Causes and Countermeasures of eight common film gr

Causes and Countermeasures of eight common film gravure printing faults

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core tip: This paper comprehensively sorts out the causes and Countermeasures of eight common faults in the process of film gravure printing, so that you can check them when you encounter problems

[China Packaging News] this article comprehensively sorts out the causes and Countermeasures of eight common faults in the process of film gravure printing, so that you can check them when you encounter problems

troubleshooting of gravure printing of eight kinds of plastic film

1. Inaccurate chromaticity

(1) the change of film tension changes the chromaticity of longitudinal printing

each tension control device should be adjusted, such as adjusting the drum brake of the unwinding device; Reasonably set the rotation speed of the roller; Improve the friction of roll surface; Adjust the coiling tension of the rewinder

(2) there is a diameter difference in the printing cylinder, and the diameter of the first, second and third color printing plate cylinder increases or decreases in turn, causing longitudinal printing chromatic variation

the plate should be remade

(3) the regular linear density is insufficient, and the printing chromaticity is longitudinally offset

the sensitivity of the photocell should be adjusted and the paste failure of the printing plate should be eliminated

(4) problems such as non parallel guide rollers, uneven printing pressure and the taper of printing plate cylinder and printing cylinder lead to lateral swing of the film, unilateral relaxation and instability of lateral chromatic registration

targeted adjustments should be made

(5) the adjusting screw at the shaft end of the plate cylinder is loose, causing instability of horizontal chromaticity

the tightness of the screw should be readjusted

(6) if the contact pressure between the rubber roller and the flower roller is too large, the printing pattern will produce a pattern with dual functional characteristics

the contact pressure should be adjusted to make the printed pattern clear

2. There are spots on the printing surface

(1) the ink viscosity is too low or the flow is poor

the viscosity of the ink should be adjusted appropriately to make the viscosity of the ink moderate and the fluidity good

(2) the printing plate depth is too deep or the scraper angle is adjusted improperly

the angle of the scraper should be adjusted appropriately, or the plate should be made again

(3) improper control of printing pressure

should be adjusted appropriately

(4) there is too much static electricity on the surface of the printed matter

static electricity should be eliminated

heating to different temperatures (5) poor drying of ink

drying should be strengthened, such as improving ventilation and drying conditions

3. Blistering on the printing surface

(1) if the ink surface has been skinned, but the internal ink is not dry, once the skinning is broken, volcanic crater like bubbles will be formed, which is mainly caused by rapid drying

low temperature high temperature low temperature drying process should be adopted, and slow drying ink should be used as far as possible

(2) during the printing process, a large number of bubbles will be generated in the ink bucket, and the bubbles will adhere to the printing roller, making the dots of the printed pattern disappear locally or contaminating the pattern

the ink should be kept at a proper viscosity, the drop of the ink should be reduced as much as possible, and a circulating pump should be used to prevent bubbles from entering the ink

4. There is pear peel pattern on the printing surface

if the base color ink is dissolved and partially mixed with the second color ink when overprinting on the dried printing surface, pear peel pattern will be produced on the printing surface

first, adjust the ink viscosity appropriately; The second is to correctly control the drying speed; The third is to reasonably determine the depth of the plate, such as with spring washers

5. Poor ink absorption

when printing the second color of ink on the film of one color when the film surface of the product is multi-color printing, if the absorption is poor, it will make the points after the ink transfer into an independent state, forming an uneven phenomenon that the color of the points is darker and the color of other parts is lighter. This has nothing to do with the amount of ink transfer or disharmony, mainly related to the diffusion of dot ink after transfer

for this, one is to use lagging solvent in the second color ink; Second, try to make the position of the second color ink scraper move close to the printing direction; Third, the ink after the second color should be pressed as gently as possible; Fourth, appropriately deepen the second color version depth; Fifth, use reductant in base color ink; Sixth, appropriately improve the printing speed

6. The printing roller is worn too fast

(1) the scraper is too thick

a thinner blade should be used

(2) the contact pressure between the scraper and the printing roller is too large

the contact pressure of both should be adjusted appropriately

7. The blade wears too fast

(1) the blade is too thin

a thicker blade should be used

(2) the contact pressure between the blade and the printing roller is too large

the contact pressure of both should be adjusted appropriately

8. Version blockage

(1) during the printing process, with a large amount of solvent volatilization, the ink viscosity increases, resulting in the drying and blockage of the ink inside the line

dry ink should be removed regularly

(2) when the position of the scraper is far from the printing roller, the diameter of the plate roller is large or the depth of the plate roller into the ink tank is not enough, the hot air blown out of the machine affects the ink on the surface of the plate roller, which is easy to cause serious blocking

targeted adjustments should be made

(3) impurities mixed in the ink cause blocking

impurities should be removed and ink should be filtered

(4) during the printing process, the operating temperature is too high, resulting in too fast evaporation of solvent in the plate roller line, resulting in plate blockage

try to reduce the operating temperature

(5) the etching depth of the plate roll line is inappropriate

the plate should be remade

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