Printing ink spraying process for color printing carton

Abstract

The invention relates to the technical field of printing and packaging, and discloses a printing ink spraying process for a color printing carton, which comprises the following steps: step 1, carton surface pretreatment: carrying out cleaning and micropore treatment on the carton surface, removing surface impurities by adopting an ultrasonic cleaning technology, and drying the carton surface; a micron-sized concave-convex structure is formed on the surface of the carton by using a low-temperature plasma technology, and the surface roughness range is Ra 1-3 microns, so that the adhesive force between the ink and the surface of the carton is enhanced; the basic ink and a functional additive are mixed in proportion according to the design pattern requirement, and the functional additive comprises nano zinc oxide particles with the mass fraction of 0.5%-2% and is used for improving the weather resistance and the antibacterial performance of the ink. The surface of the carton is subjected to special pretreatment, the adhesive force of printing ink is remarkably improved, the durability and stability of printed patterns are enhanced, high-precision pattern spraying is achieved through the intelligent image recognition and piezoelectric ink jet technology, the complex design requirement is met, and the printing quality is improved.

Description

Technical Field

[0001] The invention relates to the technical field of printing and packaging, in particular to an ink spraying process for a color-printed carton. Background Art

[0002] In the packaging industry, color-printed cartons, as an important packaging material, are widely used in commodity packaging, transportation, and display. Their appearance quality and printing effect directly affect the market competitiveness and brand image of the product. The ink spraying process is one of the key links in the production of color-printed cartons, which directly determines the clarity, color saturation, and adhesion of the printed pattern. However, the existing ink spraying process still has many shortcomings in practical applications.

[0003] The traditional ink spraying process usually relies on manual operation or simple mechanical equipment. This method is not only inefficient, but also prone to problems such as uneven spraying and obvious color difference due to human factors. In addition, the utilization rate of ink in the existing technology is low, and ink waste often occurs during the spraying process, which increases production costs and causes certain pollution to the environment. At the same time, the traditional process has poor adaptability to the surface of the carton, especially when facing cartons of different materials, shapes or surface treatments, it is difficult to ensure the consistency and stability of the spraying effect.

[0004] On the other hand, as the market's requirements for the quality of color-printed cartons continue to increase, the shortcomings of existing technologies in terms of spraying accuracy, color reproduction, and environmental performance have become increasingly prominent. Especially in multi-color printing or complex pattern printing, traditional processes often fail to meet the requirements of high precision and high efficiency. Therefore, a color-printed carton ink spraying process that can improve spraying uniformity, reduce ink consumption, enhance adaptability, and achieve high efficiency and environmental protection is developed. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides an ink spraying process for color-printed cartons, which solves the problems of poor ink adhesion, poor color uniformity and low spraying efficiency in the traditional spraying process.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions: an ink spraying process for a color-printed carton, comprising the following steps:

[0007] Step 1: pretreatment of the carton surface, cleaning and microporation of the carton surface, using ultrasonic cleaning technology to remove surface impurities, and using low-temperature plasma technology to form a micron-level concave-convex structure on the carton surface, with a surface roughness range of Ra1-3μm, to enhance the adhesion between the ink and the carton surface; Step 2: ink preparation, according to the design pattern requirements, the basic ink and the functional additives are mixed in proportion, wherein the functional additives include nano zinc oxide particles with a mass fraction of 0.5%-2%, which are used to improve the weather resistance and antibacterial properties of the ink;

[0008] Step 3: Calibrate the spraying equipment. Use a multi-nozzle array spraying equipment, adjust the nozzle spacing to 5-15mm, the spraying angle to 45°-60°, and use high-frequency vibration technology to control the ink particle size within the range of 10-30μm to ensure spraying uniformity;

[0009] Step 4: Pattern spraying: Use the intelligent image recognition system to locate the spraying area on the carton surface, and use piezoelectric inkjet technology to evenly spray the ink on the target area. The spraying thickness is controlled at 20-50μm to avoid ink accumulation or penetration;

[0010] Step 5: Rapid curing treatment: Immediately after spraying, use infrared heating technology to cure the ink. The heating temperature is 60-80°C and the curing time is 30-60 seconds to ensure that the ink dries quickly and adheres firmly to the surface of the carton.

[0011] Step 6: Surface protective coating, spray a layer of transparent protective coating, the coating material is water-based polyurethane, the thickness is controlled at 10-20μm, to improve the wear resistance and waterproof performance of the carton surface.

[0012] Preferably, the carton base material in step 1 is corrugated cardboard, and the compressive strength of the corrugated cardboard is in the range of 8-12 kN / m, and the water absorption rate is in the range of 5%-10%.

