The hottest printing ink and its cleaning agent ar

Development of printing ink and its cleaning agent (middle)

2. Cleaning of printing ink

printing equipment needs to regularly clean oil stains, ink stains and other dirt in the production process. In the printing process, when changing new varieties of ink and after the completion of printing tasks, it is necessary to clean the ink on the ink roller, and the wetting roller, silk, printing plate and font on the printing machine will be contaminated with ink in the printing process. In order to maintain the normal state of the printing machine and the quality of printed matter, the printing machine should be cleaned

the cleaning method usually adopts the brushing method of dipping a brush into the cleaning agent, and sometimes a rag can be dipped into the cleaning agent for scrubbing. When the ink is difficult to remove, you can also soak the parts in the cleaning solution and use ultrasonic cleaning. Ultrasonic concave 1 is widely used in modern printing plants The mechanical cleaning system of the printing roller when the facility suddenly breaks down in the process of experimental operation can automatically clean the printing plate roller on the machine at the end of printing, which can effectively prevent the ink from drying on the plate roller. This cleaning device can complete most of the cleaning work of the plate roller, significantly reduce the manual cleaning workload, and is also good for improving the operating environment. Cleaning the printing ink is mainly to remove the dry vegetable oil or synthetic resin and other film-forming materials in the ink. When these materials are removed, the coloring materials and other components attached to the film-forming materials are easy to be cleaned. Since dry vegetable oil and synthetic resin materials are easily dissolved in petroleum hydrocarbon solvents such as gasoline and kerosene, if the sample breaks outside the marking line, petroleum hydrocarbon solvents such as gasoline and kerosene are usually used for cleaning. Although gasoline and kerosene have the advantages of low price and strong cleaning power, they have the disadvantages of flammability and explosion, which makes the cleaning work unsafe. Moreover, gasoline is volatile and has a strong smell, belonging to VOCs that pollute the atmospheric environment. Therefore, at present, all countries are developing new cleaning agents for printing inks

3. Development of new printing ink cleaning agents

according to the data published at home and abroad, there are four types of new printing ink cleaning agents used to replace gasoline and kerosene: mixed solvent type, water-based cleaning agent, oil in water emulsion type and semi water-based cleaning agent type. The performance, preparation and application characteristics of various types of printing ink cleaning agents are introduced below

3.1 mixed solvent cleaning agent

this kind of ink enters the working cylinder through the oil pipe. The cleaning agent still mainly uses the dissolution and cleaning effect of gasoline and kerosene. However, in order to reduce its volatility and reduce the risk of flammability and explosion, non-volatile high boiling point solvents are added to the formula, so as to resonate with potential partners in related fields without affecting the cleaning effect, The safety in the cleaning process is improved

for example, an ink cleaner developed by gongguangfen and others from Hubei research and Design Institute of chemical industry basically belongs to this type. They add a kind of hydrocarbon solvent with high boiling point and low volatility to gasoline to form a mixed solvent. The added hydrocarbon solvent has aromatic smell and is an environmental friendly product that is easy to be biodegradable and can be used as liniment in the pharmaceutical industry (turpentine meets these conditions very well)

because gasoline dissolves the ink quickly, but its boiling point is low and volatile, while another solvent is added to dissolve the ink slowly, but its boiling point is high. When the two solvents are combined in a certain proportion, the purpose of both dissolving the ink quickly and reducing volatility can be achieved. The research shows that when the two solvents are mixed at a ratio of 1:1, the distillation range can be increased to 260 ℃ ~ 320 ℃, but the dissolution rate of the ink is greatly reduced, so it 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 150 ℃ ~ 250 ℃, and it has better performance of dissolving ink. So they think that when mixing at 3:1, they can not only dissolve the ink well, but also reduce the volatility of the solvent. Because the components of the ink are very complex, they also add some other components to the mixed solvent to further improve the cleaning effect of this cleaning agent (better than gasoline and other single component cleaning agents). For this reason, they added gasoline evaporation inhibitor n-1 produced by Wuhan Changjiang chemical plant to the formula. The polymer film and liquid monolayer are combined to form a surface facial mask. When it is added to volatile solvents such as gasoline, it can gather on the liquid surface to act as a barrier, which greatly reduces the volatility of gasoline. On the one hand, this greatly improves the flash point of gasoline (when its thickness on the gasoline surface is more than 1mm, the gasoline will not be ignited with a lighter), on the other hand, it also greatly reduces the consumption of gasoline during storage and transportation. In order to improve the cleaning efficiency, they also added surfactants to the formula. Surfactants can wet, penetrate, emulsify and disperse the ink and its film-forming substances, which can separate the ink and its film-forming substances from the printing cots and blanket to achieve the purpose of cleaning. They found that the use effect of surfactants such as OP-10 (alkylphenol polyoxyethylene ether), ABS Na (Sodium Alkylbenzene Sulfonate) was poor (poor placement stability and poor cleaning effect). Although the cleaning effect of Pingjia o was good, the placement stability was very poor. Therefore, they used a self-made sulfate surfactant (estimated to be alcohol ether sulfate AES), When the dosage reaches 8%, satisfactory cleaning effect and good placement stability can be obtained. According to foreign information, the detergent obtained by adding surfactant to this kind of solvent based detergent has another advantage: it can be rinsed with water. During rinsing, oily dirt is solubilized into the micelles of surfactant and will not be deposited on the surface of the cleaned object, so it can avoid re contamination of the cleaned object. In order to reduce the damage of cleaning agents to the printing press and cots, they also added mixed anti-aging agents to the formula, which can improve the rust resistance on the one hand, and prevent the swelling, shrinkage and aging of COTS on the other hand, so as to prolong the service life of the printing press and cots

(to be continued)