Micron-sized dimple screen roller for corrugated box printing and preparation method and application thereof

Abstract

The application discloses a micron-level mesh cell anilox roller for corrugated box printing and a preparation method and application thereof, relates to the technical field of flexographic printing consumable preparation, and comprises a roller body base material, a hard oxidation film layer, a channel-shaped micron-level mesh cell array, a gold or silver nano-island array and an oxygen-containing polar group modified layer; by designing the channel-shaped micron-level mesh cell array structure, matching the ink absorption characteristics of different printing substrates, optimizing the bearing, leveling and releasing process of water-based ink in the mesh cell, the problems of ink supply interruption and uneven ink hanging of the closed pore mesh cell are solved; a synergistic treatment process of hard anodic oxidation and low-temperature plasma modification is adopted to generate an oxidation film layer with high hardness and high density on the roller body surface in situ, the wear resistance and corrosion resistance of the roller body are improved, oxygen-containing polar groups are introduced into the mesh cell bottom and sidewall and the nano-island surface, the ink affinity of the mesh cell is improved, and the dynamic balance of the ink bearing capacity and transfer efficiency is realized.

Description

Technical Field

[0001] This invention relates to the field of flexographic printing consumables preparation technology, specifically to a micron-level anilox roller for corrugated cardboard box printing, its preparation method, and its application. Background Technology

[0002] Flexographic printing, with its significant advantages such as environmental friendliness, high efficiency, and wide substrate compatibility, has become the mainstream process in the corrugated cardboard packaging printing industry. It is particularly outstanding in meeting the environmentally friendly printing needs of water-based inks and is widely used in corrugated cardboard packaging production in many industries such as food, express delivery, and electronics. As the market's requirements for the quality of corrugated cardboard packaging continue to increase, high-precision and high-stability printing effects have become key goals pursued by the industry. However, the corrugated cardboard printing process involves a variety of substrates with different characteristics, such as corrugated base paper, coated paper, and kraft paper. These substrates have great differences in fiber structure and porosity, resulting in a wide range of fluctuations in ink absorption characteristics, which brings great challenges to the printing process.

[0003] In the actual industrial printing production of corrugated cardboard boxes, existing flexographic printing processes and their supporting anilox rollers have many significant technical defects. First, the cell structure of existing conventional anilox rollers cannot dynamically adapt to the ink absorption characteristics of different substrates. Due to the large differences in ink absorption characteristics of the substrates used in corrugated cardboard boxes, the continuity and uniformity of water-based ink transfer from the cells to the printing plate and then to the substrate are extremely poor. This easily leads to defects such as blurred solid areas, orange peel texture, water ripples, and edge blurring in the printed products. Furthermore, insufficient color saturation and low tonal reproduction accuracy fail to meet the high-precision printing requirements of high-end corrugated cardboard box packaging. Second, existing anilox rollers have limitations in ink carrying capacity. The imbalance between quantity and transfer efficiency leads to ink residue and uneven ink application in conventional closed-cell anilox roller structures. Furthermore, it is difficult to simultaneously balance roller abrasion resistance and cell ink affinity. During long-term batch printing, cells are prone to wear and deformation, resulting in a continuous decline in print quality stability. This leads to high replacement frequency of anilox rollers, significant ink loss, and a substantial increase in production costs for batch printing of corrugated boxes. Thirdly, for high-solids water-based inks, even with optimized cell structure and ink affinity, the ink viscosity remains high at room temperature. When printing on low-absorbency coated paper and high-roughness corrugated base paper, the problem of insufficient ink spreadability remains prominent. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a micron-level anilox roller for corrugated cardboard printing, its preparation method, and its application. The anilox roller comprises a roller substrate, a hard oxide film layer, a channel-shaped micron-level cell array, a gold or silver nano-island array, and an oxygen-containing polar group modified layer. By designing a channel-shaped micron-level cell array structure to match the ink absorption characteristics of different printing substrates, the bearing, leveling, and release processes of water-based inks within the cells are optimized, solving the problems of ink supply interruption and uneven ink application in closed-cell cells. A synergistic treatment process of hard anodizing and low-temperature plasma modification is employed to generate a high-hardness, high-density oxide film layer in situ on the roller surface, improving the roller's wear resistance and corrosion resistance. Simultaneously, oxygen-containing polar groups are introduced into the bottom and sidewalls of the cells and the surface of the nano-islands to enhance the ink affinity of the cells, achieving a dynamic balance between ink carrying capacity and transfer efficiency. A gold / silver nano-island array matching specific wavelengths is prepared within the cells, utilizing the localized photothermal effect of surface plasmon resonance to achieve on-demand viscosity control of the transient ink transfer window.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: Firstly, a micron-level anilox roller for printing corrugated cardboard boxes, comprising: Roller substrate; A hard oxide film layer, wherein the thickness of the hard oxide film layer is 30-80μm, the microhardness is ≥350HV, and the porosity of the film layer is ≤8%; A channel-shaped micron-level cell array, wherein the cells are channel-shaped structures with oblique connections at 30°-75°, is uniformly distributed on the surface of the hard oxide film layer. When the connection angle is less than 30°, the cell channels are too gentle, hindering the flow of ink within the cells, especially for high-viscosity inks, which can easily lead to poor ink release and cell clogging. When the connection angle is greater than 75°, the cell channels are too steep, causing ink to flow too quickly under the influence of gravity and centrifugal force, significantly reducing ink carrying capacity and making it impossible to form a stable ink film layer. Within the connection angle range of 30°-75°, the dynamic processes of ink support, leveling, and release within the cells can be balanced, matching the working conditions of water-based inks of different viscosities and printing speeds. The gold nano island array or silver nano island array is located at the bottom and sidewalls of the cavity, and the film thickness is 3-40nm. The surface exciton resonance absorption peak of the gold nano island array is matched at 525-535nm, and the surface exciton resonance absorption peak of the silver nano island array is matched at 800-815nm. An oxygen-containing polar group modified layer is obtained by low-temperature plasma modification treatment of the bottom and sidewalls of the mesh cells and the surface of the anilox roller.

