Printing companies are now differentiating themselves from their competition by offering an array of high valued-added options in addition to conventional four-colour printing, such as multi-colour printing with various special colours and printing using presses equipped with a coating unit.
One type of high value-added printing currently generating interest is chemical embossed printing using UV varnish, a technique that produces an embossed effect at low cost.
Chemical embossed printing is a technique for printing material with a raised 3-dimensional appearance by using two types of varnish with different properties – OP (overprint) UV varnish (commonly referred-to as OP varnish) and gloss UV varnish – to create an embossed effect with offset printing.
Embossing of printed materials is normally performed separately using a special stamping process for which a resin plate must be made followed by UV spot coating. This involves high costs and a long delivery time.
Printing using chemical embossing differs from the normal embossing process by using a coating technique combining OP varnish and gloss
UV varnish.
This technique makes it possible to achieve an embossed effect for printed materials right on the printing press
at low cost and with a short turnaround time.
The first step in chemical embossed printing is the application of OP varnish to the target image areas using a conventional metal plate.
After the OP varnish is cured, gloss UV varnish is applied to the entire surface using a varnish coater and then dried by the UV curing unit at the delivery side.
Because the OP varnish repels the gloss UV varnish, in the areas where OP varnish has been applied, the gloss UV varnish bubbles up and dries in a raised state, creating a matte effect.
In areas where OP varnish has not been applied, the gloss UV varnish dries with a glossy finish.
Chemical embossed printing exploits this difference between the matte and glossy areas to create a raised,
3-dimensional appearance on printed materials.
Chemical embossed printing is an ideal method for emphasising certain parts of a photograph or illustration, highlighting the qualities of the printing media, or bringing out the texture of a painting or pottery.
It can be used in a wide range of printing applications, including art books, catalogues, posters and packaging.
To achieve chemical embossed printing in one pass, an inter-deck UV curing unit mounted over the impression cylinder needs to be installed for the fifth colour on a five-colour press, and a varnish coater and delivery side UV curing unit are also required.
Attracting a wider range of business
Since its introduction, the Ryobi 750 series has earned a worldwide reputation for superior printing quality and performance, opening the door to higher sales and greater profitability for many printing companies.
Fully equipped with Ryobi’s most advanced technologies, the 750 series offers wider printing sizes, enhanced automation and the latest labour-saving systems. According to Australian agent, Cyber, the Ryobi 750 series is the ideal partner for attracting a wider range of business in the burgeoning market for diverse short-run printing.
The Ryobi 750 series comes in two types: the SW type press with a maximum printing area of 765 x 545mm and the XLW type press with a maximum printing area of 765 x 580mm, enabling a wider range of printing applications. The XLW can flexibly handle a wide range of paper stock from 0.04mm onion skin to 0.8mm thick board.
Ryobi Program Inking has also been upgraded for fast makeready, and reduced paper waste. Program inking automatically sets the conversion curve for each according to the image area ratio data calculated at prepress. The ink settings, ink fountain roller speed and number of contacts by the ink ductor roller are all controlled based on the conversion curves to assure optimum ink volume.
Continuing advancements in UV technology
Instantaneous UV drying and excellent printing compatibility with non-absorptive media such as metalised and synthetic paper; improved glossiness, surface protection, wear resistance, and water resistance when combined with UV coating; the environmental benefits of using solvent-free ink – offering such significant advantages, UV printing and coating systems are becoming increasingly popular.
Responding to this market trend, Ryobi offers a full line-up of UV-compatible printing presses, from the 680/750 series to the 520GX series and 3404DI digital printing system.
The Ryobi 680/750 series UV printing-compatible models equipped with varnishing coating units and UV driers have attracted particular attention.
Especially in Japan, models equipped with varnish coating units and UV driers have enjoyed brisk sales among printing companies seeking increased productivity and added value.
Semi-long delivery models in the 680/750 series, can be equipped with a UV drier unit and long delivery models with both a varnish coater and UV drier.
In addition to these UV printing compatible models, Ryobi also demonstrated the 758P 8-colour convertible perfector at Igas 2003 in Japan.
The press was equipped with an inter-deck UV curing unit mounted over the convertible perfecting device, proposing one-pass instant-drying perfecting using hybrid type ink.
The 758P attracted considerable interest for allowing smooth movement to post-processes such as bookbinding immediately after perfecting.
Ryobi also developed inter-deck UV curing unit variations including one mounted over the transfer module and a type for mounting over the impression cylinder that allows the curing unit to be freely moved.
Ryobi can thus offer UV units compatible with various printing materials for which a special printing sequence requiring setting (surface drying) on the printing press is desired.
Andrew Tribute
