With the rapid development of the domestic ink-and-wash industry, the market competition for Polyethylene Wax products as an important additive has also intensified. Many international and domestic companies have launched a large number of products targeting the ink and wash market. The descriptions of the indicators are different, and the performance varies greatly. The lack of uniform standards has brought difficulties to the choice of ink-and-wash enterprises, especially small and medium-sized enterprises. This article attempts to summarize the performance indicators of mainstream wax products and their impact on the performance of ink and wash. Improperly please the industry colleagues correct me.
The role of wax additives in water-based inks is summarized as follows: The wax particles are added to the ink by means of powders, water dispersions, etc., and the wax particles are moved through the drying process to highlight the surface of the dry ink coating and change the surface of the coating. Properties (reflection, refraction and scattering of light, changes in the coefficient of friction of the coating, and changes in the hardness and mechanical properties of the coating surface), resulting in glossiness (improved or reduced gloss) of the ink, feel (smooth, Oily or even astringent), anti-corrosion, anti-scratch, blocking and other effects.
Therefore, the choice of wax additives should mainly consider the different effects of wax properties, microscopic particle morphology, dispersion state and other factors on the above properties. At the same time, in the specific operation, the wax product often has the problem of system compatibility, and it also needs the attention of the ink and water industry engineering and technical personnel.
1, the type of wax
There are many types of waxes used in the ink-and-wash industry, such as polyethylene wax, Paraffin Wax, beeswax, carnauba wax, candelilla wax, polypropylene wax, Fischer-Tropsch wax, and polytetrafluoroethylene wax. Among them, polyethylene wax has become the main application wax in the ink industry due to its excellent performance, suitable cost, ease of compounding with other waxes, and numerous modification methods. Polyethylene waxes can be divided into high-density polyethylene waxes and low-density polyethylene waxes, and the performance varies greatly. At the same time, the performance of polyethylene wax is closely related to its manufacturing method (synthetic method, cracking method, etc.) and modification method (branching, polarity, etc.), and the performance of products from different manufacturers is also very different. If you need to improve the smoothness of the ink, you must choose a high hardness of the wax; if you need water resistance, you need to choose a poor degree of wax; if you want astringent, then select the low hardness of the wax. Therefore, a series of wax dispersions and wax emulsion products become important. This is also where there is a significant gap between China's wax product processing companies and the international advanced level.
2. The effect of the microscopic morphology of wax particles on product performance.
Wax ions are added to the ink in the form of solid particles, so their microscopic morphology has a great influence on product performance. Usually the manufacturer only provides the average particle size and particle size range of the wax product, and the particle shape is rarely described. However, the same particle size, different microscopic morphology of the wax particles vary greatly in the surface friction coefficient, gloss, etc. of the ink coating. Particles with a spherical shape with microscopic morphology can achieve smooth, frictional and other effects of irregularly shaped particles even with only half the amount added.
The effect on the glossiness is also the same. The spherical wax particles are evenly distributed on the surface of the coating, which increases the light reflection effect of the coating, so that the coating of the larger wax particles still has an ideal gloss, thus taking into account the resistance of the ink coating. Friction and gloss, this is particularly important for the production of high-grade ink.
3, different wax products, particle dispersion, particle size and particle size distribution.
At present, wax additives used in ink products are generally divided into three categories according to the mode of dispersion and particle size: wax powder, water dispersion of wax, wax emulsion.
Appearance Gloss Size Appearance Gloss Wear Resistance Applicable Wax Powder 5-20μm Powder Extinction Ink Wax Dispersion 3-15μm White Paste or Emulsion Liquid Matt or Semi-Matte Good Ink, Varnish Wax Emulsion <1μm White or Light Yellow Translucent Liquid Enhancing or Maintaining Gloss Varnishes for general oils are mainly used in high gloss systems, such as various types of varnish. Its primary requirement is that it must not affect the transparency and gloss of the system. Therefore, the particle size of the wax emulsion particles is less than 0.2μm. At present, the mainstream particle size of foreign particles is less than 0.1μm. During the drying process of the ink, some of the wax particles migrate to the surface of the coating due to the floating effect (difference in density) and play a role in wear prevention, scratch prevention, and the like. Since only part of the wax particles migrate to the surface, the same amount of wax emulsion added will definitely have less wear resistance than wax powder and wax paste.
The thickness of the ink coating after drying is generally between 5 and 10 [mu]m, so wax emulsions with a wax particle size of around 1 [mu]m are interposed between the wax emulsion and the wax dispersion. Wear resistance is less than that of wax dispersions, but its soft luster is very helpful for many high-grade inks. The 5-7 μm fine powder and wax paste are considered to provide the best overcoat protection. The best extinction particle size is about 12μm.
In order to prevent the precipitation of wax powder during ink storage, high-shear dispersing equipment and some wetting and dispersing aids should be used when the wax powder is dispersed in the ink. These additives are all within the range of surfactants. The phenomenon of excessive use of surfactants was found in the production of wax and wax milk in the early days. Due to the use of high-performance surfactant systems and the improvement of emulsifying and homogenizing equipment, the amount of emulsifiers is currently greatly reduced. Problems such as poor water resistance of the coating caused by excessive surfactant content have also been solved. From the perspective of customer convenience, the effect of wax slurry is better than that of wax powder.
Through observation of wax powders and waxes made by many manufacturers through a microscope, the particle morphology of most samples was irregular. The particle size distribution is also uneven. The ideal state should be spherical particles of uniform size. In fact, the latter is significantly better than the former in gloss uniformity and wear resistance. Therefore, the particle size distribution and particle morphology are also important indicators of wax products.
Wear resistance contrast
a No wax additives added
b Add 5% of a brand of wax emulsion
c Add 5% AF-1 Wax Emulsion
d Add 2% V-815 wax micron wax microscopic state
V815 microscopic state
V2000 Microstate
The evaluation of wax products by ink manufacturers should include the following aspects:
1) Choose the right wax product based on the gloss of the product
2) Increase in surface properties (wear resistance, slipperiness, anti-blocking) with the same amount of product (or equivalent)
3) Processing requirements
4) Storage stability
We have done chemical products for over 30years. Our main products include PVC Resin, CPE , Pe Wax, PARAFFIN WAX, TIO2 , Stabilizer, Stearic Acid ETC.
