Introduction

Digital printing is a relatively new printing system compared to conventional printing processes.

Over time, digital printing has become increasingly important in many areas of application. It refers to reproduction processes, in which the printed image is transferred directly from a computer to the output devices, such a industrial and professional level printers on a wide variety of substrates, without intermediate steps and without the need to use printing plates. Thus allowing the reduction of the time of preparation of the work and the amount of consumables spent, obtaining a greater speed and integration in the graphic process.

Print in general has always played an important role in advertising actions, from posters to packaging, through the publishing market. Nowadays, print has to compete with digital media in a wide global village.

Digital printing is having a distinct impact in a wide variety of markets and generating new business models, such as the increase in the number of publications, such as magazines that are becoming more numerous, but with shorter print runs in order to respond to a more restricted and targeted audience. The decrease in the number of readership is changing the way digital printing is used, allowing publishers to create new audiences in specialized B2B niche markets.

Objectives

The aim of this work is to analyze, identify, understand and describe the developments that have been taking place in digital printing, more specifically in ink for the inkjet process and what are the evolutions in terms of sustainability in the coming years.

The inkjet

At the level of the printing industry, it is possible to distinguish between the various types of technologies, the water-based inkjet process

The inkjet is a non-impact printing process (NIP), in which the drops of ink are deposited on the substrates to create text and images.

It is widely used in home and office desktop printers and for coding applications. Currently the inkjet has a performance and printing quality much superior, being adopted by printing companies as an alternative to conventional printing processes.

The inkjet process represents a technology that makes print supply chains substantially improved, changing or creating new markets, reducing the cost of short print runs through printing on demand, as well as with product customization, such as personalized cards, labels and packaging, allowing brands to connect with users and consumers in a more personalized way.

Technically, there are two inkjet printing systems, the “Drop on Demand” (DOD) and the “Continuous inkjet” (CIJ). In the first, in the Drop on Demand (DOD) process, only drops of ink are formed fed by the print head, if the image demands for them, which makes this technology significantly cheaper, since only what is needed is consumed. It differs from continuous inkjet (CIJ), where ink is projected out of the nozzle regardless of whether or not there is an image. Unused ink is collected on the print head to be reused.

In turn, the DOD process is divided into thermal ink jet (Thermal Injet - TIJ) and piezoelectric inkjet, that differs in the technology used.

They consist of the principle of reducing the volume of the chamber located in the nozzle, with the ink being ejected by the nozzle. This reason is the same for thermal and piezoelectric inkjet printing processes. The difference lies in the technique used to achieve the contraction of the volume of the chamber.

In the case of piezoelectric, the projection of the ink depends on a mechanical movement in the ink channel, which pushes the ink through a nozzle with the help of a embedded piezo crystal.  While the thermal ink jet (Thermal Injet - TIJ), the ink droplets are applied by heating. The ink is heated, evaporates and expands, leading to the formation of a vapor bubble, that presses the ink drop out of the nozzle.

Thermal inkjet printing

Continuous inkjet printers (CIJ) have superior speed and durability. As they provide a continuous flow of ink, they have a great advantage over drop-on-demand processes for large productions.

The thermal ink process (TIJ) competes with CIJ processes. This process has the most suitable production cost for short and medium run jobs.

It also includes environmental gains, since in this printing method the thermal process reduces Volatile organic compounds (VOCs) compared to CIJ systems.

New UV inks

There are new inks that offer new options to choose from and many more advantages, such as UV inks with LED lamp curing, allowing these inks to be printed on a wide complexity of substrates, such as heat-sensitive films. In addition to UV inks, there are also new water-based pigment inks for flexible packaging and films, as well as an electron beam cured system, suitable for food packaging.

Perspectives

Sustainability has been an issue that has been placed to the entire industrial sector. In this way, environmental solutions will become a fundamental priority for all of them.

Companies are encouraged to reduce their waste and increase their efficiency. The decrease in demand has opened up many and new opportunities for the printing industry, with inkjet as a relevant technology for the future of printing.

Therefore, inkjet technologies will also have to invest and develop further in terms of sustainability over the next few years.