1. Failure phenomenon The lines of the printed matter are spread out, the graphics are not clear and complete, and there is a dirty phenomenon in the non-graphic area, and pieces of ink-like substances are also stuck on the blanket. 2. Causes of failure (1) The water absorption area on the printing plate forms an ink absorption center. When the acidity of the fountain solution is too strong, the chemical reaction of the layout accelerates, so that the film cannot support it. In addition, when using a paste containing lead for drying, especially when the amount is too large, the very acidic fountain solution will destroy the drying oil and form a smooth film on the printing plate. Since this film layer generally contains lead phosphate or lead chromate (yellow substance), the entire layout also has a tendency to yellow, because this film layer will hinder the control of wetting, and as a result, the layout is easy to oil . Dirty phenomenon 1. Failure phenomenon There are many ink stains in the non-graphic area of ​​the printed matter. 2. The cause of the fault (1) The embossing force and operation of the printing press will destroy the isolation sensor film on the printing plate. These exposed metal areas will be immediately affected by trace amounts of surfactants, polar substances, and free fatty acids. And, absorbing ink, causing stains in non-graphic areas, destroying the quality of the entire printed product. 3. Solution (1) Add some sticky binder to the ink. Dirty phenomenon 1. Failure phenomenon The printing plate is covered with slight ink color, and transferred to the blanket, and then passed to the printed matter, so that the non-graphic area of ​​the printed matter is also covered with slight color. Although the ink color on the printing plate can be wiped off, it will appear again soon. The color in the fountain solution. This dirty version is caused by the ink or its components floating on the fountain solution or dissolving in the fountain solution. Therefore, floating dirt is sometimes called ink bleeding or water. 2. Causes of failure (1) Floating dirt is more likely to occur when printing coated paper. This is because the surfactant in the paper precipitates, forms an emulsion with the ink, and adheres to the non-graphic area. 3. Solution (1) There should be a long enough storage time after the ink is produced. Our Aluminum Fence product line is fabricated from 6063 series
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The dirty version can be divided into oily and floating. Dirty oil is mainly a phenomenon that the printing plate is easy to feel the ink, which is caused by the poor ink resistance of the printing plate. The scumming is mainly caused by ink, and generally appears more uniformly on the entire plate surface, but the hydrophilic part of the printing plate still has good ink resistance.
Dirty oil can be divided into oily and dirty. Oiling refers to the irregular enlargement of graphics and text, which causes the distortion of printed images and text, and causes the printed dots to be elongated or feathered. Dirty means that ink spots spread over a large area, often appearing in relatively large non-graphic (blank) areas.
Oil phenomenon
(2) The surfactant in the ink or paper layer migrates to the water absorption area.
(3) The acid value of the side binder in the ink is too high (4) The acidity of the fountain solution is too weak, which hinders the protection of the peach film itself.
(5) The acidity of the fountain solution is too strong. During the printing process, the metal of the layout must be decomposed by the acid in the fountain solution to keep the layout clean. However, this effect must be carried out very slowly, so that the glue film on the plate will not be damaged or disappear.
(6) The ink is too thin and too oily (7) The amount of water on the printing plate is not enough (8) The pressure on the plate roller (such as the inking roller) is too high (9) The quality of the printing plate is too poor.
(10) Improper induction treatment in non-graphic areas (11) Improper use of desiccant (12) Poor quality of water roller, improper installation
3. Solution (1) The thickness of the ink layer of the printed matter should be appropriate, not too thick (2) The ink should be thick and the oiliness should be small.
(3) The PH value of the binder used in the manufacture of ink should be lower (4) Properly increase the acidity of the fountain solution (5) Add some lanolin, beeswax, sodium silicate and other materials to the ink (6) Check The quality and speed of printing. $ Page break $
(2) The residual coating left on the printing plate during development is excessive.
(3) Improper de-sensor processing in non-graphic areas.
(4) Poor sizing (5) The connection material is too thin, the ink is too oily and too soft, and the viscosity is insufficient, which causes the plate roller to slip and at the same time makes the water roller dirty.
(6) The yield value of the ink is too high.
(7) The acidity of the fountain solution is too low.
(8) The amount of water on the printing plate is insufficient.
(9) Sticky ink on the water roller (10) The original non-graphic area is dirty.
(2) Increase the acidity of fountain solution (3) Increase the amount of water supply (4) Reduce the content of oil and fat in the ink formulation.
(5) Use thick ink to make the print thinner.
(6) Use fountain solution with relatively high surface viscosity. Otherwise, when the surface tension is too low, due to the effects of water-soluble surfactants in the paper, polar components in the ink, and washable soaps in the fountain solution, between the ink and the water film on the printing plate It is impossible to obtain proper interfacial tension, which may cause dirt.
(7) Reduce the amount of desiccant.
(8) Adjust the printing pressure between the plate cylinder and the blanket cylinder.
(9) Change to quick-drying resin ink. $ Page break $
(2) The viscosity of the connecting material in the ink is too low, and some of them form a fine emulsion of oil in water, forming floating dirt.
(3) Hydrophilic pigments are used in the ink.
(4) The ink is immature, the pigment used in the ink is poor in lipophilicity, and the pigment is not fully wetted by the binder.
(5) When a low-temperature dispersion type binder is used in the resin-based ink and the content of the ink oil is relatively high, it is easy to cause emulsification.
(2) Pigments with good lipophilicity or surface treated with hydrophilic materials should be used in the ink.
(3) The binder in the ink should have good wettability to the pigment.
(4) Reduce the acidity in the fountain solution, and the water supply can also be less.
(5) Add viscous linking material.
During the offset printing process, the dirty version of offset printing often occurs. Now a brief introduction and analysis of the fault phenomenon, fault cause and solution of the dirty version.
April 28, 2024