Offset printing, embossing, and gravure are the three most important printing methods. In the 1970s, with the advancement of the prepress technology, offset printing technology also developed exceptionally rapidly. According to incomplete statistics, as of the early 1990s, the momentum of the development of offset printing has continued to increase, accounting for almost 30% of the entire printing market. As far as the domestic situation is concerned, from the 1970s to the present, offset printing equipment has spread all over the country to major, medium, and small-scale printing factories, becoming the mainstream equipment for printing equipment. However, the model, size, and grade of offset printing equipment are different.
However, since the 1990s, digital printing technology based on electronic technology, computers, and network technology has developed rapidly and has rapidly become popular in all corners of the world. The digital printing system has realized the integration of digital pre-press, digital printing and digital post-press processing into a solution that satisfies high quality, high speed, variable data, and instant printing.
With such a severe technical challenge, where does offset printing go? How to develop offset printing in the future has become a common concern.
I. Advantages and Advances of Offset Printing Technology The reason why offset printing technology can develop at such a rapid rate is that one of the most important reasons lies in the advantages of offset printing.
Traditional offset printing technology uses the principle that water and oil are not mixed, and uses lithographic printing technology to print through an intermediate transfer blanket cylinder. In the past two or three decades, with the development of new technologies such as polymer materials and lasers, offset printing materials (including printing plates, inks, fountain solutions, blankets, etc.) and corresponding plate making technologies have also made great progress. This lays the foundation for offset printing to meet the high printing quality, high printing speed, and low printing cost required by the printing market.
At the same time, due to offset printing using indirect printing method (intermediate transfer rubber roller), the printing pressure can be smaller and better contact with printing materials, ensuring a good transfer of graphics and documents, improving the scope of application of printing materials and printing plates The imprint rate also provides a reasonable guarantee for the mechanical structure design.
Not only is the advancement of prepress technology and offset printing materials, offset printing equipment continues to improve with the rapid growth of the offset printing market. The printer has invested a lot of money and energy. First of all, a lot of improvements have been made to the structure of the offset press, and even a completely new design makes it more suitable for high-speed, high-quality printing. For example, the development of high-speed offset paper-feeding machines, pneumatic paper-feeding boards, high-speed delivery paper teeth, new side pull gauges, and other new mechanisms have been improved and developed; new types of ink delivery and water delivery systems have been developed. At the same time using a variety of roller arrangement, roller diameter ratio and paper transfer and turnover mechanism, to meet the different requirements of a variety of print printing, suitable for printing a variety of different printing materials.
In printing automation, offset printing equipment is one of the fastest growing printing equipment. From pre-press laser photocopying, electronic color separation, full-page imposition to digital proofing (CtProof), digitized film (CtFilm), digital platemaking (CtPlate) technology; automatic ink volume and register remote control system from the printing machine, The printing plate scanning device and quality control device to the all-digital "one-touch productivity" control system make the offset printing machine a market leader in improving production efficiency, reducing labor intensity, reducing printing preparation time, and reducing consumption.
In addition to the rapid development of traditional offset printing systems, the offset printing family has also added many new members. For example, with the development, development, and gradual marketization of waterless offset printing plates, the development of waterless offset printing systems has been greatly promoted, and a series of problems brought about by the use of fountain solution to print quality have been improved, such as ink balance problems, and inks. Emulsification problems, paper deformation caused by water and environmental pollution and other issues.
Second, the offset printing market, characteristics and technical limitations Printed by offset printing, the range of printing products involved is very wide, almost no products that cannot be printed with this printing process. From sheetfed to web, from thin paper to cardboard, from monochrome to multicolor, from brochures, paperback books, coloured newspapers to complex packaging folding cartons, multi-format forms, large format advertisements, book covers, promotions Labels, mail boxes, luxury letterheads, metal and plastic cans, plastic containers, and more. It can be said that offset printing is almost ubiquitous.
Offset printing equipment has many advantages. High printing speed is one of the important features. The current production speed of offset presses has reached an unprecedented high speed. The printing presses commonly used in sheet-fed formats can reach printing speeds of 13,000, 15,000, or 18,000 sheets per hour. Therefore, in recent years, the focus of the manufacturers' development work is no longer focused solely on pursuing higher printing production speeds. Turning to improvements in specific mechanical structures and reducing print preparation and set-up time. At the same time, the stability of the printing quality is ensured by improving the ink and water supply device, and consumption is greatly reduced. By adopting a new mechanism, trouble-free feeding can be achieved and color non-uniformity can be reduced.
In addition, modern offset presses also have the following main features:
It can satisfy the production of any format plate by fast, simple and economic simulation and digital production, thus ensuring high quality and long-run printing.
The printing blanket, used as an intermediary for ink delivery, is suitable for printing on a wide range of surface conditions and different grammage weights.
Whether it is short-run or long-run printing, high-efficiency and economical printing can be performed on both small-format and large-format printers to complete high-quality monochrome and multi-color rapid printing.
The production process is highly standardized and automated.
Adopt VDV central control system to ensure accurate control, management and inspection of printing work;
Adopt control technology from the network to prepress;
Different substrates with different thickness can be set automatically;
Semi-automatic or fully automatic version change;
Remote cleaning of inking device, blanket cylinder and impression cylinder;
Print sheets do not touch the transmission;
Paper automatic processing device (paper, print transport and non-stop paper change);
Infrared, UV and/or hot air drying and curing.
