Text 5 Printing Presses for Packaging

Vocabulary

cylinder roll циліндровий вал

blanket cylinder офсетний циліндр

plate cylinder формний циліндр

impression cylinder друкуючий циліндр

impression відбиток

sheet-fed offset press аркушеподавальний плоскодрукарський верстат

'blanket-to-blanket' press двосторонній друкарський верстат

in one (single) pass за один прогон

full-colour effect повноколірний ефект

to overlay накладати пошарово

register приводка

web-offset press рулонний плоскодрукарський верстат

dampening зволоження

screen printing press верстат для трафаретного друку

frame рама

hinged прикріплений на шарнірах

squeegee ракель, гумовий валик

plastic laminate пластиковий ламінат

vacuum bases вакуумна подушка

vacuum pump вакуумна помпа

vacuum suction вакуумний всмоктувач

rack стелаж

drying tunnel сушильний тунель

ultraviolet drying unit ультрафіолетовий сушильний пристрій

The printing technology of letterpress, offset, and gravure have also been used for printing packaging material for several decades. Key factors in packaging printing are the very diverse demands made on packaging, such as:

• stability and functionality, which means that substrates, such as card, board, plastic film, aluminum foil, and compounds are used;

• neutrality with respect to odor, which is especially important in food packaging;

• external appearance ranging from “purely utilitarian” to very high quality.

Because quite specific demands are also made on substrate, color, and press design, the result is that the assembly and design of individual units may differ to a relatively great extent from the traditional printing upresses used to print books, newspapers, periodicals, or other print products.

In the 19th century, letterpress printing presses available at the time were used to print simple bags, sacks, and packaging papers. At the beginning of the 20th century firms were engaged in developing a new printing technology for packaging materials, called aniline printing and brought the first aniline printing units on the market (1905). The process using flexible rubber forms as printing plates from which flexographic printing developed, works with elevated and somewhat soft image carriers and low viscosity ink (aniline dye dissolved in alcohol) and is therefore very suitable for printing on rough packaging paper surfaces and for rapid drying.

These presses, with web widths of about 60–100 cm for multicolor printing on different packaging papers, were fitted with a simple unwind unit and a rewind unit with carrier rollers for a reel diameter of 60–80 cm. When cellophane entered the market as a new packaging material, the ink drying in the presses had to be modified and intensified, and sensitive web tension control systems and center driven winding units (shafted winding units) were required. Apart from other fairly small press modifications, the major requirement was that new inks with suitable adhesion to the non-absorbent substrate be developed.

At the beginning of the 1950s the first multicolor flexographic printing presses with a central impression cylinder were produced. In these presses, flexible and even very thin webs can be held and guided accurately during the entire printing process. This was and remains the prerequisite for achieving a high level of register precision and results in improving overall flexographic print quality as well.

Since polyethylene was increasingly used to make the most varied flexible packaging products, such as bags, carrier bags, and food packaging in particular, the demands placed on flexographic printing continued to increase as well as it the printing on fairly thin polyethylene webs with existing gravure printing presses was virtually impossible.

The basis for the eventual breakthrough of flexographic printing was created in 1972/73 with the introduction of photopolymer printing plates. The preliminary requirements for flexographic printing to come closer to the high quality of offset and gravure printing had now been met.

Flexographic printing units have also been used for many years in the corrugated board industry for the direct printing of sheets of corrugated board or solid board.

Modern high-capacity presses are now available for corrugated board packaging with which good quality, multicolor printing is achieved.

As a result of the many new developments and constant improvements, the entire flexographic printing technology has in recent years become increasingly important as an industrial printing technology world-wide, with disproportionately large market growth in some fields.

Дата добавления: 2014-12-23