Planar color hot stamping method based on laser transfer printing

Abstract

The invention provides plane type color hot stamping equipment based on laser transfer printing. The plane type color hot stamping equipment comprises a control system, a laser device, an XY two-dimensional scanning galvanometer system, a feeding unit and a three-primary-color hot stamping film. The three-primary-color hot stamping film comprises a carrier substrate and a three-primary-color pigment layer coated on the carrier substrate, the carrier substrate is required to have laser transparency and non-absorptivity; the three-primary-color pigment layer comprises a red color area, a green color area and a blue color area, and each color area is coated with a thin planar film formed by the color paint. Through scanning of the XY two-dimensional scanning galvanometer system, pigment deposition can be achieved at any position of a to-be-printed piece, and large-breadth color hot stamping can be conveniently achieved; different amounts of three-primary-color pigments can be sprayed and mixed by regulating and controlling technological parameters such as laser pulse energy and the number of pulses, and the color rendition degree is high. The invention further provides a plane type color hot stamping method based on laser transfer printing.

Description

[0001] This application is a divisional application with application number 202211141053.6, application date 2022-09-19, and name "A flat color hot stamping device and method based on laser transfer". Technical Field

[0002] The invention belongs to the technical field of color hot stamping, and in particular relates to a planar color hot stamping device and method based on laser transfer. Background Art

[0003] Existing color hot stamping equipment often uses hot pressing and other methods to stamp color patterns or pigments on the target substrate. It generally has problems such as complex structure, limited hot stamping format, lack of flexibility and adaptability.

[0004] The Chinese utility model patent No. 91224573.5 discloses a portable multifunctional color hot stamping machine. When printing in color, different letterheads can be fixed on four letter plates as needed, and then different color inks can be rolled on the letterheads to evenly apply the corresponding color inks, and then the hand wheels are turned in turn and the pressure handle is pressed down to realize the color printing operation. When the hot stamping machine meets the needs of different color hot stamping, it is necessary to prepare the corresponding color inks and letterheads, which has the problems of complex operation and high cost.

[0005] The Chinese invention patent No. 200810195783.8 discloses a polyethylene plastic for color hot stamping and a hot stamping method thereof, which uses hot stamping powder foil as a film carrier pigment and a mold with a text or / and pattern action surface as a tool to transfer the pigment and the text or / and pattern to the surface of the substrate by hot pressing. However, the hot stamping method requires the pre-preparation of a hot stamping head and pigment containing the required text and pattern, and is mainly for flat substrates, which has the disadvantages of limited hot stamping format, complicated steps, and high cost. Summary of the invention

[0006] In view of the above-mentioned deficiencies of the prior art, the present invention provides a planar color hot stamping device based on laser transfer, and the present invention also provides a planar color hot stamping method based on laser transfer.

[0007] The present invention is achieved through the following technical solutions:

[0008] A planar color hot stamping method based on laser transfer comprises the following steps:

[0009] (1) Analyze the color digital image to be printed and determine the values ​​of the R, G, and B components of each pixel;

[0010] (2) According to the value of the A color component of each pixel obtained in step (1), and the relationship between the number of laser scans and the brightness value of the A color under specific laser scanning parameters, calculate the brightness of each pixel point N when transferring the A color. i The corresponding laser scanning times K i , A color is one of the three primary colors: red, green, and blue;

[0011] (4) Adjust the color area A of the three-primary color hot stamping film to the bottom of the XY two-dimensional scanning galvanometer system so that the scanning range of the XY two-dimensional scanning galvanometer system can completely cover the color area A, and the laser beam output by the laser is focused on the thin plane film in the color area A after passing through the XY two-dimensional scanning galvanometer system;

[0012] The three-primary-color hot stamping film comprises a carrier substrate and a three-primary-color pigment layer coated on the carrier substrate; the carrier substrate is required to be laser transparent and non-absorbent; the three-primary-color pigment layer comprises a red color area, a green color area and a blue color area, each color area is coated with a thin planar film formed by the color coating;

[0013] Clamp the workpiece to be printed under the A color area, and make it parallel and close to the lower surface of the A color area. The distance should be within the range of 0.05mm to 2mm.

