Application of Micro Wax in Printing Ink (Part 2)

6. Main indexes of micropowder from BYK

Third, the application of the matters needing attention

In order to facilitate transportation, micropowder wax is often supplied in the form of powder. In order to fully utilize and utilize the characteristics of wax powder, the ink factory must have a good dispersion process to ensure. Although micropowder waxes generally have better dispersibility and fineness, they are easier to disperse in inks, paints and coatings. However, for special process requirements and quality requirements, the following dispersion methods are also available:

(1) Melt dispersion method: The wax powder is melted at a high temperature and slowly sprayed in a cold solvent (usually a non-polar solvent such as toluene), so that the wax liquid quenches, showing the precipitation of small particles, the faster the cooling rate The finer the wax emulsion that is formed, the better the wax wear resistance, slippage, and minimal impact on gloss. The disadvantage is that special equipment is needed and there is a risk of fire. Mainly used in high-grade paint and coating production.

(2) Cold dispersion method: The cold dispersion method can be used to prepare high-concentration micronized wax dispersions. The solid content depends on the solvent used. Commonly used non-polar or weakly polar solvents such as mineral oil, toluene and other dispersed wax powders. , can produce high concentrations of wax, good fluidity, high storage stability, can be directly added to the ink and paint. Dispersion method is as follows: First stir at a lower speed until the resin liquid vortex, and then slowly add the wax into the whirlpool. After all the wax powder is added, increase the stirring speed to 1000 rpm, and fully stir for 10-30 min. The fineness is acceptable. can.

(3) Dispersion of cold grinding wax powder

A temperature control: low molecular weight polyethylene wax, in the process of dispersion, if the temperature is too high, it will easily lead to partial dissolution of wax powder, solvent penetration of wax powder, causing swelling, leading to re-flocculation back to coarse, forming coarse particles, wax powder failure . The general dispersion temperature is not higher than 40°C.

B Generally, esters, ketones, or ether alcohols are used as the dispersion solvent for wax powder, which is ideal, and the use of benzene-based solvents is avoided because benzene-based solvents have strong penetrating power to wax powder and can easily cause the swelling of wax powder under high temperature.

(4) Direct addition method: The easily dispersible Fischer-Tropsch wax and PE wax can be directly added to a high degree of stirring and dispersion, so that the production process is simple and the cost is reduced.

When using powdered micronized waxes for inks and paints, the following major issues should be noted:

1, temperature control: polyethylene wax will be dissolved at higher temperatures, resulting in the condensation and anti-coarse, can not be dispersed, so the stirring temperature should be controlled at 45 degrees Celsius.

The polyethylene micronized wax is soluble in aromatic, aliphatic, and chloride solvents; it has less solubility in glycol ethers, esters, ethanol, and acetone solvents.

2. Addition method: first make 20-30% wax powder and 70-80% resin to make wax, then add according to the required proportion

Or, adding it directly in the back section requires an appropriate shear force, at least with a spiral stirrer to have enough vortexes to ensure that the wax powder particles, especially secondary particles, have a suitable fraction. It is also possible to grind them together for the last time, but care must be taken to control the temperature.

3. Dispersion mode: First stir at a lower speed until a vortex is generated. Add the wax powder to the vortex center in small batches. After all the wax powder is added, increase the stirring speed to 1200 rpm, and stir until fully Disperse evenly.

4. Solvents: Preparation of wax micronized dispersions. It is generally desirable to use esters or alcohols as disperse solvents for wax powders. Try to avoid the direct mixing of toluene or xylenes with wax micropowders. The powder is dissolved and reversed when recrystallized.

5. Wetting: FTPE is not easy to disperse in solvent due to its low surface free energy (0.0184N/m). It can be wetted with a small amount of ether and then added.

Author / Boda Battery Co., Ltd. asked Lining

Xinxiang Ruifeng Chemical Co., Ltd. Qiao Qingwen)

Beijing Chemical Industry University Fine Chemical Factory Hu Weikang Chen Zhongqiang