NEW LINSEED OIL-BASED UV-CURABLE MATERIALS

Environmental concerns are increasingly present in our society. Industry must adapt to this evolution and find satisfactory solutions to solve the decrease of fossil raw materials while protecting the environment. The elaboration of “ecological” materials using a clean chemistry, i.e. without of volatile organic compound (VOC) emission, and allowing the valorisation of renewable raw materials is of increasing interest. Nowadays, vegetable oils are one of the most important classes of renewable sources. They can be obtained from common plants, such as sunflower, cotton, linseed...

Linseed oil belongs to the family of drying oils. Indeed, once deposited in thin layer, this oil can dry at room temperature according to an oxidative process consisting in reaction of the fatty double bonds with the atmospheric dioxygen. Unfortunately, this drying process is very long (several days). In order to accelerate this reaction, a process of thermal polymerization called stand reaction has been developed. It consists in heating the oil at high temperature (> 270°C) in the absence of dioxygen. These "cooked" oils are known as stand oils. The drying of stand oil is then much faster but is again too long (several hours). Another way to “dry” is to use a photochemical process of polymerization. However, since linseed oil triglycerides don’t bear any UV reactive groups, a chemical modification of these molecules is necessary to introduce photopolymerizable functions.

Thus, new materials mainly based on linseed oil were performed by means of an easy and ecological synthesis process in three stages: a thermal or stand stage, a chemical modification stage, and at last a photopolymerization stage. According to the properties of the ultimate materials, this new process could be interesting for the elaboration of flexible coatings.