Задание 4.5 Retell the technology of gravure printing using new lexical words.

Методические рекомендации:

Выполнение заданий к тексту требует его общего понимания. Контроль понимания достигается через выполнения этих упражнений. Информация, извлеченная при прочтении, текста может быть использована студентами в последующих заданиях.

Рекомендуемая литература: 1 осн. [35-42], 4 осн. [50-55]

Контрольные вопросы:

1. What are the features of gravure printing?
2. Describe process of gravure cylinder manufacture.
3. How many layers has gravure cylinder?
4. What is the average thickness of the base copper layer?
5. What methods of copper plating the gravure cylinder do you know?

Тема 5: Letterpress Printing

Задание 5.1 Read the text:

Letterpress (relief) printing, of which traditional letterpress and flexography form a part, is the oldest printing technology. Printing is done by means of raised printing elements. Letterpress printing is a mechanical technology in which a relatively high pressure is required to transfer the highly viscous, pasty ink to the paper via the hard printing elements (fig. 7). In the chronology of their development, presses and machinery are subdivided into hand presses and platens, high-speed presses and web presses, on the basis of the different pressing methods involved. For centuries letterpress printing with rigid printing plates, predominantly made from alloys of lead, tin and antimony, was the dominant printing technology. For many years letterpress printing has been increasingly losing favor, having been replaced primarily by offset printing, and it is now only used in niche areas. Letterpress printing is sometimes used for printed products such as paperbacks and telephone books that do not impose particularly high demands on printing quality, and for some daily newspapers. Indirect letterpress printing (letterset), in which the print image is transferred to the substrate from the inked-up printing plate via a blanket cylinder, is still used in certain special fields, packaging printing in particular.

In the last several decades, a modified letterpress printing method, flexography, has become increasingly more prevalent, especially in the packaging industry, for printing on the most varied materials. The term “flexography” was introduced at the beginning of the 1950s (it was previously known as “aniline printing”).Unlike letterpress printing, flexography uses low viscosity inks and resilient or soft, flexible printing plates, and the pressure applied between plate cylinder and substrate is low (“kiss printing”). Because of the flexible printing plates, which were formerly made solely from rubber and are now made mostly from photopolymeric plastic, printing can also be done on materials with very rough surfaces and even on fabrics.

Figure 7 - Letterpress (the principle of the process)

Letterpress Printing (Process and Applications)

Letterpress printing was the predominant book-printing process. For four centuries it was also the predominant printing technology for posters, announcements, printed matter for churches, government and businesses, single- or two-page local news-sheets, and daily and weekly newspapers, as well as sundry simple print jobs. Initially printing was done by the platen method. The invention of the high-speed press, a cylinder-type printing press, by Friedrich Koenig in 1812, was a decisive factor in the progress of letterpress printing, because it offered higher productivity. The invention of the semi-circular stereotype plate (1854) was a prerequisite for the construction of web presses. Large-circulation newspapers, in particular, could be printed and colorful, luxurious printed products could be produced on various special presses. Special satellite-configured letterpress rotaries (each with a large impression cylinder with up to twenty printing units) were developed for wallpaper printing. Many different letterpress printing presses were supplied for the graphic arts industry. As for instance the Heidelberg platen became the most widely-used letterpress platen press in the world. The fundamental disadvantages of letterpress printing compared to offset printing are the expensive printing plate, the costly makeready of the printing plate, the limited print quality and the limit of production speed. Letterpress is still used to print forms, labels, lottery tickets, security papers, telephone books, and paperbacks, though there is a downward trend. Letterpress was also used for newspaper web printing with inking units in accordance with figure 7 (e. g., the “Courier” model from KBA).

A few newspaper rotaries are still in use both for direct and indirect printing (letterset, with blanket cylinder). The last newspaper letterpress printing presses were delivered in the 1980s.

The most prevalent printing plate is the wash-off printing plate. There are very different wash-off systems and wash-off depths available in conjunction with different bases. The production process is described using the example of “Nyloprint” printing plates (from BASF). Steel, aluminum, and polyester are used as base materials. The plate thickness is approximately 0.8 to 1.75 mm, depending on the type, and the relief height between 0.2and 0.67mm, depending on the application and the type of plate. The relief layer consists of a photopolymer (UV light-sensitive, 360–370 nm), which is firmly attached to the base material.

The following operational steps are necessary to make the Nyloprint plate:

• Removal of the protective film.

• Exposure of the polymer coating through a negative film – the exposed areas cure (crosslink). The smaller the covered areas, the smaller the later depth of the relief. There are flat-bed and external drum imagesetters and also step-and-repeat systems available.

• The photopolymer that is not crosslinked is washed off with water or an alcohol and water mixture. The print relief is produced.

• Drying the print relief.

• The complete polymerization of the print relief, and therefore its curing, is ensured by the flat UV post-exposure. Fine lines up to 50 μm wide and small isolated dots 200 μm in diameter can be achieved.

Задание 5.2 Find the proper Russian equivalents for the following terms:

Задание 5.3 Find in the text English equivalents for these words and word combinations:

1. защитная пленка

2. полимеризующийся слой

3. глубина рельефа

4. сушка печатного рельефа

5. задубливаться (сшиваться)

6. косвенная печать

7. точка

Задание 5.4 Match the following:

1. The most prevalent printing plate is the _______________________.
2. The photopolymer that is not ___________________is washed off with water or an alcohol and water mixture.
3. The relief layer consists of a ____________, which is firmly attached to the base material.
4. Fine lines up to 50 μm wide and _____________200 μm in diameter can be achieved.
5. Letterpress printing was the________________ book-printing process.

a. photopolymer

b. small isolated dots

c. wash-off printing plate

d. predominant

e. crosslinked