[0006] Furthermore, the single hole opening diameter of the channel-shaped micron-scale hole array is 20-80μm, the hole depth is 10-40μm, the taper of the hole sidewall is 5°-15°, and the number of holes is 80-200 lines / inch.

[0007] Furthermore, the individual nanoisland particle size of the gold or silver nanoisland array is 15-150nm, the spacing between adjacent nanoislands is 20-200nm, the half-width of the surface plasmon resonance absorption peak of the nanoisland array is ≤80nm, and the absorbance at the matched wavelength is ≥0.8.

[0008] Secondly, a method for preparing micron-sized cells for printing corrugated cardboard boxes, the method comprising the following specific steps: S1: Select the roller substrate and perform surface degreasing, rust removal and precision polishing pretreatment in sequence to obtain a pretreated roller with a surface roughness Ra≤0.4μm; S2: Hard anodizing is performed on the pre-treated roller body to generate a hard oxide film layer with a thickness of 30-80μm in situ on the surface of the roller body, thus obtaining a roller body with an oxide film layer; S3: Based on the ink absorption characteristics of corrugated paper / corrugated paper used for printing corrugated boxes, a channel-shaped micron-level cell structure is designed. An ultra-short pulse laser is used to engrave the roller with an oxide film layer, forming a uniformly arranged micron-level cell on the surface of the oxide film layer, thus obtaining an engraved semi-finished roller. S4: Prepare gold or silver nano-island arrays at the bottom and sidewalls of the engraved mesh. Match the surface plasmon resonance absorption peak of the nano-island array with a wavelength light source of 525-535nm or 800-815nm to obtain a semi-finished roller with nano-island array. S5: The bottom of the cells, sidewalls and surface of the semi-finished roller with nano-island array are modified by low-temperature plasma treatment. Oxygen-containing polar groups are introduced into the bottom of the cells, sidewalls and nano-island surface to improve ink affinity, and the modified roller is obtained. The oxygen-containing polar groups are selected from one or more of hydroxyl, carboxyl, carbonyl and aldehyde groups. S6: The modified roller body is subjected to ultra-precision polishing, ultrasonic cleaning, and vacuum drying. After passing the tests on cell parameters, nano-island optical properties, and printability, a micron-level cell anilox roller for corrugated carton printing is obtained.

[0009] Further, the specific steps of S1 are as follows: Select any one of 6061 aluminum alloy, No. 45 steel, or 304 stainless steel as the roller body substrate, and use a sodium hydroxide alkaline solution with a mass fraction of 3%-8% for ultrasonic alkaline washing to saponify and remove organic contaminants such as mineral oil and animal and vegetable oil from the roller body surface. The alkaline washing time is 5-15 minutes and the temperature is 40-60℃. After alkaline washing, rinse with deionized water and then use a dilute nitric acid solution with a mass fraction of 8%-15% for acid washing to remove oxide scale, rust spots, and passivation layer from the substrate surface. The acid washing time is 3-8 minutes and the temperature is room temperature. After acid washing, rinse with deionized water again and use a diamond grinding wheel for three passes of rough grinding, semi-fine grinding, and fine grinding. Then, use nano-grade diamond polishing paste for mirror polishing to finally obtain a pre-treated roller body with a surface roughness Ra≤0.4μm, while controlling the roller body roundness ≤0.005mm, cylindricity ≤0.008mm, and radial runout ≤0.003mm.

