In modern society, customers have higher and higher requirements for the quality of printed matter. As packaging and printing, appearance quality is particularly important, and it can even directly influence the decision of customer orders. Therefore, many printing companies have also taken the improvement of product specifications as an important task. As a customer service department providing quality inspection equipment for printing manufacturers, the author has long discussed with the quality inspection department of the printing manufacturer on quality issues. The following is just a discussion of the wear resistance of the ink layer:
Instrument, friction tester, color density meter 1. Friction tester requirements:
* The friction table uses a rigid plastic body with a surface roughness of 6.3 seconds or less and has a device for fixing the sample.
* The friction body adopts two pieces of rubber of 8mm, an area of ​​50-53Hs, an area of ​​25x50mm2, and a distance of about 45mm.
* Friction speed: 43 ± 2 strokes/minute, stroke of about 60mm.
* Load 20±0.2N
2. The color density meter has an accuracy of less than or equal to ±0.02D. The American X-rite company's 500-point optical densitometer can measure the CMYK four-color density at the same time with an accuracy of 0.001D.
Test conditions* The rubbing paper is a 80 g/m2 clean offset paper with a width of 50 mm. According to experience, office A4 printing paper can meet this requirement.
* The number of friction criteria is 40 back and forth.
experiment procedure
1. The sample cut to a certain size is fixed on the friction table. The area of ​​the layer to be tested is larger than the area of ​​the friction body. Generally, the size of the sample is 300×55 mm, and as far as possible, the sample with a relatively uniform color is used to facilitate measurement.
2. Determine the color density of the ink layer to be polished on the sample, and measure the average value at three points. The color density with the highest medium density in the four colors should be taken as the measured value.
3. Fix the friction paper on the friction body and gently place the friction body on the sample to be ground.
4. Set the number of friction (40), open the friction tester back and forth friction 40 times, stop taking the sample.
5. Measure the color density on the most heavily rubbed ink layer and also measure the average at three points.
Test results The ink layer abrasion resistance = D/D was calculated as follows. ×100%
Where: D. - Average density before rubbing:
D-average density after rubbing.
GB7706-87 stipulates that the abrasion resistance of the decorative print ink layer should be ≥70%. This standard applies to the paper decoration prints of the letterpress printing process and is not suitable for plastic film prints. This indicator can effectively guide the printing plant to control the ink layer. When the wear resistance is low, the production process can be adjusted as soon as possible to reduce a large number of unqualified products. At the same time, the quality of the product can be graded according to this parameter.
In the printing of cartons and cigarette packs, the control of the abrasion resistance of the ink layer is particularly important. Due to transportation, handling, etc., the product will cause the ink layer to fall off, seriously affecting the appearance, and ultimately affecting the user's consumption, and may even cause user complaints. In actual production, the manufacturers who control the abrasion resistance of the ink layer can be roughly classified as follows:
1. The friction tester and spectrodensitometer equipment are all in strict accordance with the requirements of the national standard. Most of these manufacturers are powerful manufacturers, and they can control the wear resistance of the ink layer well.
2. Only the friction tester can carry out the abrasion resistance test. According to the degree of change of the sample before and after the friction, the comparison is performed, but the wear resistance cannot be specifically quantified. At present, such manufacturers account for the majority, and most of their customers can also accept.
3. No test equipment, experience in the production to master the wear resistance. That is, through visual inspection and hand touch, the wear resistance can be controlled to a certain degree, but the dependence on people is great. Such manufacturers also account for a certain number.
With the continuous advancement of science and technology and the intensification of market competition, not only digital printing and digital inspection technologies have become possible, but many printing companies have also realized the importance of digital printing. Digital printing and inspection technologies have received unprecedented attention. All this is a sign that domestic printing technology is moving in the direction of digitization.
Instrument, friction tester, color density meter 1. Friction tester requirements:
* The friction table uses a rigid plastic body with a surface roughness of 6.3 seconds or less and has a device for fixing the sample.
* The friction body adopts two pieces of rubber of 8mm, an area of ​​50-53Hs, an area of ​​25x50mm2, and a distance of about 45mm.
* Friction speed: 43 ± 2 strokes/minute, stroke of about 60mm.
* Load 20±0.2N
2. The color density meter has an accuracy of less than or equal to ±0.02D. The American X-rite company's 500-point optical densitometer can measure the CMYK four-color density at the same time with an accuracy of 0.001D.
Test conditions* The rubbing paper is a 80 g/m2 clean offset paper with a width of 50 mm. According to experience, office A4 printing paper can meet this requirement.
* The number of friction criteria is 40 back and forth.
experiment procedure
1. The sample cut to a certain size is fixed on the friction table. The area of ​​the layer to be tested is larger than the area of ​​the friction body. Generally, the size of the sample is 300×55 mm, and as far as possible, the sample with a relatively uniform color is used to facilitate measurement.
2. Determine the color density of the ink layer to be polished on the sample, and measure the average value at three points. The color density with the highest medium density in the four colors should be taken as the measured value.
3. Fix the friction paper on the friction body and gently place the friction body on the sample to be ground.
4. Set the number of friction (40), open the friction tester back and forth friction 40 times, stop taking the sample.
5. Measure the color density on the most heavily rubbed ink layer and also measure the average at three points.
Test results The ink layer abrasion resistance = D/D was calculated as follows. ×100%
Where: D. - Average density before rubbing:
D-average density after rubbing.
GB7706-87 stipulates that the abrasion resistance of the decorative print ink layer should be ≥70%. This standard applies to the paper decoration prints of the letterpress printing process and is not suitable for plastic film prints. This indicator can effectively guide the printing plant to control the ink layer. When the wear resistance is low, the production process can be adjusted as soon as possible to reduce a large number of unqualified products. At the same time, the quality of the product can be graded according to this parameter.
In the printing of cartons and cigarette packs, the control of the abrasion resistance of the ink layer is particularly important. Due to transportation, handling, etc., the product will cause the ink layer to fall off, seriously affecting the appearance, and ultimately affecting the user's consumption, and may even cause user complaints. In actual production, the manufacturers who control the abrasion resistance of the ink layer can be roughly classified as follows:
1. The friction tester and spectrodensitometer equipment are all in strict accordance with the requirements of the national standard. Most of these manufacturers are powerful manufacturers, and they can control the wear resistance of the ink layer well.
2. Only the friction tester can carry out the abrasion resistance test. According to the degree of change of the sample before and after the friction, the comparison is performed, but the wear resistance cannot be specifically quantified. At present, such manufacturers account for the majority, and most of their customers can also accept.
3. No test equipment, experience in the production to master the wear resistance. That is, through visual inspection and hand touch, the wear resistance can be controlled to a certain degree, but the dependence on people is great. Such manufacturers also account for a certain number.
With the continuous advancement of science and technology and the intensification of market competition, not only digital printing and digital inspection technologies have become possible, but many printing companies have also realized the importance of digital printing. Digital printing and inspection technologies have received unprecedented attention. All this is a sign that domestic printing technology is moving in the direction of digitization.
Source: China Design Printing Network
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