Failure caused by ink printing process and its treatment

The prints left on the prints are formed by ink. The ink is the colorant used for printing and is the main raw material for printing. The ink is crucial for the quality of the print. When the ink properties are not suitable for printing, it will cause a series of processes. Failures severely affect the progress of production and the quality of products. The printing operator must change some of the properties of the ink to suit the needs of the printing, but some malfunctions are caused not only by the ink, but also related to other factors, so the printing operator must carefully analyze the correct treatment. This article discusses the failures caused by the ink printing process and the treatment methods, hoping to be helpful.

First, the imprinting is slow

Phenomenon and Cause: After the imprint is transferred from the printing plate to the paper through the blanket, it is generally required to be dried in about 10 hours to facilitate the post-color printing or finished product inspection. Once the imprint has dried, this will not only make the next color impossible. Overprinting, but also easy to make the back of the print dirty. The dryness of the blot has three factors: oxidized conjunctiva, paper absorption, and moisture evaporation. We must master the operation and prevent it in advance. The common causes of slow-drying are the following:

(1) Paper pH is 6 or less.

(2) The PH value of the bucket is 3 or less.

(3) The layout of the water is large and the ink is too large to cause serious ink emulsification.

(4) The workshop temperature is low. Relative humidity is higher than 75%.

(5) Absorption of paper is poor.

(6) There are too many auxiliary materials such as ink varnish and detackifier in the ink.

(7) The amount of dry oil is too small.

Approach:

(1) In order to prevent the print from appearing slow-drying, the height of the printed matter should be reduced, fluffing loose paper piles, and the air penetration of the semi-finished product can allow air to infiltrate the stacked paper, shortening the time for oxidation and conjunctiva.

(2) If the printing is urgently needed, use the original printing plate for dry oil overprinting. The formula is 70% for VERI oil and 30% for dry oil.

(3) In order to prevent unfavorable drying, add appropriate amounts of dry oil, dry oil consumption: winter more than summer, after the color than the previous one more place, dilute the ink more than did not dilute the ink more.

Second, not color

Phenomenon and reason: Ink is added with too much dry oil or semi-finished products are stacked for too long, resulting in too fast drying to cause vitrification on the surface of the blot, the blot surface is too smooth, loses adsorption capacity, and the latter color cannot be printed. This failure is common in full version of the field, especially yellow (ink) or line prints.

Approach:

(1) Prevention is the main method. Add appropriate amount of Veoli oil, Kangbang, Magnesium carbonate powder and other auxiliary materials to the yellow ink that easily produces vitrification, to make the surface conjunctiva rough or extend the drying time.

(2) If the vitrification phenomenon has already occurred and the latter color is not printed, if the number of products is small, a soft cloth and magnesium carbonate powder can be wiped gently on each surface of the ink film, and then a color is set. Larger quantities can be printed while cauterizing alkali water.

Third, the back of the dirty

Phenomenon and reason: Back sticky refers to the semi-finished product or finished product entering the delivery pile, the back of the ink is dirty on the next sheet. The cause of back sticking is.

(1) The surface of the paper is too smooth.

(2) The ink is too thin.

(3) Layout surface water and ink.

(4) The color quality of the ink is too light.

(5) The printing pressure is too light.

Approach:

(1) In the printing process, there should be no water, big ink, or large ink. Control the layout water, darken the ink, and reduce the ink fountain ink volume. If the water content is reduced to produce a greasy or mushy plate, clean the water roller or replace the new water roller, or properly strengthen the acidity of the water bucket solution and put some gum arabic.

(2) The ink is adjusted too thin and easy to stick on the back of the dirty print. New ink or some new ink should be transferred to increase the viscosity of the ink.

(3) The use of pale complex ink is commonly used in the deployment of light red, light blue, light tea, light gray ink, and should be deep-tuned to improve its color quality, to avoid printers from feeling too light, in order to achieve the hue of the sample. The requirement to artificially increase the amount of ink to be delivered causes the ink layer to be printed too thick to produce a dirty backside of the printed product.

(4) During the printing process, the rubber roller must ensure sufficient printing pressure when transferring the paper to the paper, so that the ink is completely transferred on the surface of the blanket, and the back of the printed material is prevented from getting dirty.

IV. Powdering

Phenomenon and Cause: Ink pulverization refers to the fact that after the semi-finished product or the finished product is dried, the ink layer cannot be well combined with the paper surface, and the surface of the pigment particles will fall off as a result of slight friction. This pulverization phenomenon is related to the properties of paper and ink, in addition to the high acidity of the water bucket medicine and the presence of too much surface active material. Common ink powdering has the following reasons:

(1) The adhesive force of the ink is too small and the surface of the paper is relatively smooth, so that the ink layer and the paper surface cannot be well combined, resulting in the ink layer being wiped off from the paper surface.

(2) The ink is too thin, the linking material is easily absorbed by the paper, a large amount of the linking material penetrates into the paper, which promotes the separation of the linking material and the pigment in the ink, causing the pigment particles to float on the paper, and the pigment loses the linking material. Adhesion, the degree of its connection is reduced, and it does not adhere well to the paper surface, resulting in falling off.

