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Magnetic printing and magnetic card making

magnetic printing is the abbreviation of magnetic ink printing. It uses magnetic substances such as iron oxide as ink pigments, and completes the production of magnetic recording body through certain printing methods, so that the printed matter has the required special functions. In recent years, with the development of computer technology and networking technology, magnetic printing has been applied in many fields, such as bank passbooks, cheques, ID cards, credit cards, cards, tickets and price lists

1. Basic composition

in magnetic printing, the material constituting the magnetic recording body is magnetic ink

magnetic ink is a special ink, and its basic composition is similar to that of ordinary printing ink, that is, it is composed of pigment, binder, filler and auxiliary materials, but the pigment used in magnetic ink is not pigment, but strong magnetic material. The so-called strong magnetic material refers to a special material that is magnetized when it is inserted into the magnetic field, and can retain magnetism even if the magnetic field is removed. The ink itself is not magnetic before magnetization. The reason why it is magnetic is that the pigment used in the ink formula has the ability to retain magnetism after magnetic field treatment. Of course, there are many factors that affect the characteristics of the magnetic recording layer, such as the magnetism of the pigment, the content of the magnetic pigment in the ink, the thickness of the magnetic film, etc. the experiment shows that the thickness of the dried magnetic film is 10 ~ 20 m. In addition, in order to improve the smoothness and wear resistance of the magnetic film surface, synthetic resin can be used for surface polishing after printing

strong magnetic pigments play a functional role in magnetic inks, and ink binders that are suitable for them play an auxiliary role in printing. The following will be introduced according to the characteristics of materials

2. Magnetic pigments

strong magnetic materials mainly include magnetic elements such as iron (FE), cobalt (CO), nickel (Ni), strong magnetic alloys such as Fe Mo and Fe-W, and alloys with Nias structure such as Mn Al and Mn Bi. The pigments used as magnetic inks are mostly ferrites, that is, inorganic compounds generally represented by xo-fe2o3, in which X is a divalent metal ion. According to the different types of X, they are manganese ferrite, iron ferrite, copper ferrite, etc. Put the above strong magnetic material into the magnetic field, change the magnetic field intensity, and test its corresponding magnetization value, that is, the H-B curve of the strong magnetic material can be obtained. H-B curve is an important curve representing the characteristics of magnetic materials, where OA represents saturation magnetization value, OB represents residual magnetization value, and OC represents magnetoresistance value

the printing density value and hue are often used as evaluation parameters to detect the quality of conventional prints; For magnetic printing, the residual magnetization value and magnetoresistance value of H-B curve are used as the parameters of print quality evaluation. For example, in counting and measuring magnetic recording body printing, the magnetoresistance value of strong magnetic materials should be 20000 ~ 30000a/m, and the residual magnetization value should be 0.08 ~ 0.11t. Therefore, to carry out magnetic printing, we must understand the basic characteristics of strong magnetic materials, reasonably select strong magnetic materials, and determine the formula of magnetic ink, which is the key to obtain excellent magnetic printing materials

common magnetic pigments include iron oxide black (Fe3O4), iron oxide brown (-fe2o3), cobalt containing -fe2o3 and chromium oxide (CrO2)

3. Binder

binder is an important component of ink fluid, DZ - carton perimeter length (CM); Its main function is to give fluidity to solid powders such as pigments, so that they form a slurry fluid after grinding and dispersion, and then dry and fix on the surface of the substrate after printing

the rheology, viscosity, dryness and printing performance of ink mainly depend on the binder. Therefore, high-quality magnetic inks should not only have good magnetic materials as pigments, but also use high-performance binders

the commonly used binders for magnetic inks are vegetable oil (linseed oil) and synthetic resin (alkyd resin)

1. Printing method

magnetic printing used to adopt lithography, relief printing and developing magnetic latent image

with the popularity of various magnetic cards, magnetic printing has begun to adopt gravure printing, printing and other printing methods. In addition, there are special printing, such as forming magnetic images by spraying; High speed printing with non impact device; Magnetic capsule printing and magnetic layer transfer printing

