What is Cycloaliphatic Epoxy Resin?

Cycloaliphatic epoxy resin, a branch of epoxy resin, is a compound with general properties of cycloaliphatic compounds and carbocyclic structure.

In organic chemistry, organic compounds are generally divided into three categories: 1. Open-chain compounds, in which the carbon atoms in the molecules are connected into chains, also known as "Cycloaliphatic compounds"; 2. Carbocyclic compounds, in which the carbon atoms in the molecule are connected to form a ring, including alicyclic and aromatic compounds; 3. Heterocyclic compounds: cyclic compounds with other atoms (such as O, N, S, P, etc.) in the molecule.

The so-called alicyclic epoxy resin is usually an epoxidized alicyclic olefin compound formed by the oxidation of an alicyclic olefin compound containing two double bonds by peroxide (such as peracetic acid) in the industry.

Because the epoxy group of alicyclic epoxy resin is directly connected to the alicyclic ring, it can form a tight rigid molecular structure. After curing, the crosslinking density is high, so the thermal deformation temperature is high. The Martin heat resistance temperature is above 190℃, and the thermal decomposition temperature is above 360℃. Therefore, it has small curing shrinkage, high tensile strength, and good thermal stability. And there is no chlorine or sodium plasma in the synthesis process, so alicyclic epoxy resin has better dielectric properties, which are better than bisphenol A type epoxy resin in terms of specific resistance and dielectric loss tangent.

Different from the common bisphenol A type epoxy resin, alicyclic epoxy resin does not contain a benzene ring in its molecular structure, so it has good weather resistance and ultraviolet radiation resistance. It is very suitable to be used in photo-curing systems with cationic photoinitiator UVI-6976 or UVI-6992.

Among cycloaliphatic epoxy resins, TTA21 (equivalent to ERL4221, UVR6105), the most widely used representative product, was first developed by United Carbon Chemistry in the 1950s. It can partially replace the traditional bisphenol A type epoxy resin and has better performance in weather resistance, electrical properties, and mechanical properties. Because of its excellent performance, many new varieties were developed in later countries. For example, TTA26(UV6128), a product with an optimized side chain, has better flexibility and higher polymerization speed, which can be used with TTA21. TTA15 grafted with terminal (meth) acrylic resin is applied to waterborne UV curable coatings, which represents the latest technology in the coating industry and the development direction of green coatings in the future. TTA22 (equivalent to ERL4206) with another epoxy linked to an alicyclic ring can effectively reduce viscosity without changing the thermal deformation temperature and mechanical properties, and is an excellent active epoxy diluent.

The reactivity of cycloaliphatic epoxy resin to acid anhydride is greater than that of amine, and it can be fully cured in an acid anhydride system, which can avoid the use of amine curing agent with high toxicity and volatility, and is safer for operators.