” >The so-called Thickener, as the name suggests, is to increase the viscosity of the system so that the system can remain stable during production, transportation, storage, and construction. An additive of suitable viscosity. Inorganic thickeners in water-based systems are mainly clays. Such as: bentonite. Kaolin, diatomaceous earth (the main component is SiO2, which has a porous structure) because It has a certain degree of suspension and is sometimes used as an auxiliary thickener in the thickening system. Bentonite clay has a high water swelling capacity and is therefore more commonly used.
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” >Bentonite（Bentonite ), also known as bentonite, bentonite, etc. The main mineral of bentonite is montmorillonite, a hydrated aluminum silicate mineral containing a small amount of alkali and alkaline earth metals. It belongs to the aluminum silicate family, and its general chemical formula is: (Na ,Ca)(Al,Mg)6(Si4O10)3(OH)6•nH2O. The swelling performance of bentonite is expressed by swelling capacity, that is, the volume of bentonite after swelling in dilute hydrochloric acid solution is called swelling volume, expressed in milliliters/gram of sample. After the bentonite thickener absorbs water and swells, the volume can reach several or more than ten times that before absorbing water, so it has good suspension properties. And because it is a powder with a fine particle size, it is compatible with other powders in the coating system. The body has good miscibility. In addition, while generating suspension, it can drive other powders to produce a certain anti-stratification effect, so it is very helpful to improve the storage stability of the system.
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” >But many sodium bentonite contains calcium Base bentonite is transformed from sodium. During sodiumification, a large amount of positive ions such as calcium ions and sodium ions will be produced. If the content of these cations in the system is too high, a large amount of charge neutralization will be generated on the negative charge on the emulsion surface, so to a certain extent, It may cause side effects such as swelling and flocculation of the emulsion. On the other hand, these calcium ions will also have side effects on sodium salt dispersants (or polyphosphate dispersants), causing these dispersants to precipitate in the paint system, eventually leading to the loss of dispersion, causing the paint to become thicker, thicker, and even thicker. Severe sedimentation and flocculation may occur. In addition, the thickening effect of bentonite mainly relies on the water absorption and expansion of the powder to produce suspension, so it will bring a strong thixotropic effect to the coating system, which is very detrimental to coatings that require good leveling effects.
” >Therefore, bentonite inorganic thickeners are generally rarely used in latex paints, and only a small amount is used in low-grade latex paints or brushed latex paints. As a thickening agent. However, in recent years, data has shown that Hemmings’ BENTONE® LT. organically modified and refined hectorite has better anti-sedimentation and atomization effects when used in latex paint airless spray systems.
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