Dry carbon paper printing technology in anti-counterfeiting paper
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Dry copy paper, also known as disposable anti-counterfeit copy paper and stacked color anti-counterfeit ticket paper, is the fourth generation of high-tech products after ordinary carbon paper, carbon coated paper and carbonless copy paper.
The dry copy paper is white base paper on the front and non-toxic water-based color coating on the back. The product is divided into flat paper and web, suitable for offset printing, gravure printing, flexo printing, screen printing, computer billing, hand invoicing, and roll ticket. It does not need to be padded when used; when writing paper, you can get multiple copies in one copy, and the color is fast, the writing is clear and vivid, can not be altered, is not affected by the weather, and the file has a long shelf life.
The technical problems and related processing techniques encountered in the technical services and investigations of tax-printing companies that use dry-type carbon paper as the carrier in the country are summarized below for reference by tax-printing counterparts.
1. Dry-type copying paper must be well-conditioned before printing to ensure smooth paper feeding, paper feeding and delivery during printing.
In the service process of dry copy paper printing enterprises, it was found that the problems of elongation, curling and tight edges of dry carbon paper affected the printing work. The reasons for these problems were as follows:
1. The dry carbon paper is made by coating, drying, slitting and rewinding the base paper through a non-toxic fatty acid solution and a colored coating. The finished product actually becomes a single-adhesive paper, and the moisture absorption performance of the front and back paper surface. There is a significant difference, that is, the surface of the colored coating is extremely poor in moisture absorption, and the white surface of the base paper is extremely sensitive to moisture absorption, which is one of the main causes of curling and tightness of the paper.
2. Dry-type carbon papers have to be transported over long distances or long-term storage after leaving the factory. Due to the vast territory of China, the climate varies greatly and varies frequently. For example, in spring, the room temperature in Heilongjiang is between 18-20%, and the indoor humidity is 20%. Between 30%. The indoor temperature and humidity in Yinchuan area are basically the same, at 18-20% and 18%-20% respectively. The temperature in the coastal areas and Chongqing and Chengdu is around 15-20 degrees Celsius, and the humidity is as high as 60% to 75%. Since the hygroscopic characteristics of the dry type carbon paper are not suitable for the printing environment of the enterprise, problems such as static electricity and double sheet wrinkles appear in the printing, which brings difficulties to the printing work.
For the above reasons, in order to balance the water content of dry carbon paper with the temperature and humidity of the printing workshop environment, and ensure the high quality of E-brush products, the national tax bill printing companies have very rich experience. For example, the Taxation Center of the State Taxation Bureau of Hebei Province pays great attention to the balance between the original paper and the printing environment. Generally, two or three days before the printing, the thousand-type carbon paper is brought to the workshop to enter the natural balance. For example, in addition to the natural balance of the raw paper into the workshop, the Shanghai Commercial Factory is loaded into the plastic bag after the finished product is placed in the packaging box, and then placed in the packaging box and then transferred to the next page to code, effectively ensuring the dry copy paper height. The quality printing was successfully completed.
Since 2000, he has visited 85 key tax ticket printing companies and related universities and colleges in various provinces, municipalities and autonomous regions in China. The dry copy paper has collected and summarized their advanced experience in prepress technology processing: "Printing environment When the relative humidity is changed by 10%, the water content of the dry paper is also changed by about 1%. Under normal circumstances, the water content of the dry carbon paper changes by 0.15% every time the temperature changes by 5 degrees Celsius. Approximately 0.2%."
Second, dampening solution, printing pressure and printing speed control
Dry copy paper will undergo "quiet" changes in printing, and there are two kinds of kings to perform. First, the paper size changes, that is, the elongation or shortening of the paper in the length direction; the other is the change of the paper on the compression surface, that is, the paper undergoes elastoplastic change in the vertical direction. The reason for these two changes is that the paper is subject to changes in the printing environment (ie, the moisture content of the paper), which causes the paper to change in elasticity. The other is that the paper is subjected to pressure and causes the elastoplastic change of the paper.
In order to obtain the ideal minimum variation, the printing company has analyzed the expansion factors affecting dry carbon paper. Factors such as dampening solution, printing pressure and printing speed must be effectively controlled."
After the paper absorbs water, the volume expands and the size increases. After the water is lost, the size is reduced. Therefore, in addition to properly adjusting the paper to the printing environment before printing, it is necessary to control the consumption of the fountain solution. For the offset press, the elastoplastic change of the dry copy paper is based on the premise that the prints are clearly defined, the layers are clearly defined, the layout is separated from the oil and water of the tape, and the paste is not pasted. If there is a certain range, beyond the scope, the dry carbon paper will lose its elasticity, and the deformation of the paper will not be restored. At this time, the printed surface of the dry carbon paper will be wrinkled, uneven, uneven ink layer and back. The colored coating appears acicular.
For the regulation of the embossing force, the ink of the printed product should be gradually controlled by the purpose of the ink from scratch, the graphic is clear, and the quality requirements are met. Due to the different models, there is no uniform regulation. Many of China's tax printing companies use Hamada's WH47 machine. My service practice survey data proves that the printing pressure scale of the printing company is most suitable when it is positioned at 3-4.5.
Printing speed and printing pressure have an important influence on the printing effect of dry carbon paper. This is mainly because the length of paper staying in the embossing interval is different, and the degree of deformation of the paper is different.
