Pultrusion is a process to manufacture fiber reinforced plastic or FRP products. In this process, continuous glass or other kinds of fibers are passed through a resin bath in a controlled manner. The resin impregnates the fibers and imparts a host of properties to the fibers depending upon the kind of resin used. Fillers and catalysts can also be added to the fibers. The resin infused fibers are passed through a heated die to cure the blend of fibres, resin, fillers and catalysts, resulting in formation of FRP composite.
Isophthalic pultrusion resin manufacturers deal in thermoplastic and thermosetting resins because resins falling under both these categories are used in making pultrusion FRPs. Some of the most common types of resins manufactured for use in making pultrusion FRPs have been discussed here.
Polyester resins are widely manufactured because its share in the pultrusion resin market is 75%. This is because FRP manufacturers use polyester resins much more than other kinds of resins for making pultrusion FRPs. Polyester resins are highly customisable and can be used for making a plethora of composites in addition to pultrusion FRPs.
Isopthalic polyester resin sold under the name of premium polyester resin is highly resistant against corrosion. Hence, this kind of resin is used for making pultrusion FRPs for highly corrosive locations such as chemical factories and marine environments. Due to low viscosity of polyester resins, fillers, additives and other kinds of agents can be added to impart fire retardant properties, high mechanical strength other beneficial features.
Epoxy resins are also popular among pultrusion resin manufacturers. Epoxy resins exhibit high adhesion with substrates and high thermochemical integrity which means they bind well with fibres resulting in high strength pultrusion FRPs. The shrinkage rate of epoxy resins is low and it can also be controlled easily by adding hardeners or catalysts.
Epoxy resins impart electrical insulation, corrosion resistance and high chemical tolerance to the FRPs. In addition, epoxy resins also withstand high temperatures. The costs of epoxy resins are low as compared to many other kinds of resins.
Polyurethane resins have a number of other applications apart from making pultrusion FRPs. The major beneficial features of polyurethane resins include high load bearing capacity and durability. Thus, these resins are used for making FRPs destined to hold high weights and undergo rough handling.
The viscosity of polyurethane resins is low which makes it easy to cast the pultrusion FRPs into various shapes and sizes. Addition of fillers is also easy due to low viscosity. Polyurethane resins exhibit high heat tolerance after curing. Electrical insulation of polyurethane resins make them suitable for making FRPs for shielding electrical components.
Phenolic resins have high heat resistance which is why they are used as adhesives or matrix binders in brake pads and clutch discs. This property is useful in making highly stable pultrusion FRPs. Manufacturers have formulated phenolic resins which can tolerate even 550 degrees F temperature.
Phenolic resins also exhibit high fire resistance and low smoke emission. Other beneficial properties include corrosion resistance and thermal insulation