Traditional wine, cigarettes and food packaging use offset printing, in order to improve the contrast and gloss of the packaging surface, so that the packaging is more colorful, usually gold, silver or anodized aluminum foil, silver method. With the rapid development of high technology, companies have to establish their own image and improve the visibility of their products. They not only reform the process but also plan to pack. The screen-printing of UV light-stained matte inks on gold and silver card paper made the paper packaging noble and elegant and magnificent, resulting in a brand-name effect, and played a positive role in the promotion of the product.
First, the production of positive pictures is suitable for screen printing paper packaging box to textual description, there are ingredients, site and its Chinese-English comparison, the box is the main highlight of the main product name, is on behalf of the product patent Trademark. Here are some suggestions for the practical problems encountered by our company in mass production:
1. Due to the thick ink layer of screen printing, no subtle levels can be expressed. Therefore, we use Curves in Photoshop to make appropriate adjustments to the subtle levels of the image. Generally, the dot level increases by 1% to 2% to compensate for the loss of 1% to 5% high light dot levels in the printing process. Letters and lines must be thickened in half. If they are too thin, the printed lines will be broken due to the loss of the subtle levels in the process of printing. If they are too thick, they will be blurred due to the extrusion and diffusion of the ink.
2, matte etching positives The negatives are based on the die-cutting blades, 4mm~6mm from top to bottom, right and left indentation lines to avoid the effect of impact force during die-cutting, so that the matte peels off and fades, affecting the quality and aesthetics of printed products. .
3, in the convergence of multi-color overprint, the positive film can not touch the line film, should be based on the characteristics of the original ink and ink coloring mechanism, the best line pressure line, so that it is easy to overprint, so that printed products are not leaking, high rate of qualified products.
4. The gold-leaking or frosted lines on the frosted etched plate must be thick, preferably 1 mm to 2 mm. Because the lines are too thin, the corridors are not clear, they are not prominent enough, and disconnection will occur. Too rough will affect the visual effects.
5, text and frosted etched yin and yang to register the printing method to bring great difficulties to the mass production, in order to improve the finished product ready, either text printed directly on the matte, or directly printed on gold, silver card paper. Since the average cost of paper in a wine box is about 1 yuan, the cost is bound to increase. In addition, the color ink and the etching ink are superposed on a large area, the effect is not obvious, and only the ink can be wasted and the fastness of the ink can be reduced.
6. When bar codes, small texts, patterns, and large-area on-site color printing are used, the accuracy of the printed products should be divided and printed. That is, bar codes, small texts, and patterns are printed on the fine mesh of high nets, and printed in the field on the coarse nets of low meshes. This ensures that barcodes, small texts are clear, smooth, and free from distortion, and the fine details of the patterns are not lost, and the thick field can be guaranteed. Strong sense of three-dimensional.
Second, the choice of screen and copying due to UV light solid matte (fine, medium, coarse sand) ink particles larger, in order to improve the ink over the net performance, production often choose a smaller mesh coarse mesh printing. The number of meshes is high and the obtained prints are fine; the mesh number is low and the resulting prints are coarse.
Photoresponsive film thicker, the screen requires a longer exposure time in order to make the photo-resist layer completely hardened, at the same time, the development time appropriate lengthened in order to develop more fully.
Other color inks are determined according to text and line thickness. General bar code, small text with 300 to 350 mesh, a large area with 180 to 250 mesh.
Third, the choice of paper According to the requirements of customers and the use of the product to choose paper, according to the cost level choose to use gold, silver paper or gold, silver paper. The so-called gold and silver cardboard are vacuum polyester aluminized papers coated with glass cardboard or white paper by surface coating. The surface smoothness and stiffness of the cardboard are better than those of the board, but the cost is also high.
The thickness of the tissue paper (250 g, 300 g, 350 g) and the thickness of the backing paper (250 g to 350 g of white board, small corrugated or large corrugated board) were selected depending on the use of the product. General wine box and carton face paper commonly used 350g gold, silver paper, wine box paste back commonly used 300g white paper, carton paste back commonly used small corrugated or large corrugated to increase strength and stiffness.
According to the customer's requirements, choose the color of the paper and the transition of gold and silver. But no matter what kind of paper must have high gloss, high brightness, smooth surface, no blistering, no wrinkle, good tensile and flexural strength, toughness, good adhesion fastness of aluminized film, no fading, etc. .
4. Proofing and proofing is the inspection of the quality of plate making, and it is also the key to determine the printing suitability of inks such as curability, adhesion and rheology, and the correctness of correcting characters and patterns. Only samples confirmed by the customer can be put into mass production.
5. The printing and drying ink should be fully stirred before use, and an appropriate amount of thinner (less than 10%) can be added during the mixing to ensure that the ink is moist and can be printed on the machine after mixing. To keep the mesh open, wipe it with a cleaning agent. The viscosity of the ink is too high, sticky board; too small, no three-dimensional feeling, the effect is not obvious. After the printing is finished, the screen should be cleaned with special washing net water so that the production can be turned over for reuse. The ink needs to be sealed immediately after use. Since the ink contains a photosensitizer, direct sunlight should be avoided during the printing process.
After printing must be dried by ultraviolet light. Because UV ink is composed of pigment, photosensitive resin, and photoinitiator, major resin has unsaturated double bond. Under the action of initiator under the action of UV light, polymerization occurs to form macromolecule polymer, ie, the light-curing conjunctiva is dried. . UV curing is not complete, the ink fastness is reduced, the surface hardness is also low, the hand film is touched; the light and solid is excessive, due to the damage of the coating layer of the backing paper, the ink layer is not resistant to folding, and the ink is out of ink, and even appears. Deformation of the paper causes back-to-back difficulties in the post-processing process. That is, the backing paper and the backing paper are not tightly adhered, uneven, wrinkled, or open, affecting the quality and appearance.
Six, after the process of processing at a certain temperature, the paper and paste the back of paper (white paper, corrugated) with adhesive paste together, this is the paste back process. Since the surface of the gold and silver (paper) paper is coated with an aluminized film and aluminum is an amphoteric metal, at a certain temperature, a chemical reaction occurs between the acid and the base, so that gold or silver is originally refracted. Glossy detached aluminum particles gradually become compounds that lose their lustrous brilliance and cause discoloration of printed products. Therefore, the backing adhesive must be neutral, and the compounding temperature should not be too high.
The paper and backing must be stored under the same temperature and humidity. Generally, the temperature is controlled between 18°C and 25°C, the relative temperature is controlled between 55% and 65%, the water content of the paper is stable within a certain range, and the paper deformation is controlled. At a minimum, the processing environment at the printing site and the post process is stabilized so that the backing process can be smoothly performed. Otherwise, the amount of paper deformation will be different. The back of the paper will not be even, discounted, blistering or open, affecting the quality of printed products, or even causing scrap.
In order to emphasize the contents of the high-end box, to make the product more eye-catching, strongly highlight the three-dimensional sense of the product, so that the product has a visual effect of flying gifts, manufacturers often require pressure convex technology, the name of the product on the box convex Finally, after die-cutting, the finished product can be packaged after being glued. When packing, it is best to separate every ten sheets of paper so as to avoid damage to the matte surface during transportation and affect the appearance.
Because imitation metal etching has a strong three-dimensional sense of metal, bright colors, rich layers, high quality, good gloss and other characteristics, it is now ideal for quality packaging. (Luoyang Printing Industry Co., Ltd. Feng Zhishu)
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