What is the Prepreg Manufacturing Process?

Prepregs are a type of composite materials made up of fibres, pre-impregnated with resin, that offer excellent structural and mechanical properties.

Due to their high strength and relatively low weight, they are often used in aerospace, automotive and other industries that involve high-performance applications. For example, composites, such as carbon fibre, typically account for up to 85% of Formula 1 cars, while only accounting for 20% of the weight.

Carbon fibre, glass and aramid fibres are among the most common fibres used in prepreg manufacturing processes; pre-impregnated with thermoset and thermoplastic resins.

Where Can the Prepreg Manufacturing Process Be Used?

Prepregs are used in various composite manufacturing processes, including:

• Honeycomb panels
• Aircraft wing and body panels
• Spacecraft components
• Flooring panels
• A/C ducting
• Sporting goods
• Automotive components

Types of Prepreg Manufacturing

There are two main types of the prepreg process, as described here:

Solvent Dip

In the solvent dip prepreg method, the resin is dissolved in a solvent bath and the reinforcing fabric is dipped in the resin solution. The solvent is then evaporated off the prepreg using a drying oven. Only fabric prepregs can be produced using this process.

Hot Melt

In the hot melt prepreg method, the resin film is cast on a fibre-based carrier material, before both materials are passed between heated rollers. This transfers the resin to the carrier material and forces the resin to impregnate the carrier’s fibres.

Types of Resins for Prepreg Manufacturing

Thermoplastic Resins

Thermoplastic resins can be reheated and remoulded repeatedly as they do not chemically bond during the resin hardening process. As a result, they can produce highly recyclable materials that are susceptible to thermal deformation.

Thermoset Resins

Thermoset resins have an irreversible curing process. Once they are cured, they take on a durable and structurally solid form that cannot be softened, reformed, and rehardened. As a result, they can produce materials that are resistant to high temperatures but aren’t able to be recycled.

Top Resins for Prepreg Carbon Fibre Manufacturing

Carbon fibre can be manufactured in various ways to achieve a wide array of directional properties. Factors that can be changed to influence the final product include:

• Type of fibre
• Modulus
• Number of filaments
• Type of resin
• Application method of resin
• Resin to fibre ratio

This is why manufacturing composites can be a tricky task, depending on the specifications required.

Here we explore the top resin that can be used for prepreg carbon fibre manufacturing:

Huntsman Araldite® LY 1556 is a medium-viscosity, unmodified epoxy resin that can be used in prepreg manufacturing systems. It provides excellent mechanical properties and resistance to chemicals, which can be modified within wide limits by using different hardeners and fillers. In addition, it exhibits a low tendency to crystallise.

Our representatives have successfully used this resin, in combination with Huntsman HYPRO® 1300X13, for prepreg applications within electric bus battery manufacturing. HYPRO® 1300X13 is a liquid rubber that can be used as a reactant with a base thermoset resin to gain product performance improvements. It increases impact and crack resistance, toughness, flexibility and durability.