing can be performed. In addition, since the resin material generally has little absorption of near infrared rays, even if the resin processed product is irradiated with a near infrared laser, the entire shape of the resin processed product to be marked does not deform.

FIG. 1 is a side view schematically showing an embodiment of a laser marking device according to the present invention. It is a front view of the laser marking apparatus of FIG. It is a graph which shows the spectral characteristics of this invention implementation goods. It is a graph which shows the spectral characteristic of a comparative example. It is the photograph which image | photographed the implementation goods which gave the laser color marking by this invention.

  The form for implementing this invention is demonstrated below.

  In the laser color marking method according to the present invention, an ink containing a near-infrared absorber liquid, at least an organic solvent for dissolving the near-infrared absorber, and a dye is applied to a resin-made marking surface. Infrared laser light is applied to the ink application portion, and the near-infrared absorber is heated to fix the dye on the resin marking surface.

  In the present invention, the object to be subjected to laser color marking is a resin processed product, and in particular, a thermoplastic resin processed product. As the thermoplastic resin, general-purpose plastics and semi-general-purpose plastics as well as engineering plastics can be used, and are not particularly limited. For example, polyethylene, polypropylene, polymethylpentene, polybutene, crystalline polybutadiene, Polystyrene, polybutadiene, styrene butadiene resin, polyvinyl chloride, polyvinyl acetate, polyvinylidene chloride, ethylene vinyl acetate copolymer (EVA, AS, ABS, ionomer, AAS, ACS), polymethyl methacrylate (acrylic), polyacetal (poly) Oxymethylene), polyamide, polycarbonate, polyphenylene ether, polyethylene terephthalate, polybutylene terephthalate, polyarylate (U polymer), polystyrene, polyether Rusuruhon, polyimide, polyamideimide, polyphenylene sulfide, polyoxybenzoyl, polyether ether ketone, polyetherimide, liquid crystal polyester, cellulose acetate, cellulose butyrate, cellophane, celluloid, and the like can be exemplified a thermoplastic elastomer. These resins have little absorption in the near infrared region.

  Near-infrared absorbers have a maximum absorption wavelength in the wavelength range of 760 to 1600 nm, amiumum compound (main absorption wavelength 1 μm), diimonium compound (main absorption wavelength: 1.1 μm), cyanine compound (main absorption wavelength: 0.8 [mu] m), polymethine compounds (main absorption wavelength: 0.8 [mu] m), nickel dithiol compounds, phthalocyanine compounds, and the like can be used. When these are classified by main absorption wavelengths, they are about 0.8 [mu] m and about 1 [mu] m. It is a seed.

  The near-infrared absorber as described above can be dissolved in an organic solvent and mixed with a commercially available sublimable dye ink to prepare the necessary ink. As such an organic solvent, 2-methoxyethanol, methanol, ethanol, isopropyl alcohol, butanol, and the like, an alcohol-based organic solvent that has little influence on a processed resin product can be suitably used, and one of these organic solvents or Two or more kinds can be used according to the kind of near-infrared absorber and the kind of board | substrate (resin processed goods). Depending on the application, acetone, N, N-dimethylformamide, methylene chloride, acetonitrile, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, tetrahydrofuran, ethyl acetate, toluene and the like can be used.

  The blending ratio of the near infrared absorber, the organic solvent, and the sublimable dye ink is preferably such that the near infrared absorber is 0.3 to 3% by weight and the dye is 5 to 15% by weight. Since a certain percentage of dye is contained in commercially available sublimable dye ink, blending of sublimable dye ink so that the dye is in the above range according to the amount of dye contained in the dye ink. The percentage is determined.

  When the blending ratio of the near-infrared absorber is less than 0.5% by weight, there is a tendency that the fixing of the dye is insufficient due to insufficient calorific value due to laser light absorption, and the blending ratio of the near-infrared absorbing agent is 3%. If it exceeds 50%, the amount of heat generation is excessive, and the dye for contributing to color development tends to evaporate, and the solubility of the near-infrared absorber in the organic solvent tends to be low, which is not preferable.

