Paper Packaging Printing New Technology

1. Paper Packaging Development Trends and Requirements for Technology

In recent years, the global paper product packaging industry has developed rapidly, and the production capacity of cartons and cartons has increased significantly. In the world packaging industry, paper packaging products exceed 32%. In Europe, the proportion of paper and paperboard consumption is as high as 41%. Per capita consumption of paper and board in 2000 was 331.7 kg in the United States, 249.9 kg in Japan, 229.4 kg in Taiwan, and 28.4 kg in mainland China. In 2000, China imported 13.03 million tons of paper, paperboard and pulp (about US$6 billion), accounting for 66.7% of China’s paper and paperboard consumption. In recent years, Hong Kong's packaging industry has grown at about twice the rate of the printing industry. In 2000, Guangdong's packaging industry achieved sales of 50 billion yuan, including 18 billion yuan in paper packaging products and 14 billion yuan in packaging and printing.

With the further enhancement of people's environmental awareness, cartons, cartons, paper bags, paper cups, paper tubes and other packaging containers are used more and more widely in Europe for a variety of fruit juices, milk, cooked food, snacks, snacks and other beverages. Food carton packs are everywhere. According to relevant information of the Chinese tobacco department, the proportion of domestic hard-packed cigarettes has reached 56%.

With the continuous improvement of people's living standards and the degree of automation of commodity packaging, not only the demand for cartons/cartons has increased significantly, but also higher requirements have been placed on the printing quality and processing accuracy of color folding cartons/multicolor cartons. . To avoid rabbits in the automatic folder gluer out of waste, so that the folding cartons in the high-speed packaging machine automatically open, molding, filling, sealing and other processes, not only requires that the carton structure is reasonable in size design but also should ensure that the cartridge has enough mold Cutting accuracy and folding folder accuracy. Multi-color printing, short-lived jobs, increased printing quality and processing precision, and reduced processing costs are also the market pressures and challenges faced by carton packaging and printing companies. Therefore, only with the application of modern processing methods and new technologies, the degree of automation of the equipment, the adjustment time of the equipment, and the auxiliary preparation time of the work are continuously improved in the process of paper packaging printing and post-press processing, and constantly adapting to new changes in the market and satisfying different requirements The requirements of users can improve the competitiveness of packaging and printing companies.

2 paper packaging container CAD technology

The popular carton structure CAD software on the international market, in addition to the basic functions of commonly used interactive graphics software (high-quality, rapid completion of graphics generation, editing, modification, dimensioning, etc.), should also meet the carton design The special requirements, easy to call the cassette graphics library and select the box-shaped structure, enter the box size (length, width, height) and cardboard thickness, you can immediately display or print the cassette structure, automatic discharge, and Output cartridge sheet die cutting discharge pattern, printing outline drawing and backing (bottom mold) processing drawing; when the user design or call for the required cassette sheet structure, as long as the input paper board size and discharge gap, can be expected And compare the different discharge plans, show the optimization of die-cutting discharge diagrams and related parameters (such as the number of discharges, board utilization, etc.).

In addition to selecting the standard box type and changing the shape of the carton, you can also freely design the special box type, rotary carton stereo diagram, and the opening and closing process of the display carton; for different cutting edges, indentation lines and slotted parts should be selected Corresponding line types are used to control the manufacture of carton samples, die-cut plates, bottom molds (backing plates), and die-cutting tools to improve the accuracy of die-cut plates and backing plates, and the accuracy of carton production.

3 paper packaging printing technology
In the field of paper packaging printing, lithographic offset printing, letterpress flexo printing, gravure printing, and screen printing coexist in a variety of formats, each with its own characteristics. In the single-sheet printing, offset printing is mostly used, flat screen printing and sheet-fed gravure printing are used. In web printing, gravure and flexo printing methods are mostly adopted, and offset printing and silk are also used. In the case of web printing, there are also several combinations of printing at the same time on a printing production line. Cartons are generally between 2-8 colors, of which 4-6 colors are used most. Folding cartons, especially kits, use more spot colors, so the number of printing kits is usually 6-8 colors. The number of color groups of a sheet-fed offset press is generally 4 colors, and basically no more than 5 to 6 colors. However, the use of multicolor web printing presses (including gravure printing, flexo printing, and screen printing) has rapidly increased. The number of printing color groups has reached 8 to 10 colors.

3.1 Offset Printing Technology

(1) Digital Printing and CTP Technology

Digital printing technology is printed on the basis of personalized database information, providing paper, paper boxes and corrugated boxes with the option of individualized packaging and printing. It can change the design and processing parameters of paper packaging containers by region or product difference. Using special techniques, the folding tray can have a changeable printing color and hot stamping effect, so as to meet the needs of large-sized and short-lived jobs in the market for packaging cartons (boxes).

Agfa developed high-definition CTP technology to provide high quality outlets for modern packaging printing. The use of unique laser and optical imaging systems, intelligent multi-beam simultaneous imaging methods, IntelliSpot intelligent network points and other technologies have increased the security of the system, simplified the system structure, and improved the degree of automation and overall efficiency of the system.

(2) FM screening technology

The quality of the printed matter is mainly determined by the number of dots on the unit area and the number of successively changing series of dots from small to large. The larger the number of Internet sites in the area, the higher the clarity of the printed matter, the greater the number of changes in the outlets, and the stronger the expressiveness of the print level, the finer the look.

In order to improve the quality of printed products, AM screening, frequency modulation (FM) screening and hybrid screening techniques are often used.

