2021-07-18 Pageview：993
Micronized wax is widely used in paints and inks with its excellent performance to improve its surface scratch resistance, abrasion resistance, slip and feel; to improve anti-adhesive and anti-fouling properties, to prevent pigment sinking, to produce high-performance matte paint with matte powder, etc. It has become an indispensable and important additive in the production of paints and inks.
1, Introduction of micronized wax
Micronized wax is ultra-fine powder with particle size range from 2 to 30 μm and wide molecular weight distribution from 600 to 6000, which is widely used.
There are mainly Fischer-Tropsch wax, polyethylene wax, polypropylene wax, ptfe wax and their modified waxes.
(1) Fe-to wax: is made of gas (CO + H2) as raw material, using Ficher2Tropsch process polymerization into unbranched linear molecular weight of 500 ~ 1000g/mol) of hard paraffin wax. It has low melting point, excellent smoothness and improved handfeel. Economical and practical.
(2) Polyethylene wax: It has excellent anti-friction, anti-scratch, anti-adhesive and light retention properties, and has a wide range of application. Compared with FETO wax, it has more branched chain structure and better abrasion resistance.
(3) polypropylene wax: compared with polyethylene wax, it has higher softening point and hardness, outstanding anti-adhesive property, good effect of improving anti-metal scratch, and can prevent pigment and silica from settling in the coating, but it is slightly less compatible and difficult to disperse.
(4) PTFE wax: higher softening point, higher density, excellent heat resistance, provides outstanding slip, abrasion resistance, scratch resistance, anti-adhesion. Difficult to disperse, high price.
(5) Modified micronized wax: PTFE is used to modify polyethylene wax or synthetic wax to improve the softening point and hardness of polyethylene wax, increase smoothness, abrasion resistance, scratch resistance, anti-adhesion, and improve the disadvantages of PTFE wax which is difficult to disperse and high price. It is widely used in iron printing and steel coil coating. Generally speaking, PE wax has good smoothness and strong hand feeling, which is easy to disperse; PP wax has outstanding abrasion resistance, which is difficult to disperse; PTFE has excellent hydrophobic and anti-fouling properties and excellent comprehensive performance, which is difficult to disperse. For the same type of wax powder, the softening point increases, the wear resistance is enhanced, and the matting effect is enhanced; the permeability value of wax powder decreases, the surface hardness increases, and the hydrophobicity is enhanced; the acid value increases, the wettability is enhanced, and it is easy to disperse.
There are brands of micronized waxes, such as tianshi, ceronas micronized wax, honeywell , etc.
2, Dispersion of wax powder
In order to facilitate transportation, micronized wax is often supplied in powder form, and painters must have a good dispersion process to ensure that the properties of wax powder are fully utilized.
Several common dispersion methods are introduced.
(1) melt dispersion method: the wax powder will be melted at high temperature, slowly sprayed in a cold solvent (generally choose non-polar solvents, such as toluene), so that the wax liquid encounter sudden cold, showing small particles precipitation, the faster the cooling speed, the more delicate the formation of wax emulsion, so that the dispersion of the wax powder wear resistance, slip the best, and the minimum impact on the gloss. The disadvantage is that special equipment is required and there is a risk of fire. It is mainly used in the production of high-grade lacquer.
(2) Cold dispersion method: The cold dispersion method can be used to prepare high concentration of micronized wax dispersion, the solid content depends on the solvent used, commonly used non-polar or weakly polar solvents such as mineral oil, toluene, etc. to disperse wax powder, which can produce a high concentration of wax paste, good fluidity, high storage stability, can be directly added to the ink and paint. The method of dispersion is as follows: first stir at a low speed until the resin liquid swirls, then slowly add the wax powder into the swirls, and after all the wax powder is added, increase the stirring speed to 1000rpm, and stir fully for 10-30min, and the fineness is qualified.
(3) cold grinding wax powder dispersion precautions A. Temperature control: low molecular weight polyethylene wax, in the process of dispersion, if the temperature is too high, it is easy to cause partial dissolution of wax powder, solvent penetration of wax powder, resulting in soluble rise, resulting in re-flocculation back to coarse, the formation of coarse particles, wax powder failure. The general dispersion temperature is not higher than 40℃. B. Generally, it is better to use ester, ketone or ether and alcohol as the dispersing solvent of wax powder, avoid using benzene solvent, because benzene solvent has strong permeability to wax powder, which will easily cause the wax powder to dissolve at high temperature.
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