Analysis of Carbon Black Dispersion in Rubber Products

The problem of carbon black dispersion in rubber products refers to the uneven dispersion of carbon black added during rubber mixing, resulting in a decrease in the performance of rubber products. Carbon black is a commonly used rubber filler that can increase the hardness, strength, wear resistance, and aging resistance of rubber. If carbon black is poorly dispersed, it can lead to an increase in viscosity and a decrease in extrudability during rubber mixing, thereby affecting the mechanical properties, wear resistance, and aging performance of rubber products.

There are many factors that affect the dispersion of carbon black, mainly including material properties, process conditions, and equipment status. Below is an analysis of the dispersion problem of carbon black from three aspects.

1、 Material properties

1. Carbon black particle size and surface area

The smaller the particle size of carbon black, the larger the surface area, and it is easy to form aggregates. Therefore, choosing carbon black with moderate particle size and carbon black with smaller surface area can more easily achieve good dispersion effect.

2. Carbon black structure

The structure of carbon black is also an important factor affecting the dispersion effect. Generally speaking, carbon black with a more active surface is more easily dispersed, while carbon black with a less active surface requires the addition of dispersants to promote dispersion.

3. Carbon black content

Excessive carbon black content can increase the viscosity of rubber mixing, leading to difficulty in dispersion. Therefore, it is necessary to minimize the carbon black content while ensuring the performance of the rubber.

2、 Process conditions

1. Rubber mixing temperature and time

The temperature and time of rubber mixing are key factors affecting the dispersion of carbon black. Generally speaking, high temperature and long-term mixing can lead to a decrease in the surface activity of carbon black, thereby affecting the dispersion effect. Therefore, it is necessary to determine the optimal mixing temperature and time based on different types of rubber and carbon black to ensure good dispersion effect.

2. Mixing sequence and speed

The mixing sequence and speed can also affect the dispersion of carbon black. Generally speaking, mixing rubber and a small amount of carbon black evenly first, and then gradually adding the remaining carbon black can more easily achieve good dispersion. Slow mixing can reduce the possibility of carbon black aggregation.

3. Add dispersant

If the dispersion effect of carbon black is poor, an appropriate amount of dispersant can be added to promote dispersion. Common dispersants include low molecular weight polyethylene, wettable polymers, and surfactants. The selection of dispersants should be determined based on the type of rubber and the type of carbon black.

3、 Device status

1. Equipment cleaning

Equipment cleaning is an important factor affecting the dispersion of carbon black. If there are impurities and residues inside the mixing equipment, it will affect the dispersion of carbon black. Therefore, it is necessary to keep the equipment clean and regularly clean and maintain it.

2. Equipment performance

Equipment performance is also an important factor affecting the dispersion of carbon black. The mixing strength, oblique extrusion ratio, and motion state of the equipment will all have an impact on the dispersion of carbon black. Therefore, it is necessary to choose appropriate equipment based on the actual situation and make appropriate adjustments.

The dispersion of carbon black is an important factor affecting the performance of rubber products. To solve the problem of carbon black dispersion, it is necessary to analyze from multiple aspects such as material properties, process conditions, and equipment status to find the optimal process parameters and equipment configuration.