2.2.5 Personalized Product Printing Personalized products are individual printed products with special properties that are used for specific occasions, specific people, or specific objects. They are characterized by small quantities and strong pertinence. In the modern economy and society, more and more personalized printing products are used. For example, insurance company salespersons use printed gifts for customers, and they represent the company's basic printing graphics using offset printing technology in large quantities, and each salesperson gives The customer's words, names, etc. are not the same and can be printed using the silk screen process.
3 Requirements for Equipment and Materials for Adhesive Silk Screen Binding Process 3.1 Basic Requirements for Equipment The equipment used for the adhesive screen printing process shall not only meet the process requirements of offset printing and screen printing, but also need to consider the combination of the two processes. For example, since conventional offset printing equipment can only print ordinary offset printing inks, and printing screen printing bonding products that require silk screen printing for secondary printing or post-processing, offset printing inks are generally used in consideration of the adaptability and compatibility of offset printing inks and screen printing inks. UV inks or heat-curing inks, offset presses must add UV or heat curing drying system; for silk screen printing equipment, the traditional manual screen printing equipment or semi-automatic screen printing equipment can not meet the production efficiency can not meet offset printing tens of thousands per hour printing speed Requirements, and product quality is not stable, so the plastic screen printing process requires the use of high-speed automatic screen printing equipment, its paper feeding, registration, scraping ink are fully automatic, greatly improving the printing speed and accuracy, minus Small scrap rate.
Adhesive silk screen bonding process major equipment:
a. Compatible offset printing equipment (It is recommended to configure an offset printing press with UV drying system).
b. Screen printing equipment: automatic screen printing machine and its supporting equipment that can adapt to batch production.
c. Related post-processing equipment: UV drying equipment, thermal drying equipment and other conventional post-press processing equipment.
3.2 Basic Requirements for Materials Silk screen printing inks mainly include heat-curable inks and UV-drying inks. The selection of heat-cured screen printing inks is relatively low, but the cost is low. However, heat-curable inks are easily volatilized during the printing process, often resulting in printing processes. Drying of the ink and blocking the network, coupled with the ink on the substrate to complete the drying process requires a long time, and many of the special screen printing ink UV drying ink, so the screen printing ink UV drying ink in the mainstream. Considering that the product needs to be treated with UV drying, the offset ink in front must also be resistant to ultraviolet radiation. Therefore, it is better to use UV offset ink in offset printing. In addition, when selecting the material, the requirements for the precision of silk screen printing and the requirement for the thickness of the silk screen ink should also be taken into account (the silk screen ink film is generally required to be thicker in the process of bonding silk screen printing).
The materials required for the adhesive silk screen bonding process mainly include:
a. Ink: The main use of UV drying ink or polish.
b. Substrate: All kinds of paper, board, film ratio and metal sheet that can be used for offset printing.
c. Screen plate material: all kinds of screen printing plates, mesh range 2.4 ~ 5.9 mesh / mm.
d. Frame: Aluminum alloy frame that is not easily deformed.
4. Key technologies in the process of adhesive silk screen printing 4.1 Accuracy and adjustment of overprinting Because the materials of offset and screen printing plates are different, even films made from the same manuscript are separately tanned into PS and silk screen plates. The elastic deformation of the material during printing results in inaccurate overprinting of the rubber seal. Apart from that, overprinting of rubber screen printing graphics is controlled by the offset registration system and silk screen registration system, so the accuracy of registration is lower than that of a single offset or screen printing product. Generally, offset and screen printing accuracy of 0.2mm is register.
In order to make silkscreen printing and offset printing more accurate overprinting process, it must be properly adjusted and controlled until overprinting is accurate. Adjustment and control methods can refer to the following practices:
a. Fine-tune the screen-printing film when it is made to ensure that the overlay is accurate.
b. Keep the area of ​​the silk screen graphic slightly larger than the area of ​​the offset printing image that is overprinted with it to prevent exposure of offset printing without overprinting.
c. Use aluminum alloy frame and avoid wooden frame.
d. Stretch net tension pin is larger than a single screen printing process to reduce the elongation deformation of the screen during printing.
4.2 Adaptability of Materials and Processes Screen printing inks are usually printed on offset printing inks in the process of screen printing. Therefore, the two types of inks must have their own printing adaptability, and they must have common printing adaptability. Miscible with each other and no chemical damage. And the entire product and the materials it uses must be able to adapt to the requirements of the offset printing process, screen printing process, and post-processing process conditions. In addition, screen printing inks are often more than two kinds of problems that may otherwise cause the overprinting rate, adhesiveness, and chemical denaturation of the screen printing inks. The inks and other consumables used in the adhesive screen printing process are best known at the time of purchase through the manufacturer and supplier and supplier.
4.3 Ink Drying In the silk screen printing process, the drying speed and manner of the ink in the bonding process are very important. Especially for screen printing inks, it is required to keep the moisture on printing on the screen to ensure that it does not block the openings, and the screen printing ink must be printed on the substrate. Dry quickly. The best ink that can meet this requirement at present is UV ink.
The following points should be noted in the process of using and drying UV inks in the process of bonding plastic screen printing.
a. Printing environment and conditions: UV ink has a great viscosity change due to temperature, so pay attention to adjust and control the room temperature. Generally 15 ~ 25 °C is more appropriate. Be careful not to be exposed to direct sunlight during printing, and do not approach fluorescent and mercury lamps.
The key to the use of ink and its drying is to control the thickness of the ink film, and to design a film thickness that is compatible with the ink properties.
b. Preparation test and irradiation conditions: When determining the irradiation conditions of the UV ink, it is necessary to pass a preliminary test, and the test printing material should be the same as the material actually used in the production. Preparation test After the ink is cured by the set irradiation conditions, the printing surface is subjected to experiments such as tackiness, adhesion, flexibility, and bendability. To meet these experiments, it is necessary to adjust the irradiation conditions again. The irradiation conditions mainly refer to the height of the lamp, the number of lamps, the irradiation distance, the speed of the conveyor belt, and whether the preheating and preheating conditions are required.
c. The safety of the ink: Since the ultraviolet ink has no volatile matter, there is no need to worry about inhalation. However, it is slightly irritating to the skin, so be careful when using it.
4.4 Ink Mixing Because the composition and constituent materials of offset printing ink and screen printing ink are completely different, the color mixing rule of the ink in color matching or overprinting will be different from that of a single offset printing ink or screen printing ink. Therefore, the front end design and the printing adhesive This should be taken into account when screen printing ink overprinting or ink tone matching, production trials should be used to determine the ink color matching scheme.
4.5 Printing Ink Film Thickness Control In the plastic screen printing bonding process, it is generally required that the thickness of the silk printing ink film is large in order to achieve the effect of covering and highlighting. Compared with a single screen printing process, the following technical processes can be performed in the production and printing of screen printing plates in the adhesive screen printing bonding process to obtain a thicker screen printing ink film:
a. Select a mesh of T (medium-coarse) or HD (coarse) screens with a smaller mesh size; b. Thicken the coated sensitized film without sacrificing the printing accuracy of the prints; c. The printing distance; d. choose a smaller angle of the squeegee to 45 ~ 65 ° more appropriate; e. printing ink pressure is not too large.