Flexographic printing has been favored by many printing companies due to its high speed, low production cost, and consistent color consistency of batch products. However, the standard requirements of cigarette printing are high, which puts high requirements on the quality control of cigarette marking.
The quality control of cigarette label printing includes three steps: the detection of raw and auxiliary materials, the control of production process, and post-press processing. This article focuses on the quality control of soft-printed soft-label cigarette packs.
l Inspection of raw and auxiliary materials
Detection of raw and auxiliary materials is the premise of printing. Without qualified raw and auxiliary materials, it is difficult for Henan Golden Mango Printing Co., Ltd. Huang Guangwei to produce high-quality prints. The printed raw and auxiliary materials mainly include paper and ink.
1) Detection of paper
(1) Whiteness The whiteness of paper should be more than 85%. If the paper is yellow during dyeing, blue will affect the hue of the finished product.
(2) The tension of the tension paper must be stable, and the paper with unstable tension will be misprinted during the printing process.
(3) The tearing degree of the tearing paper must be qualified, and the tearing degree which is too low can easily cause a paper break under a large printing tension.
(4) The paper with low stiffness is difficult to be collected when it is cut and closed after printing, which can easily cause flying paper.
(5) The water content of the web of water content is generally about 6%. The paper with high water content will be deformed too much after printing and drying, which will affect the overprinting; the paper with low water content will easily cause after the printing is cut. Static electricity.
2) Ink detection
(1) Saturation It is advisable to use a little ink for scratching test, and then measure the colorimetric value with a colorimeter to judge whether or not it is acceptable.
(2) Viscosity The viscosity of a flexo ink determines a lot of printability of the ink. If the viscosity is too high, ink transfer difficulties may occur. If the viscosity is too small, the ink layer may not be thick enough.
(3) Drying speed The ink with fast drying speed will dry out when the printing plate is still in contact with the paper in the future, causing the cable to be stenciled and the dirty version appearing in the field; the ink that dries too slowly remains in the oven after the paper passes through the oven. The dry ink will get dirty after passing through the paper guide roller again.
2 production process control content
The control content of the production process should include the following aspects:
(1) Overprint. The requirements for overprinting of smoke labels are relatively strict. Printing should meet the requirements of higher standards than the national standards: the main part is less than 0.15 ram, and the minor part is less than 0.25 mm. Because the design of the cigarette label is beautiful, a slight error in the overlay will affect the appearance.
2) The ink bar. Flexo printers tend to produce ink sticks when printed on cigarette labels. The ink sticks not only affect the printing quality, but also affect the aesthetic appearance of cigarette packaging. The production of ink bars may be caused by the following reasons: a. Gear engagement is not good; b. Machine vibration; c. Improper pressure adjustment; d. Improper use of media. The operator can start from these four aspects, carefully investigate and find out the reasons. A high-strength plate material of about 2era can be widened at both ends of the plate to reduce the above-mentioned factors and eventually eliminate the ink bars.
3) Hue of spot color inks. Whether the color of the printed matter of the smoke label and the color of the proof is attached depends largely on the hue value of the spot ink, and is represented by L, a, b, E. L represents the brightness of the spot ink. A positive value of L indicates that the color is brighter than the spot color, and a negative value indicates that the color is darker than the proof. a represents red, a positive value indicates that the color is redder than the proof, and a negative value indicates greenish. b stands for yellow. A positive b indicates that the color is yellowisher than the sample, and a negative value indicates bluish. E represents the total color difference value, and E is required to be 3.5 or less.
(4) Barcodes. If the bar code is very different from the proofs, the reader of the mall cannot recognize the type and price of the product. The bar code must be printed with light pressure, insist on frequent testing, and often contrast. If the value is outside the plus or minus 24, change the plate immediately.
(5) The layout is neat. Smoke label printing requires a clean layout, no dirty spots, ink spots, printing pressure is appropriate, real. The Lg version has no eyelid phenomenon. The network cable is rich in layers. Small, clear text, clear lines, no distortion.
6 wear resistance. The cigarette label prints are packed at a high speed on the packaging machine. If they are not to be scratched, they must have a certain degree of abrasion resistance on the surface. It is advisable to take a soft label and tear it into two pieces, rubbing it together and rubbing against each other. If scratches do not occur 20 times, it means that the wear resistance is very good.
3 Postpress Finishing
1) Cutting. After finishing the printing on the printing machine, the papers should be sorted and arranged according to the size of the rules, and the papers with the same rules should be picked up and put together, and every 1,000 pieces of paper should be cut. In the cutting process need to pay attention to a. The knife is sharp. If the working time is too long, the knife edge is worn bluntly, and the edges of the product cut out are hairy. The new knife should be replaced or the raw edges should be ground with sandpaper. b. Whether the blade has a wound. The edge of the product cut with the "I95 cutter" has a score line, not only the shadow D is packaged in cigarettes but also the appearance of the product D.
2) Organize. The cut tobacco labels should be placed separately with or without defects. No faulty cigarettes should be directly over-weighed to check whether their number is correct: If there is a faulty cigarette, a separate challenge will be made to pick out the defective product.
3) Packing or packing. If there is residual odor remaining after finishing the printed matter, it must be left for a period of time before the odor disappears and then it is packaged or packaged. For slightly odorous products, apply a breathable kraft paper instead of a plastic bag to seal the package.
In short, if we want to produce exquisite printed matter, quality control work must be conducted at all levels, and all specific tasks must be coordinated and coordinated. As long as every aspect of the process is done, it will be able to produce qualified prints.
Author: Huang Guangwei
Reprinted from: Print World
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