On offset printing and four-color chromatic printi

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Talking about offset printing four-color chromatic printing

to improve the printing quality of offset printing products, in addition to high-quality paper, PS plate and other raw materials, the hue of electric four-color separation is accurately reproduced and does not deviate from the color, the plate making personnel master the correct exposure time, developer concentration and temperature of PS plate, and the master of monochrome, two-color and four-color offset printing adjusts the ink volume appropriately to achieve water ink balance, accurate color, accurate overprint In addition to promoting the establishment of the first batch of new materials with perfect risk compensation mechanism, bright and clear dot printing and good overall effect, the physical and chemical properties of inks are the conditions that determine the quality of printing products. Only high-quality inks suitable for printing adaptability can print a colorful world on smooth and white paper

offset printing ink is a tree finger bright and fast drying ink, which is composed of color material and connecting material that should be used at a relatively uniform speed (about 1 time/s), adaptability adjusting agent, dryness adjusting agent, and improving printing effect adjusting agent

function of pigment:

1. Give the ink color, and determine the ink concentration according to the amount

2. Give the ink a certain thickness and other physical properties. 3. Maximize the durability of the ink. 4. To a certain extent, it affects the dryness of ink, and the oxidation conjunctival drying is the most significant

function of binder in ink:

1. Give ink a certain viscosity, viscosity, fluidity and thixotropy. 2. Determine the drying type and drying speed of the ink. 3. Determine the gloss and firmness of the ink

all of us who are engaged in printing know that different printing methods need different inks, and lead printing needs lead printing inks in the process of printing; Offset printing requires offset printing ink; Plastic printing requires plastic printing ink and so on. Because their printing plates are different from the materials used in printing, and the substrates attached to the ink are different, all kinds of inks with different adaptability are required. For example: offset printing and gravure printing inks, because they are two completely different printing methods, the viscosity and yield value of inks are also different. However, what is the difference between various inks? It is on the binder of the ink. Therefore, different printing methods have different forms of ink flow performance and drying performance. For example, lead printing needs penetration drying, offset printing ink needs oxidation conjunctiva drying, plastic printing needs volatilization drying and oxidation conjunctiva drying, because plastic printing cannot penetrate drying, and plastic does not absorb any ink at all. The colorants of these three inks are the same, and the difference lies in the binder in the ink

offset four-color overprint printing mainly uses resin ink

resin ink has the following characteristics:

1. The ink fixation speed is relatively fast. 2. Fast drying. 3. The ink has strong luster and bright color. 4. Strong water resistance. 5. Good printing performance

types of resin ink:

1. soluble resin binder, 2. Dispersed resin binder, 3. Colloidal resin binder, 4. Volatile resin binder

in the offset printing process, the ink of the monochrome Offset Press is dry and wet printing, however, the four-color offset press is wet and wet printing. In four-color overprint, when the ink of one color adheres to the paper in a short time and is still wet, the ink of another color is immediately overprinted, which is called wet overprint. In wet stack wet printing, the viscosity, dryness, fluidity, adhesion, thixotropic property, yield value and other properties of ink determine the quality of ink stack

the auxiliary materials usually added to the ink have the following effects on the ink:

1. The addition of desiccant has a strong drying effect on the ink layer, and the content of drying oil usually accounts for about 1%. When using desiccant, use it now to avoid conjunctiva. The content of dry oil in the ink should not exceed 2%. It is easy to crystallize in excess. The second color should be put more than the first color. In winter, the temperature is lower than that in summer. 2. After adding ink blending oil, the fluidity and brushing ability of the ink are increased, but the concentration and viscosity of the ink are reduced, and the dryness of the ink is also reduced. 3. Add debonding agent to reduce the viscosity of the ink and increase the plasticity of the ink at the same time. 4. Add diluent to dilute the original ink to meet the requirements of ink color. 5. Adding gloss paste can increase the brightness of the ink

offset printing ink is required to have the following characteristics:

first, the transparency of the ink should be high. When the ink is coated into a uniform film, the clearer the background color of the material receiving the ink film is required, the higher the transparency of the ink is required. The color of ink on paper can be expressed in three forms:

it can provide processing plans for various special experiments. 1. It is expressed in the form of field and point. Point and field (i.e. 100% point) selectively absorb and reflect the polychromatic light of sunlight, and the color presented. 2. Monochrome points are displayed by juxtaposition and superposition: that is, two independent points are juxtaposed or superimposed on each other to show color on the paper. 3. Juxtaposition of overlapping color points: that is, the points of two colors overlap on the paper to display color. For example, yellow and cyan show a green hue when overprinted

second, the pigment particles of ink should be fine. In particular, the printing materials with high accuracy requirements, such as beautifully printed picture books, wall calendars, landscape paintings, etc., need the fine compressive strength/flexural strength of the ink particles, and the fine color particles can print exquisite printing products

III. strong coloring power of offset printing ink is required. Coloring power is a quantity that indicates the color intensity or concentration of ink. For inks with the same hue, the coloring power depends on:

1. The higher the dispersion of pigment on the binder, the stronger the coloring power. 2. It depends on the content of pigment. The higher the content, the stronger the coloring power

IV. the ink for offset printing requires light resistance

the color of offset printing ink is required to be light resistant under the action of sunlight and light. The fading and discoloration of the ink after exposure to light should be as slow as possible. The printing products of outdoor advertising are most likely to fade and discolour after exposure to the wind and sun. The discoloration and discoloration of blue and black are relatively slow. The key is to solve the problem of fading and discoloration of yellow and red, It is very important to improve the quality of printing products

v. high color efficiency of offset printing ink is required. Color efficiency is a comprehensive index of ink color difference and gray level. Offset printing ink requires that the hue of the color should be positive and pure, without color deviation and mottled

VI. the chemical properties of offset printing ink can be stable. The color of the ink will change under the action of some chemicals, especially acids, bases, salts and oxidants, which will have a certain chemical reaction with the pigments in the ink and are often easy to change color. Therefore, offset printing inks are required to have good chemical stability

1. water resistance. Offset printing is a kind of printing with water. Offset printing ink should have water resistance and demulsibility

2. Acid and alkaline resistance. Water should be used for offset printing, and PS version wetting powder should be added into the bucket. Offset wetting powder has the following characteristics:

1. It can fully wet PS layout and reduce surface tension. It contains surfactant, wetting agent and surfactant CMC. 2. Acidic substances should be added if it has cleaning ability. 3. Arabic gum should be added if it has a very good fat insensitivity. 4. Buffer solvent should be put in if the pH value can be stabilized. 5. Hygroscopic agent should be added if it can adapt to different climate changes. Therefore, PS version wetting powder is a high-tech product with a variety of chemical components, which requires the ink to have stable chemical properties

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