Requirements of the most popular offset four-color

2022-08-21
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Requirements of offset four-color overprint on ink

improve the printing quality of offset printing products. It was established in 2004. In addition to high-quality paper, PS plate and other raw materials, the hue of electronic four-color separation can be accurately reproduced without color deviation, and the plate making personnel master the correct exposure time of PS plate printing. In addition to the developer concentration and temperature, the monochrome, two-color and four-color offset printers adjust the ink volume appropriately to achieve ink balance, accurate color, accurate overprinting, perfect gradation reproduction, bright and clear dot printing, and good overall effect, the physical and chemical properties of the ink 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 inks are resin bright and fast drying inks, which are composed of pigments, connecting materials, adaptability adjusters, dryness adjusters, and adjusters to improve printing effect

pigments are composed of organic pigments and inorganic pigments

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, wear resistance, firmness, etc. of the ink

people engaged in printing know that different printing methods need to choose different inks, because their printing plates are different from the materials used in printing, and the substrates attached to the inks are different, so they need all kinds of inks with different adaptability. 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 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

resin ink type:

① soluble resin binder. ② Dispersed resin binder. ③ Colloidal resin binder. 5 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. When four-color overprint is finished, 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. Usually, the content of dry oil is about 17%. When using desiccant, it is now used and prepared 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 The addition of inking oil increases the fluidity and paintability of the ink, but reduces the concentration and viscosity of the ink, and reduces the dryness of the ink. ③ The addition of debonding agent reduces the viscosity of the ink and increases the plasticity of the ink at the same time. 5 add diluent to dilute the original ink to meet the requirements of spraying all surface ink colors of a large automobile trunk floor. ⑤ Adding gloss paste can increase the brightness of the ink

offset printing ink is required to have the following characteristics:

1. 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 that bears the ink film is required, the higher the transparency of the ink is required. The color of ink on paper has three forms:

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 is 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

2. the pigment particles of ink should be fine. Especially the beautifully printed picture album. Calendars, landscape paintings and other printing materials with high accuracy requirements require fine ink particles and fine pigment particles to print exquisite printing products

3. 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 dispersion of pigment on the binder. The higher the dispersion, the stronger the coloring power. ② Depends on the content of the pigment. The higher the content, the stronger the coloring power

4. offset printing inks are required to have light resistance. The color of offset printing ink is required to be light resistant under the action of sunlight and light. The fading and easy discoloration of the ink after exposure to light should be as slow as possible. Outdoor advertising printing products are most likely to fade after exposure to the wind and sun. The color changing is yellow and red, and the color changing and fading of green and black are relatively slow. Solving the problem of color changing and fading of yellow and red is very important to improve the quality of printing products

5. 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 pure, without color deviation and mottled

6. The chemical properties of offset printing ink should be stable. The color of the ink will change under the action of some chemicals, especially acids, alkalis and salts, which can be eliminated according to the actual situation Oxidants will have a certain chemical reaction with the pigments in the ink, which is often easy to change color. Therefore, offset printing inks are required to have good chemical stability

offset printing is a water-based printing method. Offset printing ink should have water resistance and anti emulsification

water is needed for offset printing. PS version wetting powder should be added to 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. ② Acidic substances should be added if it has cleaning ability. ③ Arabic gum should be added if it has a very good fat free ability. 5. Buffer solvent should be put in if the pH value can be stabilized. ⑤ Hygroscopic agent should be added to 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

(Wang Xincheng)

statement: it will further affect the quality and sales of products

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