How to choose dispersants for coatings and inks in epoxy resin systems? This dispersant should not only reduce the viscosity of the system, but also not react with epoxy resin and curing agent.
Simultaneously, it should meet the requirements of reducing viscosity, dispersion, non reactivity, and stable storage.
1、 Prohibited types:
(1) If it is a dispersant of polyacrylate type, containing - C00H will react with the amine curing agent acid-base, resulting in thickening and flocculation of the system.
(2) If it is a polyamide/polyether amine dispersant containing - NH ₂/- NHR, it will directly react with the epoxy group, resulting in the scrapping of the gel.
(3) If it is a dispersant containing carboxyl/thiol groups, it will cause thickening during storage due to the ring opening reaction between active hydrogen and epoxy.
2、 Recommended types and representatives:
(1) Phosphate ester type dispersants, which do not react with epoxy/amine, have good viscosity reducing and dispersing properties for inorganic pigments and fillers, as well as anti settling and anti floating effects. Recommended dispersants are HR-4013 and HR-4012.
(2) Modified polyester and polyester type dispersants have extremely low amine values and are compatible with both inorganic and organic pigments. They have good compatibility with various resin systems and do not react with epoxy curing agents. They have good dispersibility and viscosity reduction, good wetting properties, anti settling and anti floating properties, and stable storage. The recommended dispersant is HR-4033; HR-4016C
(3) A dispersant of modified polyurethane type, which has a low amine value and is compatible with both inorganic and organic pigments. It has good compatibility with various resin systems and does not react with epoxy curing agents. It not only has good dispersion and viscosity reduction properties, but also has anti settling and anti floating properties. It has good storage stability and is recommended to use dispersants HR-4036 and HR-4031.
