Abstract At present, gasoline is still widely used as a solvent for cleaning inks in offset printing, which brings many negative effects. This article has conducted an experimental study of high-performance ink cleaners that can replace gasoline. Based on Griffin's theory of the HLB value of the emulsifier, this study screened the appropriate emulsifier for the determined oil phase. The three-component and four-component experiments with oil-soluble emulsifiers were conducted by orthogonal experiments to obtain effective emulsifying power for gasoline, and the emulsifying efficiency and effectiveness of the mixed emulsifiers were significantly improved. In one-component emulsifiers. The experimental products have better dissolution, penetration and washing ability for wet inks. Using water-in-oil emulsification, emulsification process conditions are simple, gentle, and easy to control, providing a basis for industrialization of products. Moreover, the use of three quarters of gasoline, economic and social benefits prospects are considerable, with promotion value. Printing ink is a kind of colloid with complex structure. It is a kind of organic compound such as pigments with a particle size of about 0.1μm evenly dispersed in the organic compound. It has many advantages such as bright color variety and strong printing adaptability. The disadvantage is light resistance and heat resistance. The nature of the ink is poor. The black pigments used in printing inks are mostly inorganic substances, and the color inks used are mostly organic pigments. According to the main mechanism of ink drying, the ink is divided into four categories: oxidative polymerization drying type, osmotic drying type, volatile drying type and photosensitive curing type. Pigments include inorganic pigments and organic pigments. Inorganic pigments may be inorganic elements, metal oxides, or inorganic salts. Such as carbon black (C), titanium dioxide (TiO2), chromium green (Cr2O3), inorganic pigments are characterized by stable chemical properties, strong light and heat resistance, the disadvantage is poor coloring. The organic pigments are synthetic organic compounds, which have the advantages of bright colors and strong printability. The disadvantages are poor light and heat resistance, and the black pigments used in printing inks are mostly inorganic substances, and the color inks are mostly Organic pigments. Regardless of the type of printing ink, their common requirement is that they must maintain stable flow properties before they are transferred to the surface of the paper during the printing process, and must lose fluidity and cure and dry as soon as possible after transferring to the surface of the paper; Good adhesion to printing materials; ink should have good transferability; printing ink composition on paper must maintain a long-lasting and correct color. The ink's raw materials and composition are similar to those of paints and coatings, and have strong binding power. In addition, the ink will solidify into more solid dry oil dirt within a certain period of time, making cleaning difficult. In general, cleaning refers to the process of chemically and physically removing unwanted or harmful substances that adhere to the surface of the object to be washed, thereby cleaning the surface of the object to be washed, but it is not so simple. . For example, the interface between a hard surface such as metal and glass and a hard surface is very clear, but sometimes the interface relationship is not obvious. When the adhered matter is removed from the surface of the glass, the glass surface can be washed without damaging the glass surface. However, when the rusted metal surface is cleaned, the metal surface is subject to a certain degree of damage due to a chemical effect. From the purpose of cleaning the ink roller, not only can not have damage but also have a protective function. The attachment to the object to be cleaned adheres to the surface of the object to be washed in various forms, and its constituent parts are various. The attachments of the attachments to the objects to be washed can be classified into the following types: (1) adhesion due to intermolecular forces (called van der Waals forces) to the objects to be washed; (2) adhesion due to electrostatic forces; (3) Chemical bonding; (4) Penetration and diffusion inside the tissue on the surface of the laundry (oily bonds). 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 rollers, significantly reducing the amount of manual cleaning work and also improving the operating environment. Cleaning printing inks is mainly to remove film materials such as dry vegetable oil or synthetic resin from the ink. When these materials are removed, the coloring materials and other components 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. In the printing process, every time the color change and ink is changed, and the off-duty machine is shut down for cleaning, it is necessary to use a printing ink cleaner, that is, car wash water. Ink cleaning agents are only auxiliary materials in printing companies, but they are necessities and they are used in large quantities. At present, most printing companies still use gasoline as a cleaning agent. This not only wastes a lot of energy, but because the boiling point of gasoline is low and volatile, the workshop is filled with strong gasoline vapor whenever it is cleaned. Due to the poisonous gasoline, long-term work in such an environment, the operator inhaled large amounts of gasoline vapor, light can cause headache, nausea, tachycardia and other pathological phenomena, excessive inhalation can also cause central nervous system disorders. Therefore, the use of gasoline as a car wash water not only seriously pollutes the environment, but also affects the health of workers. What needs more attention is the low flash point of gasoline. If it encounters Mars, it will also cause a burning explosion. It is a loss of life and property.
The inks currently used in offset printing in China are mainly fast-drying bright-printing inks. Printing inks are mainly composed of binders (vegetable oils, solvent oils, etc.), fillers (gypsum calcium carbonate, etc.), colorants (organic pigments, inorganic pigments), and auxiliary agents (driers, inhibitors, etc.). A certain proportion of mixing and stirring is performed after repeated rolling by a dispersing device.
Source: Xi'an University of Technology Xu Jiaqi