Functional high-dot flexo-overprinting cartons

First, the environmental protection function flexo carton overview

Flexo is a new environmentally friendly packaging and printing technology, and flexo is a green packaging product. Thanks to the advancement of the material industry, especially the advent of polymer resin plate and ceramic anilox roller, the development of water-based ink printing technology has successfully solved the problem of ink recoating and irreversible technology, and has become the fastest growing printing in the world. the way. In particular, its obvious advantages in improving the environment have been called “the best and most promising printing method on the earth” in developed countries in Europe and America, and it has become one of the major printing techniques in the 21st century.

The domestic flexographic printing technology started late, but as a high-tech form of green packaging, it has become a new hot spot for the industry. In an era when environmental protection and resource conservation are valued, it will be widely used. In developed countries, flexible manufacturing is still a high technology, and it also belongs to a special industry in China. It has high technology content and advanced technology. The printing materials not only meet the environmental requirements, but also are suitable for high-speed and exquisite packaging graphic printing, which is extremely challenging for the carton industry.

Green environmental protection packaging refers to packaging that is harmless to the ecological environment and human health, can be recycled, recycled, and used for sustainable development. Many developed countries have also determined that packaging should meet the "4R+1D" principle. That is, low consumption, development of new green materials, reuse, recycling and degradability.

Functional corrugated paperboard and corrugated carton are special packaging, and also a technological innovation product. It is the result of the cross integration of modern science and technology and packaging engineering, reflecting the development direction of modern packaging. Its key technology is to improve the carton and corrugated board and to carry out functional design and innovation of its structure, which greatly increase the added value of raw materials, and provide domestic packaging companies with a better choice than the status quo.

Second, the high network line stack printing corrugated box technology and its solution

The flexible printing of high-line corrugated paper is an integrated system that requires adjustment and mutual cooperation of all relevant links to achieve a relatively optimal value. Such as plate making, ink painting, corrugated paper and cardboard, printing equipment, printing technology and other links are all very important and must be well coordinated. How to realize the flexible printing of high-line corrugated paper? The key technologies are:

(a) In the field of flexible platemaking, determine the best solution that can be suitable for printing, but also reflect the product design effect

1. Determine printability conditions

The first thing to know about printing equipment. Such as the unit color number, the type and number of anilox rollers, the paper feeding system, and the basic conditions of the squeegee system. There are paper types, white paper or coated paper. A conditional test plate can be provided to test the printability of the printer. It includes a ladder strip for testing the expansion of different flexographic screen points, a color patch for measuring the density of ink in the field, a simple chromatogram for the overprinting of different dot proportions, a yin and yang character and straight line with different font sizes, and a module for measuring trapping errors. To observe the pressure balance of printing pressure bar and so on. Test plates are required to be completed under normal printing paperboard, standard production water-based ink, normal printing pressure, and vehicle speed. Of course, you can change some of the printing conditions to get different test samples. Through the analysis of the test sample, we can get the printability of this type of printing machine under normal conditions. The network expansion, curve, waterborne ink density, hue value, dot impact condition, color sequence influence, reduction of fine lines, overprint error, and printing balance pressure are available for each color.

Combining the test data obtained above and the test results of the control test samples, a color matching management system for this printer can be established, such as creating a dot compensation curve for screen dot gain, screen color and gannina curve correction, and color simulation of proofing. And match and so on.

2. Determine the plate making process and color separation scheme

In the flexo platemaking, the determination of the color separation process plan is a key factor. It plays a decisive role in determining the success of the high-line cable products. The color separation of the flexible printing is to complete the superposition of color with as little color as possible and as pure color as possible, which greatly contributes to the printing and reduces the cost.

3. Selection of printing plate screen lines and angles

The number of screen printing screens is limited by the number of screens of the anilox roller, and the ratio between the two is above 1:5. The 400L/in anilox roller can print up to 80L/in. The number of lines is too high to easily paste the plate and generate moire. Therefore, the higher the number of screens, the better. Moreover, 80L/in and 75L/in print effects will not be much different in terms of fineness.

