Factors influencing emulsification / homogenization effect in practical experiments

There are three types of emulsifying machine: emulsifying mixer, colloid mill and homogenizer The type, structure and performance of the emulsifying machine are closely related to the size (dispersibility) of the particles and the quality (stability) of the emulsion Generally, as is now widely used in the cosmetics factory, the emulsion made by the agitator has poor dispersion The particles are large and rough, with poor stability and easy to produce pollution However, its manufacture is simple and its price is cheap As long as we pay attention to the reasonable structure of the machine and use it properly, it can also produce popular cosmetics with general composite quality requirements Colloid mill and homogenizer are better emulsification equipment In recent years, emulsification machinery has made great progress, such as the dispersion and stability of emulsion prepared by vacuum emulsification machine Griffin has carried out experimental research on the relationship between different types of emulsions and the size distribution of emulsion particles The results are shown in the table below Emulsification equipment and particle size distribution relationship emulsification machine type particle size range (microns) 1% emulsifier 5% emulsifier 10% emulsifier push agitator turbine agitator colloid mill homogenizer no emulsification 2-96-91-33-82-44-71-32-52-43-51-32, temperature Emulsification temperature has a great influence on emulsification, but there is no strict limit on temperature For example, if oil and water are all liquid, emulsification can be achieved by mixing at room temperature Generally, the emulsification temperature depends on the melting point of the high melting point substance contained in the two phases In addition, factors such as the type of emulsifier and the solubility of oil phase and water phase should be considered In addition, the temperature of the two phases should be kept nearly the same, especially for the wax and lipid phase components with high melting point (above 70 ℃), when emulsifying, the low-temperature water phase should not be added to prevent the wax and lipid from crystallizing out before emulsifying, resulting in massive or rough uneven emulsion Generally speaking, when emulsifying, the temperature of oil and water can be controlled between 75 ℃ - 85 ℃ If the oil phase has high melting point wax and other components, the emulsification temperature will be higher at this time In addition, in the process of emulsification, if the viscosity increases greatly, so-called too thick and affects the mixing, some emulsification temperature can be increased appropriately If the emulsifier used has a certain phase transition temperature, the emulsification temperature is also good to choose around the phase transition temperature The emulsification temperature also affects the particle size of emulsion sometimes If the anionic emulsifier of fatty acid soap is generally used, the size of the particles in the emulsion is about 1.8-2.0 μ m when the emulsification temperature is controlled at 80 ℃, and if the emulsification is conducted at 60 ℃, the size of the particles is about 6 μ M When nonionic emulsifier is used for emulsification, the influence of emulsification temperature on particle size is weak 3 Emulsification time Emulsification time obviously affects the quality of emulsion The determination of emulsification time is based on the volume ratio of oil phase to water phase, the viscosity of two phases, the viscosity of generated emulsion, the type and amount of emulsifier, and emulsification temperature However, the amount of emulsification time is closely related to the efficiency of emulsification equipment to make the system fully emulsified It can be determined according to experience and experiment To determine the emulsification time If the homogenizer (3000 rpm) is used for emulsification, it only needs 3-10 minutes 4 Mixing speed emulsification equipment has a great influence on emulsification, one of which is the influence of mixing speed on emulsification Moderate mixing speed is to make the oil phase and water phase fully mixed The mixing speed is too low to achieve the purpose of full mixing obviously However, if the mixing speed is too high, bubbles will be brought into the system, making it a three-phase system, and making the emulsion unstable Therefore, air must be avoided in the mixing process, and the vacuum emulsifier has excellent performance.