  If the blending ratio of the dye is less than 5% by weight, the ink tends to be thin and sufficient color development tends not to be obtained. If the blending ratio of the dye exceeds 15% by weight, the dye tends to be difficult to dissolve. On the other hand, it is possible to dye sufficiently even at a blending ratio of around 10% by weight.

  As the commercially available sublimable dye ink, commercially available dye inks such as cyan, magenta, yellow, black, and other ink-jet inks can be used. The dyes contained in the commercial dye inks used are dyes with little or no absorption in the near-infrared region, and are dyed to many types of resins such as acrylic resins, vinyl chloride and polyurethane. Sublimable disperse dyes, naphthol dyes and the like having good properties are preferable, and those having good dyeing properties can be appropriately selected according to the kind of the resin as described above.

  Instead of using a commercially available dye ink, a desired ink can be prepared by dissolving the above dye and a near-infrared absorber in an organic solvent. In this case, the organic solvent of the type described above can be used as the organic solvent. The blending ratio is the same as above.

  The ink prepared as described above is applied with characters, designs, etc. so as to have a predetermined shape on the resin marking surface. As a method of applying the ink to the resin-made marking surface, ink jet printing is preferable, but screen printing and other known application methods can be employed.

  In the above description, the case where an ink containing a near-infrared absorber in advance is applied to the resin marking surface by the ink jet method, but after applying the dye ink to the resin marking surface, A near-infrared absorber can also be applied to the applied dye ink portion. If the near-infrared absorber is applied to a portion other than the dye ink, the base material may be deformed. Therefore, the near-infrared absorber is applied only to the application portion along the application portion of the dye ink. In that case, the near-infrared absorbent can be dissolved in the above-mentioned organic solvent to form a near-infrared absorbent solution, which can be applied by the same spraying method as inkjet, and the near-infrared absorbent liquid is stored in the ink tank of the inkjet head. Then, the near-infrared absorbing agent liquid may be jetted. As the dye ink, in addition to the above-described commercially available dye ink, an ink prepared by dissolving a dye in a solvent can be used, and a near-infrared absorber can be made of the same material and composition as described above. .

  After the ink thus prepared or the near-infrared absorbing agent solution is applied to the resin-made marking surface, the applied portion is irradiated with a near-infrared laser. For irradiation with a near infrared laser, a small and inexpensive near infrared semiconductor laser irradiation device can be used. As the near-infrared semiconductor laser irradiating device, an oscillating laser beam having a wavelength equivalent to or close to the maximum absorption wavelength of the near-infrared absorber can be used. In addition to the semiconductor laser, a fiber laser can also be used.

  1 and 2 are schematic configuration diagrams showing an embodiment of a laser color marking apparatus according to the present invention.

  The laser color marking device 1 includes an inkjet head 2 and a near infrared semiconductor laser irradiation device 3. The laser color marking device 1 further includes a condensing lens 4 as an optical system for condensing the laser oscillated from the near infrared semiconductor laser irradiation device 3 into a beam having a desired shape, and a resin processed product to be laser color marked. The first linear actuator 6, the second linear actuator 7, and the second linear actuator 7 as a drive unit that moves the inkjet head 2 and the near-infrared semiconductor laser irradiation device 3 relative to the installation unit 5. 3 linear actuators 8.

  In the illustrated example, the inkjet head 2 is illustrated as one inkjet head for convenience of illustration, but the black ink head and the toning ink heads such as cyan, yellow, and magenta are arranged in parallel. Can be provided. As the ink jet head 2, a known one can be adopted. The ink tanks of these inkjet heads 2 each contain the above-described ink prepared by mixing a sublimable disperse dye ink with a near infrared absorber and an organic solvent.