Third, dry copy paper colored transfer coating adhered to the impression cylinder processing technology
The colored transfer coating on the back of the dry carbon paper is mainly a non-toxic acid salt solution and a colored paint. Under the action of the friction between the coated surface and the paper feed roller and the printing pressure, the paper is compressed and deformed in the embossing interval. The surface of the colored coating is powdered off (ie, colored paper powder). Since the falling powder layer contains the wax component, it is not easy to be scattered around the printing cylinder, and the impression cylinder is heated by the pressure, and it is easy to accept the adhesion of the wax, and the time is long and small. At most, the impression cylinder has a coating roller, which causes trouble in printing. At present, there are two solutions. One is a sheet-fed offset printing press, and the anti-adhesive paper is attached to the impression cylinder. The effect is ideal. Under normal conditions, it can continuously print 40,000 impressions. Some units have been mastered, simply do not stick anti-adhesive paper, when printing 6500-7000 prints, manually wipe the drum once. The other is a roll paper offset press with the same method as above. Due to the fast speed and high output, the anti-adhesive principle is used to install an anti-adhesive device under the stamping roller of the form machine to join the high-density sponge. 202 contains hydrogen silicone oil, this method is safe and convenient. In addition, for the process of letterpress printing and page matching on the collating machine, the colored coating is subjected to pressure transfer. The solution is the same as above, as long as the anti-adhesive produced by our factory is attached to the corresponding position of the plate or the pressure roller. Paper, you can achieve non-transfer letterpress printing or coding, the effect is very good.
Fourth, the choice of the bottom page paper matched with dry carbon paper
For the bottom page paper matched with the dry type carbon paper, it is recommended that the computer ticket be neutral 50-65g/m offset paper most suitable, and the minimum is not less than 50g/m (the lithographic hand-invoicing is optional). At present, some factories reduce the computer ticket invoice. The cost is 40-45g/m bottom paper. As a result, the quality of the paper is light, and the bill is not stiff. At the same time, when printing on a web press, it is difficult to find the expansion ratio of the two types of paper due to the different tension control, which causes waste and brings difficulties to the page and the user, because the computer ticket is printed on the tax control machine. Because the stiffness is not enough, it is easy to malfunction. Here, I would like to remind the printing company that the dry carbon paper is a neutral coating material paper, and can not be used together with oily paper and carbonless paper. If there is a matching, a chemical reaction will occur, and the color will not be transferred when copying. At that time, it will cause even greater losses. All ticket printing companies are advised to pay attention to the correct and reasonable selection of neutral bottom pages and supporting papers.
V. Anti-adhesive treatment technology for web printing
When the computer bill is coded, you should pay attention to the following requirements:
When controlling the tension during the production of multi-notes, it is necessary to have an understanding of the shrinkage rate of the respective bill papers during production. When the amount of the bottom sheet paper associated with the dry type paper is different from the dry type paper, the bottom sheet is the same. To be contradictory, you should obey dry copy paper.
The dry carbon paper back coating contains wax components, which is not easy to absorb moisture and damp, but the printed surface is easy to absorb moisture and moisture. The solution to this contradiction is: after printing, the printed products should be stored in plastic bags and then transferred to the matching page. .
Dry type carbon paper is a physical pressure-sensitive transfer color paper, non-chemical coating technology. When printing, a single-sided tape should be attached to the impression cylinder to prevent the colored coating from being transferred to the impression cylinder to affect the coding work. .
Sixth, the printing problem of the color anti-counterfeiting ink
The color-stacked anti-counterfeiting ink was developed by our factory according to the one-time transferability of anti-counterfeit ticket paper. When the bill is invoiced, the handwriting is transferred to the invoice paper surface with the colored transfer coating, and it becomes a double-colored handwriting. It is not easy to detect, only the bright fluorescent characters are displayed under the ultraviolet light, so the authenticity of the invoice can be identified. In the past few years, through the application of tax tickets in more than 10 provinces and cities such as Jiangsu, Xinjiang, Hebei, Shenzhen, the effect has been good.
When printing the anti-counterfeiting ticket, in the southern region, we can add the anti-counterfeiting ink of our factory to the 8# dry oil and red dry oil (the amount of addition is controlled at 3% by weight). If the humidity is high, it can be added appropriately. amount, otherwise appropriate to reduce the amount of printing ink less. In the northwest and northeast regions, the cyp404 white dry oil produced by Tianjin Ink Factory can be added to the anti-counterfeiting ink of our factory. The dosage is not more than 10% by weight, which can promote the good effect of drying the inner and outer layers of the ink layer at the same time. After printing the color-transferable anti-counterfeiting ink, the printed products should be separated for a certain period of time before printing the front side of the invoice.
Seven, the problem of glue head bonding of hand-opening bills
The back transfer coating of the dry carbon paper contains a wax component, which feels smooth when applied and printed. Therefore, conventional nail glue is used as a glue head bonding when binding, which is not effective and is easy to fall off or delaminate. It is ideal to use NYG--504 latex vinegar-acrylic copolymer latex as dry-type carbon paper adhesive. Before the gluing, the dry carbon paper should be cut flat and placed in a flat stack (note that the top can not be pressed, it is easy to glue) Infiltration), use a brush to brush NYG-504 glue to the plastic head, after 2-3 hours, you can divide the book into a book.