Digital Transfer PaperQuestions and Answers

Digital dye sublimation transfer printing

 

Questions and Answers:

 

1. What is digital sublimation transfer?

 

In digital sublimation transfer an image is printed with an inkjet printer onto transfer paper (Jetcol HTR). Using heat and pressure from a standard heat press, the image is transferred to a substrate. Digital sublimation transfer requires special inks. These inks contain disperse dyes, which have the property to sublimate (phase change from solid to gas) when heated. The sublimated dyes will bond to polyester in particular. This means that substrates must contain polyester or polyester blends to give sufficient results. Transfer can also be done on other materials like metal, glass, ceramics a.o., if coated with polyester.

Sublimation transfer is often mistaken for cold or hot peel transfer. In cold or hot peel transfer one prints with normal inkjet inks on a special transfer paper. This paper is coated with a polymer layer. This layer along with the image is transferred to the substrate, providing adhesion and a degree of protection. Contrary to sublimation transfer the stability of cold or hot peel transfer is relatively poor.

 

2. Why should I use Jetcol HTR instead of a regular inkjet paper for digital sublimation transfer?

 

Jetcol HTR is especially designed for digital sublimation transfer. The coating on top of the paper is designed to receive inks at printing, but also to release the inks during transfer. This explains the high transfer yield of Jetcol HTR as compared to a regular inkjet paper. A regular inkjet paper is developed to receive and bind the inks to the paper after printing. Advantages of using Jetcol HTR: saving on ink costs and producing deep shades at reasonable ink costs.

 

3. Can I transfer onto cotton with Jetcol HTR?

 

In sublimation transfer disperse dyes are utilised. Transfer with these dyes works best onto polyester or polyester blends (min. 60 % polyester). These transfers have high UV and washing stability. Sublimation transfer onto pure cotton will give poor results, because of the chemical properties and physical behaviour of cotton.

 

4. Can I transfer onto materials other than textiles?

 

Without special treatment of the material sublimation transfer to materials like metal, wood, ceramics or glass is not possible, because the disperse dyes have no or less possibility to fixate. When a material is coated for instance with a polyester film fixation of the dyes is possible and sublimation transfer will give good results. The transfer result depends also on the quality of the coating used.

 

5. What are the best transfer conditions using Jetcol HTR?

 

The transfer yield is influenced by two factors: transfer time and temperature. Onto textiles a temperature of 210 °C and a time of 30 seconds is generally used. On other substrates temperature and time should be adjusted, depending on the nature of the substrate. An increase in temperature will give more sublimation of the dyes, and a higher yield. An increase in time will give a higher transfer yield.

 

6. What kind of inkjet printer is best suited for digital sublimation transfer?

 

Nowadays there are many brands of inkjet printers used in digital sublimation transfer. Jetcol HTR is suitable for all inkjet printing techniques currently on the market.

 

7. When printing deep colors the paper starts cockling and sometimes touches the printer head. What can be done about that?

 

Suggestions to decrease cockling:

  • apply only the amount of ink that is necessary to reach the desired color depth through color management. Because of the high transfer yield of Jetcol HTR much less ink is needed in comparison to standard inkjet paper;
  • increasing the distance between the printer head and paper (if possible);
  • installation of guiding strips to keep the paper down, at the sides of the paper web (after printer head);
  • lead the printed paper downward and away form the printer head as much as possible;
  • apply light tension on the printed paper by attaching for instance small weights to lead the paper away from the printer head.

8. Why oil and solvent based inks?

 

 The need for speed and high outputs has resulted in the use of oil or solvents as the liquid phase in the dye-sub inks. Drying of these inks is much faster than when the ink is based on water. Possibly even more important is the fact that the fibers in a paper expand when absorbing water from the ink.

 

This process of expansion is widely known (and feared) as "cockling". Heavy cockling can lead to the collision of the print-head with the paper, often resulting in replacement of the head being required. The expansion of the paper is of course greater when the paper is wide.

 

Therefore large format printers very often use oil or solvent based inks to overcome the expansion problems associated with water based inks.



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