The thickening mechanism of alkali swelling thickeners is commonly used in water-based coatings

Original: The thickening mechanism of alkali swelling thickeners commonly used in water-based coatings

The application of alkali swelling thickeners in the field of water-based coatings is different from other types of thickeners, in addition to the influence of the traditional concept of formulation dosage, the degree to which the thickener is neutralized by alkaline substances is one

At present, most of the water-based coatings are inseparable from thickeners, which are also called rheological additives (because some of the thickeners have both rheological characteristics), and the types of water-based thickeners are also relatively rich, among which alkali swelling thickeners are one of the thickeners often selected in the industry

Thickening principle:

The thickening mechanism of alkali swelling thickener is as follows: after adding alkaline neutralizers (commonly used with ammonia or glycol amines) with the increase of neutralization, a large number of carboxyl groups on the polymer chain are neutralized into salts by alkali, electrostatic repulsion and hydration are generated within the molecule, the macromolecular structure is gradually extended by the curled state, a large number of surrounding water molecules are adsorbed, and the viscosity of

At the same time, in the main structure of the acrylate as the main chain, because the introduction of reactive associative monomers with surface activity participates in copolymerization, the side chain is grafted to a long chain having a surface-active structure, in this long chain structure there are both hydrophobic groups and hydrophilic groups, so it also has a surface activity

They can form a large micellar structure in water, which adsorbs and dissolves each other within or between molecules

Summary:

Water-based coatings are commonly used alkali swelling thickener for thickening, its biggest feature is that its thickening efficiency needs to react with alkaline substances (such as amines) to work, in other words, alkali swelling thickener is a class of rheological additives with reactivity, which is the biggest feature that distinguishes it from other types of thickeners such as cellulose and silicate.

Because of its strong acidity and reactivity with alkali neutralizers, the use process is generally not recommended to directly mix with the emulsion, previous experimental experience shows that the direct use of ASE or HASE will lead to a strong reaction to the system of rapid gel or flocculation or even destroy the uniformity

The degree of neutralization of alkali swelling thickeners and amines directly affects the final rheological properties of the coating system, including viscosity, yield value, thixotropy, etc

Source of the article: The article is from "China Federal Thickener", please indicate the source when

Responsible Editor: