In the field of anti-counterfeiting printing, paper anti-counterfeiting is ranked first. At present, the commonly used anti-counterfeiting printing papers are mainly as follows, they all have special anti-counterfeiting characteristics

1. Watermark paper

It is embossed, touchable image, barcode, etc. paper. Banknotes use watermark anti-counterfeiting technology. Because watermarks cannot be reproduced with photocopiers, scanners, etc., their anti-counterfeiting effect is highly valued. Nowadays, the application range of watermarking has been expanded to valuable notes, certificates, and even books and periodicals. Watermarking is the use of technology in the paper making process, the required logos, patterns, etc. into the paper, such as installing a pre-designed watermark graphic printing plate on the silk screen, or pressed by a printing cylinder. Due to the difference in the height of the graphics and text, the corresponding density of the pulp is formed into different thicknesses. After the paper is formed, the transmittance of the pulp is different due to the different density of the pulp at the graphics and text.

There are three types of watermarks: fixed watermark, semi-fixed watermark and unfixed watermark. The printing process of the fixed watermark is difficult, and it must be fixed at a certain position on the main body of the banknote, license, certificate, etc., and usually must be accurately matched with the printed text or other anti-counterfeiting measures visible to the naked eye, such as 100 yuan in the position of the watermark There is a fixed watermark of Mao Zedong's head. The distance and position of each group of semi-fixed watermarks are fixed, and each group is arranged continuously on the paper, so it is also called continuous watermark, and it is mostly used for special paper. The fixed watermark is distributed on the full version of the paper or ticket, so it is also called the full version of the watermark. For example, China's third and fourth sets of five yuan, two yuan and one yuan are printed on the full version of the ancient money watermark paper. However, the new version of five yuan has been printed on watermark paper fixed with water fairy patterns.

The anti-counterfeit watermarking paper has developed from the original long-mesh paper to today's highly secure long-mesh paper. Features include:

1) Up to fifteen gray levels, so there are more levels; the thickness of the black watermark area can reach 40μ, which is thicker than the average thickness of 15 ~ 20μ paper, so it has better contrast; and has better Details and watermark clarity.

2) You can obtain additional security measures that are not available with long-mesh paper, such as security threads.

3) Add long cotton fiber to wood pulp to increase the service life of paper. On the rotary screen paper machine, the watermark is formed on the surface of the watermark by fiber stains. The watermark and the paper are formed at the same time, which means that the watermark can be filled into the circular screen mold to form a very clear watermark.

With the development of electronic technology, there is now the launch of electronic watermark paper. According to the British "Times" report on May 3, 1999, a system called "microbus" uses chaos theory to encode data into the background of the file. This "microbus" is invisible to the naked eye, but can be read with a scanner to crack its password. Only the original printing plate can be printed, any precision printing equipment can not copy or can only print some blurry images. According to the development company, it is almost impossible to decipher the "micro-bar" coding system from a mathematical perspective.

2. Security paper with security thread

Refers to placing a gold or plastic thread in the middle of the paper during the papermaking process. The earliest used special metal wire, now use polyester plastic wire, micro letter safety wire, fluorescent safety wire and so on. The shape of the safety thread is straight, wavy, zigzag, etc. According to relevant information, the new version of US banknotes not only embeds a metal wire in the paper, but also miniaturized the text on the line that can only be seen with a high magnifying glass. In recent years, a thermal safety line has also been launched, which is pink and opaque at room temperature. When the temperature of the part is heated with fingers, as long as it reaches 37 degrees Celsius, the miniature printed text will appear locally. There is also a kind of security line-laser holographic security line whose color changes due to different viewing angles.

Put the security thread in the paper, the width of the thread can be as small as 1mm, if put multiple security threads at the same time, the spacing of the thread can be as small as 4mm. The pattern and text required by the user can be printed on the security line. According to the different difficulty requirements of anti-counterfeiting, the printed pattern and text can be made into a hollow or non-stripe void.

The security thread in the printing of banknotes is also the focus of research in various countries: for example, the United Kingdom uses a window-type transmission security thread, France develops a part of the aluminum plating process security line, France develops a part of the aluminum plating process security line, and Finland uses a fluorescent security line, etc. . The biochemical anti-counterfeiting mark is a major breakthrough in the development of anti-counterfeiting technology. Recently, foreign biological research machinery has been successfully developed, which mainly prints a dark note on the self-adhesive label for the purpose of anti-counterfeiting. Digital deformation anti-counterfeiting technology has also been applied in foreign countries. This technology is suitable for any printed matter that requires Arabic numerals. The deformation is realized by a computer, there is no law to follow, and the recognition is also by a computer.

3. Laser anti-counterfeit paper

Laser anti-counterfeiting technology combined with paper makes anti-counterfeiting paper. For example, by using holographic anti-counterfeiting technology and special equipment, the holographic image is made at a specific position of the banknote to improve the anti-counterfeiting performance. Its characteristics are as follows:

1) Because the holographic pattern is made directly on the paper, the plastic information layer is removed, so there is little possibility of being copied;

2) The patterns on the paper can be designed, plate-made according to the requirements of the merchant, and produce different textures and grams of paper (70-400 grams) required by the merchant, such as coated paper, cardboard, cardboard, and can also be like ordinary paper. Perform offset printing, screen printing, etc .;

3) The price is only slightly more expensive than ordinary composite gold and silver cardboard, which is equivalent to one tenth of the price of the holographic anti-counterfeiting trademark, and the labor cost of labeling is eliminated, so it is easy to be accepted by the merchant;

4) After being discarded, it can be weathered in the soil without polluting the environment.

At present, laser anti-counterfeiting paper has played a role in the packaging and printing of certain cigarettes, wine, cosmetics, food, etc. For example: Shengli Oilfield Aluminum Foil Composite Material Factory recently produced a filmless holographic dark anti-counterfeit printing and packaging paper. It has full-page anti-counterfeiting before and after printing. The entire paper can be designed and produced with special or ordinary laser anti-counterfeiting images, with a width of more than 800 mm. The pattern adopts an implicit design. Even if it is covered with multiple layers of ink, it can still be seen clearly. It has an excellent effect on light refraction and does not affect the design and printing theme.

4. Red and blue fiber paper, color dot encryption paper

When making paper, blend colored fibers such as red and blue or colored small pieces (dots) into the pulp, or sprinkle it on the surface of the paper before the paper is unshaped. There is fluorescence reflection under ultraviolet irradiation, which makes the paper with a color different from the paper fiber. The red and blue fiber filaments and colored dots in the pulp are colored fiber and colorless fluorescent fiber. The former can be seen on the paper with the naked eye, the latter and the colored dots must be visible under ultraviolet irradiation. The colors are red, blue, orange, etc., and the shape can be thick or thin, long or short. Fibers and colored dots are generally randomly distributed, so their density varies greatly. In addition to plant fibers, in recent years there have also been metal foils, plastic round small plates mixed into paper pulp for anti-counterfeiting. For example, there is a metal foil that is invisible to the naked eye on the banknotes issued in Italy, and it will make a sound when checked with a special identifier. In addition, the British research used a special fiber to spread into a small piece, and then irradiated with a specific light source from a specific angle to obtain a stereoscopic projection, and stored it in a computer, and then verified the authenticity of the marked projection by checking.

5. Anti-copy paper

One is full absorption type anti-copying paper, which is blue and brown-red on the outside, and the pictures on the paper can only be seen through the light, and its copy is dark. But this kind of paper is not convenient for daily use. The other is to coat a thin aluminum protective layer on the surface of the paper (but does not affect printing). Because the aluminum protective layer can disperse or deflect the light of the photocopier, the copy is black. After copying some copy-proof paper, the words "copy" and "invalid" will appear, which can effectively prevent color copying of important documents. In addition, there are also anti-copy papers that change color or show hidden text when they encounter the light of a photocopier. For example, Fraser Labels has developed a material to deal with color copying. When copying samples such as trademarks with a color photocopier or scanning When the device is scanned, the word "VOID" will be clearly generated, and the logo will be printed in black and white.

6. Paper with trace additives

Using the principle that organisms have a specific reaction against antibodies, a very small amount of antibiotics is added to a certain part of pulp or paper. During the detection, the corresponding specific antibody is used to bind it, and the presence or absence of specific reactions is marked by color development, fluorescence, etc. to distinguish the authenticity.

Seven, chemical encryption paper

Special chemical compounds are added to the pulp or added to the paper surface when sizing the paper. This chemical encryption paper can be colored or fluorescent when coated with specific chemical reagents. Tickets for foreign ball games are printed on this kind of paper. As long as you take a pen soaked with special reagents during the inspection, draw a stroke on the surface of the mark, and it will be displayed in black.

8. Special anti-counterfeiting paper for ionic media

Leading the country's large-scale heavy ion accelerator, super-energy ion media special anti-counterfeiting paper that integrates ion micropore technology and papermaking technology, solves the problem of effective certificate anti-counterfeiting and difficult identification for a long time.

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