[0013] Preferably, in step 4, by adjusting the voltage frequency and ink flow rate of the piezoelectric inkjet device, accurate spraying of inks of different colors is achieved, and the pattern boundary clarity deviation is less than ±0.1 mm.

[0014] Preferably, in step five, a far-infrared ceramic coating is added to the infrared heating device.

[0015] Preferably, after the protective coating is sprayed in step six, the method further includes optical inspection and quality screening of the carton surface to eliminate products that do not meet the adhesion level lower than level 3 or the abrasion resistance test of less than 500 times.

[0016] Preferably, the step of optimizing the surface pretreatment based on the carton material characteristics further comprises:

[0017] Determine the water absorption and surface flatness of the carton substrate;

[0018] Compare the effects of different treatments on adhesion;

[0019] Select the optimal roughness range and plasma treatment time based on actual parameters;

[0020] If the roughness range is R, and when Ra is less than Rmin, the plasma treatment time is extended; when Ra is greater than Rmax, the treatment intensity is reduced, where Rmin and Rmax represent the set minimum and maximum roughness range limits.

[0021] Preferably, the test is performed using a nozzle having a specific spray angle and flow rate;

[0022] Investigate the effects of different nozzle spacing, spraying angles and ink particle sizes on spraying effects;

[0023] Select the most suitable spraying parameters based on nozzle characteristics and target requirements;

[0024] If the nozzle spacing is S and the spraying angle is A, and the goal is to maximize the spraying uniformity, then when S*A≥Kmin, ensure that the process parameters are within the effective range, otherwise the nozzle position and angle should be adjusted appropriately.

[0025] Preferably, the functional additive in step 2 further includes nano titanium dioxide particles with a mass fraction of 0.1%-0.5%, which are used to improve the anti-ultraviolet performance of the ink.

[0026] The present invention provides an ink spraying process for color-printed cartons. It has the following beneficial effects:

[0027] 1. The present invention significantly improves the ink adhesion and enhances the durability and stability of the printed pattern by performing special pretreatment on the carton surface. Through intelligent image recognition and piezoelectric inkjet technology, high-precision pattern spraying is achieved to meet complex design requirements and improve printing quality.

[0028] 2. The present invention not only improves the weather resistance and antibacterial properties of the ink, but also enhances the surface protection ability of the carton by adding functional additives and a transparent protective coating. By optimizing the spraying equipment and curing process, the production efficiency is greatly improved, while the energy consumption is reduced, meeting the requirements of green environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the carton surface pretreatment process of the present invention;

[0030] Figure 2 It is a schematic diagram of the ink preparation process of the present invention;

[0031] Figure 3 It is a schematic diagram of the structure of the multi-nozzle array spraying equipment of the present invention;

[0032] Figure 4 This is a working principle diagram of the piezoelectric inkjet technology spraying pattern of the present invention;

[0033] Figure 5 This is a schematic diagram of the infrared heating curing process of the present invention;

[0034] Figure 6 The present invention is a flow chart of the transparent protective coating spraying and quality inspection. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the specification of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] Example:

[0037] Please refer to the attached Figure 1 -Attached Figure 6 The embodiment of the present invention provides an ink spraying process for color-printed cartons. First, the carton surface is pretreated in step 1. This step is intended to improve the adhesion between the ink and the carton surface and ensure the quality of the subsequent spraying process. Figure 1 The schematic diagram of the carton surface pretreatment process shown in the figure first uses corrugated cardboard as the substrate, and its compressive strength must be greater than 8kN / m and its water absorption rate must be less than 10% to ensure the structural stability and printing effect of the carton after spraying. Then, the impurities on the surface of the carton are removed by ultrasonic cleaning technology. This process uses the cavitation effect generated by high-frequency vibration to effectively remove surface dust, oil and other pollutants. Then, the low-temperature plasma technology is used to microporize the surface of the carton, and a micron-level concave-convex structure is formed by plasma bombardment, and the surface roughness range is controlled within Ra1-3μm. If the roughness is detected to be less than Rmin, that is, Ra is less than 1μm, the plasma treatment time needs to be extended; if the roughness is greater than Rmax, that is, Ra exceeds 3μm, the plasma treatment intensity is reduced to ensure that the surface roughness is in the optimal range. This pretreatment step significantly improves the adhesion of the carton surface, laying a solid foundation for subsequent spraying.

