Improve rubber performance and / or processing properties
The main purpose of rubber blending is to improve the performance of existing rubber. For example, natural rubber is widely used because of its good comprehensive mechanical properties and processing properties, but its thermal aging resistance, ozone aging resistance, oil resistance and chemical resistance are not good. Most synthetic rubbers have poor processing properties and unsatisfactory mechanical properties, which often cause difficulties in production. These synthetic rubbers are blended with natural rubber to complement each other.
The processability of the synthetic rubber z product is particularly improved. The rubber parts of the tires are widely used in combination with NR, SBR, BR, etc., and the V-shaped tape is made of 90/10 CR./NR blend rubber. NR not only improves the sticking phenomenon of CR in mixing and rolling. It also improves the low temperature resistance of the tape. Synthetic rubbers are blended with each other to improve performance. If a tire inner tube is manufactured by a single IIR, although the airtightness is good, the use of a long time will result in defects such as softening of the carcass, sticking of the tire, and enlargement of the size of the inner tube. If the IIR is blended with a small amount of EPDM, it can be effective. The above defects are overcome, which is attributed to the structural change mainly caused by crosslinking after the thermal aging of EPDM. A small amount of EPDM glue can increase the amount of carbon black and softening oil, and also improve the surface smoothness and shrinkage of the extruded semi-finished inner tube.
The blending of special synthetic rubber with general-purpose or special synthetic rubber can effectively maintain the M performance of rubber, and can effectively reduce the cost of product production and improve the utilization rate of special rubber. Such as the blending of fluororubber and acrylate rubber, the blending of silicone rubber and EPDM rubber, and the mixing of fluororubber and nitrile rubber.
The blending of rubber and synthetic resin is another important way to achieve rubber modification. The advantage of synthetic resin in performance t is that it has the strength of bismuth, excellent heat aging resistance and resistance to various chemical media, which are lacking and required for some synthetic rubbers. The rubber is blended with a small amount of synthetic resin to improve the certain properties of the rubber, thereby improving the use value of the rubber and broadening its application fields. The most successful example in this regard is the blending of NBR and PVC, and the blends are now widely used in the production of various oil-repellent, chemical-resistant, and ozone-resistant products. Other general-purpose polyolefin resins, such as poly(polyethylene) (PE), polypropylene (PP), polystyrene (PS), high styrene (HSR), etc., have been widely used* with NR, BR, SBR, IIR. , EPDM and other blends, in addition to their ability to reinforce these rubbers, they also improve resistance to aging, solvent and oil. At the same time, it can improve the processing properties of the rubber compound, such as increasing the extrusion speed of the semi-finished product, reducing the shrinkage rate, and improving the roughness. Among them, low molecular weight PE resins (relative molecular mass 500 to 5000) have been used as special additives for improving rubber processing properties. Some synthetic resins have been blended with rubber and have received unexpected results. For example, blending of germanium-density polyethylene (HDFE) with SBR can significantly improve the resistance to multiple bending fatigue of SBR. 2. Develop new ways to prepare thermoplastic elastomers (TPE).
The blending of rubber and synthetic resin not only satisfies the modification needs of synthetic rubber products, but also successfully develops a new technology for preparing TPE by mechanical co-mixing dynamic vulcanization. The birth of this technology means that the rubber modification research has been obtained. A breakthrough in progress. A variety of semi-crosslinked and fully crosslinked TPEs produced by this method have become the main source of raw materials for TPE rubber products.