The varnishing process is a technique used to protect and enhance the gloss of printed materials, suitable for paper prints or cardboard, among others. Currently, varnishing techniques are increasingly adopted by many printing factories, leading to a rising demand for varnishing oils. Based on the film-forming mechanism of varnishing oils, they can be categorized into solvent-based varnishes, water-based emulsion varnishes, and UV varnishes. Solvent-based inks and UV-curable varnishes pose issues related to Volatile Organic Compounds (VOC) emissions, while water-based inks and varnishes are environmentally friendly, offering advantages such as non-toxicity, odorlessness, strong transparency, absence of VOCs, and low cost.
The drying process of varnishing oil includes several steps: coating, transporting printed materials, electric heating drying, and automatic paper collection. Among these, the electric heating module is crucial, especially in the selection of electric heating materials. Conductive coatings can be classified into two major categories based on composition and conductivity mechanism: intrinsic conductive coatings and composite conductive coatings. Composite conductive coatings include carbon-based and metal-based types. Carbon-based electric heating coatings comprise materials like carbon black, carbon fiber, and graphite. Graphene, known for its excellent optical, mechanical, and electrical properties, holds significant promise in biomedical and energy applications. In the context of energy shortages and fierce price competition, energy consumption of varnishing machines is a critical factor that requires careful consideration.