  The ink-jet head 2 is connected to the slider 6a of the first linear actuator 6, and is provided so as to be able to reciprocate in the horizontal first direction (X-axis direction). The first linear actuator 6 is installed horizontally on the base 11 by support members 9 and 10. In the illustrated example, the inkjet head 2 is fixed to the lower part of the second linear actuator 7, and the second linear actuator 7 is perpendicular to the slider 6 a of the first linear actuator 6 (Z-axis direction). It is fixed towards.

  A third linear actuator 8 extends on the base 11 in a direction (Y-axis direction) orthogonal to the X-axis direction and the Z-axis direction, and the slider 8a of the third linear actuator 8 is processed. An installation stand for placing the processed resin product is provided.

  Near-infrared semiconductor laser irradiation device 3 is attached to slider 7a of second linear actuator 7 via arms 12a, 12b, 12c, and 12d. In the illustrated example, the near infrared semiconductor laser irradiation device 3 is fixed to a heat sink 13, and a heat radiating fan 14 is further attached to the heat sink 13. An arm 12d is fixed to the heat sink 13, and the arm 12d is attached around the shaft 15 so that the rotation angle can be adjusted. The near infrared semiconductor laser irradiation apparatus 3 can select an arbitrary wavelength in the near infrared region (0.75 to 2.5 μm).

  The condensing lens 4 is attached to the lower part of the arm 12c via the arm 12e. The condensing lens 4 condenses the laser beam oscillated from the near infrared semiconductor laser irradiation device 3 into a desired beam shape. The beam shape can be a spot shape or a line shape.

  The inkjet head 2, the first linear actuator 6, and the third linear actuator 8 are controlled by an external controller (not shown) and should process desired characters, colors, designs, and the like, similar to a commercially available home inkjet printer. It can be driven to print and print on the resin processed product W. That is, while the ink jet head 2 is reciprocated in the X-axis direction by the first linear actuator 6, desired ink is ejected from the ink-jet head 2, and the resin processed product is delivered at a predetermined feed pitch by the third linear actuator 8. Send to. The second linear actuator 7 does not need to be driven during printing and printing, and can be driven to adjust the focal position of the laser beam at the time of initial setting.

  As shown in FIG. 1, the near-infrared semiconductor laser irradiation device 3 has a laser beam center in the vicinity of a predetermined ink landing position P on the resin processed product W and a portion to which ink is applied in advance (ink application) Part). In the example shown in FIG. 1, the center of the laser beam can be directed to a position shifted from the planned ink landing position P by one to several pitches by the feed pitch of the third linear actuator 8.

  By irradiating the laser beam so that the center of the laser beam is positioned at a position K near the ink landing position P, the laser beam can be irradiated to the landed ink within a predetermined time after ink ejection. Before the aggregation starts, the laser beam can be irradiated to give a marking without unevenness. In general, unlike a paper or fiber, a resin processed product does not soak ink, so that the ink is placed on the surface of the resin processed product. In particular, with water-based inks, it takes time to evaporate water. If left as it is, pigment components aggregate and cause color unevenness. Therefore, color marking without color unevenness can be performed by irradiating the laser beam before the pigment component starts to aggregate.

  In the illustrated example, the first linear actuator 6 is configured to be movable in the X direction and the third linear actuator 8 is configured to be movable in the Y direction. However, in other embodiments (not illustrated), the first linear actuator 6 is configured to be movable. The third linear actuator 8 can also be configured to be movable in the X direction while being movable in the Y direction.

  A method for applying laser color marking to a resin processed product using the laser color marking apparatus as described above will be described below.

  First, a resin processed product W to be subjected to laser color marking is installed on a slider 5 as an installation table shown in FIGS. Then, based on a control signal from a control device (not shown), the ink 2a is ejected from the inkjet head 2 onto the surface Wa of the resin processed product W while driving the first linear actuator 6 and the third linear actuator 8. Then, print and print in the desired color.

