Abstract:

MQ silicone resin is the copolymerization product of tetraalkoxysilane （Q unit） and trimethylethoxysilane （M unit）. It has a special double-layer tightly cross-linked spherical network structure, which not only has excellent water resistance, thermal stability and compatibility, but also is long-lasting, safe and non-irritating. So it has become one of the indispensable film-forming ingredients in cosmetic formulations. Therefore, it is vital to evaluate and screen the MQ silicone resin for improving the efficiency of formulation development. The molecular structure and film morphology of 21 MQ silicone resins were analyzed by GPC, microscopy and air permeability analyzer. According to the results, the relationship between the molecular structure of MQ and its application properties, such as film forming time, film brittleness, air permeability, water resistance, sweat resistance and oil resistance, were explored. The results show that the properties or performance of MQ silicone resin are depended on the size and distribution of its molecular weight. For the MQ-type silicone resin filmogen with higher molecular weight and narrower distribution, its film properties of hardness, water resistance and sweat resistance are enhanced with the increase of molecular weight, but its air permeability is subsequently weakened and film forming time is shorter. When the molecular weight decreases and the polymer dispersity index is almost unchanged or broadened, the MQ silicone resin show softer film, better oil resistance, longer film-forming time and higher air permeability.

Key words: MQ silicone resin, film-former, molecular weight