Coating dispersant classification – Paraffin wax

2021-09-23   Pageview:289

Although paraffin wax is an external lubricant, it is a non-polar straight chain hydrocarbon and cannot wet the metal surface, that is to say, it cannot prevent resins such as PVC from adhering to the metal wall, only when used with stearic acid, calcium stearate, etc., it can play a synergistic effect.

Liquid paraffin wax: solidifying point -15–35℃, it is less compatible with resin in extrusion and injection molding processing, and the amount of addition is generally 0.3%-0.5%, but when it is too much, the processing performance becomes bad.

Microcrystalline paraffin wax: obtained from petroleum refining process, its relative molecular mass is large and has many isomers, melting point 65-90℃, good lubricity and thermal stability, but poor dispersion, the amount is generally 0.1%-0.2%, best used with butyl stearate and advanced fatty acids.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

According to the application effect, this type of dispersant can be divided into deflocculation type and control flocculation type. The deflocculation wetting and dispersing agent can rely on the polar adsorption base to strongly adsorb on the surface of the pigment. If it is electrically neutral , Because the adsorption group is in the middle, most of them will have two extended chains. In the case of anionic and cationic dispersants, one end is a polar adsorption group, and the other end extends into the base material dispersion medium. These stretched segments produce steric hindrance and stabilize the dispersion of pigments. This type of dispersant is generally recommended to be used in topcoats, which can reduce the viscosity of the coating, improve the fluidity of the coating, and increase the gloss of the coating film.

The control flocculation type wetting and dispersing agent connects several dispersed pigment particles together through the bridging effect of the wetting and dispersing agent to form a floc. The pigment particles and the resin base material still maintain a good wetting state . This kind of control flocculation will make the paint produce a weak structural viscosity, which will have a slight impact on the gloss and flow of the paint, but it can play a role in preventing settling, preventing floating color and blooming and preventing sagging. Controlled flocculation is completely different from the self-flocculation of pigment particles due to poor wetting and dispersion. The flocculation of the particles themselves will make the coating dispersion in an unstable state, causing undesirable phenomena such as floating color, blooming, and sedimentation. At the same time, basf pe wax it will also have a serious impact on hiding power, tinting power, and gloss.

Wetting and dispersing agents that control flocculation generally have three adsorption groups. There are two adsorbed on the pigment particles, and the remaining one is connected with one of the free wetting and dispersing agent in the base material. The remaining two adsorbing groups of the free wetting and dispersing agent are then connected with the other two The pigment particles with dispersant are connected to form a unit floc. The particles are connected by the auxiliary agent bridge, and they are not connected together. The particles are in a state of wetting and dispersing.

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