Smart card printing anti-counterfeiting

The printing plate and the barrel must maintain a certain gap so that the printing plate and the surface of the barrel can only come in contact with the squeegee during printing, and the squeegee passes away. The size of the print gap has a great influence on the print quality. The gap is not properly adjusted and no high-quality products can be printed.

The print gap is too small, and it is easy to generate ink in the direction of the squeegee.

Because the gap is small, it is necessary to increase the printing pressure, so that the printing plate will be slack due to excessive stretching, and the printed text will be out of shape. The graphic size on the barrel is larger than that of the printing plate. Printing gap is generally 1 ~ 6 mm, high printing accuracy, large frame area, tight mesh screen, or surface printing, small value; general printing, large frame area, loose mesh, flat printing, take Great value.

3 printing speed and squeegee angle

The squeegee angle formed by the squeegee and the platen and the speed of the squeegee blade movement should be kept constant. The squeegee angle is generally 45°~90°, and the printing speed is generally 100~300mm/s. The smaller the angle of the squeegee formed by the printing plate and the squeegee, the slower the squeegee moving speed is, and the more ink is pressed out; the smaller the squeegee angle is, the better the squeezing out of the ink is.

Smart cards are also called "Integrated Circuit Cards," or IC Cards for short. It is an integrated circuit chip module with storage, encryption, and data processing capabilities packaged in a plastic base. Smart card slaves can be divided into single-layer cards and multi-layer cards. Single-layer IC cards are produced directly from a single-layer PVC raw material or by injection molding. Multi-layer IC cards can be classified into three types: contact cards, contactless cards, and combination cards, depending on the structure and working method.

1. Printing of smart cards

The printing of smart cards is basically the same as the printing of general magnetic cards. At present, the methods of offset printing and screen printing are mainly used. Offset General printing of high-precision photos, patterns, etc., can reproduce clear dots and very thin lines, its plate making and printing costs are low, text and images are clear. Offset printing machines mainly include special PVC card printers or imported four-color printers. They mainly use UV offset printing inks. The printing is colorful and the graphics are clear. It is suitable for large-volume printing. First printed on PVC card material, and then laminated, punched card, magnetic writing, embossing, etc., but due to offset printing using UV ink, the protective film is easy to fall off. Therefore, a 2mm blank should be left around the plastic magnetic card in the design. It is best not to use fluorescent ink, and sufficient attention should be paid when performing the cutting or processing.

Screen printing has the characteristics of thick ink layer, good hiding power, rich texture, strong light resistance, colorful colors, and good printing adaptability to inks and substrates. Therefore, screen printing is the main printing method for smart cards.

Smart card printing usually uses resin-based thermal curing inks and solvent-based soft-plastic screen printing inks. The selection of inks should mainly focus on the two major elements of strong adhesion and high hiding power. This is also the key for card printing. Adhesion mainly affects the adhesion fastness of the ink and the card substrate, and the hiding power mainly affects the printing quality. Therefore, when adjusting the viscosity of the ink, it is necessary to select a solvent that is more compatible with the ink. To adjust the amount of solvent when the ink is to be controlled, the solvent is too much, the viscosity of the ink is low, and it easily flows to the back of the screen, causing the printing pattern to become thick and thick; and the solvent is too small, the viscosity of the ink is high, and the printing is liable to cause blocking The net makes it difficult to completely reproduce the printed pattern. In addition, during the printing process, the viscosity of the ink will gradually increase as the solvent continuously evaporates. Therefore, it is necessary to pay attention to the fact that the ink on the screen is often pushed, and the adjusted ink is constantly added to make it have a stable viscosity. The color of the ink must be based on the basic color, and the color number of the ink should be as small as possible. Generally, 3 to 4 colors are used to grasp the color. If you use too much ink, it will be more difficult to bring out the ideal hue. In blended inks, there are often a lot of bubbles. Low-viscosity inks will debubble naturally for a certain period of time; high-viscosity ones will require the addition of about 1% defoamer and be well-stirred. The drying time of the ink is related to the size and characteristics of the IC card printing pattern. Generally, the full-page pattern has a long drying time, and the text and small color blocks have a slightly shorter drying time. However, it should be noted that the magnetic card that has just dried is prolonged due to heat, so it must be cooled (usually cooled for about 10 minutes) to print the next color. If it can be used to print cold air, the effect is better. The production quality of screen printing plays a key role in printing quality. Because domestic mesh yarns are not ideal in terms of extensibility and wear resistance, imported nylon mesh yarns are often used. Screen printing generally chooses 150-350 mesh screens, but for gold-silver ink printing, the size of all gold-silver powder particles should be considered when selecting the number of meshes to ensure that they can pass through the mesh aperture. Usually 160-250 meshes are suitable. The network frame is made of aluminum alloy mesh frame. The selection of the frame should pay attention to the flatness of the four sides and whether the frame is distorted. When re-skewing the old frame, use a grinding wheel to grind the frame. Pay attention to check the quality of the screen plate. Make sure that the tension of each screen and each screen is the same. Tension is generally controlled at 14 to 15 N/cm. For the angle of the stretch net, besides some full-version patterns, a 90-degree straight stretch net may be used, and the general pattern may be an oblique stretch net as much as possible so as to avoid sawtooth shapes at the edges of the magnetic card pattern, and to improve the clarity and printing of the graphic and text. quality.

