The quality problems of mixed silicone rubber are caused by the violation of the process regulations during the mixing process on the one hand, and the supplementary processing and weighing of the plastics and compounding agents in the previous processes on the other hand. The quality problems that often occur in rubber materials include the following and several aspects.
1. Clumping of compounding agent
Methyl vinyl silicone rubber is not sufficiently plasticized, the roll distance is too large, the loading capacity is too large, the roll temperature is too high, and the powder compound contains coarse particles or agglomerates.
2. Plasticity is too high, too low or uneven
Plasticizing silica gel when the plasticity is not appropriate, mixing time is too long or too short, improper mixing temperature, too much or too little plasticizer, too much or too little carbon black or the wrong species, uneven mixing, etc.
3. The specific gravity is too large or too small or uneven
The compounding agent is inaccurately weighed, wrong proportion or omission of the proportioning operation, the mixing process of the wrong addition. For example, add more carbon black, zinc oxide, calcium carbonate and so on. When methyl vinyl silicone rubber and oil softener are added less, the specific gravity will be too large. When the mixing is uneven, the specific gravity will be uneven.
The compounding agent is sprayed on the surface of the silica gel raw material to form a phenomenon similar to "white frost". The main reason is that the amount of certain compounding agents is too large, which exceeds its solubility in the rubber at room temperature. If the methyl vinyl silicone rubber is mixed and mixed unevenly during mixing, or the mixing temperature is too high, the compounding agent will be caused. Partial dissolution and inaccurate weighing can also cause blooming.
5. Hardness is too high, too low, uneven
The main reason is that the crosslinker, accelerator, softener, reinforcing agent, methyl vinyl silicone rubber and other inaccurate weighing, errors or omissions caused by adding, mixing unevenly caused by uneven hardness.
6. Scorching and burning
This is the early vulcanization phenomenon of silicone rubber materials, generally improper preparation of additives, improper operation of the process of mixing silicone rubber, improper operation of cooling, climate impact, etc.