What are the factors affecting the emulsification result of a vacuum emulsifying machine?

According to Jinzong Enterprise, which has over 20 years of experience in the production and R&D of emulsification equipment, the factors affecting the emulsification results of a vacuum emulsifier are as follows:

1. Type of Emulsifier Head (Batch-type vs. Continuous) (Continuous type generally performs better than batch type)

2. Shear Rate of the Emulsifier Head (Higher rates typically yield better results)

3. Tooth Structure of the Emulsifier Head (Categorized as coarse, medium, fine, and ultra-fine teeth; finer teeth generally provide better results)

4. Residence Time of Materials in the Dispersion Zone / Emulsification & Dispersion Time (For the same motor power, a smaller flow rate/ longer residence time often leads to better results)

5. Number of Circulation Cycles in the Vacuum Emulsifier (More cycles improve results up to a point determined by the equipment's design limits)

Temperature of the Vacuum Emulsifier
Temperature significantly impacts emulsification quality, though it is not strictly limited. When both oil and water phases are liquid, emulsification can often be achieved at room temperature with agitation. Generally, the emulsification temperature depends on the melting points of high-melting-point substances in both phases, as well as factors like the type of emulsifier and the solubility of the oil and water phases. Furthermore, the temperatures of the two phases should be kept similar. Especially when emulsifying oil phases containing high-melting-point (above 70°C) waxes or fats, a cold water phase should not be added, as this can cause the wax/fat to crystallize prematurely, resulting in a lumpy or coarse emulsion. Typically, for emulsification, both oil and water phases can be controlled between 75°C and 85°C. If the oil phase contains high-melting-point components like wax, a higher emulsification temperature is required.

If the viscosity increases substantially during emulsification, hindering搅拌 (agitation/stirring), the emulsification temperature can be appropriately increased. If the emulsifier used has a specific phase inversion temperature, the emulsification temperature should be chosen around that point. Emulsification temperature also sometimes affects the particle size of the emulsion. For instance, when using fatty acid soap anionic emulsifiers with the in-situ soap method, emulsifying at 80°C yields a particle size of about 1.8–2.0 µm, while emulsifying at 60°C yields about 6 µm. For non-ionic emulsifiers, the influence of temperature on particle size is weaker.

Emulsification Time in Vacuum Emulsifier
Emulsification time obviously affects emulsion quality. Determining the optimal time depends on the oil-to-water phase volume ratio, the viscosity of both phases and the resulting emulsion, the type and amount of emulsifier, and the emulsification temperature. The purpose of emulsification time is to allow the system to emulsify fully, and it is closely related to the efficiency of the emulsification equipment. It can be determined based on experience and experimentation. For example, using a homogenizer (3000 rpm) may require only 3–10 minutes.

Agitation/Speed in Vacuum Emulsifier
The emulsification equipment itself greatly impacts the process, one aspect being the influence of agitation speed. Moderate agitation speed is necessary to fully mix the oil and water phases. Speed that is too low will not achieve sufficient mixing, while speed that is too high can introduce air into the system, creating a three-phase system (air, oil, water) and destabilizing the emulsion. Therefore, air incorporation must be avoided during agitation, which is a key advantage of vacuum emulsifiers.

Selection of Emulsifier for Vacuum Emulsifier

(1) Choose an emulsifier whose hydrophobic group is similar to the substance being emulsified.
(2) Consider using a blend of several emulsifiers.
(3) Prefer emulsifiers that are easily soluble.
(4) Consider blending a more hydrophilic emulsifier with a more lipophilic (hydrophobic) one.
(5) Use composite emulsifiers from the same hydrophobic base material but with different hydrophilicities (a homologous series).
(6) For preparing O/W (oil-in-water) emulsions, use a water-soluble emulsifier as the primary one, with the amounts of other emulsifiers decreasing multiplicatively on either side of this primary emulsifier according to their HLB values.
(7) The HLB value of the composite emulsifier blend should roughly match that of the oily substance being emulsified.