Ink failure during printing (8-10)

Eight ink powder (flaking)

The ink on a print can be wiped off like a dry powder after drying. The reason is:
(1) A large amount of binder material in the ink penetrates into the paper, causing the ink to lose its tackiness, and the particles of the pigment are too coarse.
(2) The binder in the ink is too dilute or uses too much non-volatile, immiscible solvent.
(3) Absorbency of the paper is too fast and the link material infiltrates too quickly.
Treatment methods and preventive measures:
(1) Adhesive varnish (that is, varnish with higher viscosity) is added to the ink.
(2) Appropriately increase the amount of desiccant.
(3) The pH of the wetting fluid is controlled between 5 and 6 to reduce the amount of wetting fluid.
(4) For the printed products that have been powdered, use transparent glue or varnish to cover them once for better adhesion.

[Related Links]
Now such failures rarely occur. This is mainly due to the increasing production of ink manufacturing technology and the increased awareness of competition in the market. However, there are occasions when deploying some spot color inks. If such failures occur, the best treatment is still to use masks. Varnish cover printing.

[Case 2-13]
A factory used a 100g/m2 offset paper to print the cover of "pupils' manual labor." The background ink was a large area of ​​shallow lake blue. It was mainly formulated with sky blue and white ink. As a result, the printed product experienced a powdering failure and was later treated with oil. it is good.

9. AIDS

In the printing process, the phenomenon that the ink in the solid part of the print is uneven or the ink overflows from the edge of the printed image is called the phenomenon of ink-moistening. The ink unevenness mentioned here mainly refers to the density (refers to the depth) of the unevenness.
The causes of ink-moistening are:
(1) The paper absorbs ink unevenly, especially non-coated paper. This absorption is closely related to the formation of the paper. In poorly-formed paper, the fiber distribution is uneven, and the ink absorption is also non-uniform, and ink bleed is liable to occur. For coated paper, the part that directly absorbs ink is the coating layer. If the quality of the original paper is too poor, it will cause unevenness when the adhesive in the coating penetrates into the original paper layer, and naturally it will also cause uneven ink absorption of the coating layer. Sex.
(2) The viscosity of the ink. If the ink is printed with a low viscosity, the ink film layer is prone to uneven thickness at the outlet of the ink roller, especially for poorly absorbing paper.
To sum up, the method to eliminate the black ink:
a Select the ideal paper.
b Use a suitable viscosity ink.
c To calculate the thickness of the lining, adjust the printing pressure.
[Expert Tips]
The fault is limited. The cable version does not have such a fault, but the blackbody is prone to the fault.


Ten gold, silver ink printing common fault

Offset gold or silver ink is quite different from other offset inks. When offset printing and silver printing are used, two consecutive printing methods or two printing methods are often used to enhance the saturation of gold powder and silver powder and improve the decoration. The effect of printing.

In the case of gold ink printing, the background color is generally printed first. The yellowish or fake gold ink with strong hiding power and similar color to the gold ink can be used. When printing with coated paper or glossy paper, the transparent yellow ink is used for rendering. better. When light yellow or clear yellow or fake gold ink is used as background ink, about 1% of gold ink can be added to increase the gloss of gold ink. If the printing is completed at one time, the process should be compensated during the plate making process. When the yellow plate is produced, the place where the gold is to be printed (slightly smaller than the size of the picture and text) is to be laid in a spot of 50%. If there is no yellow plate on the print, use a warm light color.


In the case of silver ink printing, generally one printing can satisfy the demand for printed matter, but some large-area silver printing products or poorly-printed silver products must be printed twice in silver in order to show a silver luster. There are two methods for the background color. One is the use of a light grey fabric to lay the base, and the other is the use of false silver on a white paper.

Pay attention to the printing operation of gold and silver ink:

(1) Improve the printing quality of the background ink The printing quality of the background ink is the basis for improving the printing quality of gold and silver ink. The background color ink layout should be smooth, the ink viscosity should be large, the ink layer is thick, dryness should be moderate, the background color ink drying should be combined with the penetration and the conjunctiva as well, avoid the crystallization of the underlying color ink layer, properly improve the bottom The tackiness and drying performance of the color ink layer can not only firmly bond with the surface of the printing material, but also firmly adhere to the gold (silver) powder and obtain a good fixing force. The gold color ink is best used black, blue, dark red, purple, dark green ink.

(2) To prevent darkening of gold and silver and de-powdering In order to avoid darkening of gold and silver inks, wetting fluids used for offset printing of silver and silver should not be acidified. Usually, we use:
a Alcohol wetting liquid: isopropyl alcohol 20% peach gum 5% water 5%
b gum wetting fluid: peach glue 15% clear water 85%
In addition, in order to prevent gold and silver ink from coming off in contact with air or other chemical elements,
After the silver ink and other colors, it is overprinted once or overlaminated.


