Causes and solutions for
bubbles generated during vulcanization of rubber products
The generation of bubbles in rubber products is a common problem in the production process. Bubbles on the surface of the product not only affect the appearance, but also the quality. There are many reasons for the generation of bubbles in molded products, including vulcanization parameters, mold structure, operation process, moisture or gas in the rubber, thickness of the product, etc. Next, we analyze the reasons for the generation of bubbles and general solutions
Reasons for the generation of bubbles in the vulcanization of rubber products
1. Raw material factors
The rubber material itself contains moisture or volatile components, which are not fully removed before processing.
Chemical raw materials and additives are damp during storage, batching and other links, resulting in increased moisture.
Reinforcement materials such as steel cords and fiber cords are damp, and the glue slurry is not dry.
2. Rubber compound mixing processing factors
The mixing process is not refined and the operation is not standardized, resulting in uneven dispersion of additives.
The mixing temperature is low, and the water is not completely volatilized; too high a temperature may cause sulfur to melt or burn.
The rubber is not parked for enough time and is not fully matured, resulting in insufficient diffusion of the additives.
3. Process operation factors
The film storage environment is not standard and poor management may introduce external impurities.
The degree of vulcanization is insufficient, resulting in incomplete cross-linking of the rubber and the formation of bubbles.
The pressure applied during vulcanization is insufficient, and the rubber fails to fill the mold tightly.
4. Vulcanization equipment and mold factors
The mold exhaust design is unreasonable, the exhaust hole is blocked or the exhaust line is thin, affecting the exhaust effect.
The mold surface is damaged or fouled, affecting the fluidity of the rubber.
Improper control of vulcanization temperature and time leads to insufficient or excessive vulcanization.
Solutions
1. Raw material processing
Ensure that the rubber material is fully dried before processing, and control the moisture and volatiles within the standard range.
Add moisture-proof measures when storing chemical raw materials and additives to avoid moisture.
Steel cord, fiber cord and other reinforcing materials are dried before use to ensure that the glue slurry is dry.
2. Optimize the mixing process
Follow the scientific order of feeding, the number of thin passes and the back pressure process after aging.
Increase the mixing temperature to fully evaporate the moisture and volatiles in the raw materials.
Optimize the production formula, select easily dispersible additives, and improve the dispersibility of additives.
3. Improve process operation
Strengthen the management of the film storage environment to avoid the introduction of external impurities.
Strictly control the degree of vulcanization to ensure that the rubber is completely cross-linked.
Appropriately increase the vulcanization pressure so that the rubber fills the mold tightly.
4. Optimize vulcanization equipment and molds
Improve the mold exhaust design, thicken the exhaust lines, increase the exhaust hole diameter, and ensure smooth exhaust.
Clean and polish the mold regularly to maintain the surface finish of the mold.
Strictly control the vulcanization temperature and time to avoid insufficient or excessive vulcanization.
5. Other measures
Add an appropriate amount of anti-bubble agent or exhaust agent during mixing to reduce the generation of bubbles.
For products that have already produced bubbles, repair measures can be taken, such as puncturing the bubbles with a needle and gluing them with glue. However, it should be noted that this method may only be applicable to individual bubbles and does not affect the overall performance of the product.
In summary, by starting from multiple aspects such as raw materials, rubber mixing processing, process operation, vulcanization equipment and molds, the generation of bubbles in the vulcanization process of rubber products can be effectively reduced and the quality and performance of the products can be improved.