[0010] Furthermore, the specific steps of S2 are as follows: The pretreated roller body is used as the anode, and the lead plate as the cathode, and placed in a sulfuric acid electrolyte solution for hard anodizing treatment. The electrolyte is a sulfuric acid aqueous solution with a mass fraction of 12%-18%. The electrolyte temperature is precisely controlled at -5 to 5°C using a low-temperature constant-temperature bath, and the anode current density is controlled at 1.5-3.5 A / dm³. 2 The oxidation treatment time is 40-90 min. After oxidation, the roller is taken out and rinsed repeatedly with deionized water to remove residual electrolyte on the surface. Then it is dried with cold air to generate a hard oxide film layer with a thickness of 30-80 μm in situ on the surface of the roller, thus obtaining a roller with an oxide film layer. The microhardness of the oxide film layer is ≥350 HV and the porosity of the film layer is ≤8%.

[0011] Furthermore, the specific steps of S3 are as follows: Based on the ink absorption characteristics of the corrugated cardboard printing linerboard / corrugated paper, a 60° obliquely connected channel-shaped micron-level cell structure is designed. For highly absorbent corrugated base paper, the cell count is designed to be 80-120 lines / inch, with a theoretical ink loading capacity of 10-18 BCM; for low-absorbency coated linerboard / kraft paper, the cell count is designed to be 120-200 lines / inch, with a theoretical ink loading capacity of 4-10 BCM; the opening diameter of a single cell is controlled to be 20-80 μm, the cell depth is 10-40 μm, and the cell side... With a wall taper of 5°-15°, picosecond or femtosecond lasers are used as the engraving light source to perform ultra-precision engraving on the roller with an oxide film layer. The laser process parameters are: laser power 10-50W, pulse frequency 50-200kHz, scanning speed 500-2000mm / s, and single pulse energy 20-100μJ. High-purity argon gas is continuously introduced as a protective gas during the engraving process, and a negative pressure dust removal device is used to collect the engraving dust. Finally, a uniformly arranged channel-shaped micron-level mesh array is formed on the surface of the oxide film layer to obtain the engraved semi-finished roller.

[0012] Furthermore, the specific steps of S4 are as follows: placing the engraved semi-finished roller body into the vacuum chamber of the magnetron sputtering coating machine, using a high-purity gold target or a high-purity silver target as the sputtering target material, and first evacuating the vacuum chamber to 1×10⁻⁶. -3 -5×10 - 3 Pa, high-purity argon gas is introduced as the sputtering gas, and the argon gas flow rate is controlled at 20-50 sccm. The sputtering power is turned on and the sputtering power is controlled at 50-150W. A gold or silver nanofilm with a thickness of 2-10 nm is deposited on the bottom and sidewalls of the cells. The roller maintains a uniform rotation speed during the sputtering process to ensure that the film thickness at the bottom and sidewalls of the cells is uniform. After the coating is completed, the roller is placed in a rapid annealing furnace and subjected to rapid thermal annealing under a high-purity nitrogen protective atmosphere. The annealing temperature is controlled at 200-400℃, the annealing time is 5-30 min, and the heating rate is 50-100℃ / min. Through rapid thermal annealing, the 2-10 nm continuous film undergoes solid-state dehumidification and is transformed into a discrete nanoisland array with a film thickness of 3-40 nm. Because its cell opening diameter is 20-80μm, its depth is 10-40μm, and its sidewalls have a taper of 5°-15°, forming a conical cavity, when pulsed irradiation light is incident from above the cell, the light is reflected multiple times between the sidewalls of the conical cavity, allowing the nano-islands deposited on the bottom and sidewalls to efficiently absorb light energy and generate a local photothermal effect. Due to the small volume of the cell, the volume of ink it carries is within a skin size, and the heat conduction distance from the solid-liquid interface of the bottom and sidewalls to the ink body is extremely short, which can be completed within a microsecond time scale. Within the transient window before ink transfer, the ink temperature field in the entire cell can be made uniform. At the same time, the edge area of ​​the cell opening maintains a high-hardness oxide film surface without nano-islands, which can prevent the ink at the opening from premature solvent evaporation and skinning under photothermal action, thereby ensuring the clean and complete transfer of ink to the printing plate.

