The printing technology of dry carbon paper in anti-counterfeiting paper (Part 1)
dry carbon paper, also known as disposable anti-counterfeiting carbon paper and laminated anti-counterfeiting ticket paper, was invented by Jiangsu Haimen carbon paper factory (the Chinese invention patent number is zl94 1147.0, and the international patent classification number is b41m5/00). It is the fourth generation of high-tech products after ordinary carbon paper, carbon coated paper and carbon free carbon paper. The products have been awarded the titles of "national new product" and "national excellent new product" by the State Economic and Trade Commission, the Ministry of science and technology, the State Administration of Taxation, the Ministry of foreign trade and economic cooperation, the State Bureau of technical supervision, and the State Environmental Protection Administration, and have been listed in the national Torch Program
the front of dry carbon paper is white base paper, and the back is non-toxic water-based colored coating. The products are divided into flat sheet paper and web paper, which are suitable for offset printing, gravure printing, as a family of flexible printing in dynamic experimental machines, printing computer tickets, manual Invoicing, roll tickets, and using relevant technical facilities without backing; If you write on paper, you can get multiple copies, and the color is fast, the handwriting is clear and bright, can not be altered, is not affected by the climate, and the archive has a long retention period
in view of the anti-counterfeiting technical characteristics of new dry carbon paper products, the tax administration department of the State Administration of Taxation, the statistics department, the former General Administration of Posts and telecommunications, the State Administration of Taxation of Jiangsu Province and other units successively sent documents to the country in 1997 to promote the trial, The General Administration also issued a document to the whole country in July 2001: "after several years of trial, the dry carbon paper has proved to be effective in curbing and combating the production and sale of fake invoices, and decided to officially put the second generation dry carbon paper developed and produced by Jiangsu Haimen carbon paper factory into use as ordinary invoice anti-counterfeiting paper"
now I summarize the printing technical problems and related processing technologies I encountered in the technical service and investigation of tax bill printing enterprises with dry carbon paper as the carrier in the country, for the reference of tax bill printing peers
I. The dry-type carbon paper must be well moistened before printing to ensure that the paper feeding, feeding and receiving are smooth during the printing process.
during my service to the dry-type carbon paper printing enterprise, I found that the dry-type carbon paper has problems such as paper elongation, curling and tight edges, which affect the printing work. After analysis, the reasons for these problems are as follows:
1. The dry-type carbon paper is coated, dried and It is cut and rewound, and the finished product actually becomes a single tape. There is a significant difference in the moisture absorption performance of the front and back paper surfaces, that is, the moisture absorption performance of the colored coating surface is extremely poor, and the moisture absorption of the white surface of the base paper is extremely sensitive, which is one of the main reasons for the curling and tight edges of the paper
2. After leaving the factory, dry carbon paper needs to be transported or stored for a long time. A brief introduction of the special experimental machine for testing steel strand in Jinan. Due to China's vast territory, large vertical and horizontal climate differences and frequent changes, for example, in spring, the room temperature in Heilongjiang region of China is between%, while the indoor humidity is between 20% and 30%. The indoor temperature and humidity in Yinchuan are basically the same, at% and 18%-20% respectively. In the coastal areas, Chongqing and Chengdu, the room temperature is about degrees Celsius, but the humidity is as high as 60% to 75%. Because the moisture absorption characteristics of dry carbon paper do not adapt to the printing environment of the enterprise, there are problems such as static electricity and double paper wrinkles in printing, which brings difficulties to the printing work
based on the above reasons, in order to balance the water content of dry carbon paper with the ambient temperature and humidity of the printing workshop and ensure the high-quality completion of e-mouth brush products, tax bill printing enterprises across the country have very rich experience. For example, the ticket center of the State Administration of Taxation of Hebei province attaches great importance to the balance between the base paper and the printing environment, and generally takes the thousand type carbon paper to the workshop to enter the natural balance two or three days before printing. For another example, in addition to entering the base paper into the workshop for natural balance, the printed products of Shanghai business factory are put into plastic bags after being off the machine, put into the packaging box, and then flow to the next page splicing and coding, effectively ensuring the smooth completion of high-quality printing of dry carbon paper
since 2000, I have visited 85 key tax invoice printing enterprises and relevant colleges and universities and research institutes in provinces, cities and autonomous regions across the country to collect Their advanced experience is summarized as follows: "when the relative humidity of the printing environment changes by 10%, the water content of dry-type carbon paper also changes by about 1%. Generally, when the temperature changes by 5 ℃, the water content of dry-type carbon paper changes by about 0.15% to 0.2% accordingly."
