Silica For Matting Agent

Jinsha Precipitated Silica Manufacturing Co., Ltd. is one of the leading manufacturers and suppliers of silica for matting agent in China. With abundant experience, we warmly welcome you to buy high quality products made in China here from our factory. Contact us for more details.

                                                                              Silica for Matting Agent

Dispersion is the process of deagglomerating, wetting,evenly distributing and stabilizing pigment particles. Aswith all pigments and fillers, silica matting agents tend  to agglomerate during storage and shipment. Due to strong attraction and compaction forces, the individualparticles tend to form the smallest external surfacecausing agglomeration.Sufficient shear for dispersion can be achieved by the use of high speed stirring equipment e.g. a dissolver, and such equipment is to be recommended in all cases. Care should be taken to avoid temperatures above 50° C when using wax treated  products .To obtain good dispersion results, it is necessary that the liquid rotates in the container with a laminar flow. The right type of flow is achieved when the mill-base forms a vortex and the central portion of the blade is barely visible. This is called the doughnut effect.Under these conditions and using a tip speed of the blade(= peripheral speed) of 5 – 6 m/sec.,matting agents with our silica will be de-agglomerated and fully dispersed within 10 –15 minutes.Relatively high shear forces are developed during the dispersion process as a result of the rotational speed and the geometry/size of the dissolver blade. The relative dimensions of the dissolver blade, the container and the filling height, as well as the optimum viscosity of the mill-

base are of decisive importance for an effective dispersion.The peripheral speed of the blade depends on the rotation speed and the size of the blade and can be calculated using the following equation:

π • d • u = peripheral speed (m/sec)

        6000

π = 3.14

d = diameter of the blade in cm

u = rotation speed per minute (rpm)

The danger of destroying the matting agent particles through excessive shear forces during dispersion, called“overgrind“, is generally not a problem for these stable

micronized silica gels. Care must be taken when a milling process is used to incorporate the matting agent. Under excessive shear conditions overgrind can occur resulting in a loss of matting efficiency and an increase of viscosity.

Example: Rotation speed = 3000 rpm, Blade diameter = 4 cm

3.14 • 4 • 3000 = 6.28 m/sec peripheral speed

    6000

The state of dispersion (= fineness of grind) according to EN 21524 can be measured by using a grind gauge, e.g.a Hegman gauge. For every JK silica  product there is a  typical achievable Hegman value depending on the particle size distribution.

Our matting agents are easily dispersible and can be incorporated directly into the finished coatings

system at any stage of the manufacturing process. This enables the postcorrection of gloss in the ready-made paint system.

JS-280C

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