Practice has proved that the stretch angle is more appropriate than 22.5°. The best selection of scraper polyurethane material, its strong solvent resistance, wear resistance, can withstand high temperatures below 90 °C. Scrapers must be ground frequently. During each print, make sure that the blades are normal. The scraper's squeegee angle, pressure, edge sharpness, and smoothness all have a direct impact on the print quality. In addition, poor control of the scraper's squeegee angle, printing pressure, hardness of the squeegee, and printing speed can cause color difference. Failure, therefore, should pay attention to continuously accumulate experience and reasonable control during operation. Magnetic card printing is mainly based on plane screen printing and drum screen printing. Plane screen printing machine is the first mechanical screen printing machine, with a wide range of semi-automatic and fully automatic models. The most prominent feature of the roller screen printing machine is that the printing table is cylindrical. Compared with plane printing machine, roller type screen printing machine has high printing speed and good product quality. However, the operation and precision adjustment are more demanding. No matter what type of screen printer, it is very important to adjust the distance. Network distance is small, because the screen cannot be ejected promptly after the ink passes, resulting in surface contact between the screen and the substrate. It is easy to cause ink bleeding and cause difficulty in drawing ink. The mesh distance is too large, and the screen extends. After being over-relaxed, it will not be easy to recover and it will cause slack. This will cause errors in the printing size and layout, and it will have the greatest impact on overprinting, causing overprinting and other faults. In addition, we must pay attention to adjust the control of a good network distance and the size of the frame, ink viscosity, screen tension between the matching relationship.

As the current screen printing cards generally only print simple text and graphics, they cannot print high-quality color patterns. Therefore, in order to produce large-volume, high-quality magnetic cards, screen printing and offset printing are usually used in combination to take advantage of the advantages of the two printing methods. In general, the large-area coloring part is screen-printed, and the thin line or small-character part is printed with a small offset press to make up for the lack of screen printing. However, because the screen printing is performed through a flexible screen printing, and there is a possibility that the tension of each screen plate cannot be completely uniform, etc., it is easy to cause a certain error between the screen printing magnetic card pattern size and the plate-making film size. Thus, the screen printing and In offset printing, there is a problem of register error. The solution to this problem is mainly to adjust the printing method. In general, screen printing should be used first, followed by offset printing. In this way, the offset can be adjusted according to the actual size of the screen printing. When the size of the cornice is different from that of the trailing edge, the longitudinal size of the offset image can be adjusted by adjusting the blanket of the offset printing press and changing the thickness of the printed liner, and the lateral size can be adjusted according to the actual size of the screen printing. . In this way, the problem of screen printing and offset printing is basically solved.

2. Smart card security printing

As an important information medium, IC cards need to be seriously considered as an important part of the overall system distribution management. The technical treatment of the card body surface is mainly color pattern printing. The surface pattern printing of the IC card mostly uses a lithographic offset process. The characteristics of the offset printing process on the plastic surface not only make the card have artistic appreciation and collection, but more importantly, it greatly improves the precision, particularity and complexity of the production, and increases the difficulty and risk of counterfeiting. Some simple monochrome prints, text, or security inks are also screen printed. In addition, some special signs can also be used, such as fluorescent security image printing, color changing mark, laser engraving signatures and images, micro-line technology, complex holographic image markings, miniature borders, and security background structures.

At present, color portrait PVC card has been widely used. It can not only print different personalized photos of color photos, names, etc. on the card, but also change the previous drawbacks of plastic cards, which are single, easy to forge, easily damaged, easy to open, and not waterproof. Strong, waterproof, good image effects, and versatile features, and can be used to identify a variety of functions such as attendance, access control, and consumption. There are two kinds of PVC color portrait card production, one is the use of thermal transfer card printer directly printed on the surface of the blank card, the cost is higher; the other is the use of color inkjet or laser printer, the content is printed to On the special PVC sheet base, after the laminating method, the finished product is made by hot pressing, punching and punching.

In order to improve the anti-counterfeiting effect of IC cards, there are multi-layer invisible optical cards. It is a major improvement to open-hole photoelectric cards and clear-coded barcode cards. Its structure includes card base, connection coating, information layer and protective layer. , stealth layer and film. Kaki is generally made of PVC, ABS, PET and other plastic materials. The connection coating is generally made of PVC material. It is a special material that can firmly connect the information layer of the powder material with the card base material. And completely through. Carbon powder is mainly used in the information layer, and the optical properties of the infrared absorption performance are greatly different or even different from those of the card base material. The protective layer can be made of a thin PVC material whose function is to protect the information layer and the connecting coating from the invisible layer. The stealth layer can be made of a material that has good transmissivity to infrared rays and low visible light transmittance, such as a stealth ink, a PVC film that transmits deep infrared rays, and the like. Its role is to mask the area composed of information points underneath the invisible layer so that it cannot be discovered visually, thus achieving the purpose of invisibility. The cover film can be made of PVC film, and its function is to protect the invisible layer from being exposed on the outermost layer, thereby improving the wear resistance of the card.

The multilayer hidden photoelectric card can be made of common materials, and the prepared information can be directly printed on the card base material by a laser printer. Finally, the multilayered material is pressed into a card by a heat sealing lamination process to form a security card. This kind of card not only has hidden information layers, it can't observe anti-counterfeit information by naked eyes and has better anti-counterfeit effect, but also has the advantages of wear-resistance, strong anti-bending ability, stable reading card, convenient manufacture and low cost.

Reprinted from: Screen Printing Industry