What is a prepreg?

Prepregs are “ready-to-use” systems that are processed without further addition of fiber reinforcement or resin. As preimpregnated fibers or fabrics, prepregs contain uniformly distributed fibers with a resin system that already contains the curing agent. It is a semi-finished product consisting of continuous fibers and an uncured plastic matrix. The continuous fibers can be in the form of a unidirectional layer, a woven fabric or a scrim.

The balanced ratio of fiber reinforcement and resin content, which can be adjusted almost individually, leads to simplified processing and increases product quality compared with regular processing. In addition, the consistent quality and individually controllable layer thickness in particular improve the use of prepregs in series production.

Prepreg systems are based on multifunctional, specially modified phenolic, polyester and epoxy resins, with a curing system that is latent-reactive at room temperature but highly reactive at elevated temperatures.

The prepreg resins are characteristically in the still reactive B-state with medium to high viscosity.

Processing of prepregs

These can be easily processed by adding energy and simultaneous shaping measures. The low-molecular, still meltable resins are converted to the high-molecular, non-meltable C-state.

Curing is initiated by increased temperature and pressure in the production process. Special prepreg systems allow curing at low temperatures without using an autoclave. Our pre-impregnated fibers are available in various combinations of fabric (glass, carbon, aramid, etc.) and resin matrix (epoxy resin, phenolic resin, and polyester resin) and are available as a solvent-based system and a hot melt system.

In combination with glass, carbon and aramid fibers, structural components with very good mechanical properties can be produced.

Applications of prepregs

Prepregs are ideal for use in numerous industries, such as the transportation sector, boat building, and medical or even orthopedic technology. They meet the stringent requirements of EN 45545-2 for railroad applications, UL94V-0 for automotive applications and FAR/JAR 25.853 and CS 25.853 for flame retardancy in aircraft interiors.

Prepreg