(3) Appropriately increasing the printing pressure and the pressure of the ink roller and printing plate The structure of gold powder and silver powder in gold ink and silver ink is generally a sheet. The transfer performance of gold and silver ink is worse than that of ordinary offset inks. To make the gold powder and silver powder transfer smoothly and evenly to the surface of the substrate, and compaction and flattening, the printing pressure and roller pressure should be appropriately large, so that not only gold can be avoided. , Silver ink exposed bottom and other failures, but also enhance the printing effect of gold and silver ink.


(4) The printing speed should not be too high, and the printing speed when printing silver should not be too high. The speed of the printing press is too high. During the transfer process of gold and silver inks, the phenomena such as stencil printing and lapping are liable to occur. In addition, the speed is too high. The high temperature causes the ink roller to heat up, and the gold and silver inks are oxidized to black and have poor transfer performance.

Table 2-1 Common failures of gold and silver ink printing are listed in the following table: Fault Name Fault Symptom Cause of Failure

Failure Name Failure Symptoms Causes of Failure Methods Stacked gold and silver ink accumulate on the ink roller and are very smooth when rotated. However, the gold and silver ink on the printing plate graphic is not enough, and the product is printed thin and flowery. The liquidity of gold and silver ink is too low, or the storage time is too long. Add a suitable amount of thin varnish to the ink to reduce the viscosity of the ink and improve the fluidity. The ink layer of the printing plate and the blanket is thick, while the product printing ink is thin. The spent gold and silver ink toners are heavy, coarse, and poorly connected, which leads to low transferability and viscosity of gold and silver inks. Too large or too small ink will cause problems in stacking ink. Or the edge of the graphic is spread, the blank word pastes the dead gold, the silver particles are coarse, and the thermal conductivity is high. After the friction, the thermal expansion occurs together with the connecting material, causing the graphic and graphic display to properly reduce the speed, and the wetting syrup suitable for the printing of gold and silver ink is selected. 5%-10% of alcohol powder can be added to the original wetting liquid. After the blot is dried and rubbed gently, the gold or silver on the paper will be wiped off. The viscosity of the gold and silver ink is too low. The drying speed of the blot surface is too slow and the paper absorbs too much. Control the amount of low viscosity varnish; Add red dry oil (do not need to add white dry oil), so that the imprinted fast dry speed is about 15 minutes, completely dry for 3-4 hours, the product is covered, oiled, on Light. The gold and silver inks are not bright, and the silver inks are not printed after being printed on the paper surface. There is no chemical reaction of metallic luster gold and silver powder to make the gloss darken, and the process conditions do not reach the ideal state. The print is not thick. The speed of the machine should not be too fast. The storage time of the ink is about 2 years. It should not be used after expiration. Increase the pressure between the rollers. A large area of ​​printing gold or silver can be overprinted with a light varnish or a film. The printing is changed to a secondary overprint. The hair color of the wool products is not real, and there are light colored plushs. The ink is too thick, the viscosity is large, and the fluidity is low; the water roller is off the hair; the roller is aged. Ink can be added to the right amount of ink and ink additives; the water flannel reversed on the water roller, the use of better printability rubber roller. The underside of the back-adhesive product sticks to the back of the top sheet, and the product makes a flower. Too much auxiliary material is added to affect the fixing speed of the ink, and the ink ink layer is too thick. Increase the proportion of dry oil, so that the ink drying speed; control the amount of ink; can add 5% of the offset printing agent; spray, dry shelves and other methods

Note: The common failure phenomena of gold and silver ink printing are similar to other ink failure phenomena.


[Case 2-14]
A certain unit printed a batch of 128g/m2 off-year almanac of “Qiao Qiao is not contending for the spring”. Its picture is dried plums and magpies, and the background is a large area of ​​silver. The silver ink was printed on the J2108 machine and printed twice. However, compared to the original proofs, silver was not as good as the original proofs. Later, a hard, soft, and soft lining method was used. The printed sample exceeded the original proofs.


[Expert Tips]
Similar to this kind of silver ink printing, if you do not change the lining method and print two silver inks, the first silver ink mark and the second silver ink mark overlap. Therefore, it cannot change the first time. The lack of. The hard and soft lining method has played a complementary role.

[Case 2-15]
A factory prints a 157g/m2 poster on the big bird facing the phoenix. The main subject is the male phoenix. There are many other birds. The background is the imported gold ink. After the gold is printed twice, the total The sensor did not feel bright. Later, the operator used a peach gum wetting fluid, which worked well.

[Expert Tips]
For large areas of gold and silver ink printing, we must pay attention to the texture of gold and silver ink. Otherwise, we will lose the meaning of gold and silver ink printing.





Source: Ke Yin Network

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