What are the stirring methods of flame retardant kneading machine?

The stirring method of flame retardant kneading machine is mainly designed according to the equipment structure, material characteristics and process requirements. The common types and characteristics are as follows:

1、 Sigma Blade Mixing

structural characteristics

Mixing blade shape: usually a Sigma or Z-shaped blade, with a small gap between the blade edge and the mixing chamber wall, which can form strong shear forces.

Movement mode: The dual propellers rotate towards or in the same direction at different speeds (or at the same speed), and some equipment blades can swing along the axial direction.

Applicable scenarios

Suitable for low to medium viscosity flame retardant materials (such as preliminary mixing of powder with resin, plasticizer), or scenarios that require uniformly dispersed fillers (such as aluminum hydroxide, zinc borate).

Advantages: Wide mixing range, able to rotate the blade to push the material up and down, left and right, achieving convective mixing.

2、 Screw Agitation

structural characteristics

Mixing component: Single screw or twin screw installed vertically (or obliquely) in the mixing chamber, and the surface of the screw can be designed with thread or ribbon structure.

Movement mode: While the screw rotates, some equipment can perform reciprocating motion along the axis of the mixing chamber (such as planetary screws).

Applicable scenarios

Suitable for high viscosity and high filling flame retardant systems (such as rubber, thermosetting resin based flame retardant materials), especially suitable for kneading processes that require overcoming material viscosity resistance.

Advantages: The pushing effect of the screw can lift the material from the bottom to the top, forming a cyclic shear, avoiding local agglomeration, and suitable for dispersing fibrous flame retardants (such as glass fiber and basalt fiber).

3、 Plow Blade Mixing

structural characteristics

Mixing component: composed of multiple high-speed rotating plow blades, flying blades (optional), and low-speed mixing paddles, the plow blades are installed at an inclined angle.

Movement mode: The plow blade rotates at high speed (100-300rpm) to generate strong shear, and the flying blade (if any) further breaks down the clumped material.

Applicable scenarios

Suitable for mixing solid flame retardant powders (such as decabromodiphenyl ether, brominated epoxy resin) with resin particles, or for scenarios that require rapid dispersion of pigments and additives.

Advantages: Strong high-speed shear force, high mixing efficiency, can achieve uniform distribution of materials in a short period of time, suitable for flame retardant formulations with high dispersion requirements.

4、 Planetary Mixing

structural characteristics

Mixing blade form: usually a frame blade or a butterfly blade, the blade rotates while revolving around the central axis, close to the wall of the mixing chamber.

Movement trajectory: The blade movement covers the entire mixing chamber and can be paired with a scraping device to remove wall sticking materials.

Applicable scenarios

Suitable for paste like or paste like flame retardant materials (such as the mixture of silicon-based flame retardants and polymer melts), or for scenarios where excessive shear degradation of materials needs to be avoided.

Advantages: The composite motion of revolution and rotation can reduce mixing dead corners, and the shearing effect on materials is mild, suitable for kneading thermosensitive flame retardants (such as organic phosphorus flame retardants).

5、 Combined Agitation

structural characteristics

Multi component collaboration: for example, the combination design of "screw+blade" and "plow blade+planetary blade", combining the advantages of different mixing methods.

Adjustable parameters: Some devices can adjust the speed of different mixing components through frequency conversion control to meet multi-stage process requirements.

Applicable scenarios

Suitable for complex flame retardant systems (such as multi-component compounding, solid-liquid mixing), or kneading processes that require multiple process steps such as dispersion, plasticization, and degassing simultaneously.

Advantages: Multi functional integration, flexible switching of mixing modes according to material status, improving production efficiency.

Comparison and summary of different mixing methods

Mixing method

Shear strength

Mixing efficiency

Applicable material viscosity

Typical application scenarios

Preliminary mixing of medium to low viscosity powder and resin in blade type (∑/Z type)

Screw type medium, high, medium, high viscosity, high filling flame retardant rubber, thermosetting resin system

Plowing blade type high, medium, low viscosity solid flame retardant powder for rapid dispersion

Planetary style low, medium, high viscosity paste, heat sensitive flame retardant kneaded

Combination adjustable (medium to high) high and wide range multi-component compound, integrated production of complex processes

Key factors in choosing mixing method

Material characteristics: viscosity, particle size, thermal sensitivity, filling amount, etc. (such as screw type for high filling materials and planetary type for thermal sensitive materials).

Process requirements: dispersion, mixing time, whether heating/cooling is required (such as plow blade type suitable for rapid dispersion, combination type suitable for multi-stage process).

Production scale: Small experimental equipment commonly uses blade or planetary type, while large-scale industrial production often uses screw or combination type.

By selecting a reasonable mixing method, it is possible to ensure uniform mixing of flame retardants and matrix materials, thereby improving the performance stability of flame retardant products.