Ink cleaning agent in carton printing

Generally speaking, the upper components of the offset printing ink are: 48% solid resin, 6% liquid resin, 20% colloidal oil, 5% wax, 2% aluminum carbonate, and 15% pigment.

The removal process is actually the use of a suitable solvent to dissolve the resin components to achieve the purpose of removal.

The resin in the printing ink is generally a phenolic resin, and commonly used resins include a rosin-modified phenolic resin, an alkyd resin and a polyurethane alkyd resin. To clear them, find the solvent that will dissolve these resins.

According to the principle of similar dissolution (that is, a solvent of a polar gene dissolves a substance having a polar gene, a non-polar solvent dissolves a non-polar substance) and a solubility parameter theory (for non-polar molecular systems, usually the dissolution of a polymer For the solvent and solutes, the solubility parameters are as close as possible, which can be beneficial for dissolution. A solvent can be found.

While considering the development of the printing industry, China must also look at the issue from the perspective of environmental protection: In the printing industry, the emission of harmful gases and the use of hazardous liquids and solids and the discharge of waste should be strictly controlled.

Some of the cleaning agents originally used in the printing industry in China are poisonous in their own right, and all of the solvent's hydrocarbon emissions cause pollution to the atmosphere. At the same time, the cleaning agents used in the offset printing process must be thoroughly reformed.

In order to limit pollution and satisfy the VOC law, printing plants generally use water-in-oil emulsion cleaners to clean rubber rollers and blankets. Water-in-oil emulsion cleaners can not only completely eliminate the dangers of certain harmful substances in solvent-based cleaning agents to printing workers, prevent organic solvents from polluting the atmosphere, but also greatly increase the flash point of cleaning agents and improve the fire safety of printing workshops. To improve the quality of the overall environment.

The so-called water-in-oil emulsion type cleaning agent means that the cleaning agent is made into an emulsion, and the external phase is oil (oil or solvent); the internal phase is water; and the interface uses a surfactant as a stabilizer. Due to the presence of water, the volatility of the oil or solvent of the external phase is greatly reduced, and the content of organic volatiles in the air is greatly reduced. And the presence of water greatly increases the flash point of the solution; it increases the fire safety of the printing shop.

The key to the study of water-in-oil emulsion cleaners is to find suitable solvents and surfactants to solve the problems of cleaning speed, protection of blankets and rollers, and emulsion stability. This requires a lot of repeated experiments.

Although water-in-oil emulsion cleaners have some unsatisfactory qualities, such as the best quality cleaner, the drying rate is not as fast as gasoline, but analyzing the advantages and disadvantages, it should be the cleaning agent of the printing shop. .

At present, there are different grades of cleaning agents on the market, and high-grade cleaning agents should have faster cleaning and drying speeds, have no impact on rubber blankets and rubber rollers, and the solvents they use meet the requirements of green environmental protection. Low-grade cleaners are lacking in the impact on the factory's rubber and plastic bottles, or they are slow to clean.