Super dispersant, also known as super dispersant, is a special type of surfactant with a molecular structure containing two groups that are opposite in solubility and polarity, one of which is a shorter polar group called hydrophilic group. Its molecular structure characteristics make it easy to orient and arrange on the surface of a substance or at the interface between two phases, reducing interfacial tension and having a good dispersion effect on aqueous dispersion systems. What are the types of hyperdispersants? According to the unit structure of solvent chains, hyperdispersants can be roughly divided into the following four types.
1. Polyester type super dispersant
The solvation chain is generally prepared by hydroxy acid condensation or ring opening reaction of lactone compounds, and its end group type and molecular weight can be controlled by adding unit carboxylic acids or unit alcohols. Hydroxy acids and lactones that are easily obtainable in industry and suitable for the above polymerization reactions are very rare, and only 12 hydroxystearic acid and its derivatives are more practicalΕ - There are two types of lactones. In the polymerization process of hydroxy acids and lactones, fatty acids or resins can be used as end capping agents to obtain carboxyl terminated polyesters. This polyester can be directly used as a super dispersant in certain situations (such as for dispersing metal oxide powders in aromatic solvents), or it can be linked to anchoring groups through certain chemical reactions. For example, carboxyl terminated polyesters can react with polyamines and alcohol amine substances to form one C-NH or one C-0— A super dispersant with bridging groups and amine anchoring groups. This super dispersant can also react with mineral acids, organic carboxylic acids, and pigment sulfonated derivatives to convert anchoring groups into amine salts. It can also react with alkylating reagents such as dimethyl sulfate and diethyl sulfate to convert the anchoring group into quaternary ammonium salts. Examples of suitable polyamine or alcohol amine substances include polyethylene polyamine, N, N-dimethylaminopropylamine, octadecylpropylamine, diethylethanolamine, etc.
2. Polyether type super dispersant
The solvation chain mainly consists of homopolymers and copolymers of substances such as ethylene oxide, propylene oxide, tetrahydrofuran, etc., including copolymers of ethylene oxide and propylene oxide. The synthesis of such hyperdispersants can be initiated by anchoring groups and prepared through ring opening reactions of cyclic ether substances under conditions of heating, pressure, and catalyst presence. For example, when using diethylethanolamine as a starting agent, the following structured super dispersants have excellent dispersion effects on inorganic pigments in strongly polar media such as alcohols and ethers.
3. Polyacrylate type super dispersant
The selection range of acrylic monomers is very wide, and the polarity and solubility parameters of their solvation chains can be easily adjusted by changing the feeding ratio of comonomers, making them widely applicable. In order to obtain solvent chains with single functional groups, thiol acids, thiol alcohols, and other substances are generally used as chain transfer agents. The relative molecular weight of solvation chains can be controlled by changing the dosage of initiators and chain transfer agents. The subsequent reaction process of the carboxyl or hydroxyl terminated polyacrylate obtained is identical to that of the polyester solvent chain.
4. Polyolefin super dispersant
Terminal polyisobutene is its most important representative. This type of super dispersant has excellent dispersion effect in hydrocarbon media, sometimes making the volume fraction of solid particles in the dispersion system reach over 65%, while the dispersion still maintains a moderate operating viscosity.