II. Control of fountain solution, printing pressure and printing speed
dry carbon paper will change "quietly" in printing, and its king has two kinds of performance. First, the paper size is changing, that is, the paper lengthens or shortens in the long and short direction; The other is the change of the paper on the compression surface, that is, the elastic-plastic change of the paper in the vertical direction. The reasons for these two changes are: first, how the paper's elasticity caused by the change of the printing environment (i.e. the water content of the paper) can be close to the reality. It is still a difficult change to imitate this kind of despicable working environment for friction and wear experiments, and the other is the elastic-plastic change of the paper caused by the pressure of the paper
in view of the change law of thousand type carbon copy paper in printing, in order to obtain the ideal minimum change, many printing enterprises have analyzed the factors affecting the expansion and contraction of dry type carbon copy paper, and the conclusion is: "the factors such as the humidity adjustment preparation of paper before printing, the fountain solution during printing, the printing pressure and the printing speed must be effectively controlled."
after water absorption, the paper will expand in volume, resulting in size increase, and after water loss, resulting in size reduction. Therefore, in addition to reasonably adjusting the humidity of the paper before printing to be basically consistent with the printing environment, it is necessary to control the consumption of fountain solution in printing. For the offset press, on the premise of ensuring that the image and text of the print are clear, the layers are clear, the oil-water separation between the layout and the tape, and the version is not pasted, the use of the fountain solution belongs to normal deformation, so the elastic-plastic change of the dry-type copy paper has a certain range, beyond which, the dry-type copy paper will lose its elasticity, and the deformation of the paper in thickness cannot be recovered. At this time, the printing surface of the dry-type copy paper will appear wrinkled, uneven The ink layer is uneven, and the colored coating on the back is needle like falling off
for the regulation of imprint force, the purpose should be to gradually pressurize and regulate the ink from scratch, clear graphics and text, and meet the quality requirements. Due to different models, there is no unified regulation. Many tax printing enterprises in China use Weihai Bintian wh47 machine. My service practice investigation data shows that the printing pressure scale of printing enterprises is positioned at.5:00
printing speed and printing pressure have an important impact on the printing effect of dry carbon paper, which is mainly due to the different length of time the paper stays in the embossing section, and the degree of deformation of the paper is also different. For example, the normal printing speed of the wh47 machine of Hebei provincial tax ticket center is 6000 rpm, and the normal printing speed of the wh66np machine of Yunnan national tax printing plant is 500 rpm. When printing form machines, such as the sun machine of Shanghai business factory, Nanjing special printing plant, Gongyao machine of Shanghai enor factory, and Xiaofeng machine of Hebei Provincial Ticket Center, they are basically controlled at the speed of 150 m/min for normal printing, punching, folding, coding, page splicing The printing quality is good
III. treatment technology for the color transfer coating of dry carbon paper to adhere to the embossing cylinder
the color transfer coating on the back of Haitian brand dry carbon paper is mainly non-toxic fatty acid salt solution and colored coating. Under the friction between the coating layer and the paper feeding cylinder and the printing pressure, the paper is compressed and deformed in the embossing section, causing the powder of the surface colored coating to drop (i.e. colored paper powder). Because the dropped powder layer contains wax composition, It is not easy to scatter around the printing cylinder. At the same time, the embossing cylinder is pressurized and heated, and it is easy to accept the adhesion of wax. Over time, from less to more, the embossing cylinder has coating adhesion to the cylinder, which brings trouble to the printing. At present, there are two solutions. One is the sheet fed offset press, which pastes anti sticking paper on the impression cylinder, and the effect is relatively ideal. Under normal circumstances, it can continuously print 40 million and 50000 times. Others, such as Changchun national tax printing factory, Nantong TongZhou ticket printing factory, Hebei national tax ticket center, Xuzhou tax printing factory and other units have mastered it. They simply do not stick anti sticking paper. When printing times, they manually wipe the roller once. The other is the paper roll offset press. Its method is the same as the above. Due to its high speed and high output, using the above anti sticking principle, an anti sticking device is installed under the embossing cylinder of the form machine, and 202 hydrogen containing silicone oil is added to the high-density sponge. This method is safe and convenient. For example, Harbin license printing plant, Zhejiang Debang company, and ticket printing plants in Shanghai, Jiangsu, Xinjiang, Shenzhen and other places have achieved good results in the past few years. In addition, for the transfer of colored coating under pressure in the process of letterpress printing and page matching and coding on the page matching machine, the solution is the same as above. As long as a piece of anti sticking paper produced by our factory is pasted on the corresponding position of the plate table or pressure cylinder, no transfer letterpress printing or coding can be realized, and the effect is very good
IV. selection of bottom paper matching with dry carbon paper
for the bottom paper matching with dry carbon paper, it is suggested that neutral g/M offset paper is the most suitable for computer tickets, and the minimum is no less than 50g/M (lithographic manual invoicing is optional). At present, some factories choose g/M bottom paper to reduce the cost of computer ticket issuance. Results due to the light weight of the paper, the stiffness of the bill made is not good. At the same time, when printing on the web printing machine, due to the different tension control, it is difficult to find the expansion rate of the two kinds of paper, resulting in waste and difficulties for page distribution and user use, because the computer ticket is easy to fail due to insufficient stiffness when printing on the tax control machine. Here, I would like to remind printing enterprises that dry carbon paper is neutral coating material paper, which cannot be used together with oily paper and carbon free paper. If there is a supporting paper, chemical reaction will occur, and the color will not be transferred during copying, which will cause greater losses. Please note that all ticket printing plants should correctly and reasonably select neutral back page and supporting paper