The flexographic screen angle mainly adopts 7, 37, 67, 82, and 7, 22, 52, and 82 angles according to the different anilox roller angles. However, the screen angle must be based on the actual product, and it cannot be cut across the board. If the monochromatic pattern is a linear pattern, the angle of the screen must be 45 degrees or 0 degrees, otherwise the edge of the screen pattern will appear more jagged. The selection of the overlapping pattern angle should be based on the principle that the hue angle of the main hue of the product pattern is different by 30 degrees. If the human portrait is dominated by yellow tones, then the color difference between magenta and yellow should be above 30 degrees; if the scenery is dominated by green, then the color difference between cyan and yellow should be above 30 degrees, otherwise it will easily produce moire . Before the plate making, the proofing of screening is performed to determine the best screening method. Discrete outlets use a certain amount of screening technology to increase the security of products.

4. At present, the direct plate-making system mainly adopts extremely high transfer technology. After color separation and imposition, images are directly formed on the resin plate. Digital printing plates have the advantages of complete dot type, extremely high light spot not easy to lose, low print dot enlargement rate, long step adjustment, large dots, and no paste, and are the best choice for flexo high net line plate making.

(II) Requirements for flexible printing of high-line screens on board, paper, board, water-based ink and equipment

1. High-line plate plate selection: For high-line printing plate, the hardness is slightly higher than the printing plate required for general printing. This is because such a printing process requires a small amount of ink in order to accurately represent fine dots. If the printing plate is too soft, it will lead to excessive transfer of ink, which is unfavorable to the control of the amount of ink, and is prone to defects such as color cast, blocking of the net, and the like. In addition, it is also required that the plate material has a good dot reproduction range, can produce fine high-gloss dots; has a uniform thickness, good flatness, easy to achieve light pressure printing, easy reproduction of the original; there is a good Elasticity, can restore the original thickness after pressing, and the plate must have a certain degree of toughness, fine mesh points are not easy to wear and so on. The plates commonly used for such printing are DuPont's TDR.

2. Cardboard: It is best to use coated whiteboard to achieve the same effect as offset printing. Because the coated white paper has a better finish, the print is more glossy and bright. Ordinary white paper surface gloss is poor, the color of the imprint is dull. In addition, coated white paper is different from offset paper and coated paper, which retains part of the original characteristics of white paper - permeability and adhesion, and is conducive to the printing of water-based ink. The paperboard can be used for cardboard with uniform thickness, smooth paper surface, moisture control of 9+2%, and good hardness. Type E, F or G corrugated, with 180g/m2 face paper. Such paperboard has low corrugation and flat cardboard, which can withstand greater pressure, reduce the appearance of lines and imprints, and improve the quality of printed products.

3. Ink: Ink is a key factor in the entire printing process. Water-soluble acrylic and acrylic emulsions are formulated and added with a high-linking agent. For four-color overprinted high net jobs, we must pay attention to the choice of ink. The printing ink of printing and coating paper is different from ordinary ink. It mainly requires the following features: Fine fineness—clean dots and fine patterns; high gloss—bright colors and glossy; low viscosity—no blocking mesh and no ink bars , Picture and text clean, refreshing; High color content - full color, rich in content; good adhesion - anti-wear, do not fade; good leveling - uniform color, no exposed bottom; fast drying - stacking effect is good, without dragging Flowers; good overprinting - good compatibility between colors, natural and harmonious colors, rich levels.

