Recycling waste rubber to make softened oil

Waste rubber undergoes cracking under the action of supercritical high-temperature and high-pressure water, and then through a series of separation, filtration and other procedures, can be re-used for the rubber processing with the softened oil.

According to the description of the patent specification, waste rubber products are first crushed, and non-rubber components such as fibers and steel wires are removed. The obtained rubber powder is placed in a reaction kettle, and then high temperature (374.2 DEG C.) high pressure (218.5 kg/cm@2) of water is introduced into it, and the water is weakly alkaline to neutralize the acidic components in the scrap rubber. The reactor is continuously oscillating. The rubber molecules react with the active water molecules under supercritical conditions. Under high temperature and high pressure, water becomes active molecules and enters into the rubber molecules to break the sulfur bonds. At the same time, The hydrophilic molecules (antioxidants, accelerators) will dissolve in water and the reaction time is about 10-30 minutes. After the reaction is terminated, the reactor is cooled. The water and the water-soluble substance are filtered out first, and the remaining oil is separated from the solid substance (carbon black and unvulcanized vulcanizate), and the liquid substance after removing the solid substance is removed again. After the molecule (molecular weight below 100), it is the desired softening oil for the rubber. This part of the softening oil has a molecular weight below 200,000. Take EPDM waste rubber as an example. The results of nuclear magnetic resonance test show that the oil is similar to the basic structure of EPDM. This oil is used in rubber formulations and its performance is similar to commercially available paraffinic softening oil. Because of its similar structure to rubber molecules, it has good compatibility with rubber. This method is applicable to the regeneration of vulcanizates of various rubbers such as NR, BR, SBR, EPDM. And the recovery rate is high, and the oily product is about 85% of the raw rubber powder (except carbon black).