With the continuous prosperity of the commodity economy, the packaging of products is becoming more and more particular, the color corrugated carton is more and more popular by merchants, and the color carton (including color boxes) has more and more market shares. Also attracted the attention of businesses. Improving the quality of color corrugated boxes has become one of the important management contents that cannot be ignored in the production process control of carton factories. Throughout the production process of color corrugated carton, the main links that affect the printing quality of carton products are: production process plan, plate making, base paper quality, ink deployment, equipment adjustment, operation technology, staff quality, etc. Careful control and control of each link can better improve the printing quality of color carton products and meet customer requirements.
1. To correctly select the printing production process plan
In the process of receiving orders and process arrangement of color carton products, first of all, we should consider what kind of production process is adopted, which can better guarantee the printing quality of the product. The author believes that the production process of pre-press platemaking and printing process should be determined according to the characteristics of the manuscript. Among them, the factors that should be considered include: the production process of the printing plate, the characteristics of the base paper, the performance of the ink, the production process, the type of equipment, etc. The production process shows that the correct setting of the color carton printing process plan is the key link that determines the production efficiency and product printing quality, and is also the source link of product quality control. Choosing the correct printing process is also a reliable guarantee to effectively prevent the occurrence of printing defects and reduce the consumption of printing raw and auxiliary materials. Therefore, for the color carton with a finer layout, it may be considered to use the pre-printing process for printing. Among them, the lithographic pre-printing process is easy and fast to make. It can print both simple layout and fine screen printing. The cost is lower and it is more suitable for printing production of less than 100,000 sheets. Although the flexo printing process is also relatively easy to make, but because the resin plate material is more expensive, and the dot reproduction and overprint accuracy are not as good as the lithographic printing process, it is suitable for printing general color carton, and it must be a product with a larger production volume to offset The cost of high plate-making costs. The gravure pre-printing process is more complicated, and the plate making cost is also the highest production process. However, its printing plate has a high printing durability, which is ideal for thick ink layer and fine color carton surface paper printing, suitable for relatively fixed layout Preprinting of long-line color carton facial paper with a particularly large production volume. For products with low production quantity, simple layout, and low quality requirements, consider using a flexo printing slotting machine to complete the direct printing of corrugated cardboard at one time. Choosing the color carton printing process plan should not only start from the factory, but also consider the performance and quality requirements of the product; not only from the perspective of reducing production consumption and production costs, but also how to shorten the production cycle, Meeting the urgent needs of customers is an important principle.
2. Control of printing plate production technology
The technical control of the printing plate production process of the color carton is of great significance to ensure the printing production efficiency and product quality. In the printing process, from the quality of the ink color to the clarity of the product printing; from the durability of the printing rate to the accuracy of the plate overprint, all involve the technical control of the printing plate production. For example, in the case of flexographic production, when the layout has both small text version, screen version and solid or large area line version, in order to ensure the production effect of solid version, line and text version and screen version, improve the printing quality and printing. The printing durability of the plate can be divided into two areas of large-area field, line plate and screen plate in the same color layout, and exposed and rinsed separately, so that the production quality of the printing plate and the print durability can be better Improvement. In this way, the plate-making can also take advantage of the flexographic multi-color printing unit, and use two color groups to print the large-area solid version, line version and text version, and the textured version, so that the solid version and line version remain thick and bright. The printing ink layer, and the text version and the textured version surface can get the appropriate amount of ink coating, which can effectively avoid the occurrence of the defects of paste version. In addition, in the printing operation, you should pay attention to check whether the printing platform is flat and whether there is leakage in the vacuum exhaust; the exposure time should be determined according to the layout structure and the characteristics of the plate material, and if necessary, a sample printing test can be carried out; for small lines 1. The resin version of the dot should pay attention to the control of the development time of the plate washing to prevent the occurrence of undesirable conditions such as line deformation and dot loss caused by excessive plate washing. [next]
3. Control of color carton printing technology
①Pay attention to the control of temperature and humidity in the printing environment. Color cartons are generally overprinted with more than 4 colors, and the horizontal direction of the facial paper is most likely to be deformed due to changes in the environment's temperature and humidity, resulting in inaccurate overprint failures. Controlling the temperature and humidity of the printing workshop has become an important part of improving the accuracy of overprinting of color carton products. Therefore, whether it is a flexographic process, lithographic or gravure production workshop, the temperature and humidity of the production site must remain relatively stable and balanced. During the printing process, there should be no obvious difference between high and low, so as to avoid the disadvantage of inaccurate overprinting. The printing process practice shows that the temperature of the printing workshop is generally controlled at about 22 ℃, the humidity should be kept at about 60%, and the paper and cardboard are not prone to deformation, which is more effective for ensuring accurate product overprinting.
