Analysis of Ink Film Float Color and Hair Blooming Problems in Packaging and Printing

6) Improve the physical properties of the ink film. Practice has proved that the best pigment dispersion can increase the absorption and reflection ability of the ultraviolet rays, increase the freshness and chemical resistance of the pigments, thereby improving the physical and chemical properties of the ink film;

7) Change the rheology of packaging printing inks. It has been proved that the use of different wetting and demulsifying agents sometimes results in a packaging printing ink of a low-viscosity dispersion close to Newtonian fluids. The pigment particles can be dispersed close to the state of the primary particles to obtain a stable and ideal dispersion system. For example, in the ink where the high pigment ratio is higher than that of the ink and the easy to form the thixotropic structure, the viscosity is lowered, the flow is improved, and the leveling property with high gloss is ensured, but some wetting and dispersing agents make the dispersion system have pseudoplastic viscosity. And thixotropy viscosity, the ink system formed a structural viscosity to make the ink system in a stable state, this anti-precipitation, anti-sag, anti-floating color hair flower is due to the dispersion agent, filler control flocculation and stability;

8) Save time and energy. The addition of a wetting and dispersing agent can reduce the grinding time of the pigments and fillers, save energy, and greatly increase production efficiency.

Contrary to the eight effects mentioned above, if used improperly, the resin binder will penetrate into the paper, leaving the pigment alone on the surface and pushing the gloss of the ink film.

In the molecule, anion and cation machine groups are known as electrically neutral surfactants. Not only does it have a good mix with all solvent-based printing ink systems, but there are no side effects due to wet dispersants. In addition, it also has ultra-dispersed polymeric dispersants.

Although the wetting and dispersing agent can form an adsorption layer and generate external forces to make the dispersion system stable, some individual particles can cause co-flocculation among the pigment particles to prevent the excessive flocculation of the single pigment, thereby preventing the floating color from blooming. According to the experience of Hangzhou Yuhang Dibang Fine Chemicals Factory and Yangzhou City Zhonglida Ink Company, the author tried to remedy the printing process, and the amount of use would increase by 10 times or more.

In addition to the above-mentioned wetting and dispersing agents to control the flocculation with the pigment in a stable, medium-dispersed state, the following discussion focuses on the effect of the leveling agent on the blooming of the floating color.

According to Nabed's eddy current theory, the purpose of adding a leveling agent is to reduce the surface tension of the ink, prevent the vortex of the packaging printing ink from causing hair growth, and make the surface smooth and flat to achieve a uniform color.

Among the additives for many leveling agents, silicone oils, silicone resins, acrylic copolymers, and the like are generally used. We have known in practice that silicone oil can not solve the problem of pigment blooming. It can only change the hair color into a pool color to form a uniform hue and a uniform hue surface, which can not solve the separation and flocculation of pigments.

Silicone oil and organic matter in printing inks are immiscible and concentrated at the interface between the air and the ink film to reduce the surface tension and expand on the surface to form monomolecular layers. The radius of curvature increases and can be extended to the entire surface. Therefore, it can be formed relatively. A good smooth surface condition prevents the vortex from creating an ink film surface to form a smooth mirror-like ink layer.

The role of polyacrylate leveling agent is roughly the same as that of silicone, but attention should be paid to the thermal stability and the amount of active groups of the silicone polymer, and some will bring obstacles to reprintability; secondly, excessive use is often associated with The resin in the ink system has poor compatibility and produces dry skin and shrinkage defects. Thirdly, thixotropic tackifiers can also make the packaging printing ink structurally sticky and improve the rheology of the printing ink. The increase in the viscosity of the ink tends to decrease the settling rate of the pigment in the system and prevent the separation of the pigment, thereby achieving the purpose of eliminating floating color and hair growth. However, this kind of additive can not be used for packaging printing inks. For example, the use of a pump to recycle ink, especially for printing ink products, is not suitable, because the addition of a thickener often directly affects the leveling of the ink after printing. The dosage should be determined after trial printing, otherwise it will cause ink flocculation.

Thickeners and thixotropic agents are widely used in packaging printing inks because such auxiliaries enable the ink system to produce a structural viscosity that changes the rheology of the ink and controls the movement of the pigment.

In addition, the surface treatment or modification of the pigments and fillers is also a common method for preventing the floating of flowers, and the amount is less.

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