[0013] The individual nanoislands have a particle size of 15-150 nm, the spacing between adjacent nanoislands is 20-200 nm, the film thickness of the nanoisland array is 3-40 nm, the center wavelength of the surface plasmon resonance absorption peak is matched to 525-535 nm or 800-815 nm, the half-width is ≤80 nm, and the absorbance is ≥0.8 in the matched wavelength range. By controlling the particle size and spacing of the nanoislands, the surface plasmon resonance absorption peak of the spherical nanoisland array can be tuned to the above wavelength range by utilizing the near-field coupling effect between particles, so as to meet the matching requirements of different types of irradiation light sources.

[0014] By controlling the particle size and spacing, the resonant wavelength can be precisely tuned using the near-field coupling effect between adjacent nanoislands. When the spacing between nanoislands decreases, the near-field coupling is enhanced, and the resonant peak red-shifts; when the spacing increases, the coupling is weakened, and the resonant peak blue-shifts. By controlling the particle size within the range of 15-150 nm and the spacing within the range of 20-200 nm, the resonant absorption peak of the spherical gold nanoisland array can be tuned to 525-535 nm, and the resonant absorption peak of the silver nanoisland array can be tuned to the wavelength range of 800-815 nm.

[0015] Furthermore, the specific steps of S5 are as follows: the semi-finished roller with nano-island array is placed in the vacuum chamber of the low-temperature plasma treatment equipment, and a mixture of argon and oxygen is introduced as the working gas, wherein the volume ratio of oxygen is 10%-30%, the vacuum degree of the chamber is controlled at 10-50 Pa, the plasma power supply is turned on, and the processing power is controlled at 80-200 W. The roller is kept rotating at a uniform speed of 5-20 r / min during the treatment process, and the processing time is 10-30 min. After the treatment is completed, the roller is taken out after the chamber returns to normal pressure to obtain the modified roller.

[0016] Furthermore, the specific steps of S6 are as follows: The non-celled areas of the modified roller are subjected to ultra-precision polishing using a wool wheel and nano-diamond polishing paste with a particle size of 30-80nm for mirror polishing. During polishing, a protective film is used to cover the celled areas to prevent the polishing paste from entering the cells and causing blockage. After polishing, the surface roughness Ra of the non-celled areas of the roller is ≤0.2μm. After polishing, the roller is placed in deionized water for ultrasonic cleaning at an ultrasonic frequency of 40-80kHz for 10-20 minutes, utilizing the cavitation effect of ultrasound. Remove residual engraving dust, polishing debris, and other impurities from the cells. After cleaning, place the roller in a vacuum drying oven and dry it for 20-40 minutes at 60-80℃ and a vacuum degree ≤-0.09MPa to remove residual moisture from the cells. Finally, conduct comprehensive performance tests on the dried roller, including three-dimensional morphology of the cells, ink loading deviation, ink affinity contact angle, nano-island resonance wavelength, abrasion resistance, and printability. Once all tests are passed, the finished micron-level cell anilox roller for corrugated cardboard printing is obtained.

[0017] Thirdly, an application of micron-level anilox rollers for corrugated cardboard box printing is characterized by assembling the micron-level anilox rollers into a water-based flexographic printing press for corrugated cardboard boxes, and providing an irradiation light source that matches the resonant wavelength of the nano-island array; during the printing process, during the transient window before the ink transfers from the cells to the printing plate, the cells are pulsedly irradiated by the irradiation light source, utilizing the surface plasmon resonance photothermal effect of the nano-island array to locally and instantaneously raise the temperature of the ink within the cells by 5-20°C, reducing the ink viscosity to improve transfer and spreading efficiency; after irradiation, the ink temperature quickly returns to room temperature. The transient window refers to the extremely short interval, ranging from tens to hundreds of microseconds, between the cells on the anilox roller and the printing plate during flexographic printing. During this window, ink is transferred from the cells to the printing plate. By detecting the rotational speed and position signals of the anilox roller (such as an encoder), the control system calculates the moment when the cells are about to contact the printing plate and triggers a pulsed irradiation light source in advance to irradiate the cell area within the transient window.

[0018] Compared with existing technologies, the preparation method of micron-level cells for corrugated cardboard box printing and its application have the following advantages: This invention effectively optimizes the carrying, leveling, and release process of water-based inks within the cells through precise design of a channel-shaped micron-level cell structure. It solves the problems of ink supply interruption and uneven ink application that easily occur in closed-cell cells, significantly improving the continuity and uniformity of ink transfer. The synergistic treatment process of hard anodizing and low-temperature plasma modification enhances the ink affinity of the cells while improving the wear resistance and corrosion resistance of the roller, resulting in increased ink transfer efficiency and significantly reduced ink residue, achieving a dynamic balance between ink carrying capacity and transfer efficiency. The gold / silver nano-island array prepared within the cells achieves on-demand viscosity control of the transient window for ink transfer through the localized photothermal effect of surface plasmon resonance. This avoids problems such as ink solvent evaporation, viscosity drift, and skinning caused by overall heating, balancing high transfer efficiency with long-term ink stability.

