Soft concave technology applied in the field of flexible packaging printing

4. Quality

The printing quality mainly has the following indexes: the number of network lines, the amount of ink on the ink, the accuracy of overprinting, and control factors for printing quality.

A. Number of screen lines: The number of screen lines per centimeter or per inch (LPC or LPI is an important parameter to measure the print quality. Gravure printing can reach: 70 lines/cm (175 lines/inch), and general flexographic printing can reach 48 Lines/cm (120 lines/inch), high quality level flexo printing up to 52-60 lines/cm (133-150 lines/inch).

B. Inking amount: In normal printing, the amount of ink on the concave, soft, and offset printing is: gravure: 4-8 g/m2; flexo: 3-5 g/m2, 0.8-2 g/m2 (UV); Offset: 1-2 g/m2. The proportions of gravure, flexo, and offset printing on average are: 400%, 267%, and 100%. From this it can be seen that the gravure print has the greatest brightness.

C. Accuracy of overlay: Like the gravure machine of the unit type, the satellite type flexo press can obtain similar overprint accuracy (color-color), but the unit type flexo press is generally difficult to obtain the above accuracy.

D. Difficulty of quality control: Gravure printing is a relatively simple process with few variables, so quality control is simple and reproducibility is high. Flexographic printing has more influencing factors and it is more likely to cause problems. The quality of flexographic printing depends on elements such as color separation, negative film, plate exposure, print mounting (mounting the plate on the platen), tape thickness and quality. All these elements have been continuously improved in recent years, and the gap between the quality of flexographic printing and gravure printing is continuously decreasing. The use of laser imaging technology for flexographic plates has eliminated the negative film production process described above. When laser imaging is used for plate making, a clearer image can be obtained: 1% dots and 60 lines/cm (150 lines/inch) can be achieved. Laser engraving can use rotary platemaking equipment to make sleeve-type flexographic plates, which also facilitates quality control.

5. Investment and Cost One of the major advantages of flexographic printing is its low investment and low cost. However, it must be pointed out that at present, some people in China think that flexo equipment is 1/4 and 1/3 of the price of gravure printing equipment. This conclusion is somewhat overstated.

A. Equipment investment. In some cases, flexo and gravure printing equipment prices are comparable, but in more cases, there is no point in comparing the two. The price of imported narrow-width flexo presses in China is around 500,000 US dollars, while other prices will reach 80-100 million US dollars. The difference between the two is 60%-100%. The reason for such a large gap is due to different manufacturers, different configurations and technical specifications. In addition, there are certain gaps in the prices of equipment manufactured at different times.

Now, there are increasing numbers of manufacturers that can provide both gravure and flexo presses. In the past, the cost of a flexographic press was only 50% of a good gravure press. However, gravure and flexo printing have continued to improve since the 1980s, and the gap between them has been continuously narrowed. Flexographic press improvements include: impression cylinders, wall panels, temperature control, drive systems, tension control systems, printing unit stiffness, independent drives, and more. Now, under comparable conditions:

a. Unit-type gravure printing machine is 20-25% higher than the price of satellite type flexo printing machine;
b. The price difference between the unit type gravure printing machine and the unit type flexo printing press is less than the above value.

B. Platemaking cycle and costs. Flexo has a clear advantage in this regard, and the production cost of gravure can be up to 2 times that of flexo. In addition, there is a need to invest in the storage of the plate cylinders. Compared to gravure printing, the flexo belt has a short length and reduces power consumption by 50%. In addition, the hot air required for drying is less, which means that flexographic printing presses also have lower running costs than gravure printing. However, only in combination with printing pattern requirements and batch size, the gravure and flexographic cost comparison issues can be reasonably answered. In flexo printing, the cost of various batches does not change much: small batches have greater advantages, and the cost is lower by 2-3% in medium batches, but the cost of intaglio printing in long live printing is greater, and the flexographic phase There are advantages compared to the contrary. The intersection of this cost is about 50,000-75,000 meters.

6. Environmental protection

The environmental protection of printing technology is mainly determined by the following factors: environmental pollution, health and resource consumption.

A. Flexible version has better environmental protection than gravure, basically uses water-based ink, and has lower energy consumption.

B. The use of solvents is not the essential difference between gravure and flexo. Both gravure and flexo can use solvent, water or other inks. At present, gravure printing has basically adopted water-based inks in the publishing field, and mostly uses water-based inks in the field of decoration (grainy paper printing); in the packaging field, especially flexible packaging, the proportion of using solvent-based inks is still quite large.

From the experience of Europe over the past 10 years, compared with the use of solvent-based inks, the current use of gravure printing ink is mainly less than two aspects: First, the printing quality, especially the brightness of printed products is slightly poor; Second, the printing speed low. The same gravure printing machine uses water-based ink at 15-25% lower speed than solvent-based ink. However, Japan has made great efforts in water-based ink R&D in recent years.

7. Market and Technical Conditions

Several important market and technological factors that affect the development of gravure printing and flexo printing are: consumption habits, technical support, and market environment.

A. Appreciation and spending habits. Of all the factors that affect the development of flexographic and gravure printing technologies, appreciation and consumption habits are the most easily overlooked but fundamental factors.

At present there are roughly two modes in the world: the American model and the Euro-Asia model. The development of fashion is very similar to the development of printing. Countries that value fashion culture tend to pursue high-end and specialty packaging, preferring gravure printing. China is closer to the European and Asian (Japan, South Korea) model. Consumption and appreciation habits can be changed, but it takes a long process.

B. Technical foundation or technical support. Technical support plays an important role in the promotion of a technology, such as the teaching and training courses, the supply of equipment and raw materials, and the degree of technical support. In countries with more advanced equipment such as equipment, plates, inks, etc., this kind of technology develops faster. Another aspect of the technical foundation is whether the equipment needs to be imported or not, and how domestic manufacturing levels are. The development level of a country's flexo and gravure has a great correlation with the level of manufacturing. Our country has very good technical conditions in offset printing and gravure printing, but it is weak in flexo printing.

C. Market environment and scale. The market's specifications and scale have a major impact on the promotion of flexographic printing technology.
a. Whether the market is normative determines the confidence to promote flexographic printing.

b. The average batch size of the product also directly affects the choice of gravure or flexo. The larger the average batch size, the more likely it is to use gravure printing. The population determines the average batch size of the product and thus also determines the market share of gravure and flexo printing. From these two factors, the current gravure printing has more advantages in China.

Renewal:

A. To properly view the relationship between flexo, gravure, and offset printing, in some areas, competition between flexo and offset, or competition between gravure and offset, and in other areas, gravure and flexo Competition, while other areas may be offset printing, gravure and flexo.

B. Flexo and Gravure are mainly coexistence and complementarity. Both are constantly improving their technology and overcoming their own shortcomings.

C. The market share of flexo and gravure varies from country to country. Both gravure and flexo have good development prospects in China, provided that we cannot copy the development model of other countries.