1.Research on Wet Process of Polyimide Wet-laid Nonwoven Fabric

Polyimide wet-laid nonwoven fabric is a very special fiber material widely used in many high-tech fields, such as aerospace, electronic communications, and automotive manufacturing. It possesses high thermal stability, high-temperature resistance, and excellent electrical insulation properties, making it practically a versatile fiber.

The wet process is one method for manufacturing Polyimide Wet-Layer Nonwoven, but its main steps are dissolving the polyimide raw material in a solvent and then spinning the dissolved polyimide liquid into fibers.

 Simply put, it's about making fibers from liquid polyimide material! This requires very precise control; otherwise, quality problems will occur, affecting the fiber's performance.

2.Polyimide Wet-laid Nonwoven Fabric Process Steps

1) First, the polyimide raw material is dissolved. This process is carried out at high temperatures. Commonly used solvents include N,N-dimethylacetamide (DMAc) and N-methylpyrrolidone (NMP), forming a polyimide solution with a concentration of 10% to 20%. 

Special attention must be paid to the temperature and concentration of the solvent; if the temperature or concentration is too high, the fibers may become uneven or stick together.

 2)In this step, the dissolved polyimide solution is extruded through a nozzle to form filaments. These filaments require careful adjustment and control to ensure their diameter is uniform. 

The fiber diameter of wet-spun fibers is typically between 10 and 20 micrometers, depending on the solution concentration and spinning speed. Spinning too fast may cause the fibers to break; spinning too slowly may result in uneven fiber quality.

 3)After spinning, the fibers enter a special coagulation bath. This is the most important step in the wet spinning process. After exiting the spinneret, the fibers enter a bath containing water or other solvents. After cooling and solidification, the polyimide fibers are finally formed. 

The temperature during this process must be controlled between 20 and 40 degrees Celsius; excessively high temperatures may cause changes in the fiber morphology.

After these steps, the wet-spun polyimide fibers possess excellent mechanical properties, making them particularly suitable for applications requiring high strength, high-temperature resistance, and high electrical insulation.

3.Advantages and Disadvantages of Polyimide Wet-laid Nonwoven Fabric

It can produce high-performance polyimide fibers with excellent heat resistance and mechanical properties. Because wet spinning can be operated at lower temperatures, it is more energy-efficient than dry spinning. 

The more uniform fiber morphology during wet spinning ensures product consistency. However, wet spinning also has some disadvantages. Some solvents are toxic and volatile, and improper handling can lead to environmental pollution.