[0038] In step 2, ink is prepared according to Figure 2The schematic diagram of the ink mixing process shown in the figure mixes the base ink with the functional additives in proportion. The functional additives include nano zinc oxide particles with a mass fraction of 0.5%-2%, which are used to improve the weather resistance and antibacterial properties of the ink. Specifically, when the design pattern requires high weather resistance, the addition amount of nano zinc oxide particles can be set to 2%; for general use, an addition amount of 0.5%-1% can be selected. In addition, the mixing of the base ink and the functional additives needs to be fully stirred evenly, the stirring time is 10-15 minutes, and the rotation speed is controlled in the range of 300-500rpm to ensure that the nanoparticles are evenly dispersed and avoid agglomeration. Through the above-mentioned mixing process, the ink not only has good printing performance, but also has excellent functionality, which meets the spraying requirements of complex patterns.

[0039] Step three involves calibration of the spray equipment, such as Figure 3 In the schematic diagram of the multi-nozzle array spraying equipment structure shown, the nozzle spacing is adjusted to 5-15mm, the spraying angle is 45°-60°, and the ink particle size is controlled within the range of 10-30μm by high-frequency vibration technology. The specific calibration process is as follows: First, select the appropriate number of nozzles and arrangement according to the size and shape of the target spraying area, and determine the optimal nozzle spacing S and spraying angle A through experiments. If the goal is to maximize the uniformity of spraying, the condition of SA≥Kmin must be met, where Kmin is an empirical constant, usually 75. For example, when the nozzle spacing is 10mm and the spraying angle is 60°, SA=10*60=600 is calculated, which is much larger than Kmin, indicating that the process parameters are within the effective range. In addition, high-frequency vibration technology controls the ink particle size within the range of 10-30μm by adjusting the vibration frequency, further ensuring the uniformity of spraying. After the above calibration steps, the spraying equipment can efficiently complete high-quality ink spraying tasks.

[0040] Step 4 is the pattern spraying stage, combined with Figure 4The working principle diagram of the piezoelectric inkjet technology spraying pattern shown in the figure uses an intelligent image recognition system to locate the spraying area on the carton surface, and the piezoelectric inkjet technology is used to evenly spray the ink on the target area. In the specific operation process, the carton surface is first scanned by the intelligent image recognition system to obtain the precise position and boundary information of the spraying area, and the data is transmitted to the piezoelectric inkjet device control system. Then the voltage frequency and ink flow rate of the piezoelectric inkjet device are adjusted to achieve accurate spraying of different colors of ink. For example, for dark inks, the voltage frequency can be appropriately increased to 10kHz, while the ink flow rate can be reduced to 5ml / min; for light inks, the voltage frequency can be set to 8kHz, and the ink flow rate can be adjusted to 8ml / min. In addition, the spraying thickness needs to be strictly controlled within the range of 20-50μm to avoid ink accumulation or penetration. Through the above process, the pattern boundary clarity deviation can be controlled within ±0.1mm, which meets the requirements of complex design and greatly improves the printing quality.

[0041] Step five is a rapid curing process, such as Figure 5 In the schematic diagram of the infrared heating curing process shown, infrared heating technology is used for curing immediately after spraying is completed, the heating temperature is 60-80℃, and the curing time is 30-60 seconds. In the specific implementation, a far-infrared ceramic coating is added inside the infrared heating equipment to improve the thermal radiation efficiency and energy utilization rate and reduce energy consumption. The far-infrared ceramic coating absorbs infrared radiation and converts it into heat energy, so that the surface of the carton is quickly heated to the set temperature. For example, when the heating temperature is set to 70℃, the infrared heating equipment can raise the surface temperature of the carton to the target value within 30 seconds, ensuring that the ink dries quickly and adheres firmly to the surface of the carton. In addition, the curing time can be dynamically adjusted according to the ink thickness and ambient temperature. For example, when the spray thickness is 50μm and the ambient temperature is low, the curing time can be extended to 60 seconds; when the spray thickness is 20μm and the ambient temperature is high, the curing time can be shortened to 30 seconds. Through the above curing process, not only the production efficiency is improved, but also the energy consumption is significantly reduced, which meets the requirements of green environmental protection.

[0042] Step six is ​​spraying of surface protective coating, such as Figure 6In the transparent protective coating spraying and quality inspection flow chart shown, a layer of transparent protective coating is sprayed, and the coating material is water-based polyurethane, and the thickness is controlled within the range of 10-20μm. In the specific implementation process, the water-based polyurethane coating material is first evenly sprayed on the surface of the carton, and the spraying thickness can be accurately controlled by adjusting the spray gun pressure and spraying speed. For example, when the coating thickness is set to 15μm, the spray gun pressure can be set to 0.3MPa and the spraying speed can be adjusted to 10cm / s. After the spraying is completed, the surface of the carton is optically inspected and quality screened to remove products that do not meet the adhesion level of less than 3 or the abrasion resistance test of less than 500 times. Optical inspection measures the coating thickness and surface flatness through a high-precision laser scanner to ensure that the coating is evenly distributed and has no obvious defects; quality screening evaluates the adhesion and wear resistance of the coating through pull-out tests and abrasion tests. For example, when the adhesion level is lower than level 3 or the abrasion resistance test is less than 500 times, the product will be automatically rejected and reworked. Through the above-mentioned protective coating process, not only the wear resistance and waterproof performance of the carton surface are improved, but also the overall protection capability is further enhanced.