  In parallel with the ink ejection, the laser beam 3a is irradiated from the near-infrared laser irradiation device 3 to the ink application portion applied to the surface of the resin processed product W.

  When the near-infrared absorber in the ink absorbs the energy of the laser beam and generates heat, the ink is heated to diffuse the dye in the ink inside the surface of the resin processed product 1, and as a result, the resin processed product 1 Color marking is applied to the surface. At this time, the near-infrared absorber evaporates due to heat generation, but the resin processed product and the dye for color development absorb little near infrared light and hardly generate heat. The dye can be fixed on the inner surface of the resin without evaporating.

  By defocusing the laser beam as necessary, it is possible to prevent deformation of the resin processed product due to energy concentration. When the laser beam is defocused and scanned for irradiation, partial overstrike can be performed. That is, when the laser beam is defocused, the energy density in the peripheral portion is lower than the energy density in the central portion, so that the laser beam may be overlaid to compensate for the reduction.

  Further, in order to suppress heat generation inside the resin processed product W, the laser beam to be scanned may be a pulse laser. In this case, the duty ratio of the pulse is preferably 20 to 50%.

  In the above-described embodiment, an example in which a near-infrared absorber is included in all of the ink tanks (only one is shown in the figure for convenience of illustration) of the inkjet head 2 arranged in parallel is shown. In yet another embodiment, although not shown in detail, one of the inkjet heads 2 in which a plurality of heads are arranged in parallel or, if necessary, a plurality of inkjet heads does not put dye ink in the ink tank. The near-infrared absorber liquid which melt | dissolved the near-infrared absorber in the organic solvent can be accommodated. In this case, the inkjet head containing the near-infrared absorbent liquid functions as a near-infrared absorbent liquid ejecting apparatus. By doing so, the dye ink and the near-infrared absorbent liquid are jetted separately, but the near-infrared absorbent liquid is controlled so as to be applied onto the application part of the dye ink. If the near-infrared absorber liquid layer is the lower layer of the dye ink layer, there is a risk of heat deformation of the resin processed product under the near-infrared absorber liquid layer when irradiated with a near-infrared laser. It is.

The features of the present invention will be described more specifically with reference to the following examples. However, the scope of the present invention is not limited to the examples.
Example A cyanine-based near-infrared absorber (Cy-20T manufactured by Nippon Kayaku Co., Ltd.) was dissolved in 2-methoxyethanol to prepare a near-infrared absorber solution having a cyanine-based near-infrared absorber concentration of 2% by weight. 25 parts by weight of the obtained near-infrared absorbent solution was added to 50 parts by weight of sublimable dye ink (Nippon Kayaku Co., Ltd. sublimation transfer ink: cyan) and stirred to prepare cyan ink (C1).

  Similarly, yellow ink (Y1), magenta ink (M1), and black ink (B1) were prepared.

  Printing was performed on a resin plate having a length of 5 cm, a width of 5 cm, and a thickness of 0.2 cm using these inks using the same apparatus as that shown in FIGS. The resin plate was made of polyethylene terephthalate (PET), acrylic, polycarbonate, vinyl chloride, polypropylene, and ABS resin.

  FIG. 3 shows spectral characteristics obtained by applying four color inks to a PET plate. The PET plate was solid-coated on the right half and a character pattern was printed on the left half, and the spectral characteristics of the solid-coated portion were measured. U-4100 manufactured by Hitachi, Ltd. was used for the measurement of the spectral characteristics. In the spectral characteristics of FIG. 3, the horizontal axis represents wavelength (nm), and the vertical axis represents transmittance (%).

  As the fixing laser, a semiconductor laser (multi-mode laser manufactured by Opto Energy) having a maximum output of 4 W and an oscillation wavelength of 805 nm was used because the cyanine-based near-infrared absorber mainly absorbs at a wavelength of about 800 nm. The laser beam was condensed by a condenser lens, and the ink application part was scanned and irradiated.