[0019] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0021] Figure 1 A flowchart illustrating a method for preparing micron-sized cells for printing corrugated cardboard boxes; Figure 2 This is a flowchart of step S4 in a method for preparing micron-sized cells for printing corrugated cardboard boxes. Detailed Implementation

[0022] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0023] Example 1 This embodiment provides a method for preparing a micron-level anilox roller for corrugated cardboard box printing, such as... Figure 1 As shown, it includes the following steps: S1: Select 6061 aluminum alloy roller body substrate, and successively use 5% sodium hydroxide alkaline washing to remove oil and 10% dilute nitric acid pickling to remove rust, remove surface oil and oxide layer, and then use diamond grinding wheel for multi-pass precision polishing to obtain a pre-treated roller body with surface roughness Ra=0.3μm, roundness 0.003mm, cylindricity 0.006mm, and radial runout 0.002mm; S2: The pre-treated roller body undergoes hard anodizing treatment using a 15% (w / w) sulfuric acid aqueous solution as the electrolyte. The electrolyte temperature is controlled at 0℃, and the current density is 2.5 A / dm³. 2 The oxidation treatment time is 60 min, and a hard oxide film layer with a thickness of 50 μm is generated in situ on the surface of the roller. The microhardness of the film layer is 380 HV and the porosity is ≤6%, thus obtaining a roller with an oxide film layer. S3: Targeting the ink absorption characteristics of the coated paperboard of corrugated cardboard boxes, a 60° obliquely connected channel-shaped micron-level cell structure was designed. Each cell has an opening diameter of 50μm, a depth of 25μm, a sidewall taper of 10°, a cell line count of 120 lines / inch, and a theoretical ink capacity of 10 BCM. A picosecond laser is used to engrave the roller with an oxide film layer. The laser power is 30W, the pulse frequency is 100kHz, the scanning speed is 1200mm / s, and the single pulse energy is 50μJ. The engraving process is protected by high-purity argon gas, forming uniformly arranged micron-level cells on the surface of the oxide film layer of the roller, resulting in an engraved semi-finished roller. S4: As Figure 2 As shown, a silver nano-island array was fabricated on the bottom and sidewalls of the sculpted cells using a magnetron sputtering combined with rapid thermal annealing method: first, a 5 nm thick silver nanofilm was deposited on the bottom and sidewalls of the cells by magnetron sputtering at a sputtering power of 100 W and a sputtering vacuum of 3 × 10⁻⁶. -3Pa, argon flow rate 30 sccm; then rapid thermal annealing at 300℃ under nitrogen protection atmosphere, annealing time 15 min, heating rate 80℃ / min, after cooling, a uniformly distributed array of silver nano-islands is formed at the bottom and sidewalls of the mesh; the obtained individual nano-island particle size is 50 nm, the spacing between adjacent nano-islands is 80 nm, the film thickness is 15 nm, the center wavelength of the surface plasmon resonance absorption peak is 532 nm, and the absorbance is 0.85, thus obtaining a semi-finished roller with nano-island array; S5: The bottom of the mesh, sidewalls and surface of the semi-finished roller with nano-island array are subjected to low-temperature plasma modification treatment. The working gas is a mixture of argon and oxygen, with oxygen accounting for 20% of the volume. The plasma treatment power is 150W, the treatment vacuum degree is 30Pa, the roller rotation speed is 10r / min, and the treatment time is 20min to obtain the modified roller. S6: The modified roller body is polished with a wool wheel and diamond polishing paste with a particle size of 50nm for ultra-precision polishing. After polishing, the roughness of the non-cell area of ​​the roller surface Ra=0.15μm. Then, it is ultrasonically cleaned with deionized water and vacuum hot air dried. After passing the three-dimensional morphology detection of cells, ink load deviation detection, ink affinity contact angle detection, nano island resonance wavelength detection, and wear resistance detection, the micron-level cell anilox roller for corrugated carton printing is obtained.

[0024] The anilox roller prepared in this embodiment is assembled into a water-based flexographic printing press for corrugated cardboard boxes, and equipped with a pulsed laser with a center wavelength of 532nm. The printing material is 250g / m². 2 Coated corrugated cardboard boxes were printed using water-based ink with a viscosity of 25s (coating cup 4, 25℃), at a printing speed of 150m / min and a printing pressure of 0.2MPa. During the printing process, a laser pulse irradiation was applied to the cell area during a transient window of 50μs before the cells contacted the printing plate. The laser pulse width was 1ns, and the single pulse energy density was 0.5J / cm³. 2 The ink inside the cells instantly heats up by 12°C, and the ink viscosity instantly decreases by 45%.

