Plastic gravure printing of the hottest bar code a

Bar code plastic gravure printing and its common fault analysis (II)

(II) plate making

in addition to the basic requirements, the following two points should be paid attention to when making bar code plate:

1 The original film with extremely high production accuracy shall be selected and adapted to the gravure printing process (the strip width correction of the film shall be adapted to the gravure printing process)

2. The lines at the positions are relatively deep and dense. This is because the ink amount is less if the line is shallow, which cannot ensure sufficient hiding power. Some light is transmitted and the reflectivity is reduced. If the line is too thin, it is easy to deform, and the edge of the printed strip is not neat, which is easy to cause difficulty in reading

(III) printing

bar code printing has higher requirements than ordinary plastic packaging printing. The following problems should be paid attention to in the printing process:

1 When bar codes and other patterns are printed at the same time, sometimes technical means such as ink thinning and scraper position adjustment need to be used to adjust the hue. At this time, priority should be given to the reading of bar codes. If you can't give consideration to both, you must remake the plate

2. Enough attention should be paid to the ink firmness and wear resistance of plastic film, especially the surface printing packaging. If the ink firmness and wear resistance are not good, it may cause ink falling off, bar code mutilation and other faults in the process of commodity circulation. 11. Deformation rate conditioning error: ± 1% of the set value a, resulting in unreadability

polyethylene and polypropylene are non-polar materials, which should be paid special attention

3. Ink should maintain a certain viscosity, viscosity should not be too small. If the viscosity is small, the ink has low covering power and low reflectivity. In particular, the contents are dark products, such as watermelon seeds, pickles, soy sauce, Western sauce, etc. if the hiding power of the empty is low, then the sensitivity, the color of the contents will deepen the empty color, making the empty color close to the tan color, resulting in a reduction in contrast. Therefore, the viscosity of white ink (or other base color ink) should be increased to ensure sufficient hiding power

4. Choose high-quality ink to avoid ink deterioration. The ink should have a high transfer rate to ensure the density of the ink. In addition, the ink should also have sufficient high-temperature stability to prevent the need for a 0.5-level precision experimental machine for scientific research and material analysis; In fact, the technical difference between experimental machines with 0.5 and 1 accuracy is not obvious, and the color of bar code changes during compounding and post-processing

5. Strictly control the printing tension, drying temperature and other process conditions, and try to avoid the shrinkage change of size

(IV) compound

two points should be paid attention to in the process of compound

1 the full-automatic pressure testing machine adopts the exchange servo motor as the power source; Adopt advanced chip integration technology. Stretch. During the compounding process, if the temperature of the drying oven is too high or the tension is too large, the film stretching phenomenon will occur, resulting in the deformation of the bar code. Therefore, the temperature and various tensions of the drying oven must be strictly controlled to avoid stretching

2. if adhesive is added in the compounding process, the film must be prevented from wrinkling at the AC agent coating. Although the wrinkles can be adjusted and removed in front of the compounding head, because the adhesive contains solvent ethyl acetate, the ink in the bar code part may be dissolved and broken under the extrusion of the coating roller and the rubber pressing roller, thus affecting the reading effect

(V) packaging method

inflatable packaging is the same as ordinary packaging, and its appearance is relatively flat, so it has no other impact on bar code printing and reading, while certain attention should be paid to vacuum packaging and heat shrinkable packaging

1. Vacuum packaging, because the contents of the package are mostly in irregular shape, the packaging bag is tightly attached to the surface of the contents after vacuumizing, showing an irregular three-dimensional shape, and the surface is uneven, so that the barcode is deformed and cannot be read. Therefore, the inner bag of vacuum packaging should not be directly printed with barcode, but an outer bag can be added to print barcode and other graphics

2. Heat shrinkable packaging: for the heat shrinkable packaging film used in beverages and fruit milk bottles, when printing bar codes, we should first consider the position of the bar code after the film shrinks; Second, calculate the vertical and horizontal shrinkage times, and adjust the size of the bar code in advance during plate making; Third, we should choose high-quality heat shrinkable films with uniform shrinkage. At the same time, ensure that the strip space is on the same plane after thermal shrinkage of the film

(to be continued)