2. Performance requirements

the function of most printing inks is to obtain plane graphics and texts, while magnetic printing uses the special graphics and texts obtained from printing as detection and recording. In addition to taking the magnetic parameters of the ink as the key indicators to evaluate the performance of magnetic ink, we should also pay attention to the printability and ink adhesion. For example, the magnetic ink used in lithography must solve the problem of ink emulsification caused by hydrophilic magnetic materials, because emulsification will make the ink adhere to the blank part, weaken the magnetism of the image and text part, and bring adverse effects to the next magnetic detection and discrimination. Generally speaking, compared with other ink pigments, magnetic pigments have the characteristics of high density and high content. Therefore, it is necessary to ensure that the affinity between binder and pigment is good

in order to improve the printability and ink adhesion of magnetic ink, at present, iron powder and other permanent magnetic substances are mixed with polyamide resin, thermoplastic epoxy resin, asphalt fiber, polystyrene, oxygen (hetero) indene and other resins, and then suspended in aqueous medium in molten or liquid state to obtain developing magnetic latent image ink suitable for high-speed printing

because the magnetic recording material used in the magnetic card has stable physical and chemical properties and good reliability; It is convenient for long-term storage, has good effect and can be used repeatedly; It can be recorded again after eliminating magnetism, with good economy; The reading and writing equipment is simple, small and light, easy to carry and use; Its types and application fields are gradually expanding

1. Classification of magnetic cards

(1) classification by purpose: generally divided into magnetic cards, password cards, prepaid cash cards

(2) classification by production and information reading methods: generally divided into magnetic card and special magnetic card

2. Magnetic card sheet base material and specification

the sheet base material used for magnetic card needs to meet some basic requirements. Considering the use conditions, it should have corresponding physical and chemical properties, and it is required to have good durability. The performance will not change greatly during use and long-term storage

(1) material type: commonly used magnetic card base materials can be divided into plastic base and composite paper base. Plastic sheet based materials require good mechanical properties, stable size, smooth surface, but need to be pretreated; Composite paper-based materials have good printability and do not need prepress treatment, but their comprehensive indicators are far inferior to plastic sheet based materials

(2) performance characteristics of plastic sheet base materials: plastic sheet base can be divided into polyester (polyester) sheet base, cellulose acetate and polyvinyl chloride sheet base according to material composition. Performance comparison of several commonly used sheet based materials

(3) size specification of plastic magnetic card: the international standardization organization has formulated the size specification of plastic magnetic card, that is, ISO specification, which stipulates that the size of standard magnetic card is:

length: 85.47 ~ 85.72mm

width: 53.92 ~ 54.03mm

thickness: 0.68 ~ 0.84mm

ISO standard size of plastic magnetic card

in addition, on the premise of meeting ISO standards, countries have formulated corresponding national standards according to their actual situation. For example, Japan has formulated JIS x6301 standard, which is divided into type I and type II. The magnetic strip of type I card is located on the back of plastic magnetic card; The magnetic strip of the type II card is located on the front of the plastic magnetic card

3. Magnetic card processing technology

(1) production process

design plate assembly, correction, plate making, printing, film coating, magnetic stripe leveling until a certain load can no longer rise, cutting, forming and expansion processing magnetic inspection, degaussing data writing to the final inspection finished product

(2) main production process

magnetic processing and expansion processing are important processes in magnetic card printing processing, including magnetic processing, hot pressing, no need to lay foundation plastic characters and coloring Signature marking processing, etc

① magnetic processing, stick a magnetic strip with a width of about 6mm on the designated area of the magnetic card, and write the necessary magnetic information after leveling, magnetic inspection and degaussing

② hot pressing plastic words and coloring. The surface of the magnetic card is embossed by the hot pressing device to form words such as number and expiration date. Color foil can also be used for coloring processing

③ signature label processing, which is made by silk printing or pasting and hot pressing

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