Nowadays, it is becoming increasingly important to find alternatives to mineral oil-based products. This also applies to printing inks, as current trends (e.g. mineral oil-free newspaper printing inks) show. Formulations based on vegetable raw materials already exist for conventional printing inks. The current project aims to develop new binders for UV-curing offset printing inks based on renewable raw materials.
Besides the raw materials, the environmental compatibility of the resulting printed products is of great importance. For this reason, incorporating various chemical functionalities into the oligomers (large binder molecules) aims to enhance recycling options. This approach is intended to improve the deinking properties of printed products and to make printing ink films biodegradable (compostable).
Solution steps
The following steps are necessary to achieve the targeted results of the research project:
- Synthesis and characterisation of biogenic binders, reactive diluents, and plasticisers
- Testing and qualification of the newly synthesised components concerning their material compatibility with printing press parts
- Development of a printing ink formulation from the qualified components
- Testing of the printing ink formulation for material compatibility to ensure that no damage occurs to printing presses
- If necessary, modification of the ink formulation to optimise printability
- Examination of the deinking behaviour of the resulting printed products with the optimised printing inks
- Analysis of the biodegradability of the components and printing inks
Targeted results
The aim of the research project is to realise all the binders required for a polymeric network of UV-curing offset printing inks on the basis of renewable raw materials and to achieve good deinkability and rapid biodegradability of such UV-curing offset printing inks through the targeted introduction of functional groups into this network. The bio-based offset printing inks are based on polymerisable polyesters as binders. The polymerisable polyesters are made from dicarboxylic acids (e.g. dodecanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, furandicarboxylic acid, malic acid, tartaric acid) and diols (e.g. isosorbitol, 1,4-butanediol, 1,3-1,3-propanediol, propylene glycol, dihydroxyacetone), which can be obtained in an environmentally friendly way from renewable raw materials (e.g. fermentation).
In order to enable UV-induced crosslinking of the binder, varying amounts of bio-based dicarboxylic acids and/or diols with polymerisable double bonds are added to the polyesters.
In order to achieve a significantly better separation of the bio-based offset printing inks in the deinking process compared to currently used systems and thus enable good integration into established recycling processes, functional groups are introduced into the binder by polymerising suitable biogenic components, which increase the hydrolysis sensitivity of the ester bonds under alkaline conditions.