[0025] Example 2 This embodiment provides a method for preparing a micron-level anilox roller for corrugated cardboard box printing, which differs from Embodiment 1 only in that: S2: Electrolyte temperature is -2℃, current density is 3.0A / dm³ 2 The oxidation treatment time was 75 min, the thickness of the hard oxide film was 65 μm, and the microhardness of the film was 420 HV. S3 micron-level mesh design: designed for 180g / m² 2The ink absorption characteristics of the corrugated base paper are as follows: single cell opening diameter is 70μm, cell depth is 35μm, cell sidewall taper is 12°, cell line count is 90 lines / inch, and theoretical ink capacity is 16BCM; the laser engraving parameters are: laser power 40W, pulse frequency 150kHz, scanning speed 1000mm / s, and single pulse energy 80μJ. S4 Metal Nanoisland Array Preparation: Gold nanoisland array was prepared by magnetron sputtering deposition of a gold nanofilm with a thickness of 8 nm, sputtering power of 120 W, annealing temperature of 350 °C, and annealing time of 20 min; the obtained individual nanoisland has a particle size of 80 nm, an adjacent nanoisland spacing of 120 nm, a center wavelength of the resonance absorption peak of 808 nm, and an absorbance of 0.82. S5 plasma modification treatment: oxygen volume ratio 25%, treatment power 180W, treatment time 25min; the remaining steps and process parameters are completely consistent with those in Example 1.

[0026] The anilox roller prepared in this embodiment is assembled into a water-based flexographic printing press for corrugated cardboard boxes, and equipped with a high-power LED array with a center wavelength of 808nm. The printing target is 180g / m². 2 Corrugated base paper for corrugated cardboard boxes; water-based ink viscosity 30s (Coating Cup 4, 25℃); printing speed 120m / min; printing pressure 0.25MPa; during printing, pulse irradiation is applied during the transient window of 80μs before the cells contact the printing plate, with a pulse width of 50ns and a single pulse energy density of 0.8J / cm³. 2 The ink inside the cells instantly heats up by 18°C, and the ink viscosity instantly decreases by 55%.

[0027] Example 3 This embodiment provides a method for preparing a micron-level anilox roller for corrugated cardboard box printing, which differs from Embodiment 1 only in that: The S1 substrate is 45 steel, with a surface roughness Ra=0.25μm, roundness 0.004mm, and cylindricity 0.007mm after pretreatment. S3 micron-level mesh design: designed for 300g / m³ 2 The ink absorption characteristics of kraft paper are as follows: the opening diameter of a single cell is 30μm, the cell depth is 15μm, the taper of the cell sidewall is 8°, the cell line count is 180 lines / inch, and the theoretical ink capacity is 6BCM; the laser engraving uses a femtosecond laser with a laser power of 20W, a pulse frequency of 80kHz, a scanning speed of 1500mm / s, and a single pulse energy of 30μJ. S4 metal nanoisland array preparation: Silver nanoisland array was prepared by magnetron sputtering to deposit a silver nanofilm with a thickness of 3 nm, sputtering power of 80 W, annealing temperature of 250 °C, and annealing time of 10 min; the obtained individual nanoisland has a particle size of 30 nm, the spacing between adjacent nanoislands is 50 nm, the center wavelength of the resonance absorption peak is 532 nm, and the absorbance is 0.88. S5 plasma modification treatment: oxygen volume percentage 15%, treatment power 120W, treatment time 15min; The remaining steps and process parameters are completely consistent with those in Example 1.

[0028] The anilox roller prepared in this embodiment is assembled into a water-based flexographic printing press for corrugated cardboard boxes, and equipped with a pulsed laser with a center wavelength of 532nm. The printing material is 300g / m². 2 Kraft paper corrugated boxes, water-based ink viscosity 20s (Coating Cup 4, 25℃), printing speed 180m / min, printing pressure 0.15MPa; during printing, pulse irradiation is applied during the transient window of 30μs before the cells contact the printing plate, pulse width 500ps, single pulse energy density 0.3J / cm³. 2 The ink inside the cells instantly heats up by 8°C, and the ink viscosity instantly decreases by 35%.

[0029] Example 4 This embodiment serves as a control group without nano-island arrays and photothermal regulation. The preparation method is completely consistent with that of Example 1, except that the S4 nano-island array preparation step is omitted. The irradiation light source is not turned on during the printing process, and the remaining printing substrate, ink parameters, printing equipment, and process conditions are completely consistent with those of Example 1.

