A novel photocurable modified epoxy resin for high heat resistance coatings
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ORIGINAL CONTRIBUTION
A novel photocurable modified epoxy resin for high heat resistance coatings Bangchao Yin 1 & Junhua Zhang 1 Received: 12 March 2020 / Revised: 18 June 2020 / Accepted: 13 July 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract In this paper, in order to further improve the heat resistance of UV-curing epoxy cresol novolac (EOCN), 2,2bis(hydroxymethyl)propionic acid (DMPA) was firstly introduced to open epoxy groups in EOCN and then the hydroxyl groups reacted with acryloyl chloride to make sure the resin has sufficient UV-curing double bonds. Compared with the system that uses acrylic acid to open epoxy group and the secondary hydroxyl group reacting with unsaturated anhydride, up to 1.5 times double bonds were potentially introduced. The structure of the resins was characterized by FT-IR and 1H-NMR. Influences of double bond content on thermal behavior, photopolymerization kinetic behavior, and basic properties of the cured films were investigated. Thermal performance analysis demonstrated that the glass transition and the initial decomposition of the cured films were increased with the rising proportion of acryloyl group. Moreover, doping of abundant acryloyl chloride caused a significant increase of unsaturated double bond conversion, though the initial photopolymerization rates declined. Cured films with less acryloyl chloride modified showed better adhesive. For solvent-resistant test, with the increase of the acryloyl group, the cured film displayed good resistance to strong acids and alkalis. These attractive features give this process potential applications in soldering ink and protective coatings. Keywords UV curable . Modified epoxy cresol novolac . Acryloyl chloride . Kinetic of photopolymerization
Introduction Over the past decades, UV-curing technology has a wide range of applications in coatings, inks, adhesives, and printing plates due to its unique advantages, such as low energy consumption, environmentally friendly, efficient production, and low process costs [1–3]. Among various UV-curable resins, epoxy acrylate resins have become the most popular materials in UV-curing technology owing to their excellent photosensitivity, adhesion, hardness, and solvent resistance [4, 5]. However, in some special fields, such as printed circuit board (PCB) processing, it is necessary to go through a leadsoldering process above 260 °C. As a result, the cured
* Junhua Zhang [email protected] 1
The State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065, China
soldering ink must not only have high electrical insulation properties but also be resistant to solder heat treatment [6]. In addition, for materials that have been used under severe conditions for a long time (high temperature, strong acid, alkali environments), protective coatings are widely used. They protect materials from surface damage such as thermal decomposition, corrosion, and scratches by creating a barrier between the material and th
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