Important factors affecting extrusion process of reclaimed rubber products

Extrusion is one of the basic processes in rubber processing, and the extrusion expansion rate is a common process problem in the extrusion process. Therefore, the extrusion process performance should be fully considered when designing the extrusion formula of reclaimed rubber. In actual production, rubber variety, filling system and softening system are the main factors affecting the extrusion process of reclaimed rubber products. Manufacturers of reclaimed rubber products should select appropriate rubber according to actual needs, reasonably design the formula of reclaimed rubber products, and further improve the extrusion process of reclaimed rubber products.

1. Rubber varieties

Rubber molecular chain flexibility, intermolecular force, molecular weight, molecular weight distribution, branching degree and rubber content will affect the extrusion properties of rubber. In actual production, the rubber with large molecular chain flexibility and small intermolecular force has low viscosity, short relaxation time and small expansion ratio; When the molecular weight is large, the viscosity is large, the fluidity is poor, the relaxation time for elastic deformation caused by flow is long, and the extrusion expansion ratio is large; The wider the molecular weight distribution, the larger the expansion ratio; High branching degree and large expansion ratio; The raw rubber content is large, the elastic deformation is large, and the extrusion expansion ratio is large. Generally, it is difficult to extrude when the rubber content is more than 95%.

When using reclaimed rubber to produce rubber products, select appropriate rubber varieties and reasonably control the rubber content to ensure the extrusion performance of rubber.

2. Filling system

The addition of filler can reduce the rubber content, then reduce the elastic deformation of the rubber, and reduce the extrusion expansion rate of the reclaimed rubber. In general, the extrusion expansion rate of reclaimed rubber decreases with the increase of carbon black content; The higher the carbon black structure, the smaller the expansion rate. The extrusion expansion rate of reclaimed rubber can be significantly reduced by increasing the amount and structure of carbon black. It should be noted that excessive amount of high structure or activated carbon black will make it difficult to press out the reclaimed rubber, so it is necessary to reasonably control the amount of filler.

3. Softening system

Proper use of softener in extruded rubber can significantly reduce the extrusion expansion rate of rubber and make the specification of extruded semi-finished products accurate; However, when the amount of softener is too large or the softener with high viscosity is used, the extrusion speed of reclaimed rubber hyl13y9y2y-lyy will be reduced; In addition, for the semi-finished products of recycled rubber that need to be bonded with other materials, the use of softener that is easy to eject shall be avoided as far as possible.

When adjusting the formula to improve the extrusion process of recycled rubber products, manufacturers of recycled rubber products also need to comprehensively consider the appearance quality of extruded semi-finished products, extrusion speed and feeding stuttering amount; The vulcanization system of reclaimed rubber extrusion compound formula shall ensure that the compound has sufficient scorching time, try to avoid the use of volatile or moisture containing compounding agent, and appropriately increase the amount of reinforcing agent to improve the strength and Mooney viscosity of the compound.