There are many printing methods for plastic products. Commonly used are screen printing, embossing on the mold, anodized aluminum hot stamping, dry offset printing, in-mold lamination printing, and thermal transfer printing.
The screen is stretched on the screen frame, and a publication film is made on the screen, and the blank part except the picture and text is covered with the plate film. Put the ink in the screen frame, use a squeegee to move it under pressure in the screen frame, the ink will penetrate through the mesh of the non-plate film (picture and text part), and the ink picture and text will be printed on the plastic product. The ink layer of the silk screen is thick, the image and text are strong, the printing plate is soft and flexible, printing on hard plastic products can also ensure uniform inking, and printing on products with rough surfaces can be printed on all kinds of curved plastic products.
②Concave and convex printing on the mold
It is printed during the plastic molding process. Concave-convex graphics and text are made on the wall of the forming mold, and the hot-melt plastic is molded into products while forming convex-concave graphics and text.
The concave-convex printing on the mold has the following characteristics:
a) The printing range is wide, and it is not limited by the shape, hardness and softness of the product. As long as the concave-convex printing plate can be made on the mold, printing can be carried out. It is not limited by the material and can be printed on thermoplastic and thermosetting plastics.
b) No ink is needed, other products will not be smeared, and the environment will not be polluted.
c) It is to complete the printing at one time during the product forming process, the process is simple, and the printing cost is low. Mountain printing graphics will not fall off, and the three-dimensional sense is strong. However, it uses the raised or recessed surface of the product to display graphic information. The color of the graphic and the product is the same, so the color is monotonous. It is mainly used for text printing.
③ Anodized aluminum hot stamping
Anodized aluminum hot stamping (commonly known as hot stamping) is to use a heated printing plate to pressurize the anodized aluminum and the product, so that a part of the hot stamping foil on the anodized aluminum adheres to the plastic product, so that the product can obtain the required graphics and text. It is generally used Copper-zinc letterpress printing.
Anodized aluminum hot stamping has the following characteristics:
a) The printed pictures and texts have metallic luster, bright and eye-catching, and give people a luxurious and solemn feeling. b) The printing method is simple, does not require surface pretreatment, does not require drying, and will not smudge other products.
c) No solvent is needed, no solvent pollution on the printing site. But for thermosetting plastic printing, the effect is not ideal. The printing pressure is relatively high, so there should be a liner in the product during printing.
④Dry offset printing
Dry offset printing uses copper-zinc letterpress or photosensitive resin letterpress. First coat the ink on the convex part of the printing, then transfer the ink on the printing plate to the blanket cylinder, and then print the ink on the plastic product through the blanket cylinder. This solves the problem that the hard plate is printed on hard plastics. The problem of uneven ink in the product. Its printing gloss is poor, and it is mainly used for printing on plastic containers.
⑤In-mold laminating printing
The so-called in-mold lamination printing is to place the film with graphics and text on the mold wall, and bond it with the hot-melt plastic during the molding process. After cooling, the film with graphics and text is firmly adhered to the plastic. On products, in-mold lamination printing can be used for various thermoplastic products, but the printing surface of the product is required to be flat or curved with a large radius of curvature, and it is not suitable to print on uneven surfaces.
Features of in-mold lamination printing:
a) The ink will not fall off between the film and the product.
b) There is a film on the outside of the ink, which increases the gloss of the graphics and text, and the printing effect is good.
c) Multi-color printing is also very convenient. However, improper mold design or poor film placement can easily cause failures such as wrinkles in the laminated film.
⑥ Thermal transfer
Thermal transfer is to place the sticker paper (printed on paper or film with sublimation ink or other materials) on the product to be printed, heat and press on the sticker paper to transfer the ink on the sticker paper to the product. Finish printing. It is somewhat similar to the aforementioned anodized aluminum hot stamping, but anodized aluminum hot stamping generally uses a copper-zinc relief plate, and only the hot stamping foil on the raised part of the printing plate is transferred to the product. For thermal transfer, heat-resistant silicone rubber lithography (or roller) is generally used to press and heat all the sticker paper, but only the ink of the graphic part is transferred.
Features of thermal transfer:
a) Multi-color printing is convenient.
b) The reproducibility of printing is good, the pictures and texts are clear, and it can be used for the printing of exquisite pictures.
c) Printing is convenient and simple.