Hot vulcanized silicone rubber is a large output of silicone products, the application of a very wide range of products. Silicone rubber has excellent resistance to high and low temperatures, can be used for a long time in the range of -60 ~ 250 ℃, and also has excellent electrical insulation properties, ozone resistance, weather aging, water repellent, moisture-proof, and has a good physiological inertia.   

In the hot vulcanized silicone rubber raw rubber with reinforcing filler, vulcanizing agent (or first without) and other additives, by mixing that is, into a hybrid rubber, can be molded, extrusion and other general rubber processing methods into a variety of silicone rubber products.  

Blended silicone rubber can generally be prepared on a general-purpose rubber refining machine, large-scale production is in the kneader or closed mixing equipment.

Detailed description of each process.

1、Kneading.

Kneader for silicone rubber, pumping vacuum. Generally choose 800-2000L special kneader, raw rubber and silica, silicone oil, institutional control agent, special requirements for small materials into the kneader mixing, generally 2-3 hours, the temperature rises to 130 ℃ -150 ℃, and then vacuum half an hour later, pour the material over the knapper out of the piece of parking.

2、Heat treatment.

When fumed silica without surface modification is used as reinforcing agent, structural control agent must be added to the rubber. Therefore, the heat treatment of the rubber material becomes a necessary process. The purpose of heat treatment is to further bond the structural control agent with the silica surface (Si-OH) and to eliminate low molecular volatiles from the adhesive. The general conditions of heat treatment are: 160℃～200℃ under nitrogen protection or reduced pressure in the kneader for 1～1.5h.

3、Filtration.   

For extruded products, calendered products, coated products and film products, mechanical impurities and undispersed compound particles are one of the main factors leading to the quality problems of the products. Therefore, the rubber used in the above products must be filtered. The filtering can be done by using a glue filter or by using a common extruder instead. The temperature of the barrel and screw should be controlled to the minimum, and the specification of the filter is 120-200 mesh.   

4、Return refining.   

The gel content increases and the plasticity decreases after the rubber is parked, so it is necessary to refine it when it is used. If the refining is not enough, the rubber will not be soft and the surface will not be flat; if the refining is too much, the surface of the rubber will be sticky, which is not good for operation.

Translated with www.DeepL.com/Translator (free version)