Classification:
Generally, there are dozens or even hundreds of varieties and brands of silicone rubber manufacturers, most of which are numbered according to commodity characteristics and uses, and some are classified according to vulcanization methods and chemical structures.
According to the curing temperature, silicone rubber can be divided into high temperature vulcanized silicone rubber and room temperature vulcanized silicone rubber. From the packaging form, it can be divided into one-component and two-component room temperature vulcanized silicone rubber. According to the degree of polymerization, silicone rubber can also be divided into mixed silicone rubber and liquid silicone rubber.
1, high temperature vulcanized silicone rubber
High-temperature vulcanized silicone rubber refers to the process that polysiloxane is vulcanized into elastomer at high temperature (1 10- 170℃). It mainly uses high molecular weight polymethylvinyl siloxane as raw rubber, with reinforcing filler and vulcanizing agent, and vulcanizes it into elastomer under heating and pressure. The reinforcement of silicone rubber is mainly various types of white carbon black, which can improve the strength of vulcanized rubber by dozens of times.
Sometimes, in order to reduce the cost and improve the properties of rubber compound, various special properties are given to vulcanized rubber, and corresponding additives are added. Vulcanizing agents are various organic peroxides or addition reaction catalysts.
2, room temperature vulcanized silicone rubber
The main difference between room temperature vulcanized silicone rubber and high temperature vulcanized silicone rubber is that it is based on polysiloxane with small molecular weight and can be vulcanized into elastomer at room temperature or with a little heating under the action of crosslinking agent and catalyst. Room temperature vulcanized silicone rubber consists of basic rubber, crosslinking agent, catalyst and filler. From the packaging form, it can be divided into one component and two components.
3. Add liquid silicone rubber
Addition-type liquid silicone rubber is mainly based on polydimethylsiloxane containing terminal vinyl group, polydimethylsiloxane containing dimethyl chain and methyl hydrogen chain as crosslinking agent and platinum complex as crosslinking catalyst. In the presence of catalyst, silicone rubber with network structure can be obtained by addition reaction of rubber mixture at room temperature or heating.
Extended data:
Attention:?
1, in the production of mixed silicone rubber, the first thing to pay attention to is the hygiene of the factory and the cleanliness of the machine. If it is produced in a dirty environment, it is very likely that impurities will be mixed into the mixed silicone rubber, leading to the pollution of the mixed silicone rubber; ?
2. The mixed silicone rubber must be stirred evenly in a kneader before use. Time can't be too short or too long. If the time is too short, uneven mixing will occur. If the time is too long, the rubber will heat up, and it is easy to burn your hands when cutting. The correct way should be to see the rubber mixed into balls or the colors have been mixed evenly; ?
3. Matters needing attention in mixing silicone oil paper (also known as film paper). Generally, silicone rubber is colored with sulfur and then packaged with oil paper. When mixing silicone oil paper, you must not use an open mill to mix the oil paper into the rubber compound. Once oiled paper is involved in the rubber compound, if it is not stopped in time, the second batch of rubber compound will be completely scrapped; ?
4. Precautions for adding sulfur to mixed silicone rubber must be added according to the dosage ratio. Ordinary double 25 vulcanizing agent can be added in kneader or mill, and it must be added step by step. Adding too much at a time will lead to the loss of vulcanizing agent or the liquid splashing directly or even into the eyes of production personnel. The best way to add sulfur is to add it in the kneader; .