The screens of the amplitude modulation and screening are arranged regularly, and the size of the printing ink is changed depending on the size of the dots. While the size of the dots of the FM screening is fixed, the distance between the dots can be changed, and the printing distance can be adjusted by changing the distance of the dots and the number of the dots. The amount of ink on the paper to achieve the color change. AM screening has three elements: screen number, dot shape, and screening angle. FM screening has only one element of dot size. The smaller the dot, the finer the print, the better the visual effect, which is equivalent to the number of high-adding lines when the amplitude modulation is added. However, the smaller the dot of the frequency modulation and screening, the higher the requirement for printing conditions. Hybrid screening is a hybrid screening technology that combines amplitude modulation and frequency modulation screening technologies and is formed on the same image. In homogeneous tone zone cities, especially in highlight zones, conventional screens produce a smoother appearance than FM screens. But for high detail, FM screening is better. Advanced screening software can analyze the image to determine where to use the appropriate screening geometry, and then combine FM screening with conventional screening to achieve the best overall results.

Using FM screening technology, you can eliminate moire, improve the level of reproduction uniformity, improve the resolution and clarity of the image, easy to achieve high-fidelity printing (Hi-Fi). Although FM screening imposes stringent requirements on printing conditions, water-based printing processes are suitable. High-definition FM network can significantly improve the clarity and level of print performance. The arrangement of FM network points is not limited by the amplitude and arrangement angles of the networks, as is the case for AM sites. Selecting FM network points in printing and copying can express more detailed changes, improve the clarity, and have anti-counterfeiting features.

(4) Printing color management technology
The CP2000 integrated offset printing press center control system developed by Heidelberg has adopted TFT ultra-thin screen display technology, and is equipped with prepress interface technology, image control technology, printing color management system, online help system and information management system, etc. Quality control mode under integrated conditions. Multi-level printing color management system PCM, including consulting, standardization, prepress and printing optimization, generation and implementation of Icc color profile and other content. In order to optimize the color flow and improve the printing plant's production efficiency, it effectively coordinates prepress and printing equipment. Not only can you get high fidelity, you can save time, reduce waste, and get productive production.

(5) Waterless Printing Technology

Waterless offset printing is a lithographic offset printing method that uses special silicone rubber-coated printing plates and inks, and does not require isopropyl alcohol or other chemical fountain solutions that are necessary in conventional lithographic offset printing. The printing process is easy to operate, and the ink is transferred to the printing plate within a certain temperature range without adjusting the ink-water balance relationship.

The plate used for waterless offset printing is a gravure plate, and the graphic part is lower than the surface of the plate. Although the plate making process is the same as the PS plate, it is different from the PS plate. Therefore, waterless offset printing plates have unique processing difficulties. Plate material, ink and temperature control are the key to waterless offset printing technology and directly affect the development speed of waterless offset printing. Plates are the core of waterless offset printing. Waterless offset printing plates have the advantages of easy operation, good image quality, high printing density, brilliant colors, and good quality of printed materials. However, the printing plate's resistance to printing force is easily manipulated. Conditions and the effect of special prints. The special inks used in waterless offset printing are characterized by low viscosity, high viscosity, high thixotropy, and stable performance. Because different colors of ink respond differently to temperature changes, it is necessary to control the temperature of different printing color groups. Although the cost of consumables for waterless offset printing itself is high, the rejection rate of printed products is low and the production efficiency is high. It can be seen that with the advancement of technology and the increase of labor productivity costs, waterless offset printing technology occupies certain advantages, especially for high-quality fine paper packaging, and will be further developed and promoted.

3.2 Flexo Technology
New flexible plate and thin plate process, sleeve type plate and computer direct plate making technology, environment-friendly UV ink, high network cable ceramic anilox roller laser engraving technology, closed squeegee blade system, gearless transmission technology, no downtime change The development and application of related technologies such as roll devices and automatic control technologies have promoted the rapid development of flexographic printing.

(1) Thin plate and CDI technology

The improvement of the quality of the photosensitive resin plate and the appearance of the thin plate process have laid a good foundation for improving the quality of the plate. The emergence of the CTP technology and the emergence of the digital flexographic plate making technology (CDI) can effectively overcome the dot gain phenomenon and guarantee Print quality, shorten production cycle, reduce cost.

The digital thin sleeve plate has good stability, can effectively control the control of dot enlargement, reduce photopolymer, improve image quality and register accuracy. Not only can improve the quality of printed paper packaging, flexographic quality to offset and gravure quality level. It can also reduce the printing pressure, reduce the number of plate cleaning, prolong the service life of the printing plate (time limit can be increased by 10-25%), further reduce the machine preparation time, reduce the number of shutdowns and IT (10-20%) when the machine stops.

The CDI system jointly developed by DuPont and DuPont Xili can transfer the digital information directly to the laser photosensitive plate. Spark XT, a CDI plate-making machine developed by Esko-Graphics, is mainly aimed at the packaging and printing market, especially for small and medium-sized label and folding carton flexo printing companies. As technology continues to advance and the cost of various systems for flexographic digital imaging and plate-making systems has continued to decline, the proportion of paper products such as cartons, paper bags, and multi-layer bags has increased.

(2) Sleeve type high mesh ceramic anilox roller

The laser-engraved ceramic anilox roller is used as a primer layer on the surface of the treated base roll, and then plasma sprayed with high-temperature ceramic powder. After grinding and polishing with a diamond, a high-energy laser beam is used to accurately sculpt the contours. Steep nets, the final fine throw. The number of mesh lines and the amount of ink in the mesh are the production of laser-engraved ceramic mesh