Application of pearlescent ink in wrapping paper printing II

2 Pearlescent ink light effect and its preparation The pearl is formed by alternate wrapping and covering of the calcium carbonate layer and the protein layer, both of which have different optical refractive indexes, and thus multiple reflections occur at different levels of the pearl. In the same direction, multiple beams of light are reflected in a parallel state after experiencing a different optical path inside the pearl. The optical interference that occurs between these rays is the main reason for the formation of the so-called “pearlescent effect,” the light. The principle of reflection is shown in Figure 1. Pearlescent ink utilizes mica flakes in mica pearlescent pigments, which produce a rainbow-like color due to the interaction of refracted light, reflected light, and transmissive light on specific layers, giving the particles a pearlescent color. As a result, pearl-like brilliance is displayed on prints. Mica titanium pearlescent pigments are suitable for a variety of ink systems. In fact, various binders can be used to disperse mica titanium pigments. For example, ethylene copolymers can use ketones as solvents, and polyamides and acrylic copolymers can also use ketones as solvents. Nitrocellulose The esters can be used as solvents. Pearlescent inks are usually formulated by adding 10-20g of pearlescent pigment per 100g of ink, or blending the pearlescent pigment directly with the binder in a 1:1 ratio. In addition, some micro organic pigments can be added to mix color pearlescent inks to reduce costs. When formulating pearlescent inks, pearlescent pigments should be added at the final stage of blending, that is, when all the other components have been mixed evenly before they are added. This prevents the pearlescent pigments from being damaged by excessive shearing. The more pearlescent pigments are distributed in the printing ink layer, the better the uniformity is, the better the pearlescent effect will be. The other point is also very important. The ideal pearlescent effect will be obtained only when the pigment chips are arranged in parallel with the surface of the printing material. 3 Pearl ink advantages and disadvantages Since pearlescent ink pigments can provide a special pearlescent effect different from metallic pigments, unique printing effects, strong stereoscopic effect and artistic appeal, the application in printing is becoming more and more common. 1) With a special printing effect, colorful eye-catching, good gloss, artistic sense. Improve the quality of printed products, with other ink can not be compared to the advantages. 2) The use of non-metallic mica titanium pearlescent pigments to replace traditional, low-source, high-cost natural pearlescent pigments and toxic synthetic pearlescent pigments for printing inks for printing, the printing effect is more prominent. 3) The material composition, the pearlescent pigment used is an inorganic form of pigment, non-flammable, non-explosive, is an electrical insulator, even for the diluted acid, alkali solution, but also stable. Of particular importance is that no matter organic matter or water does not affect pearlescent pigments, traditional inks do not have this feature. 4) Pearlescent inks have high temperature resistance and can fully meet the printing requirements, and their chemical inertness and extremely low heavy metal content make them very safe for the environment. 5) Printability is good. In addition to offset printing, which requires higher graininess, pearl ink can be used for gravure printing, flexo printing, and screen printing. In addition, the use of special printing ink pearlescent way to obtain high-end E-mouth brush products, than the choice of expensive substrates (printing materials) more environmentally friendly, and thus has good economic benefits. Of course, pearl ink also has its shortcomings. The reason for this is related not only to the quality of the ink itself, but also to the compatibility of the solvent and the effect of dispersion. In addition, the control of the ink during the printing process, the printing speed, and the selectivity of the paper also affect the pearlescent effect of the product. However, with the continuous improvement of process conditions and the growing maturity of additive technology, it is believed that in the near future, pearlescent ink will have a broader market space and development prospects in the printing field, so that printed products will have a dazzling appearance. (to be continued)