Gravure technology: printing good Gift Box, only need to control seven points

Gravure technology: printing good Gift Box, only need to control seven points

In the gravure work, process control is a very complicated procedure, and it is also a very important procedure. Improper handling of the process details may have a serious impact on the quality of Gift Box.

Therefore, in order to make good use of the gravure printing process in flexible packaging printing and obtain high-quality printing effects, some details of the gravure printing process cannot be ignored. Here, we will discuss with netizens the handling of some details worthy of attention in flexible packaging gravure printing.

1. Arrangement of printing color sequence

In the gravure printing of flexible packaging, the arrangement of the printing color sequence is very important, and the following rules are generally followed.

(1) The printing color sequence of the printed inks is arranged according to the rules from dark to light, generally black, cyan, magenta, yellow and white.

(2) The printing color sequence of the surface printing ink is arranged according to the rules from light to dark, generally white, yellow, magenta, cyan and black.

(3) The spot color ink is generally arranged before the white ink and after the yellow ink, and can also be arranged after the black or three primary color inks, but generally not between the cyan, magenta, and yellow inks. Typically, no more than 3 spot inks should be used in a print job.

It should be noted that, for patterns with strict overprinting requirements, it is not advisable to add any spot colors between the three mesh palette colors of cyan, magenta, and yellow. For series versions, sometimes to ensure that the ink tank is not replaced during the Gift Box printing process, It is required that the printing color sequence must be consistent. In addition, because the surface printing ink is more vivid than the inner printing ink, it is customary to use the surface printing ink when proofing, but in some special cases, such as the customer provides a color sample, the anti-counterfeiting version needs to be used, and the gold ink or anti-counterfeiting needs to be printed. When using special inks such as ink, it is also necessary to pay attention to the reasonable arrangement and adjustment of the printing color sequence of the printing ink.

2. Scaling and scaling of adjacent colors

In gravure production, in order to compensate for the leakage between adjacent different colors caused by inaccurate overprinting, it is usually necessary to expand and shrink the printed part, also known as trapping or trapping.

When the inks of two colors are in contact, overlap, and tangent, they generally need to be expanded and contracted, and sometimes they must be expanded each other. The overprinting error is compensated by increasing the gap between the two, so as to make the printed matter more beautiful. The principles generally followed for scaling processing are: expanding down but not up, expanding shallow but not deep, and expanding flat networks without expanding on the ground.

The amount of expansion and contraction depends on the characteristics of the printing material, the overprinting accuracy of the printing machine and the different printing methods. Generally, the amount of expansion and contraction of offset printing is smaller, and the amount of expansion and contraction of gravure printing and flexo printing is larger, generally {{0}}.2 0.3mm (depending on the specific requirements of printing accuracy), and the amount of expansion and contraction of similar colors is usually 0.3 mm mm, the amount of expansion and contraction of the opposite color is usually 0.2mm, and it is also required that the printed pattern after expansion and contraction is not deformed.

3. Determination of surface tension

In actual production, the surface of the printed film should be corona treated to ensure that it has a reasonable surface tension. The measurement method of the surface tension of the printed film is generally as follows: use a cotton swab to dip the dyne solution corresponding to the surface tension of the measured film, and coat a liquid film with a length of about 10mm on the surface of the film. If within 5 seconds, the surface of the liquid film film does not shrink or the shrinkage amplitude is small, the surface tension of the film can be considered to be qualified; if the liquid film is completely ruptured or shrunk into a strip with a length of less than 8mm, it can be considered that the film has a good surface tension. Surface tension failed.

4. Determination of the direction of unwinding

During the compounding process, attention should be paid to check whether the compound rolls used are provided by the same designated manufacturer, whether the compound rolls of special materials have special requirements, and also judge whether the unwinding direction of the special films (such as yin and yang films) is correct.

The principle for determining the direction of scrolling is: the first out of the text or the first letter of the word is the first out, the last out of the text or the last letter of the word is the last out; For the head out, the first out below the pattern or the right is the tail out.

5. Determination of ink and adhesive viscosity

In order to get a good printing effect, it is necessary to pay attention to measuring the viscosity of the ink and adhesive during the production process. The measurement method is: after the Zahn cup is filled with the ink or adhesive to be tested, use a stopwatch to measure the time for the ink or adhesive to flow out from the small hole at the bottom of the cup, so as to measure the viscosity of the ink and the adhesive.

In addition, it is also necessary to understand and be familiar with the manufacturer, scope of application and solvent ratio of the selected ink to ensure the accuracy of the measured data.

6. Production of control signs

In order to ensure the overprinting of the printed film is accurate, and to facilitate the smooth progress of subsequent bag making and slitting, it is usually necessary to make some marks on the printing plate for position control and judgment. The following issues should be paid attention to in the process of making control signs.

(1) The production of the cross registration mark: the cross registration mark is generally used together with the bar mark, and the numbers indicate the printing color sequence, which are respectively produced on the printing plates of various colors.

(2) Production of Mark Line (Light Spot Logo): Mark line can play the role of tracking and slitting in slitting and bag making. Generally, the darkest color is used, the width is greater than 2mm, less than 10mm, and the length is generally greater than 5mm.

(3) Production of detection line: The detection line is mainly used to ensure that the film does not deviate laterally during slitting and bag making, and the color is generally dark.

Seven, printing quality control points

The main points of printing quality control mainly include color difference, color registration deviation, ink fastness, defect detection, etc. The basic requirements are as follows.

(1) Color difference: ΔE Less than or equal to 5, ΔH Less than or equal to 1.5 for the spot color part; ΔE Less than or equal to 5, ΔH Less than or equal to 2.5 for the light color part of the hanging net.

(2) Color registration deviation: It is required that the color registration deviation of the main pattern of the biaxially oriented film is Less than or equal to 0.20mm, and the color registration deviation of the secondary pattern is Less than or equal to 0.35mm; the color registration deviation of the main pattern of the non-biaxially oriented film is required to be Less than or equal to 0.30mm, and the color registration deviation of the secondary pattern is Less than or equal to 0.30mm. Less than or equal to 0.60mm.

(3) Ink fastness: Usually, a transparent tape with a width of 24mm and a length of 250px is used to stick it on the printing surface, tear the tape, and observe the ink marks left on the printing surface to judge.

In addition, strobe lights (synchronized lights) can also be used in printing production to observe whether abnormal conditions such as knife lines, stains, missing points, and color registration occur.

The embankment of a thousand miles collapses in the ant's nest. In the process of gravure printing, these small details are often overlooked and cause large quality problems. Therefore, special attention must be paid to these subtleties in gravure production to ensure high quality. D.

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