[Waste Rubber Tyre Recycling Machine] Progress in the recycling and utilization of waste rubber

Reclaimed rubber

 

Rubber regeneration methods can be roughly divided into three categories: physical regeneration, chemical regeneration, and biological regeneration. Physical regeneration is the use of external energy, such as force, heat-force, cold-force, microwave, ultrasonic, ray energy, etc., to break the three-dimensional network of cross-linked rubber to form a fluid reclaimed rubber. Chemical regeneration is the use of chemical additives, such as organic disulfides, mercaptans, alkali metals, etc., under a certain temperature, with the help of mechanical force to directionally catalyze the cracking of rubber cross-linked bonds, and stabilize the breaking point to achieve the purpose of regeneration. Biological regeneration is when the sulfur cross-links of vulcanized rubber are broken or desulfurized under the action of microorganisms so that the waste rubber can be processed again. The following briefly introduces several methods of physical regeneration.

 

Physical regeneration technology

1.1 Microwave regeneration

The microwave desulfurization method is a non-chemical and non-mechanical one-step regeneration method. It uses microwave energy to cut the sulfur-sulfur bond (s-s) and sulfur-carbon bond (s-C) without destroying the carbon-carbon bond (C -C), thus achieving the purpose of regeneration. Because the microwave energy is controllable, the bond energy of various chemical bonds is different, and the energy required for breaking is also different, such as s-s bond (213 kJ/m01), s-C bond (259 kJ/m01), CC bond ( 347 kJ/m01), so the bond breaking by microwave energy is selective. Therefore, the performance of the reclaimed rubber produced by this method is close to that of the original rubber. There is no need to add any additives in the microwave desulfurization process. Therefore, microwave desulfurization is basically pollution-free.

 

1.2 Ultrasonic regeneration

The use of ultrasound can also selectively destroy the cross-linked bonds while retaining the molecular backbone so that the vulcanized rubber can achieve the purpose of regeneration. The ultrasonic desulfurization process of vulcanized rubber not only destroys the three-dimensional network structure but also leads to the breaking of the c-C bond of the macromolecular chain. Therefore, further research is necessary to improve the selectivity of ultrasonic desulfurization. Only by selectively breaking the chemical bonds can the properties of the original gum be maintained to the utmost extent.

 

1.3 Electron beam regeneration

The electron beam irradiation regeneration method is to use the unique characteristics of butyl rubber (IIR) to radiation, with the help of the high-energy electron beam of the electron accelerator, it produces a chemical bond-disaggregation effect. Regenerate it. Most rubber elastomers undergo structural cross-linking reactions under the action of radiation, and only a few rubber species containing structural units of tertiary carbon atom groups, such as IIR and IIR vulcanizates, exhibit degradation reactions in the field. Regeneration of electron beam radiation is exactly the use of the degradation reaction in the high-energy radiation field. Electron beam radiation regeneration is the use of the unique radiation chemical properties of butyl rubber, which constitutes the technological basis for electron beam radiation regeneration of butyl rubber.

 

The traditional production processes of reclaimed rubber mainly include oil method (direct steam static method), water-oil method (cooking method), high-temperature dynamic desulfurization method, extrusion method, chemical treatment method, microwave method, etc. But the principle of the application is basically a water method and oil method. The manufacturing methods of reclaimed rubber mainly used in our country are oil method, water-oil method, and high-temperature dynamic desulfurization method. The main process, method characteristics, and some equipment are briefly described as follows.