[0014] (4) Using the specific laser scanning parameters in step (2), control the laser to output the laser beam and scan the color area A several times, so that the color A coating is deposited on the surface of the workpiece in each scan, and it is required that all laser scan times K are scanned in the jth scan. i ≥j pixels, where j≥1; after all scans are completed, each pixel N i The corresponding number of laser scans is K i , thereby transferring a single A color image to the surface of the workpiece to be printed;

[0015] (5) According to the method of steps (2)-(4), the single images of the other two colors are sequentially transferred to the surface of the workpiece to be printed, and finally an RGB color image is formed on the surface of the workpiece to be printed.

[0016] The present invention has the following beneficial effects:

[0017] 1. The color hot stamping equipment in the prior art requires different hot stamping heads or hot pressing for different patterns, and the equipment structure is complex and the process is cumbersome. The flat color hot stamping equipment described in the present invention uses laser pulses to deposit pigments in situ to achieve color hot stamping, which only requires a laser and a hot stamping film, without a pad printing roller, and has the advantages of simple structure, high efficiency, and low consumables and equipment costs.

[0018] 2. The flat color hot stamping equipment of the present invention can realize pigment deposition at any position of the printed workpiece through the scanning of the XY two-dimensional scanning galvanometer system, and can conveniently realize large-format color hot stamping. In addition, the laser spot diameter is small, the pulse width is narrow, and the control accuracy is high, which can realize high-precision deposition of pigments (below 10 microns); by adjusting the process parameters such as laser pulse energy, pulse number, etc., different amounts of three primary color pigments can be sprayed and mixed, and the color reproduction degree is high.

[0019] 3. The pigment film on the three primary color hot stamping film in the flat color hot stamping equipment described in the present invention is transferred to the surface of the workpiece to be printed in the form of sputtering of micro droplets or particles after being heated by laser pulses, and is cooled and solidified after contacting the surface of the workpiece to be printed, and is firmly bonded to the surface of the workpiece to be printed and is not easy to fall off. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic structural diagram of the flat color hot stamping equipment of the present invention. DETAILED DESCRIPTION

[0021] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] like Figure 1 As shown, the present invention provides a planar color hot stamping device based on laser transfer, including a control system 1, a laser 2, an XY two-dimensional scanning galvanometer system 3, a feeding unit 4 and a three-primary color hot stamping film 5.

[0023] The laser 2 is used to emit a laser beam, which may be a nanosecond, picosecond or femtosecond laser, preferably a femtosecond laser.

[0024] The laser beam emitted by the laser 2 is incident on the XY two-dimensional scanning galvanometer system 3, and the XY two-dimensional scanning galvanometer system 3 is used to collimate the laser beam and then reflect it through the X and Y axis reflectors and focus it through the focusing lens, and then output it to the focusing work plane. The focusing method can be either rear focusing or front focusing. By controlling the rotation of the X-axis and the Y-axis, the laser beam can be moved on the focusing work plane. The scanning range of the XY two-dimensional scanning galvanometer system 3 is required to completely cover a color area of ​​the three primary color hot stamping film 5.

[0025] The three-primary-color hot stamping film 5 includes a carrier substrate and a three-primary-color pigment layer coated on the carrier substrate. The carrier substrate is required to be laser transparent and non-absorbent, that is, the transmittance to the laser is greater than 90%, and the absorption rate to the laser is less than 5%. The carrier substrate can be a fused quartz carrier or a polymer film, etc.

[0026] The three primary color pigment layer includes a red area 51, a green area 52 and a blue area 53, each of which is coated with a thin plane film formed by the color coating. The three color areas of red, green and blue are arranged along the length direction of the three primary color hot stamping film 5, and the three have the same length, width and thin plane film thickness. The thickness of the thin plane film is preferably 5 to 20 μm;

[0027] The size of the carrier substrate can be larger than that of the three-primary color pigment layer, and there is space at both ends for mounting the three-primary color hot stamping film 5 on the feeding unit 4, and the feeding unit 4 can drive the three-primary color hot stamping film 5 to perform translational motion along the length direction. The carrier substrate can also be the same size as the three-primary color pigment layer, in which case another connector is required to mount the three-primary color hot stamping film 5 on the feeding unit 4.