4. Equipment requirements: (1) Scraper: The printing machine that can complete the high-line printing must have a scraper. It also requires a sealed double scraper and maintains the effectiveness of the scraper so that the ink can be accurately controlled; (2) Closed circulation ink Road: Sealing the ink path will help prevent excessive contact between ink and air, prevent certain components of the ink from evaporating, oxidizing, and dissolving bubbles, and maintain the stability of the ink composition in order to successfully complete high-quality printing; (3) High-line screen printing Ink roll: This is one of the most important conditions for high-line printing. The higher the number of reticulate lines, the higher the printable mesh line, and the smaller the amount of ink to be transferred, which helps to reproduce tiny high-gloss dots; (4 ) Suction and paper feeding, full absorption of paper: It can improve the flatness of paperboard, smooth the paper, ensure the accuracy, and ensure the accuracy of registration; (5) The liner (lining between printing plate and plate roller): better lining The pad cushions and adjusts pressure to protect small dots and increase plate life.

Third, technological innovation and economic analysis

1. At the technical level, the environment-friendly high-net multi-color overprinting carton technology provides another technological route. It is currently an advanced method and has made new breakthroughs on the basis of absorbing other printing technologies. Qingdao Shuangtai Industrial Co., Ltd. through the development and screening of various raw materials and auxiliary materials, production technology and process equipment and equipment for the establishment and transformation, independently created the first case of flexible printing corrugated production line bonding equipment, innovative design of a flexible network of resin equipment .

(1)Using advanced multi-color high-density printing machine and scientific high-density 480 mesh ceramic anilox roller, the traditional steel and rubber roller transfer process is improved, and a high-strength, high-seal, under-seal air bag squeegee process technology is implemented. , so as to achieve a multi-color cover light anti-counterfeiting effect. Can not be seen directly with the naked eye, one of which can be identified with a 40x magnifying glass;

(2) The multi-color overprinted corrugated boxes produced by the company were tested by authoritative departments and met or exceeded the national standard GB6543-1986, “Technical Specifications for Environmentally-friendly Functional High-net-point Multi-color Overprinting Carton” Q/02 STS001-2005, and comply with National export packaging standards, product side pressure index ≥ 5390N/M. The comparison test and user's use showed that the packaged product is better than the performance indicators of similar packaging products in China, fast drying (instant 0.5 seconds), sun (two working days) does not fade, the surface splashing water does not leak, anti-friction (surface Fight 50 times);

(3) The cost per square meter of concealed light is 75%-85% lower than the cost of hand-painted oil. The cost and product price of the product is lower than that of the domestic industry by 20%-30%, which is only 1/4 of that of wood. The Tsingtao beer environmental protection packaging box produced by this technology is welcomed by consumers and users, and has a promising market prospect.

2. Self-innovation has been achieved in many aspects. The innovations are summarized as follows:

(1) Self-innovating high-net point flexible cover platemaking technology solves the technical difficulties of the non-lining of the flexible cover plate.
(2) Developed a high-precision, high dot water-based over-printing overlay technology. The hue covering is reasonable, the color gradation is pure and bright, the printing pressure is controlled properly, the overprinting effect of the ink overprinting is excellent, and the water-based multi-color dot overprinting time is shortened;
(3) The production process of this project is pollution-free and pollution-free, and it is an integrated multi-functional environmental protection package;
(4) There is no mention of multicolor overprinting in domestic related literature. In this project, anti-counterfeiting was achieved through multi-color overprinting. There was no report in the investigated literature, and there was no similar or similar research in China;
(5) To adapt to the current development trend of the international market and the domestic market, this packaging product has aesthetic effects such as three-dimensional, spatial, texture and aesthetic appearance. It is a patented technology of the packaging industry.

3. Analysis of social and economic benefits:

Adapted to the outer packaging of goods, it is an ideal anti-counterfeiting and environmental protection product, replacing the hazards of wooden packaging tapeworms, removing the pollution, and harming the printing plates, machines and human health. The product can be arbitrarily selected according to different commodities and different patterns and boxes. The thickness is 2.5mm-11mm, and the size can be arbitrarily determined. Widely used in knitwear, native products, food, cotton textile products, sports equipment and other packaging.

Qingdao Shuangtai Industrial Co., Ltd. developed a high-tech multi-color overprinting carton technology with environmentally friendly functions, which has significant social benefits: all physical indicators passed the quality of Qingdao products.