Offset printing quality and ink requirements
We are a big printing company in Shenzhen China . We offer all book publications, hardcover book printing, papercover book printing, hardcover notebook, sprial book printing, saddle stiching book printing, booklet printing,packaging box, calendars, all kinds of PVC, product brochures, notes, Children's book, stickers, all kinds of special paper color printing products, game cardand so on.
For more information please visit
http://www.joyful-printing.com. ENG only
http://www.joyful-printing.net
http://www.joyful-printing.org
email: info@joyful-printing.net
The offset ink is a resin bright and fast drying ink, which is composed of a color material, a binder, a suitability adjuster, a drying property adjuster, and a printing effect modifier.
The colorant is composed of an organic pigment and an inorganic pigment.
The role of colorants:
1. Give the ink a color and determine the ink concentration based on the amount used.
2. Give the ink a certain thick physical property.
3. Maximize ink durability.
4. To a certain extent, it affects the drying of the ink, and the oxidized conjunctival type is most effective.
The role of the binder in the ink:
1. The ink is given a certain viscosity, viscosity, fluidity and thixotropy.
2. Determine the type of drying and drying speed of the ink.
3. Determine the gloss, abrasion resistance, firmness, etc. of the ink.
People who work in printing know that different printing methods use different inks. Because their printing plates are different from the materials used for printing, the inks are attached to different substrates, so different types of inks are needed. For example, the inks used in offset and gravure, because they are two completely different printing methods, the inks require different viscosities and yield values.
However, what is the difference between the various inks? It is on the binder of the ink. Therefore, different printing methods have different flow properties and drying properties. If the printing needs to be infiltrated and dried, the offset printing ink needs to be dried by the oxidized conjunct film, the plastic printing needs to be evaporated and dried, and the oxidized conjunctiva is dried. Because the plastic printing cannot be infiltrated and dried, the plastic does not absorb a little ink at all, and the color materials of the three inks are consistent. The difference lies in the binder in the ink.
Offset printing mainly uses resin type inks.
Resin type inks have the following characteristics:
1. The ink is fixed at a faster rate.
2. Dry quickly.
3. The ink has a strong gloss and a bright color.
4. Strong water resistance.
5. Printing performance is better.
Resin type ink:
1 Dissolved resin binder.
2 Dispersed resin binder.
3 colloidal resin binder.
4 volatile resin binder.
The monochrome offset press ink is dry-wet printing during the offset printing process, however, the four-color offset press is wet-stack wet printing. When four-color overprinting is done, when a certain color is printed on the paper in a short time, the ink is still wet, and the ink of another color is immediately superimposed as "wet-wet". The viscosity, dryness, fluidity, adhesion, thixotropic properties, and yield value of the ink during wet-wet printing determine the color of the ink overlay.
The auxiliary materials normally added to the ink have the following effects on the ink:
1 Adding a desiccant has a strong drying effect on the ink layer. Usually, the dry oil content is about 17%. When using a desiccant, it is used now to avoid conjunctiva. The dry oil content in the ink should not exceed 2%, the excess is easy to crystallize, the second color is placed more than the first color, and the winter temperature is lower than in the summer.
2 Adding varnish increases the fluidity of the ink and exhibits brushability, but reduces the concentration and viscosity of the ink, and also reduces the drying property of the ink.
3 Adding a detacking agent reduces the viscosity of the ink while also increasing the plasticity of the ink.
4 Add a thinner to dilute the original ink to meet the requirements of the ink color.
5 Adding a bright paste increases the brightness of the ink.
Offset inks require the following characteristics:
1. The transparency of the ink is high. When the ink is applied as a uniform film, the clearer the background color of the substance that is required to withstand the ink film is, the higher the transparency is required for the ink. There are three manifestations of ink color on paper:
(1) In the form of solid and dot, the dot and the ground (ie, 100% dot) selectively absorb and reflect the sun's complex light, and the color is presented.
(2) The juxtaposition of the monochromatic dots is superimposed and superimposed: the two independent dots are juxtaposed or superimposed on each other to present a color on the paper.
The juxtaposition of 3 stacked dots: that is, the dots of two colors overlap on the paper to display the color. Green and hue are displayed when overprinting such as yellow and cyan.
2. The pigment particles of the ink are required to be fine. Especially the beautifully printed album. Calendars, landscape paintings, etc., which require high precision, require fine particles of ink, and fine pigment particles can print beautiful printed products.
3. The offset strength of the offset ink is required to be strong. The tinting strength is an amount representing the color intensity or concentration of the ink. For an ink of the same hue, the tinting strength depends on:
(1) The dispersion of the pigment on the binder. The higher the dispersion, the stronger the tinting strength.
(2) depends on the content of the pigment. The higher the content, the stronger the tinting strength.
4. Offset inks are required to have lightfastness. The color of the offset ink is required to have light resistance under the action of sunlight and light. The degree of fading and easy discoloration of the ink after being irradiated by light is as slow as possible, and the printed products of outdoor advertising are most likely to fade after being exposed to the sun. The color changes are yellow and red. The color changes of green and black are relatively slow, and the fading and discoloration of yellow and red colors are solved. It is very important to improve the quality of printed products.
5. The color efficiency of the offset ink is required to be high. Color efficiency is a comprehensive indicator of the color difference and gray level of the ink. Offset inks require that the hue of the color be pure, not color cast, and no mottle.
6. The chemical properties of offset inks should be stable. The color of the ink changes under the action of some chemicals. Especially the acid, alkali, salt and oxidant will react to the color of the ink, and it is easy to change color. Therefore, offset inks are required to have good chemical stability.
Offset printing is a way of printing with water, and offset printing inks must have water resistance and emulsification resistance.
Offset printing should be done with water. The PS version of the wetting powder should be added to the bucket. Offset wetting powder has the following characteristics:
1 can fully wet the PS layout and reduce the surface tension. Contains surfactants, wetting agents, surfactants.
2 has the ability to clean to add acidic substances.
3 has a very good non-lipid ability to add gum arabic.
4 can stabilize the pH value to put buffer solvent.
5 can adapt to different climate changes to add moisture absorbent. Therefore, the PS version of the wetting powder is a high-tech product with a variety of chemical components, requiring the ink to have stable chemical properties.