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Summary

A German institute in Saarland has invented completely new photoinitiators for
printing inks, lacquers and adhesives based on photo catalytic functionalized semiconductor nanoparticles. The new photoinitiators as compared to the commercial initiators offer the opportunity to cure printing inks, lacquers and adhesives very fast and without contaminating the environment. Production and distribution partners who are interested in purchasing an exclusive license of the technology are sought.

Full description

Conventionally, the curing or rather drying of printing inks, lacquers and adhesives is based on the evaporation of solvents. As an alternative, the use of photoinitiators has been established. These substances enable a fast and controlled curing without the help of solvents by the use of UV radiation. A disadvantage of the conventional molecular photoinitiators (e.g. Irgacure 651 or Darocur 1173) is that they are toxic for human beings due to their high chemical reactivity. During the UV curing process only about 10% of the substance is converted. The remaining 90% can diffuse or migrate through the cured matrix. This causes problems, especially for the food industry because the toxic substances can merge into the food by different means.One possibility is by diffusion through a printed packing which has no barrier like for example an aluminium layer. Furthermore, a “transfer” may occur while storing packing materials, e.g. on a roll or by stacking beakers, the printed outside gets in contact with the inside. Thus, packing food might lead to a contamination with toxic substances resulting in a risk to health. Approaches using non-fragmented initiators or initiators that are bound to complex
organic macromolecules have not proven to be efficient or implicate unknown risks to health.
The completely new photoinitiators for printing inks, lacquers and adhesives presented here are based on photo catalytic functionalized semiconductor nanoparticles. The photo catalytic activity could be increased considerably through a synergetic effect between the nanoparticle and the mediator molecule. A single nanoparticle is 700 times more efficient than a classic molecular initiator molecule. Due to its mass the particle cannot migrate through the cured matrix. Moreover, it was proven that the curing starts from the particle, so that the particle-modificator-matrix is the nucleus of the curing area itself. The molecules which have not been converted by UV irradiation stay attached to the immobilized nanoparticle. In conclusion, the new photoinitiators as compared to the commercial initiators offer the opportunity to cure printing inks, lacquers and adhesives very fast and without
the contamination of the environment.

Innovative Aspects

The nanoparticle containing paste is dispersed in ethanol. The dispersion can be
brought into the binding agent by classical procedures. The content of material according to the present invention can be up to 20% of weight.

ADVANTAGES
- Improvement in efficiency
- Fully immobilized after curing – no more migration is possible
- No contamination of the environment, no risk to health (e.g. in the food
sector)
- Simple and economic production
- Less odour of the cured product

Partner expertise sought:

- Type of partner sought: Production and distribution partners
- Specific area of activity of the partner: industrial printing, printing of consumer products including food products.
- Task to be performed by the partner sought: purchasing the exclusive license as well as the further development of nanoparticulate photoinitiators applicable for UV curing printing inks, lacquers and adhesives.