Butyl rubber and butyl reclaimed rubber have excellent air tightness, water tightness, chemical stability, heat resistance, ozone resistance, shock absorption and insulation, and are widely used in various fields. The molecular chain flexibility, intermolecular force, relative molecular weight and branching degree of butyl rubber and butyl reclaimed rubber of different grades and different manufacturers are different, which will affect the extrusion properties of the rubber, but due to the internal molecules of the butyl rubber. Structural differentiation is not particularly large, so in actual production, the formulation is used to improve the extrusion properties of the compound.
1. The rubber content of butyl rubber products affects the extrusion properties of the rubber compound
Butyl rubber or butyl reclaimed rubber is used as the main body of elastic deformation in rubber products. In theory, the larger the amount of rubber, the greater the elasticity of the rubber, the greater the relative expansion and the expansion, and the pressure is too low. It is difficult to press out; tests have shown that rubber compounds with a gel fraction of 95% or more and 25% or less are difficult to extrude. In the production process of butyl rubber/recycled rubber products, when the rubber content is generally controlled at about 30%, it is more advantageous for the rubber material to be extruded. Due to the different butyl content in the butyl reclaimed rubber produced by different manufacturers and different raw materials, the rubber content of the butyl product containing butyl reclaimed rubber should be carefully calculated.
2. The type and amount of compounding agent in the formulation of butyl rubber products affect the extrusion performance of the rubber compound
(1) Reinforcement filling: rubber reinforcing agent can significantly improve the mechanical strength of butyl products. The proper use of carbon black with high structural strength in butyl rubber products can improve the extrusion performance of rubber compounds; rubber fillers increase the volume of products. The main way to reduce the amount of rubber and reduce the cost; the rubber content of the butyl rubber product formula will decrease with the increase of the amount of filler, thereby reducing the elastic deformation of the rubber compound, and theoretically, the rubber material extrusion process can be improved. Under normal circumstances, in order to ensure the smooth extrusion of the rubber compound, the amount of carbon black in the formulation should not be less than 40 parts by mass, and the filler should be no less than 60 parts.
(2) Softening and plasticizing: Softener is another major factor affecting the extrusion performance of butyl rubber. Appropriate use of softener can reduce the extrusion expansion rate of rubber compound. In actual production, avoid using softener which is easy to spray. And reasonable control of the amount of softener, otherwise it will affect the rubber extrusion performance and extrusion speed.
When using butyl rubber or butyl reclaimed rubber to produce rubber products, choose a vulcanization system with sufficient scorch time as much as possible, avoid using non-volatile compounding agents and aqueous compounding agents as much as possible to avoid bubble generation; use non-reinforcing rubber properly. The filler can reduce the viscosity of the rubber and avoid the gas. A small amount of vulcanized rubber powder can further reduce the deformation of the semi-finished product and facilitate the exhaust. In the production process of butyl rubber/recycled rubber products, an appropriate amount of paraffin wax, low molecular weight polyethylene, and chlorinated polyethylene may be added as a lubricant.