How much do you know about the emulsification process in cosmetic production?

Compared to general fine chemicals, the production process for cosmetics is relatively simple. The main production process involved is emulsification. Let's follow Jinzong Enterprise's editor to understand what emulsification is, what methods of emulsification exist, and what factors affect emulsification.

Emulsification is a phenomenon in which one liquid is uniformly dispersed in the form of extremely fine droplets into another immiscible liquid. Emulsification is a liquid-liquid interface phenomenon. Two immiscible liquids, such as oil and water, separate into two layers in a container, with the less dense oil on top and the denser water below. If an appropriate surfactant is added under vigorous stirring, the oil is dispersed in the water, forming an emulsion. This process is called emulsification.

Methods for preparing emulsions, in addition to the nascent soap method, the agent-in-water method, and the agent-in-oil method, also include the oil-water mixing method, phase inversion emulsification method, and LEE (also known as low-energy emulsification).

Influencing factors:

1. Emulsification equipment
   The mechanical equipment used to prepare emulsions is mainly the emulsifier, which is a device that uniformly mixes the oil and water phases. There are three main types of emulsifiers: emulsifying stirrers, colloid mills, and homogenizers. The type, structure, and performance of the emulsifier are closely related to the size of the emulsion particles (dispersity) and the quality of the emulsion (stability).

2. Temperature
   Emulsification temperature has a significant impact on the quality of emulsification, but there are no strict temperature limits. If both the oil and water are liquids, emulsification can be achieved through stirring at room temperature. Generally, the emulsification temperature depends on the melting point of the high-melting-point substances in the two phases, as well as factors such as the type of emulsifier and the solubility of the oil and water phases. Additionally, the temperatures of the two phases need to be kept nearly the same, especially when emulsifying oil-phase components containing high-melting-point (above 70°C) waxes and fats. The low-temperature water phase should not be added to prevent the crystallization of waxes and fats before emulsification, which could result in a lumpy or coarse, uneven emulsion.

3. Emulsification time
   Emulsification time clearly affects the quality of the emulsion. The determination of emulsification time depends on the volume ratio of the oil phase to the water phase, the viscosity of the two phases and the resulting emulsion, the type and amount of emulsifier used, and the emulsification temperature. However, the purpose of emulsification time is to ensure sufficient emulsification of the system, which is closely related to the efficiency of the emulsification equipment. Emulsification time can be determined based on experience and experimentation.

4. Stirring speed
   Emulsification equipment has a significant impact on emulsification, and one of these impacts is the effect of stirring speed. A moderate stirring speed is necessary to fully mix the oil and water phases. If the stirring speed is too low, it will not achieve thorough mixing. However, if the stirring speed is too high, air bubbles may be introduced into the system, turning it into a three-phase system and making the emulsion unstable. Therefore, the entry of air must be avoided during stirring. Vacuum emulsifiers offer excellent performance in this regard.