[0028] The feeding unit 4 is used to clamp the three-primary-color hot stamping film 5 and drive the three-primary-color hot stamping film 5 to perform reciprocating translational motion along its length direction, and ensure that the surface of the three-primary-color hot stamping film 5 always remains horizontal, and the distance that the feeding unit 4 moves each time is the width of a color area.

[0029] The installation of the three-primary-color hot stamping film 5 requires that the carrier substrate faces upward and is arranged facing the XY two-dimensional scanning galvanometer system 3; the three-primary-color pigment layer faces downward and is arranged facing the to-be-printed workpiece 7. The red, green and blue color areas are required to be exposed outside the feeding unit 4, and the upper surfaces of the red, green and blue color areas are all on the same plane as the focusing working plane.

[0030] The workpiece 7 to be printed is clamped and fixed by the clamp 6. The surface to be printed of the workpiece 7 to be printed and the lower surfaces of the red, green and blue color areas are parallel to and very close to each other, and the distance between them is required to be within the range of 0.05mm to 2mm.

[0031] When the laser beam is incident on the three-primary-color hot stamping film 5, it will pass through the carrier substrate and focus on the thin plane film in a certain color area. By adjusting the applied laser energy, a forward thrust can be generated in the irradiated film volume, and the absorbed laser photons cause partial ablation of the film material, thereby causing a sharply triggered volume expansion and pressure jump, thereby pushing away the coating on the film material and catalyzing the deposition onto the receiving surface, that is, the surface to be printed of the workpiece 7 to be printed.

[0032] The present invention also provides a planar color hot stamping method based on laser transfer, the basic idea of ​​which is to first decompose the RGB color image to be hot stamped into three component images of red, green and blue, and then use laser transfer technology to deposit a specific color of paint on the receiving surface to first form a single color component image; then, on the basis of this single component image, superimpose and deposit the second color and third color component images, and finally form an RGB color image on the receiving surface.

[0033] The method is specifically implemented by the following steps:

[0034] (1) Analyze the color digital image to be printed and determine the values ​​of the R, G, and B components of each pixel.

[0035] (2) According to the value of the A color component of each pixel obtained in step (1) (the A color is one of the three primary colors of red, green, and blue), and the relationship between the number of laser scans and the brightness value of the A color under specific laser scanning parameters, calculate the value of each pixel point N when transferring the A color. i The corresponding laser scanning times K i .

[0036] Among them, the relationship between the number of laser scans and the brightness value of color A under specific laser scanning parameters needs to be obtained through experimental methods before hot stamping. The specific method is:

[0037] Adjust the A color area of ​​the three-primary color hot stamping film 5 to below the XY two-dimensional scanning galvanometer system 3, so that the scanning range of the XY two-dimensional scanning galvanometer system 3 can completely cover the A color area of ​​the three-primary color hot stamping film 5, and the laser beam is focused on the thin plane film in the A color area, and the test piece with a blank surface is clamped below the A color area.

[0038] Under the laser scanning parameters, the laser is controlled to scan once according to the set path, so that the A color paint in the scanned area is deposited on the surface of the test piece. Then, the A color image on the surface of the test piece is analyzed by image processing software to obtain the average A color brightness value of the image.

[0039] Afterwards, the same laser scanning parameters and the same scanning path were used to perform laser scanning experiments on the test piece with increasing times, and the relationship between the laser scanning times and the brightness value of color A was obtained by fitting.

[0040] (3) Adjust the A color area of ​​the three-primary color hot stamping film 5 to below the XY two-dimensional scanning galvanometer system 3, so that the scanning range of the XY two-dimensional scanning galvanometer system 3 can completely cover the A color area of ​​the three-primary color hot stamping film 5, and the laser beam is focused on the thin plane film of the A color area. Clamp the workpiece 7 below the A color area and make it parallel to and very close to the lower surface of the A color area. The distance is required to be in the range of 0.05 mm to 2 mm.

