What is HLB?

Emulsifier is a kind of substance that can make the mixed liquid of two or more immiscible components form a stable emulsion. Its principle is that the dispersed phase is dispersed in the continuous phase in the form of micro droplets (micron level) during the emulsification process. The emulsifier reduces the interfacial tension of each component in the mixed system, and forms a relatively strong film on the surface of the droplet or a double electric layer on the surface of the droplet due to the charge given by the emulsifier, which prevents the droplets from aggregating with each other and maintains a uniform emulsion. From the point of view of phase, the emulsion is still a heterogeneous system. The dispersed phase in the emulsion can be either water phase or oil phase, most of which are oil phase; The continuous phase can be either oil phase or water phase, most of which are water phase. Emulsifier is a kind of surfactant with hydrophilic and lipophilic groups in its molecule. In order to express the hydrophilicity or lipophilicity of emulsifier, "hydrophile lipophilic balance value (HLB value)" is usually used. The lower the HLB value, the stronger the lipophilicity; On the contrary, the higher the HLB value, the stronger its hydrophilicity. 

HLB value, the full name of Hydrophilic Lipophilic Balance, also known as water oil degree, is a measure of the balance between hydrophilic and lipophilic groups in surfactant molecules, that is, HLB=hydrophilicity of hydrophilic groups/lipophilicity of lipophilic groups.

In 1949, Griffin took the lead in proposing the concept of HLB value, and set the range of HLB value of non-ionic surfactant as 0-20, the HLB value of paraffin wax with the largest hydrophobicity and composed entirely of saturated alkane group as 0, the HLB value of polyoxyethylene with the largest hydrophilicity and composed entirely of hydrophilic oxyvinyl group as 20, and the HLB value of other surfactants as 0-20. The larger the HLB value is, the stronger its hydrophilicity is. The smaller the HLB value is, the stronger its lipophilicity is. With the advent of new surfactants, more hydrophilic varieties have been applied in practice, such as the HLB value of sodium lauryl sulfate is 40.

The HLB value of surfactant is closely related to its application:

Surfactants with HLB values of 3-6 are suitable for W/O emulsifiers;

Surfactants with HLB values of 8~18 are suitable for use as O/W emulsifiers;

HLB value as solubilizer is 13~18;

HLB value as wetting agent is 7~9;

HLB value as detergent is 13~16;

HLB value comparison table of non-ionic surfactant of jiahua：