Introduction of cobalt-free desiccant

2021-10-10   Pageview:412

In coating and printing ink applications, cobalt (Co), a metal salt, is generally used to improve curing or drying properties, but cobalt is environmentally damaging and costly. The company has developed a cobalt-free desiccant. This product not only has excellent quick-drying performance, but also can reduce the damage to the environment while reducing costs. It can be used not only for solvent-based but also for water-based products.

 

 

 

 

 

 

 

 

 

 

 

 

 

Carbon black is mainly composed of carbon element, combined with a small amount of oxygen, oxygen and other impurities (including sulfur, ash, tar and water).
The conductivity of carbon black is related to the structure and composition of carbon black. Generally, some high-structure carbon blacks, such as acetylene carbon black and conductive furnace black, have particle chains and networks that can form conductive complexes; while low-structure carbon blacks lack particle chains and have poor conductivity. The smaller the particles of carbon black, the larger the surface area, and the better the electrical conductivity. When the carbon black particle spacing is 10nm, it can allow electrons to wax emulsion structure flow through. In the composite material of carbon black and polymer, the greater the number of carbon black particles with a spacing of 10 nm, the greater the conductivity of the composite.

The higher the hydrogen content in carbon black, the better the electrical insulation of carbon black. The higher the volatile content, the worse the conductivity and the lower the ash content, the better the conductivity. In addition, the surface chemistry of carbon black also affects the conductivity of carbon black. For example, the surface of furnace carbon black often adsorbs a layer of oxygen complexes, most of which are adsorbed on the surface of the particles in the form of carbon dioxide, and a small part are bound to the carbon black particles in the form of hydroxyl, carboxyl, quinone, and aldehydes and ketones. Active groups will lead to a decrease in the conductivity of carbon black. According to reports, people have successfully developed a composite carbon black with carbon black and carbon fiber tightly combined, with a resistivity of 0.03~0.150·cm, which is close to graphite (described below) The electrical resistivity (0.010·cm) is 2-10 times that of ordinary carbon black.

Due to the strong cohesion between carbon black particles and weak affinity with other substances (such as organic polymers, water and organic solvents, etc.), it is difficult to uniformly mix and disperse under normal circumstances. In order to solve this problem, people have explored many methods, such as coating the surface of carbon black with various surfactants or resins to improve the affinity of carbon black and the base material, so that the carbon black can be uniformly mixed and dispersed. In recent years, suitable polymerizable monomers are used to polymerize in the presence of carbon black to make carbon black graft polymers, which greatly improves the hydrophilicity or lipophilicity of carbon black. For example, Wu Biyao et al. [*] Acrylonitrile is grafted and polymerized on the surface of carbon black to disperse the aggregates of carbon black particles into smaller primary particles, so that it has good dispersion stability in organic solvents (DMF). Liu Changsheng et al. [281 The anionic graft polymerization of ethylene on the surface of carbon black improves the dispersion stability of carbon black.

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