â‘¡Technical control of plate mounting technology. The production process of pre-printing carton facial paper with an offset press is very important for the control of plate mounting operation technology. Because the PS plate is thin, the total thickness of the photosensitive layer and the base is about 0.3mm, and the base of the aluminum plate, the material has a relatively brittle character, you should be careful in the process of installing the plate, and you should pay attention to avoid the layout It is scratched by the parts on the machine; when correcting the version, pay attention to grasping the moderate force to prevent the excessive force from causing the plate to deform and deform, resulting in inaccurate product overprinting and reduced printing resistance. The flexible plate should pay attention to the position of the sticky plate at one time as far as possible, to avoid repeated dismantling of the plate to deform the printing plate and affect the fastness of the sticky plate. When the temperature is particularly high, you should consider using high-quality double-sided tape to prevent the printing plate from running out of position during the printing process. The high-quality double-sided adhesive tape should have strong viscosity, good flatness, uniform thickness, and good temperature resistance. It can ensure the stability of viscosity in high and low temperature operating environments, and no residual glue will be left on the plate material and plate cylinder when removing the plate.
â‘¢Control of offset ink-water balance. The control of water and ink balance is a crucial technical link in the offset printing process. When printing on facial paper, it is often because the water and ink balance control is not in place, and there are many situations that affect the color quality of ink. The amount of supply is ideal for printing under the condition of maintaining the balance of water and ink. Never use the balance method of "big ink and big water" to print. The key to water-ink balance control is to require the ink to maintain good cleanliness and reasonable fluidity. Try not to use or use a drier to prevent the skin from forming during the early drying of the ink; the printing workshop should pay attention to dust and powder protection ; Try to avoid mixing new and old inks; the pH value of fountain solution should be properly controlled and the water quality should be kept pure; rubber rollers and water rollers must maintain good accuracy and appropriate hardness; the printing speed should be kept moderate and constant, these are the realization of ink Balanced technical essentials and effective guarantee conditions.
â‘£Control of color sequence arrangement of offset printing. The printing of color carton is usually completed by a multi-color printing machine at one time. During printing, the ink is "wet-pressed" overprinted and overprinted in an instant. The stacking time between the colors is very short. Therefore, the printing color sequence It should be reasonably determined according to many factors such as layout structure, ink characteristics and paper performance. In general, the arrangement of printing color sequence should be controlled according to the actual situation, such as printing first with a small printing area and ink volume, and printing after a large layout and ink volume; printing with poor transparency and printing with good transparency ; Ink with high viscosity is printed first, and ink with low viscosity is printed; ink with slow drying is printed first, and ink with fast drying speed is printed. Considering the light resistance of the ink, yellow and magenta have poor light resistance, and should be arranged first, and cyan and black have good light resistance and can be printed in turn. When there are differences in surface strength, gloss, ink absorption, moisture content and acidity, etc. of the material, in order to prevent the defects such as dusting, brushing, dirty, overprinting and poor drying, it will cause obstacles to normal printing, so the color The sequence arrangement should be considered from the characteristics of the paper. Taking the paper with good gloss and high tightness as an example, the dark color should be printed first, and then the light color should be printed later. On the contrary, if the paper surface is rough and loose, it should be printed with light color and then dark color. [next]
⑤Control of product overprint accuracy. When there are foreign objects or tooth wear on the roller's teeth, the bite force is insufficient or the amount of teeth is uncomfortable; the positioning device is worn or loose, which causes abnormal operation; the pressure of the paper guide wheel is inconsistent or the conveyor belt is not tight; ; Excessive printing pressure or improper handover of cardboard; uneven cardboard or wavy deformation of the paper edge; too much fountain solution or ink coating, etc., will affect the quality of the product's overprint, so in order to improve the accuracy of the product's overprint Pay attention to the careful inspection and control from the above links, and if problems are found, corresponding measures should be taken in time to deal with them.
