Bio-based polyester itaconates as binder resins for UV-curing offset printing inks Tobias Robert , Steven Eschig, Toine Biemans, Frank Scheifler Ó American Coatings Association 2018 Abstract UV-curing inks have several economic and environmental advantages compared with standard printing inks, such as high printing velocities, low VOC emissions and good adhesion to nonabsorbing substrates. However, there are also some drawbacks, such as residual monomers, pungent odor and allergic potential of monomers and prepolymers derived from acrylic acid. In addition, only few examples of UV- curing inks derived from renewable resources are known. Herein, acrylate-free UV-curing polyester itaconates with a renewable content up to 100% and their application as binder resins in UV-curing offset ink formulations are presented. In order to obtain a high renewable content in the polyester resins, Zn(OAc) 2 had to be used as polycondensation catalyst, as standard Brønsted acid catalyst led to undesired side reactions. The resins obtained with this synthetic protocol were tested on their reactivity, which was slightly lower than a commercial polyester acrylate. Printing inks formulated from these polyester ita- conates showed interesting properties despite the fact that no acrylic acid was incorporated in the resins. Keywords Polyester itaconates, UV-curing, Bio- based polyester, Printing inks Introduction Over the last decade, the interest in more sustainable materials has increased substantially. This is driven by several factors, such as fossil fuel depletion and rising customer awareness. Therefore, the chemical industry has started to devote more research efforts in devel- oping products with a substantial amount of bio-based building blocks. 1–7 However, renewable resources can be more than a mere replacement to their petrochem- ical counterparts. They also allow for new molecular structures that are not accessible from fossil sources. 8–10 The printing ink industry traditionally utilizes a high amount of renewable building blocks such as veg- etable oils, cellulose derivatives and colophony. 11,12 However, development of innovative inks in the last decades was mostly based on petrochemical resources with some exceptions utilizing renewable resources. 13 This is especially true for UV-curing printing inks. Here, the binder resins and other components used are almost solely derived from petrochemical feedstock. At the same time, this field of the printing ink industry has seen considerable growth over the last years, which is due to the high printing speeds and new field of applications, such as digital printing. Examples of inks derived from renewable resources in this field are scarce. Epoxidized vegetable oils have been used as bio-derived UV-curing binder resins after reaction with either acrylic acid 14 or with hydroxyethyl acry- late. 15 In both cases, the epoxide gets attacked by an oxygen nucleophile and undergoes a ring-opening reaction to the desired products. In a different exam- ple, Kela and co-workers used hemicellulose that was esterified with acrylic acid. 16,17 The resulting resin was used as binder for UV-curing ink formulations. But also other bio-based building blocks have been exam- ined as starting materials for UV-curing polymers, T. Robert (&), S. Eschig Fraunhofer Institute for Wood Research – Wilhelm- Klauditz-Institut WKI, Bienroder Weg 54E, 38108 Braunschweig, Germany e-mail: tobias.robert@wki.fraunhofer.de T. Biemans Worle ´ e Chemie GmbH, Worle ´ estraße 16, 21481 Lauenburg, Germany F. Scheifler Ja ¨ necke+Schneemann Druckfarben GmbH, Hannoversche Straße 33, 31319 Sehnde, Germany J. Coat. Technol. Res. https://doi.org/10.1007/s11998-018-0146-4