New ink development for digital indirect sublimation printing is providing more choice, greater productivity and reduced cost for digital textile printers.

A recent innovation within digital textile transfer printing is the possibility of indirect sublimation printing onto uncoated papers. This introduces new possibilities for textile printers, who previously only had 2 options of printing indirect transfer onto coated papers, or to use direct sublimation printing. The fact is that if you are able to sublimation print on lower grade, uncoated paper, you can now achieve high productivity at reduced cost, without compromising quality. And this is now possible with the introduction of next generation inks.

Sublimation printing onto coated papers is already an established process for indirect digital textile printing, and for sublimation ink technology itself, this is based on the property of dyestuff.

The inks currently available are able to sublimate onto coated paper at a very hot temperature, whilst being able to permanently dye textile fibres or synthetic materials that they are in contact with during the sublimation process.

The application of the ink is made by inkjet printing with piezo technology, onto sublimation paper. Traditionally the paper must be coated in order for the ink to adhere properly during the sublimation process. This is followed by drying, coupling with the substrate, which the coloured effect has to be adhered by the hot transferring of the colour, by calender or flat press, at a temperature range of 180 to 220°C, for between 30 and 180”.

So it is clear that the role played by the coated paper in the indirect printing process is very important. The paper must have special features allowing it to be a perfect transfer medium in order to achieve an effect that is as similar as possible to the image that the operator can see on the display.

Understandably, print production companies demand to be able to print with inks that easily allow them to reach a wide colour gamut, in order to be able to reproduce their output as accurately as possible.

Up to the present day, in order for this to be possible, papers that have a surface coating have been used, allowing the ink to deposit in the most effective way: the ink remains on the surface of the paper, so that it can create a “means” that is as suitable as possible for the decoration of synthetic materials, offering the right compromises in the best balances in the process. This is important among the “surface floating”, the drying time and the quality results.

With the introduction of next generation inks, such as KIIAN’s DIGISTAR HI-PRO - more choice is given to the printer who may now print on uncoated, lower cost papers that have a much lower weight (g/m2) than the traditional coated papers.

It should be noted that coated papers were developed for a purpose that is completely different from sublimation printing, and are typically coming from, and designed for food packaging.

The use of the uncoated, lower cost papers with new inks such as DIGISTAR HI-PRO significantly reduces production costs (that are meant as the sum of the cost of the ink and the cost of the paper) of about 30-40%. Only sublimation inks with a particular formulation enable the use of this kind of paper. These inks have to be formulated, so that they have a higher colour power than the standard ones, being able to assure a bright chromatic effect, by “opposing” the paper absorption, caused by the lack of coating. At the same time, they have to dry quickly on the paper – whilst remaining stable during printing - so that they can enable high productivity.

Initially, the sublimation process was adopted by the sportswear market and used as a key process for the production of 'soft' textile signage. But the new combination of DIGISTAR HI-PRO and lower cost paper is also very well suited to the fashion world, since it is able to achieve the colours and shades that the designers are so fond of.

For sure, traditional coated papers will not disappear, since they still afford, in general, a high quality in the decoration of the synthetic fibres. But certainly, for some kinds of application, it will be possible to replace them with this new technology. This trend is already underway in different markets, and many customers are attracted by this new offer, since they are excited by the remarkable saving it can give them, whilst also adding new possibilities with markets such as fashion.

The future

According to KIIAN’s expectations, the next generation of inks will slow down the trend forecasted by many sector studies (2012-2017) of a slow, but inexorable loss of the sublimation indirect transfer printing to direct sublimation printing.

Whilst direct sublimation textile printing may increase, we do not see a reduction, now or in the near future, for high quality indirect sublimation textile printing. There is growth potential for both processes as demand remains high.

There is no doubt that for some applications, removing paper printing altogether from the production process (even if the paper is cheap), could reduce production cost further. It is logical that a removal of one element of a process should make the production more efficient.

For example, all of the troubles with paper skewing and wrinkling will be eliminated!

But despite this, the fact remains that printers understand that skilled indirect transfer printing still provides unquestionable advantages and excellent quality in terms of both brightness and image definition that direct sublimation printing is not yet able to match.

Another aspect of direct printing should also be considered, namely that of the cost of production. Especially so in relation to the preparation and pre-treatment of fabrics, as direct printing is simply more expensive to print. It is essential to achieve good quality with sublimation direct printing, through the washing processes after printing which is an essential action in order to eliminate the chemical effect of the pre-treatment.

Nowadays, these costs, due to the pre-treatment and washing of the fabrics, together with the resulting relatively average quality, make the direct printing of sublimation inks far less attractive than indirect transfer printing.

But these comments are not solely intended to position direct printing as second rate to transfer printing. However, these facts do need to be considered before a print company makes a choice for the most appropriate technology, in order to achieve the desired result with a full knowledge of the investment it will take to create the finished product.

As mentioned before, the lower cost papers, or “poor” papers, as they are called in some markets, are really suited to the fashion sector. In the next few years, KIIAN expects a trend related to the geographical relocation and reorganisation of printing processes related to this field. The general increase in the productivity of digital printing and the reduction in the production costs, thanks to the introduction of lower cost papers, could actually encourage a return of printing processes to Europe.

This fact, allied to the need from fashion brands and retailers for local production that will quickly respond to local and personalised demands means that Europe, in our opinion, can expect continued growth of digital textile print, especially so in relation to fashion print production.

Conclusion

Indirect sublimation printing is here to stay. Whilst there will be a growth in direct sublimation printing, continued innovation with indirect sublimation printing, and the introduction of indirect sublimation printing onto uncoated papers offers print production more options.

The outstanding quality and the appealing cost reduction with indirect sublimation transfer printing is still very appealing for printers.

And for printers, having 3 process choices, we think, is much better than 2.