[0043] In summary, the present invention solves the problems existing in the traditional spraying process through a series of innovative processes. By performing special pretreatment on the surface of the carton, the ink adhesion is significantly improved, and the durability and stability of the printed pattern are enhanced; high-precision pattern spraying is achieved through intelligent image recognition and piezoelectric inkjet technology, which meets complex design requirements and improves printing quality; by adding functional additives and transparent protective coatings, not only the weather resistance and antibacterial properties of the ink are improved, but also the surface protection ability of the carton is enhanced; by optimizing the spraying equipment and curing process, the production efficiency is greatly improved, while the energy consumption is reduced, which meets the requirements of green environmental protection.

[0044] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An ink spraying process for color-printed cartons, characterized in that: The following steps are involved: Step 1: pretreatment of the carton surface, cleaning and microporation of the carton surface, using ultrasonic cleaning technology to remove surface impurities, and using low-temperature plasma technology to form a micron-level concave-convex structure on the carton surface, with a surface roughness range of Ra1-3μm; Step 2: ink preparation, mixing the base ink with the functional additives in proportion, wherein the functional additives include nano zinc oxide particles with a mass fraction of 0.5%-2%; Step 3: Calibrate the spraying equipment. Use a multi-nozzle array spraying equipment, adjust the nozzle spacing to 5-15mm, the spraying angle to 45°-60°, and control the ink particle size within the range of 10-30μm through high-frequency vibration technology; Step 4: Pattern spraying: Use the intelligent image recognition system to locate the spraying area on the carton surface, and use the piezoelectric inkjet technology to evenly spray the ink on the target area, with the spraying thickness controlled at 20-50μm; Step 5: Rapid curing treatment: Immediately after spraying, use infrared heating technology to cure the coating. The heating temperature is 60-80°C and the curing time is 30-60 seconds. Step 6: Surface protective coating: spray a layer of transparent protective coating. The coating material is water-based polyurethane and the thickness is controlled at 10-20μm.

2. The ink spraying process for color-printed cartons according to claim 1, characterized in that: The carton base material in step 1 is corrugated paperboard, the compressive strength of the corrugated paperboard is in the range of 8-12 kN / m, and the water absorption rate is in the range of 5%-10%.

3. The ink spraying process for color-printed cartons according to claim 2, characterized in that: In step 4, the voltage frequency and ink flow rate of the piezoelectric inkjet device are adjusted to achieve accurate spraying of inks of different colors, and the pattern boundary clarity deviation is less than ±0.1 mm.

4. The ink spraying process for color-printed cartons according to claim 2, characterized in that: In step five, a far-infrared ceramic coating is added to the infrared heating device.

5. The ink spraying process for color-printed cartons according to claim 1, characterized in that: After the protective coating is sprayed in step six, the carton surface is optically inspected and quality screened to remove products that do not meet the adhesion level below level 3 or the abrasion resistance test of less than 500 times.

6. The ink spraying process for color-printed cartons according to claim 5, characterized in that: The step of optimizing the surface pretreatment based on the carton material characteristics further includes: Determine the water absorption and surface flatness of the carton substrate; Compare the effects of different treatments on adhesion; Select the optimal roughness range and plasma treatment time based on actual parameters; If the roughness range is R, and when Ra is less than Rmin, the plasma treatment time is extended; when Ra is greater than Rmax, the treatment intensity is reduced, where Rmin and Rmax represent the set minimum and maximum roughness range limits.

7. The ink spraying process for color-printed cartons according to claim 1, characterized in that: The test is carried out using a nozzle having a specific spray angle and flow rate; Investigate the effects of different nozzle spacing, spraying angles and ink particle sizes on spraying effects; Select the most suitable spraying parameters based on nozzle characteristics and target requirements; If the nozzle spacing is S and the spraying angle is A, and the goal is to maximize the spraying uniformity, then when S*A≥Kmin, ensure that the process parameters are within the effective range, otherwise the nozzle position and angle should be adjusted appropriately.

8. The ink spraying process for color-printed cartons according to claim 1, characterized in that: The functional additives in step 2 also include nano titanium dioxide particles with a mass fraction of 0.1%-0.5%, which are used to improve the anti-ultraviolet performance of the ink.

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