Innovation in industrial inkjet technology - I4T

Industrial inkjet technology involves the generation, manipulation and deposition of very small drops of liquid (typically 20-50 um diameter) under digital control. The UK is recognised internationally as a leader in this area. Inkjet technology already dominates the desktop printing market. In commercial printing, it is rapidly becoming established for short-run applications and has, in only a few years, conquered a market previously occupied by conventional screen-printing equipment, where its great flexibility and inherent scalability give significant advantages. If higher printing speeds and greater quality can be achieved, then it will also be able to move into large-volume commercial printing. Apart from these printing applications, novel opportunities for inkjet deposition are also beginning to be exploited commercially in the manufacturing of high-value, high precision products (e.g. flat-panel displays, printed/plastic electronics, photovoltaic cells for power generation). By extending the existing benefits of inkjet methods (e.g. flexible, digital, non-contact, additive) to attain the speed, coverage and material diversity of conventional printing and manufacturing systems, we can transform inkjet from its present status as a niche technology into a group of mainstream processes, with the UK as a major player. But in order for this transformation to happen, we need a much better understanding of the science underlying the formation and behaviour of very small liquid drops at very short timescales, and to widen the range of materials which can be manipulated in this way, especially to allow fluids with high solids content (i.e. colloidal fluids) to be deposited. This cross-disciplinary programme of research is strongly supported by a consortium of nine UK-based companies and will bring together established research groups from three major UK universities to study three themes focused on key aspects of the industrial inkjet process: the formulation, rheology and jetting behaviour of colloidal printing fluids; understanding and controlling dynamic micro-scale drop impact, spreading and fixing; and development and validation of an advanced process model for industrial inkjet. Within these themes we aim to: develop a theoretical and practical understanding of how to make stable high solid-content colloids suitable for inkjet deposition, and how they behave in an inkjet system and on the substrate; explore post-impact processes that determine the structure and functionality of the printed features, including surface morphology, chemistry and surface treatment, fluid dynamics of wetting and the interaction of successively printed materials; and develop a set of models, validated by precise measurements and underlying physical theory, to describe all aspects of the formation and ultimate fate of ink drops. Industrial beneficiaries will include companies in the fields of inkjet printing and digital manufacturing, as well as other companies involved in the precise manipulation of small liquid droplets: examples of sectors include pharmaceuticals, agrochemicals, combustion, coating application, materials processing, and particle technology. Academic beneficiaries, apart from researchers working directly on inkjet technology, will include those in the fields of rheology, fluid mechanics, microfluidics, materials science and surface engineering.

Immediate beneficiaries from the research will include the nine Project Partners, who represent the majority of UK companies involved in the development of equipment and materials for the industrial application of inkjet and several companies at the forefront of the application of inkjet to printing or manufacturing. The UK is recognised internationally as a leader in this emerging area. The printing industry plays a major role in the UK economy (the printed products market alone is worth ~14 billion annually, not including any manufacturing). In industrial printing, benefits from the work will include: faster printing, in terms of substrate speed and fluid throughput; seamless single-pass printing with sequential deposition of several different kinds of fluid; more accurate feature definition; reduced development timescales for fluids and printing systems, through the use of validated modelling; and the availability of novel tools for monitoring, process design and control, and optimization. Inkjet is also an enabling technology for the potentially disruptive plastics electronics industry, on which the UK is well-placed to capitalise in the near to medium term; it is also employed in the manufacture of photovoltaic power generators. There are also numerous potential applications of inkjet technology within the direct-write area and in other manufacturing sectors; one in particular is the dosing of active agents in pharmaceutical manufacture. The UK has a global presence in the pharmaceutical industry. For manufacturing applications such as these the benefits will include: the ability to deposit a much wider range of materials, including fluids with high solids content; improved ability to predict and control the behaviour of drops on impact; and better fundamental understanding of droplet deposition and spreading. Other industrial sectors which may benefit from the research outputs, either directly or via the enhancement of fundamental understanding, include pharmaceuticals (for drug delivery by inhalation), agrochemicals (e.g. crop spraying and product manufacture), combustion, coating application, materials processing, and particle technology. The use of inkjet printing as a tool for depositing cells and other biological materials for tissue engineering and the fabrication of diagnostic sensors forms a lively research area, and outputs from the programme should be of benefit to future developments, both academic and commercial, in these healthcare-related areas. The generic expertise developed by research staff during the project will be of direct benefit to potential future employers in all the above sectors. The investigators have experience of working with industrial partners and outputs will be transferred through written reports, exchange of 'know-how' through training workshops and/or exchange of staff, through commercial development of instrumentation, and through the supply of software. Benefits to the wider industrial user community, both in the UK and abroad, will result from delivery of the outputs via the usual channels of academic publication and academically-focused seminars and conferences, but also through publication of summary articles in the trade press and through presentations and tutorials at conferences and meetings with a strong industrial attendance. A biennial Symposium on Applied Inkjet Science is also planned and aimed to attract delegates from the industrial research and development sector. In some cases (e.g. improved rheological measurements, diagnostic instrumentation or modelling) outputs may lead to new instruments or software which will be exploited through the universities in accordance with the consortium agreement, for example through licensing agreements or the formation of spin-out companies; the investigators have experience of both routes.