[0030] Comparative Example 1 This comparative example uses a commercially available laser-engraved ceramic anilox roller with a cell count of 120 lines per inch and a theoretical ink load of 10 BCM. The other printing substrates, ink parameters, printing equipment, and process conditions are completely consistent with those in Example 1, and are used for printing corrugated boxes with the same coated paper.

[0031] Comparative Example 2 This comparative example uses the same anilox roller as in Example 1. During the printing process, the ink temperature is constantly raised to 35°C by heating the entire ink tank, so that the ink viscosity decreases in the same way as in Example 1. The other printing substrates, ink parameters, printing equipment and process conditions are completely the same as in Example 1, and the pulsed irradiation light source is not turned on.

[0032] Performance testing Standardized tests were conducted on the printing effects, anilox roller performance, and ink stability of Examples 1-4 and Comparative Examples 1-2. The test results are shown in the table below: Table 1 Performance Comparison of Examples

[0033] Table 2 Comparative Performance Comparison Table

[0034] In summary, the micron-level anilox roller with nano-island arrays prepared by this invention, combined with transient photothermal viscosity control technology, can improve ink transfer efficiency to over 85%, solid density uniformity to nearly 99%, printing defect rate to below 0.1%, and color saturation to over 30% higher than conventional anilox rollers. This is significantly better than Example 4 (without nano-island photothermal control) and Comparative Example 1 (with conventional anilox roller). Compared to Comparative Example 2 (with overall ink heating), the transient localized photothermal technology of this invention achieves the same viscosity reduction and transfer efficiency, but the ink viscosity change rate during continuous printing is only about ±2%, with no plate clogging and batch-to-batch color difference ΔE ≤ 1.1. This solves the problems of decreased ink stability, increased color difference, and plate clogging caused by overall heating, perfectly balancing high transfer efficiency and ink printing stability. The technical solution of this invention exhibits excellent adaptability to different types of corrugated cardboard printing substrates, with printing durability increased by over 50% compared to conventional anilox rollers, fully meeting the needs of high-speed, high-precision, and high-stability mass industrial printing of corrugated cardboard.

[0035] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A micron-level anilox roller for printing corrugated cardboard boxes, characterized in that, include: Roller substrate; A hard oxide film layer, wherein the thickness of the hard oxide film layer is 30-80μm, the microhardness is ≥350HV, and the porosity of the film layer is ≤8%; A channel-shaped micron-sized cavity array, wherein the cavity is a channel-shaped structure that is obliquely connected at 30°-75°, and the channel-shaped micron-sized cavity array is uniformly distributed on the surface of the hard oxide film layer; The gold nano island array or silver nano island array is located at the bottom and sidewalls of the cavity, and the film thickness is 3-40nm. The surface exciton resonance absorption peak of the gold nano island array is matched at 525-535nm, and the surface exciton resonance absorption peak of the silver nano island array is matched at 800-815nm. An oxygen-containing polar group modified layer is obtained by low-temperature plasma modification treatment of the bottom and sidewalls of the mesh cells and the surface of the anilox roller.

2. The micron-level anilox roller for printing corrugated cardboard boxes according to claim 1, characterized in that, The channel-shaped micron-scale cell array has a single cell opening diameter of 20-80μm, a cell depth of 10-40μm, a cell sidewall taper of 5°-15°, and a cell line count of 80-200 lines / inch.

3. The micron-level anilox roller for printing corrugated cardboard boxes according to claim 1, characterized in that, The gold or silver nanoisland array has a single nanoisland particle size of 15-150 nm, a spacing of 20-200 nm between adjacent nanoislands, a surface plasmon resonance absorption peak half-width of ≤80 nm, and an absorbance of ≥0.8 at the matched wavelength.

4. A method for preparing a micron-level anilox roller for printing corrugated cardboard boxes, characterized in that, The method includes the following steps: S1: Select the roller substrate and perform surface degreasing, rust removal and precision polishing pretreatment in sequence to obtain a pretreated roller with a surface roughness Ra≤0.4μm; S2: Hard anodizing is performed on the pre-treated roller body to generate a hard oxide film layer with a thickness of 30-80μm in situ on the surface of the roller body, thus obtaining a roller body with an oxide film layer; S3: Design a channel-shaped micron-level mesh structure, and use an ultra-short pulse laser to engrave the roller with an oxide film layer, forming a uniformly arranged micron-level mesh on the surface of the oxide film layer, to obtain an engraved semi-finished roller; S4: Prepare gold nano islands or silver nano island arrays at the bottom and sidewalls of the engraved mesh. The surface exciton resonance absorption peak of the gold nano island array is matched at 525-535nm, and the surface exciton resonance absorption peak of the silver nano island array is matched at 800-815nm, to obtain a semi-finished roller with nano island array. S5: The bottom of the cells, sidewalls and surface of the semi-finished roller with nano-island array are modified by low-temperature plasma treatment. Oxygen-containing polar groups are introduced into the bottom of the cells, sidewalls and nano-island surface to improve ink affinity, and the modified roller is obtained. S6: The modified roller body is subjected to ultra-precision polishing, ultrasonic cleaning, and vacuum drying. After passing the tests on cell parameters, nano-island optical properties, and printability, a micron-level cell anilox roller for corrugated carton printing is obtained.

