Faults caused by the hottest ink printing and thei

2022-08-14
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Faults caused by ink printing and treatment methods

the imprint left on the printed matter is formed by ink. Ink is the colorant for printing and the main raw material for printing. Ink is very important to the quality of printing. When the ink performance is not suitable for printing, it will cause a series of process faults, which will seriously affect the progress of production and the quality of products. The printing operator must change some properties of the ink to meet the needs of printing, but some faults are not only caused by the ink, but also related to other factors, so the printing operator must carefully analyze and correct treatment. This paper discusses the faults caused by the post printing process of ink and the treatment methods, hoping to be helpful

I. slow drying of imprints

phenomenon and reasons: after the imprint is transferred from the printing plate to the paper through blanket, it is generally required to gradually grow into a company that mainly deals with membrane water treatment business and dry it within about 0 hours, so as to facilitate post color printing or finished product inspection and delivery. Once the imprint is slow drying, it will not only make the next color impossible to overprint, but also make the back of the printed matter very easy to get dirty. The drying of imprinting has three factors: oxidation conjunctiva, paper absorption and water evaporation. We must correctly grasp the operation and prevent it in advance. Common reasons for slow drying of imprinting are as follows:

(1) the pH value of paper is below 6

(2) the pH value of the bucket is below 3

(3) large water and ink in the layout cause serious ink emulsification

(4) the temperature in the workshop is low and the relative humidity is higher than 75%

(5) poor absorption of paper

(6) too many auxiliary materials such as inking oil and adhesive remover are mixed into the ink

(7) the amount of dry oil is too small

treatment method:

(1) in order to prevent the slow drying of printed matter, reduce the height of stacked printed matter, shake the paper stack, and ventilate the semi-finished product to make the air penetrate into the stacked paper and shorten the time of oxidation and conjunctiva

(2) if the print is in urgent need, use the original image text printing plate for dry oil overprint, and the formula is Weili oil 70% and dry oil 30%

(3) to prevent adverse drying factors, add an appropriate amount of dry oil. The amount of dry oil is: more in winter than in summer, more in the latter color than the former, and more in diluted ink than in undiluted ink

II. Phenomenon and cause of chromatic printing failure

phenomenon: excessive dry oil is added into the ink or semi-finished products are stacked for too long, resulting in too fast drying, resulting in vitrification on the imprinted surface. The imprinted surface is too smooth, losing adsorption capacity, and the latter color cannot be printed. This kind of failure is common in the full version field, especially in the Yellow Version (ink) or line pattern prints

treatment method:

(1) prevention first, add an appropriate amount of auxiliary materials such as Weili oil, kangbang, magnesium carbonate powder, etc. to the yellow ink that is prone to vitrification in advance to make its surface conjunctiva rough or prolong the drying time

(2) if the vitrification phenomenon has occurred and the latter color cannot be printed, if the number of products is small, you can use a soft cloth dipped in magnesium carbonate powder to gently wipe on each surface ink film, and then set the next color. If the number is large, you can set the color while covering caustic soda and water for printing

III. phenomenon and cause of dirty back:

dirty back refers to that the back of semi-finished products or finished products is dirty by the ink on the next print sheet after they enter the paper receiving pile. The reasons for sticking dirt on the back are:

(1) the paper surface is too smooth

(2) the ink is too thin

(3) the layout is big in water and ink

(4) the ink color quality is too weak

(5) the printing pressure is too light

treatment method:

(1) do not have the phenomenon of large water and ink during the printing process. Control the moisture of the layout, darken the ink, and reduce the ink volume of the ink bucket. If greasy or paste occurs after reducing water content, clean the water roller or replace it with a new one, or appropriately strengthen the acidity of the bucket potion and put some Arabic gum liquid

(2) if the ink is adjusted too thin, it is easy to stick to the back of the printed matter. Replace it with new ink or add some new ink to increase the ink viscosity

(3) the use of light multicolor inks is common in the deployment of light red, light blue, light tea and light gray inks. It is advisable to tone them deeper to improve their color quality, so as to avoid the printer from artificially increasing the ink output in order to meet the requirements of the sample hue because the ink color is too light, resulting in the ink layer printing too thick and the back of the print is sticky and dirty

(4) during the printing process, when the rubber drum transfers pictures and texts to the paper, it is necessary to ensure sufficient printing pressure, so that the ink can be completely transferred on the surface of the blanket, so as to prevent the back of the printed matter from sticking dirty

IV. phenomenon and cause of chalking

ink chalking refers to that the ink layer cannot be well combined with the paper surface after the semi-finished product or finished product is dried, and the pigment particles on its surface fall off like powder due to slight friction. In addition to the high acidity of the water bucket solution and too much surfactant, this pulverization phenomenon has a lot to do with the properties of paper and ink. Common reasons for ink chalking are as follows:

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

(2) the ink is too thin, and its binder is easy to be absorbed by the paper. A large amount of binder penetrates into the paper, making the binder in the ink separate from the pigment, causing the pigment particles to float on the paper, and the pigment loses the adhesion of the binder, and the degree of its connection is reduced. The initial loading method is mainly that the ordinary exchange machine drives the transmission system to load, so it cannot be well attached to the paper, causing falling off

(3) the ink used is seriously emulsified, which not only reduces the viscosity, drying speed and increases the penetration, but also more importantly, the emulsified ink cannot be well combined with the paper surface after the film is formed, and the adhesion is poor, and the firmness of the film is extremely poor. A slight rub will break the film and fall off

