Silicone rubber compound is made of methyl or vinyl group-containing linear polymer polyorganosiloxane (commonly known as raw rubber) as the basis, with reinforcing filler, incremental filler and give a variety of properties of the additives formulated into the base compound. The main raw materials used in methyl or vinyl rubber, adding silica, bridging agent, structure control agent, coupling agent and other materials, after high-temperature mixing and refining machine.

1, factors affecting the resilience of vulcanized rubber and vulcanization speed and solutions:

Factors affecting the resilience of the rubber and vulcanization speed and solutions can be from the following aspects:

① The vinyl content within the rubber material is not enough or the raw rubber itself vinyl content distribution is not uniform, so that the rubber in the vulcanization did not reach the positive sulfur point, the vulcanization speed is long, vulcanization is not sufficient, resulting in poor elasticity of the rubber material. Can be improved by increasing the overall vinyl content of the rubber, and in the formula to add an appropriate amount of hydrogen silicone oil, reduce the amount of filler to increase the amount of rubber to solve the poor resilience and slow vulcanization; can also be used in different models of vinyl content of the raw rubber, with a small amount of high vinyl raw rubber for use, to control the permanent deformation of the material tore, the formula to find an optimal balance in the Avoid the emergence of brittle rubber to achieve the purpose of improving the elasticity of the rubber.

The acidic nature of the rubber itself is also an important factor leading to the poor resilience of the rubber and slow vulcanization speed. Due to the acidity of silica itself, coupled with the addition of structure control agents are mostly acidic, so that the rubber is acidic, acidic rubber has a delayed effect on the vulcanization, while the high temperature resistance will also decline. Can be improved by adding appropriate weak alkaline material to improve the acidic content of the rubber, the general PH value of the rubber in the neutral or weak alkaline range to improve the elasticity and vulcanization speed is good.

③Other aspects: too much plasticizer or structure control agent in the rubber, resulting in poor elasticity and slow vulcanization speed of the rubber; too much plasticizer or structure control agent in the rubber, there is a delay in the vulcanization of the rubber, resulting in poor elasticity and slow vulcanization speed of the rubber, you can use the molecular weight distribution of the narrower and with a certain volatile components of the raw rubber, to improve the release of the rubber, so as to reduce the dosage of plasticizers; Use alkoxysilane to treat the surface of silica, with the use of hydroxyl silicone oil, using a two-step method to allow silica molecules and raw rubber molecules to have a certain bonding reaction time, the process can be adopted to reduce the amount of structural control agents, to improve the elasticity of the rubber and the vulcanization speed of the purpose.

At the same time each type of rubber material to establish a standard vulcanization curve, is also a means of controlling the production quality of good mixing rubber stability.

2, extruded rubber bubble causes and solutions:

Causes: Due to the greater water permeability of silicone rubber, especially the precipitation method of silica made of rubber mixing, with the increase in relative humidity in the air, the moisture content in the rubber mixing also increases linearly. When the moisture is too much, the silicone rubber from transparent to opaque, especially in winter due to the low ambient temperature, the rubber surface of the moisture release time is very slow or not released at all, resulting in easy bubbles on the surface of the extruded products. General precipitation method of silica, due to its own high water content is not suitable for extrusion molding with silicone rubber filler.

Solution: Alkoxysilane can be used to treat the surface of silica, so that it has a hydrophilic surface into a hydrophobic surface, reducing the water absorption rate of the rubber material; can also be processed at high temperatures to reduce the water absorption rate of the rubber material, so as to achieve the improvement of the bubble problem of the extruded rubber material.

Currently in the production of extruded rubber, in the existing formulation system, you can replace the 2 # structure control agent for the diethoxysilane, silica surface moisture for better processing, of course, in the production process to pay attention to the safety of the process can be used in the first step of the gas-phase method of mixing rubber, rubber cold refining out of the rubber, will be placed in the 30 ~ 40 ℃ health room for health care treatment for 8 hours or so, and then the rubber Vacuum heat treatment, strict control of the rubber effective refining time and refining temperature, that is, the rubber in the high-temperature section of the refining time and temperature, so as to improve the extruded rubber bubble problem.

3, how to improve the transparency of the key material?

The transparency of the key material and the transparency of the silica has a direct link, you can choose a better transparency of the silica.

In the formula and process, the transparency of the material is not good, that is, the hydroxyl of the surface of the silica is not fully processed, affecting the transparency of the material, that is to say, we add the hydroxyl silicone oil, the hydroxyl of the surface of the silica is not enough to deal with the hydroxyl of the surface of the hydroxyl of the hydroxyl silicone oil there are part of the pseudo-hydroxyl, in the process of vacuuming or heat treatment to extract a portion of the material does not participate in the reaction; at the same time also indicates that the silica molecules and the raw rubber molecules are not combined properly. At the same time, it also indicates that the combination of silica molecules and raw rubber molecules is incomplete or the combination of the molecules is not complete.