However, the potential and indicators of offset printing still need to be carefully studied. Because both the offset printing press itself and the physical and chemical issues involved in the offset printing process still have problems that need to meet the constantly updated and developing printing market requirements. The offset printing process needs water-based or acid-wetting solvents and oily inks, and this brings about a series of problems such as ink balance, ink drying, color reproduction, and environmental protection. Therefore, many aspects of the offset printing process still need to be improved. Therefore, only through targeted research and development can make the new process more innovative and more reliable, so that offset printing can still occupy the market leading position and become the future printing process.
Third, the current status of offset printing With the research and development of digital offset printing presses, digital manuscripts can be directly plated on the printing press cylinder, thus providing the concept of offsetless and unprinted offset printing. This CtPress technology is based on the latest lasers. Technology applied to offset printing. Through the several new concept CtPress systems displayed at Drupa'2000, we can further understand the current development direction of offset presses.
1. The quality of modern offset printing and plate making systems depends largely on the adaptability of the printing plate (various types of offset printing presses, different printing formats, different numbers of prints, and various printing quality requirements), Price and high sensitivity controllable.
The most commonly used plates at present are:
Positive printing plate, usually anodized aluminum plate;
Negative plate type printing plate, generally a cathode aluminum plate;
For waterless offset negative or positive aluminum version.
In the relatively low print quality requirements used for printing, short and large offset printing, plastic plates, paper plates, and metal foils are often used as printing plates, and some platemaking systems are used for offset printing in the “no-printing†mode.
It can be seen from the current development that the development of high-sensitivity plates and high-speed, low-cost, and even bright-room plate laser light sources have become one of the research directions of the future plate-making system. The continuous deepening of research topics and continuous research results, the adoption of CtP technology for digitally controlled laser platemaking systems will have greater and greater selectivity.
2. Ink and Sheung Shui In sheetfed and web offset printing, the interaction between the printing ink and the fountain solution is extremely important. It will affect the printing quality and the smooth progress of the printing process. Nowadays there are many inks available for selection, and it can also meet any special needs of printing and printing through fine ink dispensing. The use of ordinary water can be used to formulate suitable fountain solution, which is very convenient to use. At the same time, waterless offset printing has been well developed and is currently being promoted in some countries. As its technology matures, it will be promoted globally. Drupa'2000 exhibited the latest waterless offset inks, some for specific press systems, while others developed for ordinary waterless offset systems.
3, seven-color printing, network cable number and frequency modulation in 1995 introduced European standard offset ink color standard, but also brought the corresponding problems. Printing with standard four-color inks (yellow, pink, black, and black) did not achieve the desired result, especially the reproduction of orange, purple, and green colors, and could not meet the requirements for print color reproduction. For this reason, offset printing printers added three auxiliary inks, orange, purple and green, based on four-color printing, and formed a seven-color printing mode.
In some prints, infrequent fine mesh lines were used to achieve amazing aesthetic results. The use of FM network points, although not as eye-catching as the early days of development, is still used in printing.
4. The DI system (Direct Image) represents a mechanism version system, which is an important digital offset printing method. At present, with the improvement of offset printing automation, automatic plate change has become the standard configuration of most offset presses, while the DI offset press has installed a plate making device on each printing unit to make four or more units. It is possible to conduct exposure plate making at the same time, which greatly reduces the auxiliary time and improves the degree of automation. However, since each unit needs a plate making device, the investment cost of the equipment will be too high. Therefore, the development of a digital offset press with strong functions, shorter plate-making time, and lower investment costs is a higher level of offset press development.
Fourth, the development of offset printing press
1. The sheetfed offset press is a complete type of sheetfed offset press. It can not only satisfy the printing of various size and size prints, but also can form almost any unit of single-color or multi-color printing, even 10~12. Offset printing machines are no longer rare. So many printing units are connected to each other by new control and drive technologies, and their print quality is assured by microelectronics and new measurement and control technologies.
According to India, printers can choose from the following printer types:
A printer that does not require switching from single-sided printing to double-sided printing can be switched from single-side printing to double-side printing. The first unit is a multi-color printing machine with an inverting device (for printing one side of monochrome, the other side of multicolor Postcards and folding cartons)
A direct or double sided direct-printing press can be printed without the need for a switch. There is one or more in-line coater offset presses. Digital plate module An integrated offset press (CtPress)
2. Web offset presses Web offset presses are ideally suited to the diversified requirements of today's print market and the growing demand for on-demand printing.
In the printing of newspapers, cold-cured web offset presses have been basically established in design and technical development. It can meet the requirements of different printing numbers, and has the functions of print-and-live conversion, multi-color and high-quality printing, reduction of production cycle time and digitization (CtPlate).
Newspaper printing must deal with issues such as page numbers and print numbers of newspapers according to the final production task. The future newspaper printing will use CtP and full-page imposition technology to finally realize the direct plate making from the digital database to the plate cylinder, and further connect prepress and printing.
In commercial thermosetting web printing presses, the most varied feature is the folding mechanism of the printing press and the front structure of the folding device, which brings about a variety of printing