Lignin is the second most abundant natural polymer with aromatic structure in nature and is an important renewable biological resource. The depletion of traditional mineral resources and the enhancement of human environmental awareness have brought strong impetus to the basic research and industrial utilization of lignin. Calcium lignosulphonate is a derivative of lignin. Its modification to prepare surfactants has developed rapidly in recent years and made a series of important progress. The modified products are widely used in industrial and agricultural production.
Calcium lignosulphonate is one of the lignin derivatives obtained in the pulp industry. Its molecular structure basically retained the structural characteristics of lignin, that is, phenylpropane unit structure and a large number of ether bond structure, and a large number of sulfonate groups were introduced into its side chain. Therefore, some intermolecular and intramolecular condensation of calcium lignosulphonate should occur when heated.
Although calcium lignosulphonate is a waste product produced in the paper making process, it still has the basic structure of lignin, and its sulfonate group makes it soluble in water. Calcium lignosulphonate contains a variety of chromophore groups, and its solid powder is yellowish brown and easy to wet and agglomerate.
Calcium lignosulphonate contains a large number of active groups, such as phenolic hydroxyl group, carbonyl group, sulfate group, alcohol hydroxyl group, etc. It can condense itself or react with other substances. Calcium lignosulphonate has different molecular weight and functional groups, and therefore has different degrees of dispersion, which can be adsorbed on the surface of a variety of solid particles.
Industrial lignin itself has the characteristics of polymers and some special properties, is mainly used for water treatment agents, concrete admixtures, dye dispersants and a variety of complexing agents, adhesives, etc., but the scope of application is still relatively limited.
Calcium lignosulphonate used as a dispersant in pesticide formulation processing, has the following advantages:
- First, it has good compatibility with all kinds of pesticide active ingredients.
- Second, no matter in the processing of pesticide solid preparation, or liquid preparation, it has good dispersion. Sometimes there is a certain wettability.
- Third, it can be completely biodegradable in nature, green environmental protection.
- Fourth, abundant resources and low prices.
- Fifth, in addition to having a good dispersion effect, there are anti-precipitation and protective colloid effects.
- Sixth, it can chelate with metal ions.
- Seventh, it can enhance the resistance of the suspension agent to hard water.
Its disadvantages compared with other dispersants:
- First, it is poor in reducing surface tension, wettability and permeability.
- Second, it has color, and cannot make white dosage form products.
- Third, calcium lignosulphonate products that have not been desugared are susceptible to moisture absorption.
As calcium lignosulphonate is a kind of anionic polymer dispersant, the molecular weight is large, it not only provides electrostatic repulsion, but also can provide steric hindrance, so that the dispersed particles do not aggregate or do not condense between suspended particles.
In the processing of pesticide dosage forms WP, SC and WG, it can provide very good dispersity and suspension ability. Therefore, it is widely used in pesticide powder, wettable powder, and can be mixed with other dispersants.
Calcium lignosulphonate can be used as a dispersant, emulsifier, wetting agent and so on. It can be used for industrial detergents, pesticides, insecticides, herbicides, fungicides, brick and refractory, concrete, cement, coke and charcoal processing, dyes and pigments, casting, gypsum products, granulation processing, petroleum, electroplating bath, tanning leather, wax emulsion and so on.