Letterpress printing technology of the hottest pha

2022-07-25
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Letterpress printing technology of pharmaceutical label products

pharmaceutical label is an indispensable product identification of drugs. It can be said that it is also an ID card of pharmaceutical products and an important production process in the packaging and printing process. The main contents of the pharmaceutical label shall generally include: product name, adaptation to symptoms, production date, production batch number, specification, quantity, precautions, shelf life, dosage, usage, storage environment requirements, manufacturer name, etc. Product labels are printed in monochrome, or overprinted or overprinted in multicolor; Some are printed with offset paper, others are printed with coated paper and other self-adhesive paper. From the perspective of health and safety, the printing quality control of medical labels is a very important technical link. Therefore, the instructions in the product layout must be clear and the printed color must be accurate and consistent. It can be seen that medical labels should have the requirements of easy identification and good anti-counterfeiting effect. A considerable part of medical labels are printed by traditional letterpress printing technology. The author has also printed medical label products in clinical production practice in the past, and has personal experience in letterpress printing technology of medical product labels. This article talks about the experience of process technology control based on the practice of letterpress printing process

rational design of printing colors for medical label pages

medical labels generally adopt neutral series colors, and the printing pages with cooler colors can give patients a sense of peace and restlessness. The design of light red, golden, red and gold printing pages can make patients have the psychological feeling of restoring their vitality, Yang, health and vitality. The blue and silver layout can give patients a sense of security. Although Mei Lan, the color of printing plate, developed earlier in the field of fluorine materials, it can also color according to the differences of drug use characteristics. For tonic and nutritional drugs, the printing layout is mainly designed in gold, bronze, coffee or red, with other colors as appropriate. Analgesic, sedative, sleeping, hypotensive and cardiovascular drugs should be mainly green and blue. The insect repellent is packed in white with other light colors. The labels of anti-inflammatory cold medicines such as cough relieving, phlegm eliminating, cooling and detoxifying granules are generally printed in green. The reasonable design of the printing color of medical labels can make patients feel safe and get better curative effect

accurate ink allocation based on the change principle of three primary colors

the purity of printing color of medical label is the basic requirement of product quality. Therefore, how to carry out accurate ink allocation is a very important technical link. According to the change principle of the three primary colors, except for the gold silver color (the substrate is the material of aluminum spray paper), any color can be mixed and blended by using different proportions of the three primary colors. For example, the three primary color inks can become approximately black after being mixed and blended in the same amount. Three primary color inks can be mixed with different proportion of white ink to form light gray inks with different hues. If the three primary color inks are mixed according to various proportions, they can be mixed into a variety of intermediate colors or multi colors with different hues, but their hues prefer the primary colors with a large proportion. If the two primary color inks are mixed in equal quantity, they can be adjusted into standard intermediate color; After mixing the two primary color inks in different proportions, they can be matched into a variety of intermediate colors with different hues, but their hues tend to be primary colors with large proportions. In addition, any color of ink, after adding white ink, its hue will appear brighter. On the contrary, after adding black ink, its hue becomes dark. Whether the method of blending ink is appropriate directly affects the color quality of printing. Therefore, when mixing ink, we should first analyze the excellent phase according to the original, and determine which kinds of ink should be used to mix properly. For example, to adjust lake blue ink, it can be preliminarily determined by visual inspection and practical experience. White ink is the main color, malachite blue is the auxiliary color, which should be slightly added. If it needs to be darker, it can be slightly added with magenta blue. As long as the main color is determined, other colors are auxiliary colors, which should be added gradually and stirred evenly. Then, use two pieces of paper (the same as the printing paper) to apply a little of the adjusted ink on the surface of one piece of paper, and use the other piece of paper to scrape it until it is roughly close to the thickness of the printed ink layer, and then compare it with the original to see if it is appropriate. When comparing the sample, you should compare the thin and light parts of the ink layer of the paper scraping sample to see more accurately. When adjusting ink, you should also master a principle, that is, try to use less ink of different colors, that is, if you can use two kinds of ink, you should not use three kinds of ink to adjust, so as not to reduce the gloss of the ink. On the other hand, the ink color of scraping sample should be slightly darker than the primary color, so that the printed color sample can be accurate or close. After the ink color of small samples is adjusted, they can be adjusted in batches according to their respective ink proportion

some technological measures to improve the printing quality of label products

1 pay attention to the technical control of paper cutting process. The accuracy of paper specifications directly affects the overprint accuracy of products. Because of different machine structures, the positions of the front gauge and the pull gauge are not the same. In this way, if the edge of the paper is not cut squarely enough, and there are inclined edges or wavy edges, it will cause inaccurate overprint. This requires that the edges of the paper must be cut into right angles and straight lines for the products with glue convex combination, and there must be no beveled edges or wavy edges. In order to improve the cutting accuracy of the paper, the cutting thickness must be strictly controlled, because the thicker the paper stack, the softer the paper, and the more severe the paper surface deformation when the paper presser is pressed down. Therefore, the less the cutting thickness of each stack, the more conducive to improving the cutting accuracy of the paper. In addition, the blade edge should be kept sharp, and the appropriate blade angle should be selected according to the hardness of the paper, which is also an important measure to improve the cutting accuracy

