Where should I find someone to do the scratch layer on the invoice?

It's lead, the radiation protection suit is made of lead, and the radioactive material is packed in a lead box, because I'm afraid you can see what's inside with X-rays, and lead can prevent X-rays from passing through.

Some packaging and printing companies can do it. You can search for local ones online. This is called "lead printing". I found the process flow to show you. ...

1. Printing process flow

Scraped invoices are not only printed with ordinary graphic contents, but also with some special printing effects. After several years of development and improvement, the current popular printing technology is: special paper for bills → printing opaque ink on the back → printing invoice graphics and texts on the front → printing tax bills → printing invoice numbers and passwords → coating isolation oil → printing silver paste covering layer → finished products.

Compared with ordinary paper, special invoice paper has higher opacity and tensile strength, and has good adaptability to various printing methods. In order to prevent the information of the prize-winning area from leaking when observing through light, a layer of opaque ink, usually printed in black, should be printed at the corresponding position of the prize-winning area on the back of the invoice. Then, the device prints the front content through the automatic turnover device. When printing the front, the background and ordinary text are printed first, and then the tax bill is printed with spot color fluorescent ink, which is completed by different color groups of the same printing machine. The number of the invoice and the contents of the prize area are completed by the digital printing system. After spraying the contents of the prize area, print a layer of isolating oil on the corresponding position, and finally print a silver paste covering layer on the isolating oil, so that the silver paste covering layer can be scraped off conveniently. This completes the printing of the scraped invoice.

2. Printing method

Scrape invoice is a kind of high-quality printed matter that is not easy to be forged. Various printing methods, such as general offset printing, waterless offset printing, relief printing, screen printing, flexographic printing and digital printing, have been applied, giving full play to the powerful advantages of computer information technology and embodying the perfect combination of modern printing methods and digital printing technology.

When printing invoices, ordinary graphic content is completed by offset printing, including waterless offset printing. The equipment can be a professional bill printing machine or a rotary offset press with more than five colors. Digital printing system completes variable information such as numbers and passwords by inkjet; The coating of isolating oil usually adopts embossing method; The printing of silver paste veneer is a link with the highest technical content and the most difficult process in scraping invoice printing, so there is also some controversy about its printing method.

At present, screen printing, flexographic printing and relief printing are commonly used in the printing of silver paste coatings. There are the most screen printing production lines in China, and the application of the other two methods is gradually increasing. The three printing methods have their own characteristics. The silver paste coating of screen printing method has smooth edge, smooth luster, easy scraping and the best printing effect. However, due to the low printing resistance of screen printing itself, it is difficult to process and clean, which improves the added value of products and is bound to bring resistance to its further development. With the further development and perfection of technology, flexographic printing and relief printing will gradually expand their market share with the characteristics of low cost and high efficiency, and their development prospects are promising.

3. Process requirements

(1) printing speed

Because the printing of scraping invoices is a combination of various printing methods, the printing speed should take into account the bearing capacity of various printing methods, so the printing speed is relatively low, usually between 50 ~ 100 m/min. On the one hand, the number, isolation oil and silver paste coating should be printed separately in the scratch area, and the drying device installed on the equipment still cannot meet the requirements of high-speed printing; On the other hand, the high resolution of digital printing, because the resolution of code-sprayed content is 200 ~ 300 dpi, the shape of ink dots can only be distinguished under a five-fold magnifying glass. If the printing speed is too fast, the clear reproduction of ink dot shapes cannot be guaranteed; Finally, in order to ensure no information leakage, it is required that the ink thickness of the silver paste cover layer is not less than 5μm, but the drying speed of the ink layer will be slow, which will limit the overall printing speed.

(2) the proportion of silver paste

Silver paste (scraping ink) is made by mixing silver powder and silver blending oil in a certain proportion, and mixing evenly under the stirring of electric mixer. Among them, silver powder is extremely fine aluminum powder, and silver blending oil is a chemical raw material sensitive to ultraviolet rays. After the silver paste is printed on the substrate, it should be ensured that it has considerable fastness in the process of transfer and transportation, and it is easy to scratch when drawing. The ratio of silver powder to silver blending oil in silver paste is generally between 1:9 ~ 1:6, but in actual production, manufacturers will keep the specific composition ratio secret, which is related to the function of drying device and the quality of printing paper. If the substrate is smooth and flat, the ratio can be smaller; If the substrate is rough, the amount of silver powder will be more and the proportion will be larger. The drying of silver paste mainly adopts ultraviolet drying method. If the sensitive wavelength of silver paste to ultraviolet light coincides with the main luminous wavelength in the drying device, the drying speed will be faster and the proportion will be smaller. If the wavelength matching is not good, it will inevitably affect the drying speed, and the proportion will be larger. In addition, different silver powders and silver blending oils should be printed with the same effect and different proportions.

The proportion of silver paste is influenced by many variable factors. For example, when the thickness of the silver paste layer is determined, the smaller the ratio, the more liquid components, and the more difficult it is to dry. However, in actual production, it is difficult to determine the proportion of silver paste because the thickness of silver paste coating is a variable factor. Because the more liquid components, the thinner the silver paste coating that can be printed and the faster the drying speed; When the ratio is large, it is difficult to realize a thin ink layer, although the liquid component is small, so it is still impossible to ensure a high drying speed. In addition, the liquid component in silver paste is silver blended oil sensitive to ultraviolet rays, so the increase of its content is also a factor conducive to drying, so its properties affecting drying speed are different from ordinary liquids. Therefore, the proportion of silver paste is a difficult parameter to determine.

(3) Drying method

In order to improve the speed of bill printing, almost all printing units have corresponding drying devices. The offset printing part generally adopts UV curing drying method, and the digital inkjet printing part generally adopts hot air drying method. Because the isolation oil printing part contains components sensitive to ultraviolet rays, it also adopts UV curing and drying method, and the scraping layer adopts UV curing and drying method regardless of the printing method.

The ultraviolet drying device needs a set of ultraviolet lamps. Generally, the power of each inch of lamp is required to be between 10 ~ 20kW, and the maximum power cannot exceed 600w ... There are generally two kinds of ultraviolet lamps: mercury tube and metal tube. Ultraviolet ink should match the luminous wavelength of ultraviolet lamp to improve drying efficiency. Manufacturers can also choose suitable drying methods and drying equipment according to their own product characteristics.