Introducing the Mixing Machine (Enclosed Type)

Closed mixing is divided into three stages: wetting, dispersing, and kneading, as well as the mixing of the kneading machine under high temperature and pressure. The operation methods generally include one-step mixing and two-step mixing.

A single-stage mixing method involves completing the mixing process in one go using a mixing machine, followed by pressing the mixture into compounded rubber. It is suitable for materials made entirely of natural rubber or those containing no more than 50% synthetic rubber. During a single-stage mixing operation, a batch-by-batch, stepwise addition method is commonly used. To prevent the rubber material from experiencing a sharp increase in temperature, a slow-speed intensive mixer is typically employed, or a two-speed intensive mixer can be used. The temperature must be below 100℃ when sulfur is added. The sequence of addition is as follows: raw rubber, small materials, reinforcing agents, fillers, oil softeners, discharge, cooling, and the addition of sulfur and accelerators.

The two-step blending method refers to the process of blending and pressing to produce compounded rubber through two passes through a blending machine. This method is suitable for rubber compounds with a synthetic rubber content exceeding 50%, and it can avoid the drawbacks of the single-step blending method, such as longer blending times and higher rubber temperatures. Similar to the single-step blending method, the first stage does not include sulfurization and highly active accelerators. After the single-step blending is completed, the rubber is cooled, stored for a period, and then the second step of blending is conducted. After the blending is uniform, the material is discharged onto the press for sulfurization, and then the rubber is taken off. The segmented blending method has shorter blending times, lower temperatures, more even dispersal of additives, and higher rubber quality.

Open Mixing Machine Introduction:

The mixing process of the open mixing mill is divided into three stages: roller covering (the softening stage of adding raw rubber), powder intake (the mixing stage of adding powders), and kneading (the stage after powder intake, ensuring the even dispersion of raw rubber and additives).

The Difference Between Enclosed Mixing and Open Mixing

Open molding typically occurs at temperatures below 80°C, classifying it as a low-temperature mechanical blending method. Enclosed blending discharges at temperatures above 120°C, sometimes reaching as high as 160-180°C, which is considered a high-temperature mechanical blending process.