Method for preparing polyurethane dispersants

Abstract

The invention discloses a preparation method for polyurethane dispersant. At first, anchorage group A is composed under lower temperature. The anchorage group is constituted by polyisocyanate and diol or amine or phenol. Polyurethane pre-polymer with two segments of isocyanate root block is composed. Then water polymer root block is used. Two ends of the water polymer are active hydroxyl groups or on two ends of the water polymer there are active hydroxyl groups. Under higher temperature and catalyst condition, polyurethane dispersant with BAB segment-embedded type is composed. The polyurethane dispersant can wet grain quickly and fully. Grinding time for achieving qualified grain fineness is shortened. The content of solid grain in grinding material can be improved greatly. Processing equipment and energy consumption can be saved. Dispersion is uniform and stability is good. The final using performance of dispersion system is improved obviously.

Description

A kind of preparation method of polyurethane dispersant 【Technical field】 The present invention relates to a polymeric dispersant for hydrophobic particles comprising pigment particles in an aqueous system, more particularly, the present invention relates to an aqueous polyurethane dispersant capable of forming a stable dispersion with good dispersibility for hydrophobic pigment particles method of preparation. 【Background technique】 In order to uniformly disperse solid particles such as pigments in the water-based system, high-strength mechanical shear force must be applied, and these pigment particles tend to aggregate in the water-based system after dispersion. In order to easily disperse and form a stable dispersion system, a dispersant is usually added to the system, which mostly involves anionic or cationic or nonionic surfactants. The dispersant can prevent the aggregation and precipitation of pigment particles, help to crush the hydrophobic particles into small s...

AI Technical Summary

Problems solved by technology

The molecular structure of traditional dispersants (surfactants) contains two dissolving and polar opposite groups, one of which is a longer non-polar hydrocarbon group called hydrophobic group or lipophilic group; One is a short polar group, called hydrophilic group, whose molecular structure makes it easy to align on the surface of the material or the two-phase interface, reducing interfacial tension, and has a good dispersion effect on water-based dispersion systems, but The limitations of its molecular structure: (1) the combination of hydrophilic groups on the surface of particles with low polarity or non-polarity is not firm, and it is easy to desorb and cause the re-flocculation of dispersed particles; (2) the lipophilic groups do not With sufficient carbon chain length (generally no more than 18 carbon atoms), it cannot produce enough steric hindrance effect in the aqueous dispersion system to play a stabilizing role. In order to overcome the limitations of traditional dispersants in the aqueous dispersion system, foreign Since the 1970s, a new type of polymer dispersant has been developed, which has a unique dispersion effect on aqueous systems

The use of polyelectrolyte dispersants will introduce ions into the water-based system, and the polyelectrolyte dispersant itself can be fully dissolved at a pH of 8 to 9. This sensitivity to pH brings unstable factors to the system

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