Under the influence of anti sagging agent and leve

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The effect of Hang prevention agent and leveling agent on the performance of ink (Part 2)

there is also treated ultra-fine calcium carbonate (most of which have a particle size of 2llm '601xm, and the surface is treated with fatty acid and resin) used in long oil alkyd ink and vinyl internal printing ink. Excessive dosage often affects the water resistance of the ink film. The organic system is to swell and disperse in the ink to form a like structure, which gives the printing ink structural viscosity, making it thixotropic, which we hope to transform 3D printing from small batch production to large-scale industrial production. In recent years, the application range of this kind of additives is slightly smaller than that of inorganic additives. B organic additives have little impact on the performance of printing ink, and have good anti sedimentation, which can keep the ink in a good storage and stable state. However, the effect and stability of the ink system will not be the same depending on the type of binder and use temperature. For example, castor oil derivatives are often divided into aliphatic and aromatic solvent inks and aliphatic oil inks. In addition, the use temperature is also different due to different manufacturers' brands. Its biggest feature is that if the temperature is too high, the auxiliary dissolves, and the operation can be stopped so that the swelling particles can be separated out. After heating to the required temperature under shearing, it can be restored to a fully activated state, and a stable thixotropic ink additive can still be prepared

organically modified bentonite (containing more than 85% montmorillonite, which is a high-quality clay with various uses), is a 2:1 layered clay. The upper and lower layers are silica tetrahedrons, and the middle layer is octahedron, which is formed by the coordination of aluminum or magnesium with 6 oxygen atoms or hydrogen and oxygen atoms. The hydrogen bond structure is easy to be destroyed, resulting in viscosity reduction; When the shear is cancelled, the hydrogen bond recovers and the viscosity increases again. This is the basic principle that organically modified bentonite can make printing ink form thixotropic fluid, and it is also the reason why bentonite has anti sedimentation effect. Bentonesd-1 on the market is a kind of material that does not need polar activators, nor does it need to be made into gel, but only needs appropriate stirring shear force, Just add it directly to the printing ink {of course, the gelling effect of making it is much better than that of directly adding dry powder).

as an organic thixotropic agent, metal soap has great swelling and gelling ability, and it can show viscosity increasing effect even at low temperature.

in nonpolar solvents, due to the role of coordination bonds, metal soap thixotropic can form micelles', these micelles can form a like structure, resulting in the increase of the viscosity of ink. But this kind of thixotropic agent has a common defect The point is: the swelling effect is different with the temperature and solvent; The structure of the generated gel is unstable. Especially when water and polar solvents are mixed, it is easy to precipitate or precipitate particles. The advantage of the additive is that it can be used at weak shear force and temperature of 40 ℃ - 60 ℃

to prevent the inferior scrapping of packaging and printing products, not only anti sedimentation and anti sagging additives should be added, but also necessary leveling additives should be added to prevent ink from shrinking edges, pinholes, bubbles, floating color blooming, and frosting during printing

printing ink leveling agent

additives that improve the leveling property of printing ink film (improve gloss, improve film covering and composite flatness) are collectively referred to as leveling agents. After different printing inks are printed with different printing methods, there is a process of flowing and drying to form a film, and finally a flat, smooth and uniform ink film is gradually formed. Whether the printing ink film can achieve the characteristics of flatness and smoothness, choose one buffer, which is called leveling. In the actual packaging and printing process, scratches, orange peel and water marks often appear during printing due to poor leveling. During the drying process, there are shrinkage, edge shrinkage, pinholes and other phenomena, which are called poor leveling. These failures are related to the quality of printing ink, printing environment and process. General leveling agents are high boiling aromatic hydrocarbons, esters, ketones, ether alcohols and other solvents and their mixtures with excellent solubility, or silicone resins miscible with inks, such as polyurethane inks, are added to them. Because no solvent or less solvent is used in its components, it is easier to produce the fault of poor leveling performance. Therefore, polymer leveling agents such as cellulose acetate butyrate and polyacrylic acid are often used to improve the ink performance. Its purpose is to reduce ink viscosity and improve ink film leveling

adding leveling agent is often prone to sagging with the increase of flow, so we should find an optimal range between adjusting sagging and leveling; The use of leveling agent will reduce the solid content of ink, which is not in line with the development trend of high solid ink that saves energy and reduces pollution. Therefore, when using this additive, designing mixed solvent ink and adding an appropriate amount of coupling agent to form a gradient is a major trend in ink formulation today. This not only overcomes the defect of reducing solid content, but also avoids the reduction of film formation by drying with a part of low volatile slow drying solvent. For example, the pet gravure thick ink designed by the author for Fushan Shunde Yingpeng Plastic Co., Ltd. a few days ago can reach 50um after one-time printing, drying and film forming, opening up a new way to save energy. 1. Try it first

both the German byketol-ok and the domestic sf-723 leveling agent belong to solvent type, and basically have the effects of preventing bubbles', pinholes and shrinkage, improving leveling and increasing adhesion. It must be operated under the guidance of skilled staff. As far as the author knows, it was very difficult to increase the levelness of ink by improving the surface tension of ink in the past, but in fact, it was just the opposite

the function of leveling agent is to reduce the interfacial tension between the ink and the substrate, improve the wettability of the ink to the substrate, and reduce the shrinkage, poor adhesion and other failures caused by the substrate. Moreover, it has the characteristic of migrating to the surface of ink film, which can form a monolayer on the surface of ink film, reduce the surface tension, make the surface tension tend to balance, and then reduce various surface and surface faults caused by surface tension gradient difference. The third is to adjust the evaporation rate of the solvent in the ink, especially to design the gradient balance of the mixed solvent in the system

author/Liu Jiaju source: China Packaging News

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