CROSS-REFERENCE TO RELATED APPLICATION

This is the United States national phase of International Patent Application No. PCT/162018/057048, filed Sep. 14, 2018, which application claims priority to India Patent Application No. 201711032920, filed Sep. 18, 2017. The entirety of each of the foregoing applications are hereby incorporated by reference.

FIELD OF THE INVENTION

The present disclosure relates to an epoxy resin system. Specifically, the disclosure relates to an epoxy resin system for structural composites.

BACKGROUND

Epoxy resins are a class of synthetic resins used extensively in structural composites applications. Epoxy resins offer a unique combination of properties that are unattainable with other thermoset resins. Due to the excellent physical and chemical properties in the industrial production, the epoxy resins have been widely used in adhesives, coatings, composite substrates, resin wind blades, and even aviation, space materials etc. Since 1980, epoxy resins are largely employed in composites and adhesives needed to produce wind rotor blades and other structural elements. The wind industry has quickly established itself as one of the largest composite applications of the world. Epoxy resin systems are preferred as matrix materials for high performance structural composites on account on their ease of processing, user friendliness and high mechanical strength and stiffness. For demanding applications such as wind turbine blades (which are one of the largest composite structures) made by infusion process, epoxy resins are widely used as they enable blades with exceptional fatigue behavior in both static and as well as dynamic loading conditions. In last, few years the wind energy industry has been growing exponentially with new blade designs being developed for higher MW (megawatt) ratings and subsequently longer length blades and rotor diameter. This has necessitated need for new epoxy resin systems which are slower in reactivity as these can provide long working time for controlled infusion process and reduce processing defects in manufacturing of rotor blades. Slow reacting infusion systems however increase the curing time and thus affect productivity due to increase in blade manufacturing cycle time.

Previous other attempts and development of suitable epoxy resin systems have also focused either on alternative chemistry and/or use of catalytic curing agent(s). Epoxy systems based on alternative chemistries have proved promising however, their compatibility with other blade materials and latency at ambient temperature are seen limiting and need validation for each design and process. Likewise, system based on catalytic curing agents are prone with issues like hot spots due to exothermic reaction temperature especially when handled in large masses.

Therefore, there is a need for an epoxy resin system that has desirable mechanical and performance properties suitable to for use in the wind blades.

SUMMARY OF THE INVENTION

The present disclosure relates to a slow reacting epoxy resin system. The slow reacting epoxy resin system comprises a high purity epoxy resin component selected from the group comprising of a high purity Bisphenol A(BPA), a high purity Bisphenol F (BPF), and a combination thereof, and an amine curing agent. The initial viscosity after mixing the high purity epoxy resin component and the amine curing agent is less than 350 mPa·s at 25° C.