  FIG. 4 shows the spectral characteristics of the sample used for the spectral characteristics of FIG. 3 after irradiation with laser light. Comparing the spectral characteristics of FIG. 3 and FIG. 4, in FIG. 3 before the laser irradiation, absorption is observed in the vicinity of 800 nm, which is the absorption wavelength region of the near-infrared absorber (IR agent). It is estimated that the near-infrared absorber is transpired at almost 800 nm without being absorbed.

  FIG. 5 shows a photograph of the printed character pattern after the sample used for the spectral characteristics of FIG. 3 is irradiated with laser light. The photograph in FIG. 5 is displayed in grayscale, but is actually a color photograph, and four character patterns of cyan, magenta, yellow, and black are displayed.

  After the laser irradiation, none of the resin plates used for the samples were deformed so as to be visually confirmed.

  Next, the printing characteristics after laser irradiation were evaluated. The evaluation method is to visually evaluate the familiarity of the ink on the printing surface, ◎ when the ink repellent is not visible on the fabric of the ink, ◎, when the repellent is seen and faint, ○ A case where fading or aggregation was observed was judged as Δ. Further, as another evaluation method, the sticking property of the dye after wiping the printed surface with alcohol is evaluated using a spectrophotometer, and the case where the spectral characteristics hardly change is ◎, and the transmittance in the spectral characteristics is The case of rising was evaluated as Δ, and the case where the absorption of the dye disappeared in the spectral characteristics was determined as ×. The determination results are shown in Table 1 below.

Comparative Example As a comparative example, the same sublimable dye ink as in the example was printed on the same resin plate as in the example by the same method as in the example, then left for 1 day, and the printed surface was wiped off with alcohol. In the same manner as described above, the familiarity of the ink and the fixing property of the dye were determined. Table 2 shows the determination results.

  From Tables 1 and 2 above, it can be seen that the examples of the present invention are superior in ink compatibility and dye fixing properties than the comparative examples. Further, in the examples of the present invention, since the dye was diffusely dyed in the resin, the printed matter was more excellent in abrasion resistance than the comparative example in which the ink film was formed on the resin surface.

DESCRIPTION OF SYMBOLS 1 Resin processed goods 2 Inkjet head 2a Ink 3 Near-infrared laser irradiation apparatus 3a Laser light 4 Optical system (condensing lens)
5 Installation base 6, 7, 8 Drive unit (linear actuator)

Claims (6)

Applying an ink containing a near-infrared absorber liquid, at least an organic solvent for dissolving the near-infrared absorber, and a dye to the surface to be marked of the resin processed product;
Irradiating the application part of the ink with a near infrared laser beam, and fixing the dye to the surface to be marked by causing the near infrared absorber to generate heat; and
A laser color marking method comprising: Applying dye ink to the marking surface of the resin processed product;
Applying a near-infrared absorbent solution in which a near-infrared absorbent is dissolved in an organic solvent on the dye ink application part;
Irradiating a near-infrared laser beam to a coating portion of the dye ink to which the near-infrared absorbent solution is applied, and fixing the dye to the surface to be marked by causing the near-infrared absorbent to generate heat; and
A laser color marking method comprising: The laser color marking method according to claim 1, wherein the ink contains 0.3 to 3 wt% of the near infrared absorber. An inkjet head that ejects ink containing a near infrared absorber and a dye, and near infrared laser irradiation that irradiates near infrared laser light to cause the near infrared absorber to absorb and generate heat. And a laser color marking device. An inkjet head that ejects dye ink, an ejection device that ejects a near-infrared absorbent solution, and a near-red laser light that is absorbed by the near-infrared absorbent and emits near-infrared laser light to generate heat. A laser color marking device, comprising: an outside laser irradiation device. The laser color marking device according to claim 5, wherein the inkjet head and the ejection device are arranged in parallel.