Precautions for foaming of Rubber and plastic mixed foaming materials

Rubber and plastic blended materials maintain the dual characteristics of rubber and plastic, and are currently one of the most common production methods in the product processing industry; with the continuous development and progress of recycled rubber production technology, more and more recycled rubber is first used in preparation of rubber and plastic blending materials. When using reclaimed rubber or original rubber to produce rubber-plastic blended foam materials, the setting of the foaming process and the type of foaming agent directly affect the quality of the rubber-plastic blended foam materials.

Reasonably set the foaming temperature of rubber-plastic blending materials
In order to ensure that the recycled rubber or rubber materials and the plastic are evenly foamed, the foaming temperature of the rubber-plastic blending material needs to match the decomposition temperature of the crosslinking agent. In general, the crosslinking temperature and the foaming temperature of the crosslinking agent should be between the lower limit of the decomposition temperature of the foaming agent and the upper limit of the decomposition temperature of the crosslinking agent. For example: when reclaimed rubber and plastic are used together, peroxide DCP (decomposition temperature between 140-170℃) is used as vulcanization crosslinking agent, foaming agent AC foaming (decomposition temperature between 160-200℃) The optimal foaming temperature and the temperature range of the rubber compound are between 160-170℃.

During actual production, sometimes it’s difficult to match the decomposition temperature of the blowing agent and the decomposition temperature of the vulcanized crosslinking agent and the decomposition temperature of the blowing agent is generally higher. At this time, in order to reduce the decomposition temperature of the foaming agent, rubber product manufacturers can add appropriate amounts of cadmium, chromium, zinc, lead and other metal compounds or urea to the foaming agent to reduce the decomposition temperature of the foaming agent; the typical application is to use zinc oxide as an auxiliary foaming material, which can help reduce the decomposition temperature of the AC foaming agent to 130-155°C.

The particle size of the foaming agent affects the foaming speed of the rubber-plastic blending material
When reclaimed rubber or rubber is blended with plastics, the particle size of the foaming agent affects the foaming speed of the foamed material. For example, when regenerating tread rubber and blending to prepare a foamed material, choose a foaming agent of different particle size at normal temperature and pressure The time required for full foaming is extended with the increase of the particle size of the blowing agent. The smaller the particle size is , the faster the foaming speed will be. But this doesn’t mean that the smaller the particle size is, the better when selecting the blowing agent, because the smaller the particle size is, the more easily the blowing agent will decompose. While in some special occasions, the larger size of the foaming agent may be more appropriate; the effect of the particle size of the blowing agent is negligible during the high-pressure foaming process.

Rubber and plastic blending materials are widely used in production and life. The use of recycled rubber and plastics to prepare blending materials can further reduce the cost of raw materials while ensuring the performance of the blending materials.choose foaming agents carefully, and set vulcanization and foaming process conditions reasonably so that the performance of the rubber-plastic blended foam material can be optimized again and the service life can be extended.