Pultrusion process
Pultrusion process:
1. The continuous fiber bundle or ribbon-shaped fabric impregnated with resin glue is shaped by the forming mold under the action of the traction device;
2. It is cured in a mold or in a curing oven to make composite materials with specific cross-sectional shapes and unlimited lengths, such as pipes, bars, trough profiles, I-shaped profiles, and square profiles.
Generally, the preform is only heated in the forming mold to the extent of pre-curing, and the final curing is completed in the heating box.
In the process of pultrusion, the reinforcing fiber is required to have high strength, good bundling, no drape and easy to be infiltrated by resin glue.
Commonly used reinforcing fibers such as glass fiber, aramid fiber, carbon fiber and metal fiber.
In addition, the pultrusion process based on thermoplastic resins with better heat resistance and lower melt viscosity has also made great progress.
The key to its pultrusion molding is the impregnation of reinforcing materials.
In the pultrusion process, currently commonly used methods such as hot melt coating method and mixed braiding method.
The hot melt coating method is to make the reinforcing material pass through the molten resin, and then the resin is impregnated and then cooled and shaped in the mold;
In the mixed knitting method, the thermoplastic polymer fiber and the reinforcing material are mixed and braided into a belt-like, hollow-core and other geometric fabrics according to a certain ratio;
Then, when the fabric with a certain geometric shape is passed through the hot mold, the matrix fiber is melted and impregnated with the reinforcing material, and the product is cooled and shaped.