â‘¥ Reasonable control of printing pressure. Doing a good job of controlling the printing pressure is very important to improve the printing durability of the printing plate, prevent printing quality failures such as pasting, dirty, and off-set, and ensure the clarity of printing. In special lithographic and flexographic printing processes, the lightest pressure must be used for printing, and the flatness of the liner should be good. The local depressions should be partially padded, and it must not be adjusted by comprehensive blind pressurization for the sake of effort. When adjusting the pressure, it should be carried out gradually from light to heavy under the condition of the normal amount of ink coating, so as to avoid the unclear imprinting caused by the insufficient ink volume and the wrong pressure.
⑦The selection of ink and the control of blending process technology. For color carton facial paper printing, ink with good fineness and moderate dryness should be used for printing. Different types of inks should not be mixed and used to prevent abnormal damage to the PS film, to avoid dirty, pasted, and off-set Wait for the printing quality defects. For large-area spot color printing, it is advisable to use the "deep ink thin printing" process for printing, that is, to adjust the ink hue appropriately to make the ink layer thinner during printing, so that it can meet the requirements of the printing hue and be effective Prevent the occurrence of printing defects such as dirty, pasted plates, and overprinting.
⑧ Check the "three times" of printing. After the proofreading work is completed, although the printing pressure and ink coating amount have been adjusted normally, due to various variability factors in the printing process, such as environmental temperature and humidity changes, ink thixotropy, and the quality of the base paper Instability, unexpected equipment failure, etc., may affect the stability of printing quality. Therefore, a skilled printing operator with a certain production experience and a strong sense of responsibility will always perform diligent sampling and inspection during the printing process. Stir the ink in the ink fountain and observe the moisture of the layout frequently. This is an important measure to improve printing quality and production efficiency, and it is also a reliable guarantee to effectively avoid printing quality failures. By checking the "three diligence" of printing, the balance of water and ink can be maintained, and hidden dangers of printing quality can be found in time, so that preventive and corrective measures can be taken in time to reduce the occurrence of defective products and improve the pass rate of printing.
⑨Technical control of printing process to remove paper dust. Due to the increasingly fierce market competition, the small profits of the carton industry are gradually emerging. It has become an objective situation that the packaging of general products is difficult to use high-quality base paper for production. Some medium- and low-grade base papers are often prone to appear in the printing process due to the poor surface strength. Powder, hair loss and other quality defects, but also easy to cause chain printing faults such as paste version, dirty version and version loss, seriously affect production efficiency and product printing quality. In order to reduce or avoid the occurrence of these problems, the redundant printing color set of the multi-color printing machine is used. In the first one or two color sets of the machine, the base paper is first subjected to water and air embossing, which can better overcome and compensate for the quality of the base paper Poor defects, effectively reduce or eliminate the printing quality problems of powder, hair loss and ink skin. [next]
4. Correct maintenance and adjustment of the machine
The machine is an important factor that determines the productivity level and product quality, and is also the source link of the printing quality. Therefore, you should usually pay attention to strengthening the maintenance of the machine, and the key parts of the machine, such as the paper delivery tooth, the pull rule, the front rule, the tooth Rows, roller shafts and other relevant parts should be strictly maintained according to the requirements of the equipment specifications to prevent the wear and looseness of key parts from causing overprint faults. It should be noted that the machine is regularly checked, and if problems and hidden troubles are found, timely measures are taken to deal with them. Through careful maintenance of the equipment, the accuracy of the machine is kept in good condition. In addition, the correct adjustment of the machine is also an operational technical link that can not be ignored to improve the printing quality of the product. The production process practice shows that the thickness of the lining of the drum must be strictly controlled according to the parameters of the equipment specification, and the tight liner, blanket and printing plate should be tightly packed. The pressure of the roller's teeth should not be too small; the mouth should be kept moderately and not too small. For the use of worn teeth, the pads should be replaced with new accessories in time; the printing speed of the entire batch of products should be consistent, and the printing speed should not be too slow or too fast. In this way, the overprinting accuracy of the product can be better ensured.
In summary, optimizing the production process technology of color carton involves all aspects of the entire production process, so as long as we strengthen the control of production process technology, scientifically and rationally formulate flexible and standardized production operation process plans, focusing on pre-press Design to production process control; from raw material use to equipment operation; from production process to printing operation technology check; from semi-finished product production to finished product inspection, systematically and systematically control step by step, not only can effectively reduce various printing defects Occurs, and the production efficiency and product quality can be improved simultaneously.
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