[0041] (4) Using the specific laser scanning parameters in step (2), the laser is controlled to output a laser beam and scan the A color area several times, so that the A color coating is deposited on the surface of the workpiece 7 during each scan. It is required that all laser scan times K are scanned during the jth scan. i ≥j pixels, where j≥1. This ensures that after all scans are completed, each pixel Ni The corresponding number of laser scans is K i , thereby transferring a single A color image onto the surface of the workpiece 7 to be printed.

[0042] (5) According to the method of steps (2)-(4), the single images of the other two colors are transferred to the surface of the to-be-printed workpiece 7 in sequence, and finally an RGB color image is formed on the surface of the to-be-printed workpiece 7.

[0043] Preferably, after the deposition of the three primary colors is completed, the three primary color hot stamping film 5 can be removed, so that the laser beam is directly incident on the surface of the workpiece 7 to be printed, and the image is scanned once to promote the fusion of the three primary colors.

[0044] The present invention can be modified in many ways that are obvious to those skilled in the art, and such modifications are not considered to depart from the scope of the present invention. All such modifications that are obvious to those skilled in the art are intended to be included within the scope of the present claims.

Claims

1. A planar color hot stamping method based on laser transfer, characterized in that: The following steps are involved: (1) Analyze the color digital image to be printed and determine the values ​​of the R, G, and B components of each pixel; (2) Based on the value of the A color component of each pixel obtained in step (1) and the relationship between the number of laser scans and the brightness value of the A color under specific laser scanning parameters, calculate the brightness of each pixel when transferring the A color. Ni Corresponding laser scan times Ki , A color is one of the three primary colors: red, green, and blue; (3) Adjust the color area A of the three-primary color hot stamping film to the bottom of the XY two-dimensional scanning galvanometer system so that the scanning range of the XY two-dimensional scanning galvanometer system can completely cover the color area A, and the laser beam output by the laser is focused on the thin plane film in the color area A after passing through the XY two-dimensional scanning galvanometer system; The three-primary-color hot stamping film comprises a carrier substrate and a three-primary-color pigment layer coated on the carrier substrate; the carrier substrate is required to be laser transparent and non-absorbent; the three-primary-color pigment layer comprises a red color area, a green color area and a blue color area, each color area is coated with a thin planar film formed by the color coating; Clamp the workpiece to be printed under the A color area, and make it parallel and close to the lower surface of the A color area. The distance should be within the range of 0.05mm~2mm. (4) Using the specific laser scanning parameters in step (2), control the laser to output the laser beam and scan the color area A several times, so that the color A coating is deposited on the surface of the workpiece during each scan. It is required that all laser scan times are scanned during the jth scan. Ki ≥j pixels, where j≥1; after all scans are completed, each pixel Ni The corresponding number of laser scans is Ki , thereby transferring a single A color image to the surface of the workpiece to be printed; (5) According to the method of steps (2) to (4), the single images of the other two colors are sequentially transferred to the surface of the workpiece to be printed, and finally an RGB color image is formed on the surface of the workpiece to be printed.

2. The flat color hot stamping method according to claim 1, characterized in that: After the deposition of the three primary colors is completed, the three primary color hot stamping film is removed, so that the laser beam is directly incident on the surface of the printed workpiece and the image is scanned once to promote the fusion of the three primary colors.

3. The flat color hot stamping method according to claim 1, characterized in that: The relationship between the number of laser scans and the brightness value of color A under specific laser scanning parameters in step (2) needs to be obtained by experimental methods before hot stamping; the specific method is: Adjust the A color area of ​​the three-primary color hot stamping film to the bottom of the XY two-dimensional scanning galvanometer system, so that the scanning range of the XY two-dimensional scanning galvanometer system can completely cover the A color area of ​​the three-primary color hot stamping film, and the laser beam is focused on the thin plane film in the A color area, and the test piece with a blank surface is clamped under the A color area; Under the laser scanning parameters, the laser is controlled to scan once along the set path, so that the A color paint in the scanned area is deposited on the surface of the test piece. Then, the A color image on the surface of the test piece is analyzed by image processing software to obtain the average A color brightness value of the image. Then, the same laser scanning parameters and the same scanning path are used to perform laser scanning experiments on the test piece with increasing numbers, and the relationship between the laser scanning times and the A color brightness value is obtained by fitting.

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