Printing equipment needs regular cleaning of dirt such as oil and ink in the production process. In the printing process, when replacing the new ink type and after the printing job is completed, the ink on the ink roller needs to be cleaned, and the wetting roller, the screen, the printing plate, and the printing plate on the printing machine are contaminated with ink during the printing process. In order to maintain the normal state of the printing press and the quality of printed matter, the printing machine should be cleaned.
The cleaning method is usually a brush scrubbing cleaning agent, sometimes using a rag to pick up the cleaning agent for scrubbing. When the ink is difficult to remove, the parts can be soaked in the cleaning solution and used in combination with ultrasonic cleaning. In a modern printing factory, a mechanical cleaning system using ultrasonic gravure rollers is generally used to automatically clean the printing plate rollers on the machine at the end of printing, which can effectively prevent the ink from drying on the plate rollers. This type of cleaning device can complete most of the cleaning of the printing plate roll, significantly reducing the amount of manual cleaning, and also improving the operating environment. Cleaning the printing ink is mainly the removal of dry film vegetable oil or synthetic resin and other film-forming materials. When these materials are removed, components such as colorants attached to the film-forming material can be easily washed away. Since dry vegetable oils and synthetic resin materials are easily dissolved in petroleum hydrocarbon solvents such as gasoline and kerosene, petroleum hydrocarbon solvents such as gasoline and kerosene are often used for cleaning. Although gasoline and kerosene have the advantages of cheap price and strong cleaning power, they have the disadvantages of being flammable and explosive, causing unsafe hidden dangers in the cleaning work, and volatile odors of gasoline, which are VOCs that cause pollution to the atmosphere. substance. So at present all countries are developing new types of printing ink cleaning agents.
3. Development of a New Printing Ink Cleaner
According to information published at home and abroad, there are mainly four types of new printing ink cleaning agents used for replacing gasoline and kerosene: mixed solvent type, water-based cleaning agent, oil-in-water emulsion-type and semi-water-based cleaning agent. The following describes the performance of various types of printing ink cleaners, their preparation and use characteristics.
3.1 mixed solvent type cleaning agent
This kind of ink cleaning agent still mainly uses the dissolving and cleaning effects of gasoline and kerosene, but in order to reduce its volatility and reduce its risk of flammability and explosiveness, a non-volatile high boiling point solvent is added to the formula, so that no Under the premise of influencing the cleaning effect, the safety in the cleaning process is improved.
For example, an ink cleaning agent developed by Gong Guangfen et al. of the Hubei Provincial Chemical Research and Design Institute basically belongs to this type. They add a higher boiling point, less volatile hydrocarbon solvent to gasoline to form a mixed solvent. The added hydrocarbon solvent has an aromatic odor and is a kind of easily biodegradable. It can be used in the pharmaceutical industry. The environmentally friendly product of the agent (turpentine meets these conditions very much).
Since gasoline dissolves the ink faster, it has a lower boiling point and is more volatile. The other solvent added dissolves the ink at a slightly slower rate, but its boiling point is higher. When the two solvents are combined in a certain proportion, It can achieve the purpose of quickly dissolving ink and reducing volatility. Studies have shown that when the two solvents are mixed 1:1, the distillation range can be increased to 260Â°C to 320Â°C, but the dissolution rate of the ink is greatly slowed down and is not suitable for use. When the ratio of gasoline to the added solvent is 3:1, the distillation range can be increased to a higher range of 150Â° C. to 250Â° C., and there is better performance of dissolving the ink. Therefore, they believe that the 3:1 mixing can achieve the purpose of both dissolving the ink and reducing the solvent volatility. Because the ink composition is very complex, they also added some other ingredients in the mixed solvent to further improve the cleaning effect of this cleaning agent (better than a single component cleaning agent such as gasoline). For this purpose, they added the gasoline evaporation inhibitor N-1 produced by Wuhan Changjiang Chemical Plant into the formula. The surface film was formed by a combination of a polymembrane and a liquid monolayer. When it was added to volatile solvents such as gasoline, it was Can gather on the liquid surface to play a barrier role, so that the volatility of gasoline is greatly reduced. On the one hand, this greatly increases the flash point of gasoline (when it is more than 1 mm thick on the surface of the gasoline, the use of lighters will not ignite the gasoline), on the other hand, it will also greatly reduce the amount of gasoline lost during storage and transportation. In order to improve the cleaning efficiency, they also added surfactants to the formulation. The surfactants have wetting, penetrating, emulsifying, and dispersing effects on the ink and its film-forming substances, which can cause the ink and its film-forming substance to deviate from the printing roller. And blankets reach the purpose of cleaning. They found that the use of surfactants such as OP-10 (alkyl phenol ethoxylate) ABS-Na (sodium alkyl benzene sulphonate) was not effective (poor placement stability, poor cleaning results), and that they were not evenly coated with O. Although the cleaning effect is good, but the placement stability is very poor, for which they use a homemade sulfate surfactant (presumably alcohol ether sulfate AES), when the amount of 8% can achieve satisfactory cleaning results And good placement stability. According to foreign data, the cleaning agent obtained by adding surfactant to this type of solvent-based cleaning agent has an advantage: it can be rinsed with water, and the oily soil is solubilized into the micelles of the surfactant during rinsing. It will not be deposited on the surface of the object to be cleaned, so it can avoid re-contamination of the object being cleaned. In order to reduce the damage of the cleaning agent to the printing machine and the rubber roller, they also added a mixture of anti-aging agents to improve the anti-rust ability on the one hand, and on the other hand to prevent the swelling, shrinkage and aging of the roller, so that the printing press and glue The service life of the roller is extended.
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