Printing of plastic products

Screen printing
In order to print inks with a thickness of 10 to 100 μm in some cases, many graphics and texts have strong hiding power, strong three-dimensional effects, or special shaped plastic products that are not suitable for dry offset printing. Many use screen printing. This printing method has great flexibility and wide applicability.
The screen printing process is to stretch the screen on the wooden frame or the aluminum alloy frame, apply the photosensitive liquid on the net to form a photosensitive plate, and then seal the positive plate on the plate, print it through the exposure, and print the plate. Part of the light cured film, the mesh sealed, the printing ink can not pass, and then the plate on the plastic substrate with polyurethane or rubber scraper at a certain angle of inclination and pressure, the ink from one end to the other end, the ink Through the hollow section of the screen, attached to the surface of the printing plastic.
Printing inks are solvent-based and UV-based and can be selected according to the properties of the printed plastic. Screen printing plates are easy to make, low cost, and have a resistance force of 1 to 50,000. The drying method is the same as dry offset printing, and it is also divided into infrared drying and ultraviolet drying. Some varieties of plastics also need to be pre-processed before printing.
Screen printers are flat and curved, semi-automatic and fully automatic. Its investment can be high or low, users can choose the appropriate equipment according to their own strength and business needs, especially for China's national conditions, in recent years, it has shown its unlimited vitality in the country.
Pad printing
For some irregular surface printing, pad printing process is often used.
The process is to lay the ink on the gravure surface, scrape the excess ink on the gravure with a scraper, and then transfer the ink in the gravure groove to the soft silicone rubber head, and then press the print head onto the plastic product. Because the silicone rubber head has a fairly consistent attachment to a variety of concave and convex surfaces, pad printing is the most ideal printing process for various irregular surfaces.
Pad printing plate is made by gravure photographic etching, high resistance to printing force, gravure and very fine, clear and beautiful graphic printing. Pad printers have 1 to 4 colors, semi-automatic and fully automatic.
Heat transfer printing
Sometimes in order to make plastic products fake, imitation leather, imitation wood grain, imitation marble, imitation metal antique ... ..., realistic patterns, so that cheaper plastic looks like high-end decoration products, handicrafts, we often use thermal transfer process.
The process is the use of hot pressure (copper mold or silicone rubber roller heating and pressure), the color of the text from the substrate to be printed on the plastic, a success. Among them, the copper mold is used for intermittent imprinting, and the silicone rubber roller is used for continuous transfer of building materials or other large-area flat surfaces.
Stamping foils need to be prepared in advance according to the required design drawings and texts. There are many printing methods, including gravure printing, offset printing, silk screen printing, depending on the product. At present, the most widely used at home and abroad is gravure printing, which requires high precision and exquisite graphics. , Or the need for continuous hot stamping must use a gravure multicolor machine to produce a roll of hot stamping foil.
The advantage of thermal transfer is that plastic products do not require pre-treatment or post-treatment, and the process is simple. Manufacturers using hot stamping foil only need to add a stamping machine, which means less equipment investment and low cost. The process has a wide adaptability and is very suitable for plastic mounting. With the successful production of domestic hot stamping foils and the continuous improvement of the stamping equipment, the scope of application of thermal transfer will be further expanded, and the added value of the products will also be greatly increased.
The latest transfer technology is the water transfer printing method. It is a unique transfer property using a water-soluble transfer film. The transfer film floats on the surface of the water. The ink is facing upwards, and the pressure-printing plastic is pressed to make the ink film completely. Uniformly sag transfer, apply a protective ink overcoat after the water is dry.
New types of plastics emerge in an endless stream, and plastics applications continue to expand and play an increasingly important role in various industries. How to adapt the printing technology and printing materials to the ever-changing plastics market is a topic worthy of continuous research and discussion.