Synthesis Of Polyether Side Chain Combed Polycarboxylate Dispersant And Its Application

Pesticide suspensions have developed rapidly in China in recent years,because of their good efficacy,safe production and low environmental pollution.But pesticide suspensions belong to thermodynamics unstable system,which may lead to demulsification,stratification,precipitation,flocculation and so on,which will affect the storage,sale and use of pesticides.So we need to add dispersant to make the water suspension of pesticide more stable.Polycarboxylate dispersant is a new type of high efficient agricultural dispersant with long carbon chain and many adsorption sites.Branched chain groups such as carboxyl,sulfonic acid,amino,and polyoxyethylene side chains can play a spatial repulsive role,so its special structure has good dispersion performance for suspension system.Compared with the traditional lignin sulfonate,naphthalene sulfonate formaldehyde condensate sodium salt dispersant,the dispersion stability of polycarboxylate dispersant is higher,and it is not easy to be affected by ions,p H and temperature in suspension system.Secondly,the polycarboxylate dispersant can adsorb on the surface of the raw drug particle,so that the raw drug particle has good spreading property on the plant leaf surface,so that the maximum drug effect is achieved.The comb-type polycarboxylate dispersant,because of its comb structure has independent adsorption,can form multi-point adsorption at the interface of the original medicine,and the hydrophobic groups of the appropriate length of high molecular carbon chain extend into the water around the particles.The stability of dispersant system can be improved by the effect of stereoscopic barrier.The results show that the side chain polycarboxylate containing polyether has good dispersibility.When the polycarboxylic acid polymer is added to the water suspension of pesticide,the hydrophobic chain is adsorbed on the surface of the pesticide particle,and the carboxyl group enhances the electrostatic repulsion between the pesticide particles.Oxygen on the side chain of polyoxyethylene forms hydrogen bonds with water molecules,thus forming hydrophilic stereoscopic membranes,which results in wetting and adsorption at the solid-liquid interface,thus dispersing the system.In this study,three monomers of methacrylic acid,allyl polyoxyethylene ether and n-butyl acrylate were studied.The monomer ratio was 4:1:1.When the reaction temperature is 90 ? and the amount of initiator is 6,the comb polycarboxylate dispersant containing side chain of polyether and hydrophobic ester group is obtained by solution polymerization.The synthetic dispersant contains carboxyl groups to enhance the electrostatic repulsion between the pesticide particles,and the ether bond energy forms a hydrogen bond with water to form a hydrophilic solid film,which improves the dispersion of the dispersant.The structure of the polymer dispersant was determined as the desired target polymer by IR and NMR analysis.The surface tension,hlb and other properties of the dispersant were determined.The comb-type polycarboxylate dispersant was applied to the imidacloprid water suspension of 600g/l.The effects of dispersant on the zeta potential,viscosity,suspension rate,thermal storage stability and rheological properties of the water suspension were determined.It was found that dispersant DJ-C had better stability to 600g/l imidacloprid,and could solve the problems of high concentration imidacloprid water suspension,such as stratification,precipitation,flocculation,paste and so on.The optimum formulation of 600g/L imidacloprid water suspension was as follows: imidacloprid 50%,dispersant DJ-C6%,dispersant sd-518 x 2%,wetting agent SR-08 %,thickener xanthan 4%,silicone defoamer 1%,Deionized water supplements.The properties of the prepared aqueous suspensions are stable and the thermal storage stability meets the requirements of the suspensions.