Study on New Type Printing Ink Cleaner (2)

3.1 The choice of solvent

The solvent used is a common solvent containing ester ketoether alcohols and aromatic hydrocarbons. It is not only cheap and easy to obtain, but due to the large amount of ink components, cleaning agents made from this solvent containing mixed components are made of a single solvent such as kerosene and gasoline. The cleaning agent has a better effect.

3.2 The choice of surfactant

Surfactants mainly include anionic surfactant cationic surfactant nonionic surfactant amphoteric surfactant and the like. The surfactant used as an emulsifier in this experiment should be a composite emulsifier composed of hydrophilic and lipophilic nonionic surfactants. It has the following advantages: 1) Non-ionic surfactants are not ionic in solution, so they are highly stable and can be well mixed; 2) Two sets of mixed emulsifiers consisting of water-soluble and oil-soluble surfactants After adsorption on the interface, the “composite” formed on the interface is tightly aligned, the interfacial tension is greatly reduced, and the strength of the interface film is increased, which has a great effect on improving the emulsion efficiency and increasing the stability of the emulsion. Through screening experiments, the two selected emulsifiers were water-soluble fatty alcohol polyoxyethylene ether (A) and oil-soluble sorbitan fatty acid ester (B). A:B=1:3~1:4.

3.3 Other additives

In order to increase the stability of the emulsion, a small amount of adjuvant must be added. The greater the strength of the interfacial film formed by the surfactant adsorbed at the water-solvent interface, the more stable the emulsion. Experiments have shown that when polar organic molecules, such as fatty alcohol fatty acids, are present in the interfacial film, the strength of the interfacial film increases significantly. The reason is that in the interface adsorption layer, the emulsifier molecules interact with polar organic molecules such as alkyd to form a “complex” and increase the strength of the interfacial film. In the experiment, we screened out an aromatic alcohol compound as an auxiliary agent, which significantly improved the stability and cleaning ability of the cleaning agent. Comprehensive consideration from the economic and stability, combined with the experiment found that the additive amount of 5% to 10% (volume percentage).

3.4 The amount of emulsifier and the amount of solvent

In theory, when the surfactant concentration is high, the number of molecules adsorbed at the interface is large and the stability of the emulsion is high. However, excessive surfactant concentration not only increases the cost, but also affects the cleaning effect, so the amount can not be too large. The relationship between the amount of emulsifier and the stability of the emulsion cleaning ability in Table 2 can be seen from Table 2, the optimal amount of emulsifier is 7%

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The amount of solvent in the emulsion is closely related to the nature of the cleaning agent. Theoretically, according to the calculation of the closest packing, the volume of the dispersion medium is less than 20.98%, and the emulsion is unstable. However, in practice, the droplets are not uniform, so the amount of solvent is 20%~25%. (Volume percentage), the best stability and cleaning ability. The relationship between the amount of solvent and the nature of the emulsion is shown in Table 3.

3.5 Emulsifier addition method

Adding emulsifier to prepare emulsion can be divided into: 1) emulsifier in the oil phase method, that is, first emulsifier added to the oil phase, then add the water phase; 2) emulsifier in the water phase method, that is, the first emulsifier Add to the aqueous phase, then add the oil phase; 3) interactive addition method, that is, gradually add the oil phase and the water phase to the emulsifier under stirring, so that the two phases are mixed. Through comparative experiments on the above methods, it was determined that the emulsifier can obtain a more stable O/W emulsion in the aqueous phase method with the best cleaning effect. The results are shown in Table 4.

3.6 Effect of Emulsification Time

By measuring the relationship between emulsification time and emulsion properties (Table 5), it can be seen that the optimal emulsification time is 30-40 minutes.

3.7 Conclusion

The oil-in-water ink cleaners made by emulsifying the selected solvents have been tried on offset presses in several printing plants and are completely replaceable with gasoline and kerosene to clean the black and color inks on the rollers. After the trial, manufacturers believe that the product is safer to store and use than petrol kerosene; the smell is light when cleaning; the cleaning speed is fast and the effect is good. Compared with printing ink cleaners produced in Shanghai and other places that are sold on the market, its advantages are: fast cleaning speed, especially better cleaning effect for color inks, lower cost, and better stability. Its formula is 20%~25% (volume percentage) of the solvents containing ester alcohols and aromatic hydrocarbons, 70%~75% (volume percent) of water, 5%~10% (volume percent) of additives, and 7% of surface active agent. (Weight percentage, based on the weight of solvent, where A:B=1:3~1:4), emulsification time 30~40min.


Author: Yu Qiang Jiang Baiquan Ma Qi Wuxiao Cong