Analysis of Ink Film Floatation and Hair Blooming Problems in Packaging and Printing Process II

Second, to prevent and remedy the floating color flowers
Around the above ink ink film floating flower hair several forms of expression, carried out analysis and induction. But how can we prevent and remedy faits accomplis, and the literature is very few. For this reason, the authors described each case according to accumulated experience.

The stability of the packaging printing ink is the result of the simple interaction between the components. For example, the polarity of the solvent is different, and the adsorption of the surface of the active agent pigment is also different. For example, the order of the adsorption amount of octadecylamine in each solvent is: toluene>dichloroethane>mixed solvent. Most people think that various solvents only affect physical adsorption without affecting chemical adsorption. At the same time, it is also believed that the binder and the active agent will produce competitive adsorption on the surface of the pigment, which has been proved by junior high schools to be correct. This shows that the competitive adsorption depends on the size of the binder, the active agent and the color, and the surface affinity of the filler. If the pigment or filler is hydrophilic, the polarity of the pigment is greater in the non-polar solvent. If it is hydrophobic, in the polar solvent, the more hydrophobic substance is selected for adsorption. The physical adsorption of the surfactant does not affect the chemical attachment of the polymer, because the physical adsorption of the surfactant on the surface of the pigment and the filler is not strong, and the solvent is easily extruded from the surface of the pigment by the resin. The chemisorption surfactant formed on the surface of the pigment cannot be extruded from the surface of the pigment filler by the resin polymer. The greater the adsorption saturation of the surfactant on the surface, the greater the resistance to polymer adsorption. On the other hand, if the dispersion grinding time is slightly shorter during the ink manufacturing, the ink is not easily expelled from the pigment surface by the resin in the solvent during the manufacturing process or the ink storage, but other phenomena may still occur. To be proved by practice.

In polar solvents, ultrafine active calcium and alkyd resins can be adsorbed on the surfaces of Tiafranine and Chromium Yellow. This is because the pigment has two active sites, so it is slightly acidic active calcium and alkyd resin. Can still suck on the surface, but its rate is low, resulting in poor wetting and dispersing properties, when dispersed to 7.5 microns, the surface will have a floating color; when dispersed to 1-2 micro materials will be disappear. If thinner is added during the printing process, the floating color will flash out again to select the appropriate dispersant. Adding the wetting dispersant can not only reduce the grinding time of the pigment and filler, but also save energy and improve work efficiency.

In order to prevent the floating color of the ink, the wetting and dispersing agent should be introduced into the packaging printing ink system. Its purpose is nothing but:

1) Increase the gloss of the ink film and improve the leveling of the ink film. It can greatly improve the fineness of the pigments and fillers, ensure the storage stability of the ink, prevent the generated flocculation particles, and improve the flatness of the printing ink film;

2) Reduce the viscosity of the ink and improve the fluidity of the ink. Under the same conditions, the concentration of the pigment filler can be greatly increased, and its filling property can be increased to reduce the material cost;

3) Improve the storage stability of packaging printing inks. The storage stability of the package printing ink depends entirely on the dispersion quality of the pigment. If the dispersion is not good and the precipitate is precipitated, the floating color, hair growth, and coloring power will be reduced. Secondly, the rheology also changes, and the reason is closely related to the ratio of the resin and the solvent and the dispersion of the resin. When the resin can not achieve a good wetting and dispersing effect, it can only be assisted by the wetting dispersant. If used properly, all wetting and dispersing agents have this function. Such as domestically produced P-104S, lecithin, CP-88, TC series products, especially TM-27 and TM-200S with coupling bridging are very effective for pseudoplastic fluid packaging and printing inks. The general dosage is 0.1-3. %;

4) Improve the coloring power and hiding power of pigments. It is known that the degree of light scattering and the hiding power of pigments tend to have a maximum value with the change of the particle size, and it is preferable that the viscosity of the pigment is small in the printing ink. The simplest method of identification is: A. Take 0.1g of ink droplets in the scraper fineness meter slot, hold the scraper at 90 degrees, and scrape it from top to bottom quickly. If the ink is interrupted or interrupted, the coloring power will not reach 100%. That is to say, the printability of the ink is poor or bad, and when printing on the machine, it is not the tail of the printed graphic or the like, that is, the appearance of the dry patch or the like. B, take 0.1 grams of ink droplets on the 65 × 195mm blueprint base paper, holding the blade 25 degrees, quickly from top to bottom, if the sun surface pattern paint pigments do not reach the degree of saturation, it proves that its coloring power can not reach The requirement of printing, that is, poor printability, and easy floating color;

5) Prevent floating color, sagging and sedimentation effects. The use of a controlled flocculating wetting and dispersing agent can prevent the floating color, hair growth, and stability of the multi-color or inter-color ink;
(to be continued)