2 pay attention to the reasonable selection of the bottom support of the printing plate. The characteristics of the plate base material of the relief printing press with circular flattening structure have a great impact on the overprint accuracy and ink quality. The traditional wooden bottom support is not solid, squareness, flatness and stability are poor, prone to bow and deformation, and the printing quality is difficult to guarantee. Therefore, relief printing should use solid, flat, square and stable aluminum or cast iron and other metallic materials, which is a reliable guarantee to improve the overprint accuracy and ink quality

3 pay attention to the rational use of paper. Paper is very sensitive to the temperature and humidity changes of the external environment, especially the newly produced paper, which is most prone to expansion and variation due to the temperature and humidity changes, resulting in inaccurate overprint of the product. In order to reduce the chance of this bad situation, the newly produced paper usually needs to be stored for about half a year after it is transported back by the printing plant, so that the paper can be put into use after its characteristics are relatively stable, so it is not easy to have overprint problems. In addition, it is also beneficial to the registration of products by hanging the paper and placing the cut paper in the printing workshop for several days to balance with the temperature and humidity of the printing workshop for a period of time

4 pay attention to the selection of appropriate printing plates. Letterpress printing process adopts copper plate, zinc plate, resin plate and other plates. Due to the different characteristics of printing plate materials, there are also obvious differences in their printing suitability and printing quality. According to the conditions of ink affinity, ink transmission, gloss and pressure effect, resin plate performs best, copper plate takes second place, and zinc plate performs worst. If the printing quality of dots is considered, the printing quality of dots on copper plate is better, and the dot expansion rate is the least. Therefore, according to the characteristics of products, we should reasonably select plates for printing, so as to better improve the printing quality of products

5 pay attention to the reasonable arrangement of printing color sequence. Reasonable arrangement of printing color sequence is an important measure to improve printing quality. Reasonable arrangement of printing color sequence should be considered from these aspects, namely: arranging printing color sequence according to the characteristics of substrate; Arrange the color sequence according to the difference of printing machine structure; Arrange the color sequence according to the different graphic structure of the printing layout; Arrange the color sequence according to the color characteristics of the original; Arrange the color sequence according to the difference of ink characteristics; Arrange color sequence according to ink drying characteristics. This method can reduce wear and tear, arrange printing color sequence scientifically and reasonably, and improve production efficiency and product printing quality

6 pay attention to the lining process. Lining is the medium to realize pressure and imprint transfer. Its characteristics also affect the registration and ink quality of products. Therefore, the deformation coefficient of the lining material should be smaller, and the material should be neutral and hard. At the same time, the thickness of the lining must be determined in strict accordance with the technical parameters of the equipment specifications. In addition, the lining must be tight and tight, and there must be no virtual looseness and bulge. It is forbidden to make repeated patching or hollowing on the lining, so as to prevent inaccurate overprint and ghosting when the workpiece is small or unstable

7 pay attention to adjust the appropriate printing pressure. The printing pressure should be adjusted evenly and moderately. Excessive pressure is easy to stretch and deform the printing sheet, resulting in inaccurate overprint. Therefore, the appropriate printing pressure should be adjusted, and the printing pressure should not be biased, so as not to make the edges of the printing plate rough and enlarged

8 pay attention to the overprint production cycle of the product. After the printing of the previous color or several colors of the printed matter, those that can be overprinted should be overprinted immediately, so as to avoid stretching and variation of the printed matter due to too long delay, resulting in inaccurate overprint quality

9 pay attention to prevent the printing products from sticking. When medical label products are printed by relief process, when the paper surface gloss is good and the paper is acidic, which affects the drying and printing of the ink layer, the ink supply is large, the ink drying speed is slow, and the semi-finished products are stacked too high, it is easy to cause the water level in the product sink to be rubbed and dirty on the back automatically controlled by a water level controller. The solution is to adopt the "deep ink thin printing" process for printing, that is, to darken the ink hue to make the printing ink layer thinner. In this way, it can not only meet the printing ink color requirements, but also reduce the chance of dirt. In addition, you can add some dry oil in the ink to dry the ink layer in time; Add some anti adhesion agent in the ink to make the ink layer on the surface of the printed product difficult to transfer; The surface of the printing ink layer shall be properly dusted to prevent the surface ink layer from transferring to the back of the printing; The stacking amount of printing semi-finished products shall be appropriately reduced, and the semi-finished products shall be hung in small stacks by using the drying rack

10 pay attention to prevent the printing plate from being pasted. When the printing pressure is uneven or the particles of the overweight ink are too coarse, the fluidity of the ink is poor, and the paper surface has powder falling, roughening, and the height adjustment of the inking roller is inappropriate, as well as the poor contact between the inking roller and the inking roller, it is easy to cause the plate pasting phenomenon. Therefore, corresponding measures should be taken for adjustment

11 pay attention to prevent the ink color on the printing plate from crystallizing. When too much dry oil is added to the ink, the ink layer on the surface of the print is excessively dried to form a glass surface, which makes it difficult for the overprinted ink to adhere to the bottom color of the print. Even if it can be printed, the ink color will only show obvious blooming, which is the phenomenon of ink film crystallization. To prevent the printing ink film from crystallizing, we should strictly control the amount of dry oil and try to shorten the overprint production cycle. For semi-finished products that have crystallized, add some soap chips to the overprint ink. The method is as follows: first mix the soap crumbs with resin oil to

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