Reactor vs Sigma Mixer

Resin Types Used in Reactor

Applicable conditions:

Low viscosity (≤100,000cps)
Solvent-based system or low-solids reaction
Controllable exotherm and uniform temperature are sufficient.

Common Resin Types

Resin types	Main equipment	Reason
Alkyd resin	Jacketed reactor (with condensation and dehydration devices)	The system contains a solvent, has good fluidity, and requires a continuous dehydration reaction
Acrylic resin	Stirred reactor	The reaction temperature is controllable, the viscosity is low, and solution polymerization or emulsion polymerization is often used
Epoxy resin	Jacketed reactor	The viscosity is moderate, requiring temperature control and vacuum degassing
Unsaturated polyester resin (UPR)	Electrically heated or thermal oil heated reactor	Medium-to-low viscosity systems require stable temperature control to avoid side reactions
Urea-formaldehyde / Melamine resin (UF/MF)	Stainless steel reactor	Aqueous systems with low viscosity require precise pH and temperature control

**For resins with low viscosity, which require continuous heat exchange and precise temperature control, reactor is more suitable.

reactor

Resin Types Used in Sigma Mixer

Applicable conditions:

High viscosity systems (≥100,000cps)
Mid- to late-stage reaction materials are paste-like or semi-solid
Vacuum dehydration, desolventization, and dealcoholization are required
Solventless, high-solids or modified systems

Common Resin Types

Resin types	Main equipment	Reason
Silicone resin	Sigma mixer	The late-stage viscosity is extremely high, requiring vacuum dealcoholization during polycondensation
Phenolic resin	Sigma mixer / reactor	Particularly for solid, powdered, or modified phenolic forms, strong shear mixing is required
Epoxy-modified resin	Double planetary mixer / sigma mixer	High viscosity and high filler content make traditional reactors difficult to stir
Polymide precursor	Sigma mixer	High-temperature polycondensation systems have extremely high viscosity, requiring a closed reaction system
Solvent-free polyurethane	Sigma mixer / double planetary mixer	The reaction is rapidly exothermic, resulting in high viscosity and requiring high shear dispersion
Solid epoxy resin	Sigma mixer	After cooling, the product solidifies into agglomerates, resulting in high viscosity and slow heat transfer

**Sigma mixer is most suitable for resins with high viscosity, difficult to stir in the late reaction stage, requiring vacuum concentration or high shear.

sigma mixer

Some resins can be used in "reactor + sigma mixer" combination.

Some resins (such as silicone resin, phenolic resin and epoxy-modified resin) are produced using a two-stage process:

Front-end reaction (low-viscosity stage) → initial polycondensation in the reactor.
Mid- and late-stage (high-viscosity stage) → transfer to sigma mixer for further reaction and concentration.

This ensures a thorough reaction while avoiding the problem of the reactor becoming unstirable.

If you want to set up resin production line, feel free to chat with us: +86-181 3837 3963 (Whatsapp, Wechat) or george820606@gmail.com.