Security ink performance and printing points II

3. Photochromic security ink

Under sunlight, the ink changes from colorless to colored, but it can be reduced to a colorless security ink after removing the light source. The surface of the ink is discolored due to sunlight, and it is also substantially discolored by ultraviolet light. At present, several kinds of daylight-activated color-changing anti-counterfeit inks that have been successfully developed in the country have their anti-counterfeit characteristics: under the sunlight, they have a discoloration effect, and can change from colorless to violet, blue, yellow, etc., and can also be designed to change from colored to colorless. .

The advantages of photochromic inks are easy identification and good anti-counterfeiting performance, which have been widely used. The disadvantage is poor offset printing and embossing.

4. Magnetic security ink

Magnetic anti-counterfeiting inks are anti-counterfeit printing inks made of magnetic powder materials (cobalt oxide and iron oxide, etc.) as a functional component. It is the most commonly used anti-counterfeiting ink, and its outstanding feature is its deep appearance, simple detection instruments, and many anti-counterfeiting applications such as bills and certificates. Magnetic inks are characterized by two kinds of characteristics and non-characteristics. The so-called characteristic magnetic ink means that the magnetic powder in the ink contains a specific magnetic signal, while the non-characteristic magnetic ink means that the magnetic powder in the ink does not contain a specific magnetic signal and is only magnetic.

Magnetic ink In addition to bank and postal use for magnetic ink alphabet recognition, there are also readers, also known as optical scanners, which are devices that use optical principles to recognize alphabetic symbols. Another major use is for printing tapes, shopping cards, meal tickets, IC cards, and visiting cards on credit cards. Magnetic ink is used for anti-counterfeiting packaging. It is mainly printed in a certain position of the packaging with magnetic ink, and is detected by special means to achieve the purpose of anti-counterfeiting. The printing method is generally flat printing and embossing.

5. Visual color security ink

Visual color change security ink is a kind of high-tech security anti-counterfeiting ink, which can be printed by traditional engraving and gravure printing. It does not need complicated or extra testing equipment to distinguish between authenticity and fakeness. It is suitable for banknotes, trademarks, securities, packaging and printing. Visually discolored anti-counterfeiting inks are well concealed and difficult to decipher. They are developed for the rapid development of color reproduction technologies such as laser scanning color separation machines and color copying machines.

The principle of visual discoloration security ink is: When the viewing angle is changed by 60 degrees, it will produce two distinct colors, the first color is seen in total reflection, that is, the color seen at a viewing angle of 90 degrees, when When twisting 60° to a viewing angle of 30°, the first color is cancelled and the second color is strengthened.

6. Pressure-sensitive security ink

Pressure-sensitive anti-counterfeit inks are inks that can appear in color under pressure or friction. It is made by adding special chemical agents or color changing substances to the ink. Colored or invisible graphics printed with this type of ink, when rubbed or pressed with a hard object or tool, a chemical pressure change occurs or the microcapsule breaks down the dye and the color appears (red, blue, black, Green, purple, yellow, etc.) The color of the display can be selected according to the user's requirements and the design is memorized.

7. Anti-flood security ink

Anti-cure and anti-counterfeit inks are inks that have a color-developing chemical reaction to chemical substances used for conversion. Ink-printing invoices and the shading of all securities are printed with anti-alteration inks. When shading liquids are encountered, these shadings disappear or change color to reveal traces of alteration.

The principle of anti-counterfeiting ink anti-counterfeiting is as follows: 1 The pigments that can fade by encountering erasing spirits or other correction fluids, such as some basic dyes, can be printed with shades of the securities amount column. (2) Use a linking material such as biphenol, which can be discolored by erasing chemicals or some other chemical substances, to make anti-alteration inks. The cheque writing column printed with this ink is discolored or appears to be "waste" if it encounters eradicators or other correction fluids.

Third, the anti-counterfeiting ink in the printing need to pay attention to the problem

1. Many anti-counterfeiting inks are colorless inks, that is, they are colorless or white on the prints. Therefore, before printing such inks, ink rollers, ink fountains and ink knives must be cleaned to avoid imprints on the prints. Anti-counterfeiting effect.

2. Many anti-counterfeiting inks have poor alcohol resistance, such as fluorescent and thermal inks. Therefore, when using such inks, it is best not to use alcohol dampening.

3. Due to the restriction of raw material properties, many anti-counterfeiting inks in offset printing will have poor ink properties compared to ordinary inks. Therefore, it is imperative to increase the number of hard copies and strengthen product inspections in order to prevent ink color differences from affecting product quality and anti-counterfeit effects.

4. As the direct irradiation of 254nm UV light will harm human skin and eyes, when using short-wavelength fluorescence, product detection must use a detection device with a protective device, so as not to affect the health of the body.