Classification of common preservatives

2021-09-25   Pageview:820

There is a wide variety of preservatives on the market. In terms of their active components, they can be divided into the following categories: isothiazolinones, formaldehyde release, benzimidazoles, substituted aromatics, organic bromines, organic amines, perphenazines, etc.











Although the leveling of group B is better, but there is stratification after storage, why?
Analysis: The Stormer viscosity (KU) of the two groups A and B are the same. The Brinell 60r/min is within the Stormer viscosity range, but the viscosity is very different from the 6r/min viscosity. This is the role of TI as a storage stability control parameter.

The relationship between syneresis and rheology
The higher the proportion of free water in the coating, the better the leveling effect, but the worse the sag resistance. The stratification can be controlled by the water retention effect of inorganic substances, but the leveling becomes worse. After the associative thickener has established a reliable associative network, it must also be able to hold the entire amount of free water. Because the association is unstable, or the pseudo-thickness formed by the repulsive force of the strong hydrophobic surfactant and water, or the excessive amount of water in the system, the hydration will be destroyed and the water will be separated from the network system.

Associative system experiment: In a stable associative system, use hydrophobically modified multi-element copolymer dispersant, H-34 and polyether associative rheology modifier DSX-2000 to prepare two coatings with 45% PVC , But the non-volatile volume (NV V) is 35% and 45%, ptfe powder hs code respectively.

Just because of the high water content, there will be syneresis and stratification after thermal storage. It is generally believed that delamination cannot be controlled without the use of hydrated thickeners. However, in medium and low PVC paints, due to the high amount of emulsion, a large amount of water is contained in the emulsion, which limits the use of HEC and other hydrated thickeners. use. At this time, the use of associative thickener alone can also achieve no delamination.


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