(4) coated paper is made by coating on the base paper. Both the coating and the base paper have strong absorption, and the paper is thick, which can absorb a large amount of binder. In addition, the surface of the coating is smooth, and the pores are very fine, so it is impossible to absorb the pigment together, which plays the role of a filter layer, resulting in the pigment particles floating on the paper and falling off due to the lack of wrapping of binder

treatment method:

(1) do not print products with coated paper with strong absorption (absorption is less than 30 seconds), otherwise it must be printed with resin ink with strong adhesion

(2) add an appropriate amount of No. 0 inking oil or adhesive to enhance the adhesion of the ink to the paper

(3) control the emulsification of ink and reduce the water consumption of the layout. Often measure the pH value of the water bucket solution and adjust it to the required value. Add the dry oil as you use it, and reduce the emulsification of the ink to facilitate the control of the drying time

(4) fine products that have been powdered can be solved by glazing or coating

v. ink discoloration phenomenon and reasons: ink discoloration refers to the change of oil ink color phase and color, which makes the printed matter lose its due artistic value. The common ones are golden red discoloration, azure discoloration, malachite orchid and pale blue discoloration. The disappearance of yellow ink and transparent yellow luster, as well as the discoloration caused by the heating of semi-finished products or finished products. The reasons for the above disadvantages are:

(1) the ink pigment itself is unstable

(2) the acid potion diffuses after penetrating into the ink

(3) oxidation heating reaction

treatment method:

(1) when using oily golden red ink, the pigment powder will react chemically with iron, and the hue is very easy to blacken. Use resin ink, which is called to avoid the phenomenon of color bleeding

(2) Tianlan ink will turn red after being printed on the paper for a few days, and the ink color looks darker than the original. This phenomenon should be noted that when encountering batch printing of bulk products, the modulation formula of the ink color must be consistent, and cannot be changed at will, so as to avoid inconsistent product hue

(3) Malachite orchid, light blue ink meets chromic acid water bucket solution, the ink color is very easy to turn yellow, so you can use white potion

(4) sunlight can fade the finished product, which can be solved by polishing or sticking film on the printed paper

(5) semi finished products or finished products are easy to generate great heat during the stacking process. The intermediate test items are: tension, contraction, twists, low cycle and high cycle fatigue, crack expansion, fracture mechanics test and anoxia. If the time is a little longer, the product will heat and darken. Prevention should be the main. The stacking of products should not be too high, and ventilation should be guaranteed once an hour to accelerate the air flow between papers, Help it diffuse heat and shorten the time of oxidizing conjunctiva

(6) reduce the use of cobalt drying oil (i.e. 402 red drying oil), because the red drying oil is easy to darken the hue of the ink after heating

VI. phenomenon and cause of ink through printing

part of the printing ink penetrates into the back of the paper, and there are obvious imprinting patterns or oil stains on the back of the paper, especially for products requiring double-sided printing, which is more harmful. The quality of the product is affected, resulting in the through printing of the product. In addition to the paper itself being too thin or transparent, the common reasons for the through printing of ink are as follows:

(1) the ink is too thin and contains too much binder, and a large amount of binder is absorbed by the paper and penetrates into the back of the paper

(2) there are too many dry binders in the ink. Too many dry binders will slow down the oxidation conjunctiva on the surface of the paper, and the penetration drying will accelerate. A large number of binders will penetrate into the paper and be transparently printed on the back

(3) the ink is printed too thick and dried too slowly, which also makes the binder penetrate into the paper and penetrate to the back

(4) the oily pigment contained in the ink is dissolved in the binder. During the printing process, the pigment is transparently printed into the paper together with the binder and transparently printed to the back of the print

treatment method:

if there is through printing on the printed product, there is no way to remedy it. Only take precautions in advance to prevent the occurrence of through printing

(1) properly add No. 0 inking oil into the ink to increase its viscosity

(2) do not choose non drying oil as binder, and reduce the proportion of non drying or permeable auxiliary materials

(3) improve the color value of the ink, make the imprinted ink layer thinner, and accelerate the drying

(4) if the pigment is oil soluble, it is best to use resin ink for printing

VII. Phenomenon and reason of printing gloss

printing is the reproduction of artistic reproduction. It should be bright in color, clear in layers, and have a strong sense of texture, space and material. On the contrary, printing will lose its due value. Common reasons that affect the gloss of printed products are as follows:

(1) low grade inks are used in printing, and the gloss of products is poor after color formation (except for low-grade products)

(2) the paper surface is rough, and the larger the fiber gap is, the stronger the absorption capacity of the binder is. After the ink is transferred to the paper, the binder is absorbed by the paper fiber without film, and the remaining pigment particles of the ink are attached to the paper surface, so the product is dim

treatment method:

how to make the printed products have better gloss from the samples of other inspection items? Use the random sampling method to select the gloss from the samples that pass the dimensional deviation and appearance quality inspection. The actual operation experience tells us that the gloss of the printed products can be obtained from the following aspects:

(1) the gloss of the ink itself is the most basic element. When printing high-end fine products, High grade quick drying bright ink should be selected for printing to obtain the best gloss

(2) when printing, dry oil is properly added to the ink to help the ink surface form a good film, so that the product can obtain a proper gloss. To correctly grasp the performance and dosage of red and white dry oil, the type and dosage of dry oil have a certain impact on the gloss. No. 402 red dry oil is mainly composed of cobalt titanate, and its drying effect is to oxidize the conjunctiva on the surface

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