Tetra Unveils Electronic-Grade Hydrogenated Bisphenol A Epoxy Resin

Professional Interpretation

Architectural coatings, adhesives, rubber products, etc., are used in outdoor environments and are subject to natural climatic tests, such as light exposure, temperature variations, wind, rain, and other combined damages. This leads to a series of aging phenomena such as fading, discoloration, cracking, chalking, and strength loss, collectively known as "weather resistance" issues of materials. These issues significantly impact the material's service life. As one of the three major thermosetting resins, epoxy resin has numerous applications. To address weather resistance problems, the industry often adds light stabilizers and antioxidants to enhance the weather resistance of ordinary epoxy resin. However, these methods usually treat the symptoms but not the root cause. The fundamental solution lies in modifying the resin's structure by introducing a saturated backbone structure to improve the resin's weather resistance. Consequently, alicyclic epoxy resins and hydrogenated bisphenol A (HBPA) epoxy resins emerged. Among them, HBPA epoxy resin has similar curing properties to bisphenol A epoxy resin and also exhibits excellent weather resistance. This article focuses on discussing HBPA epoxy resin.

HBPA epoxy resin was first commercialized by companies such as Japan's Tohto Kasei. The main brands currently available on the market include Epalloy5000, AL-3040, ST-3000, EP-4080, YDH3000, EX-252, XY518, JH3000, etc. The specifications from different manufacturers are quite similar (see the table below).

HBPA epoxy resin production processes are similar to those of bisphenol A epoxy resin, with the main process involving HBPA and epichlorohydrin as the primary raw materials. The catalyst (typically Lewis acid, varying among manufacturers) facilitates etherification, cyclization, and refining steps (see the diagram below).       

 Due to the primary raw material HBPA not being domestically produced for a long time and the small-scale production leading to most manufacturers utilizing batch processes, control over the "three wastes" is limited. This results in a high price for HBPA epoxy resin, which affects its downstream usage.        

Mainstream Synthesis Process of HBPA Epoxy Resin

In recent years, with the large-scale domestic production of key raw material HBPA, domestic companies such as Anhui Xinyuan, Yantai Oliver, and Hubei Jinghong have achieved technological breakthroughs, leading to the commercial production of HBPA epoxy resin series. Once HBPA epoxy resin was introduced, it gained widespread use in fields like adhesives and electrical insulation materials due to its high bonding strength, excellent chemical stability, low curing shrinkage, outstanding mechanical properties, good insulation performance, and simple processing techniques. However, according to customer feedback, most of the HBPA epoxy resins currently on the market have high total chlorine content (>15000ppm), making it difficult to meet electronic applications. At the request of customers, Jiangsu Taitel began developing electronic-grade HBPA epoxy resin in March 2023. After six months of experimenting with different synthesis routes, they finally produced a qualified product using the company's specialized epoxidation process (see the analysis indicators in the figure below).

Meanwhile, initial tests of the curing performance of this epoxy were conducted, and the performance indicators are shown in the table below: