Desizing process of carbon fiber chopped strands

1. Purpose and significance of desizing
The main goal of desizing is to completely remove the sizing layer on the surface of carbon fiber filaments. In the production process of carbon fiber filaments, sizing plays a vital role in protection and lubrication. It can effectively prevent the filaments from being damaged during weaving or processing and ensure the smooth movement of the filaments. However, when the carbon fiber filaments enter the chopped process, these sizings may become obstacles, affecting the accuracy and efficiency of chopped strands, and may even have a negative impact on the performance of the final product.

Therefore, desizing is particularly important. Through effective desizing, the surface of carbon fiber filaments can be ensured to be clean and free of sizing residue, thereby improving the accuracy and efficiency of chopped strands and laying a solid foundation for subsequent processing. At the same time, good desizing can also enhance the bonding strength of carbon fiber chopped strands with the matrix material and enhance the overall performance of the composite material.

2. Overview of desizing methods
At present, the desizing methods of carbon fiber chopped strands mainly include pyrolysis and solvent bathing with water-soluble sizing agents.

Pyrolysis method
The pyrolysis method is a method of decomposing the slurry by high temperature. During the desizing process, the carbon fiber filaments are placed in a dedicated heating device. By controlling the heating temperature and time, the slurry is chemically decomposed under the action of high temperature, thereby separating from the carbon fiber surface. The pyrolysis method has the advantages of fast processing speed and high efficiency, and is particularly suitable for large-scale and continuous production scenarios. However, it should be noted that excessively high heating temperature or excessively long processing time may damage the carbon fiber itself, so the heating conditions must be strictly controlled.

Solvent bath method of water-soluble sizing agent
The solvent bath method of water-soluble sizing agent is a method of dissolving the slurry using a specific solvent. During the desizing process, the carbon fiber filaments are immersed in a bath containing a specific solvent, and the solvent reacts chemically with the slurry to dissolve it from the carbon fiber surface. This method has the advantages of thorough treatment and little damage to the carbon fiber, and is particularly suitable for occasions where the surface quality of the carbon fiber is required to be high. However, choosing a suitable solvent is the key. The solvent must be able to effectively dissolve the slurry and be non-corrosive to the carbon fiber.

3. Desizing Process
Select Desizing Method
Select the appropriate desizing method according to the specific situation of the carbon fiber filaments and the subsequent processing requirements. If the sizing layer on the surface of the carbon fiber filaments is thick or difficult to remove, you can choose the pyrolysis method; if the surface quality requirements of the carbon fiber are high, you can choose the solvent bath method of water-soluble sizing agent.

Desizing
According to the selected desizing method, the carbon fiber filaments are desized. If it is the pyrolysis method, the heating temperature and time need to be strictly controlled to ensure that the sizing can be fully decomposed without damaging the carbon fiber. If it is the solvent bath method of water-soluble sizing agent, it is necessary to ensure that the solvent concentration and temperature in the bath are moderate so that the sizing can be quickly dissolved.

Cleaning and Drying
After desizing, the carbon fiber filaments need to be thoroughly cleaned to remove residual solvents and sizing. Clean water or specific cleaning agents should be used during the cleaning process to ensure the cleaning effect. After cleaning, the carbon fiber filaments are dried to ensure that their surface is dry, clean, and free of moisture.

Quality inspection and packaging
Finally, the quality of the carbon fiber filaments after desizing is inspected. The inspection content includes the cleanliness and damage of the carbon fiber surface, as well as the dimensional parameters such as length and diameter. Ensure that the carbon fiber filaments after desizing meet the requirements of subsequent processing. After passing the inspection, the carbon fiber filaments are packaged for storage and transportation.

IV. Precautions for desizing treatment

Strictly control the treatment conditions
Whether it is the pyrolysis method or the solvent bath method of water-soluble sizing agent, the treatment conditions need to be strictly controlled. Parameters such as heating temperature, treatment time, and solvent concentration must be precisely controlled to ensure the desizing effect and avoid damage to the carbon fiber.

Choose a suitable solvent
For the solvent bath method of water-soluble sizing agent, it is crucial to choose a suitable solvent. The solvent must be able to effectively dissolve the sizing agent and be non-corrosive to the carbon fiber. When choosing a solvent, its environmental protection, safety and economy must be fully considered.

Take safety precautions
During the desizing process, harmful gases or vapors may be generated. Therefore, safety precautions must be taken, such as wearing protective masks and gloves. At the same time, ensure that the workplace is well ventilated and remove harmful gases or vapors in a timely manner.