Radiation-cured coatings, particularly UV-curable systems, have experienced strong growth in China and globally due to their fast curing, low energy consumption, and very low VOC profiles. In this context, China-made epoxidized linseed oil (ELO) has gained attention as a bio-based reactive diluent and oligomer component that can enhance flexibility and sustainability in UV-curable coatings for wood, plastic, and metal substrates.
UV-curable coatings typically rely on acrylate or epoxy-acrylate oligomers combined with reactive monomers. These components influence viscosity, cure speed, hardness, flexibility, and shrinkage. Traditional reactive diluents such as TPGDA, HDDA, and TMPTA are effective but fully petrochemical and may pose irritation or odor concerns. In contrast, epoxidized linseed oil derived in China from renewable vegetable oils can be functionalized into acrylated or urethane-modified derivatives or used directly in cationic-cure formulations.
One pathway is to acrylate ELO by reacting its epoxy groups with acrylic acid or other unsaturated acids, yielding ELO-based epoxy acrylates. Chinese resin producers have developed proprietary processes to control molecular weight, epoxy conversion, and residual acidity, providing oligomers with suitable viscosity and reactivity for UV curing. These ELO-based oligomers can be blended into standard UV wood coatings to increase flexibility and toughness while maintaining high crosslink density. The long aliphatic chains of linseed oil offer internal plasticization, reducing the risk of brittle cracking on flexible substrates like wood veneers or plastics.
Another promising approach is to employ China-made ELO in cationic UV-curable systems. Epoxy groups can undergo cationic ring-opening polymerization initiated by onium salt photoinitiators under UV or electron beam irradiation. ELO’s high epoxy functionality, together with its hydrophobic backbone, can produce crosslinked networks with good chemical and solvent resistance. Cationic systems are less sensitive to oxygen inhibition than free-radical acrylates, making them suitable for thick films, pigmented coatings, and 3D objects.
From a processing perspective, ELO has a relatively low glass transition temperature and can significantly reduce formulation viscosity, acting as a reactive diluent. Chinese suppliers are able to offer ELO grades with different viscosity and epoxy values, enabling formulators to fine-tune their UV formulations for specific application methods such as roller coating, spray, curtain coating, and inkjet printing. Because ELO is primarily incorporated into the polymer network during curing, it shows less migration and lower odor than non-reactive diluents.
In wood coatings, especially flooring and furniture finishes, the flexibility and impact resistance imparted by ELO-based components are highly valued. The coating must withstand everyday wear, impacts, and dimensional changes of wood. Formulations containing China-made ELO acrylates have demonstrated improved resistance to cracking at edges and joints, as well as better adhesion on various wooden substrates. At the same time, hardness and scratch resistance can be balanced with other oligomers such as polyester acrylates and urethane acrylates.
For plastic substrates like PVC, ABS, and polycarbonate, ELO contributes to reduced internal stresses during curing, which helps minimize warping or delamination. Its polar nature can improve adhesion to certain plastics when combined with suitable adhesion promoters. Because many plastic parts are used in consumer electronics, appliances, and automotive interiors, the low VOC and odor profile associated with ELO-modified UV coatings is an additional advantage.
Chinese manufacturers and research institutes are actively exploring synergistic combinations of ELO with other bio-based materials, such as soybean oil-based acrylates, itaconic acid derivatives, and cardanol-based oligomers. The goal is to create high-bio-content UV-curable systems that meet or exceed the mechanical and chemical performance of conventional systems. Some pilot studies from Chinese universities indicate that ELO-rich UV coatings can reach high conversion degrees under industrial UV curing lines while maintaining good yellowing resistance through appropriate photoinitiator and stabilizer selection.
Regulatory and market drivers are also supporting the use of ELO in radiation-cured coatings. Many OEM customers, especially in electronics and packaging, request reduced carbon footprint and higher renewable content in coatings and inks. China-made ELO offers traceable plant-based origin, and several producers are working toward international certifications related to bio-based content and environmental management systems. As UV-curable technology expands further in China—into areas such as 3D printing, optical fiber coatings, and high-speed packaging lines—epoxidized linseed oil is expected to play an even greater role as a versatile, renewable backbone for advanced coating chemistries.