5. The method for preparing a micron-level anilox roller for corrugated cardboard box printing according to claim 4, characterized in that, In the S2, the hard anodic oxidation treatment adopts sulfuric acid system electrolyte, the electrolyte temperature is controlled at -5 to 5℃, the current density is 1.5-3.5A / dm 2 , the oxidation treatment time is 40-90min; the microhardness of the hard oxidation film layer is ≥350HV, and the porosity of the film layer is ≤8%.

6. The method for preparing a micron-level anilox roller for corrugated cardboard box printing according to claim 4, characterized in that, In S3, the channel-shaped micron-level cell structure is a channel-shaped cell array with 60° oblique interconnection. The opening diameter of a single cell is 20-80μm, the cell depth is 10-40μm, the taper of the cell sidewall is 5°-15°, and the cell line count is 80-200 lines / inch.

7. The method for preparing a micron-level anilox roller for corrugated cardboard box printing according to claim 4, characterized in that, In S3, the ultrashort pulse laser is a picosecond laser or a femtosecond laser, and the laser engraving process parameters are: laser power 10-50W, pulse frequency 50-200kHz, scanning speed 500-2000mm / s, single pulse energy 20-100μJ, and high-purity argon gas is used as a protective gas during the engraving process.

8. The method for preparing a micron-level anilox roller for corrugated cardboard box printing according to claim 4, characterized in that, In step S4, the gold or silver nanoisland array is prepared using a magnetron sputtering combined with rapid thermal annealing method. Specifically, a gold or silver nanofilm with a thickness of 2-10 nm is deposited by magnetron sputtering on the bottom and sidewalls of the cells. The sputtering power is 50-150 W, and the sputtering vacuum is 1×10⁻⁶. -3 -5×10 -3 Pa, argon flow rate of 20-50 sccm; then rapid thermal annealing at 200-400℃ under nitrogen protection atmosphere, annealing time of 5-30 min, heating rate of 50-100℃ / min, and after cooling, a uniformly distributed array of nano-islands is formed at the bottom and sidewalls of the mesh. The continuous gold or silver film with a thickness of 2-10 nm deposited by magnetron sputtering is transformed into a discrete nanoisland array with a thickness of 3-40 nm by rapid thermal annealing.

9. The method for preparing a micron-level anilox roller for corrugated cardboard box printing according to claim 4, characterized in that, In step S5, the working gas for the low-temperature plasma modification treatment is a mixture of argon and oxygen, wherein the volume percentage of oxygen is 10%-30%, and the plasma treatment process parameters are: treatment power 80-200W, treatment vacuum degree 10-50Pa, roller rotation speed 5-20r / min, and treatment time 10-30min.

10. The method for preparing a micron-level anilox roller for corrugated cardboard box printing according to claim 4, characterized in that, In step S6, the ultra-precision polishing is performed using a wool wheel in conjunction with nano-diamond polishing paste, and the roughness Ra of the non-cell area of ​​the roller surface after polishing is ≤0.2μm; the performance testing includes three-dimensional morphology detection of cells, ink loading deviation detection, ink affinity contact angle detection, nano-island resonance wavelength detection, wear resistance testing, and printability testing.

11. An application of a micron-level anilox roller for corrugated cardboard box printing, characterized in that, The micron-sized anilox roller according to any one of claims 1 to 3 is assembled in a corrugated cardboard water-based ink flexographic printing press unit, and an irradiation light source matching the resonant wavelength of the nano-island array is provided; during the printing process, in the transient window before the ink is transferred from the cells to the printing plate, the cells are pulsedly irradiated by the irradiation light source, and the surface plasmon resonance photothermal effect of the nano-island array is used to locally and instantaneously raise the temperature of the ink in the cells by 5-20°C, thereby reducing the ink viscosity and improving the transfer and spreading efficiency. After the irradiation is completed, the ink temperature returns to room temperature.

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