(3) The used ink is emulsified seriously, which not only reduces the viscosity, drying speed, and increases the penetration. More importantly, the emulsified ink conjunctiva does not combine well with the paper surface, the adhesion is poor, and the film is firm. Very poor, slight rubbing will cause the film to break and fall off.

(4) Coated paper is made by coating the base paper. The paint and base paper have strong absorption, and the paper is thicker, can absorb a large amount of linking material, and the coating surface is smooth and the pores are very fine. It is possible to inhale the pigment together and act as a filter layer, causing the pigment particles to float on the paper and fall out of the package due to lack of binder.

Approach:

(1) No printing paper with strong absorptivity (absorbency less than 30 seconds), otherwise it must be printed with resin ink with strong adhesion.

(2) Add appropriate amount of No. 0 varnish or adhesive to enhance the adhesion of the ink to the paper surface.

(3) Control the emulsification of the ink, and the water consumption of the layout should be small. The PH value of the water bucket solution is often measured and adjusted to the required value. The dry oil is added with the use, and the ink emulsification is reduced so that the drying time can be grasped.

(4) Fine products that have been pulverized can be treated by glazing or filming.

Five, ink pan color

Phenomenon and reason: Ink flooding is the change of hue of ink, and the color changes, which causes the printed product to lose its due artistic value. Commonly there are pan-black, pan-blue, blue and yellow. The yellow ink and transparent yellow color disappear, and the pan-color caused by the heating of semi-finished products or finished products. The causes of the above drawbacks are:

(1) The ink pigment itself is not stable.

(2) Acid dyes flooded after infiltrating the ink.

(3) Oxidation fever reaction.

Approach:

(1) When oily gold-red ink is used, the pigment powder reacts with iron to produce a chemical reaction, and the hue is very easy to blackish. The resin ink is used instead, so as to avoid pan-color phenomenon.

(2) Tianlan ink will be reddish on the paper a few days later, and the ink color will look deeper than the original. This phenomenon should be noted that when encountering batch printing of bulk products, the formula of ink color must be consistent. Do not arbitrarily change, so as not to cause product inconsistencies.

(3) Malachite blue, pale blue ink met chromic acid water bucket liquid, the ink is easy to yellow, can use white potion.

(4) Daylight illumination can fade the finished product, which can be solved on printed paper surface or film.

(5) During semi-finished or finished products, during stacking process, it is easy to generate a great amount of heat, and there is a lack of oxygen in it. The time is longer and the product will become hot and dark. It should be mainly prevention, and the product should not be stacked too high, and it should be guaranteed 4 - Ventilate once in 6 hours to speed up the flow of air between the sheets, helping them spread heat and shorten the time for oxidizing the conjunctiva.

(6) Reduce the use of Cobalt Drying Oil (ie, 402 Red Dry Oil) because the red dry oil tends to darken the hue of the ink when heated.

Six, ink through the India

Phenomenon and reason: The ink part of the print penetrates into the back of the paper, and there are obvious imprint patterns or oil stains on the back of the paper, especially for products that require double-sided printing. Affect the quality of the product, resulting in product printing through the printing, in addition to the paper itself is too thin or transparent, the common reasons for ink penetration are as follows:

(1) The ink is too thin and contains too much of the binder material. A large amount of binder material is absorbed by the paper and penetrates the back of the paper.

(2) There are too many non-dried binders in the ink. Too many non-drying binders will slow the oxidative conjunctiva on the surface of the paper, and the penetration drying will accelerate. A lot of the binder will seep into the paper and print through to the back. .

(3) The ink is printed too thick and is too slow to dry. It also causes a large amount of the binder to penetrate into the paper and print through to the back.

(4) The oily pigments contained in the ink are dissolved in the binder. During the printing process, the pigments are printed in the paper along with the binder and printed on the back of the printed product.

Approach:

If there has been a printout on the printed products, there is no way to remedy the situation. Only prevention is done in advance to prevent the occurrence of print-through.

(1) Ink is properly added to No. 0 varnish to increase its viscosity.

(2) Do not use non-dry oil as the linking material, and reduce the proportion of non-dried or highly permeable excipients.

(3) Increase the color value of the ink, make the ink layer thinner, and accelerate drying.

(4) If the pigment is oil-soluble, it is better to use resin ink to print.

Seven, print gloss

Phenomenon and reason: The printed matter is a reproduction of art reproduction, which should be bright in color, distinct in structure, have a strong sense of texture, sense of space, and material sense. On the contrary, the printed matter will lose its due value. The common reasons that affect the gloss of printed products are as follows:

(1) Low-grade ink is used for printing, and the gloss of the product is poor (except for low-grade products).

(2) The surface of the paper is rough, and the larger the fiber gap is, the stronger the absorption ability of the linking material is. After the ink is transferred to the paper, the linking material is absorbed by the paper fibers in the unconjuncted condition, and most of the ink remains. The particles attach to the surface of the paper, thus making the product dull.

Approach:

How to make the printed products have a better luster, the actual operating experience tells us that the print product luster