Gravure printing material selection method!

[Chinese Packaging Network News] gravure printing is a direct printing method, so it has more requirements on the material. This article lists the printing adaptability of commonly used printing materials and the corresponding process production methods for different printing substrates.

Printability of commonly used printing materials

The printing of plastic film requires that the substrate film to be printed meet the following five requirements:

1 The surface is smooth, without obvious deadlock, yellow and black spots, holes, and no excessive wrinkles.

2 The average thickness of the substrate film to be printed should be within 10% (1m printing width).

3 Under the printing tension, the elongation of the substrate film to be printed should be within 1%.

4 The surface tension of the substrate film to be printed is d40 dyn/cm.

5 Knowing in advance the affinity between the substrate film and the printed ink For printing-dissolving and swellable films in the ink, the printing speed and ink concentration may be greater. When printing a coating layer of a coated substrate film, it is necessary to understand the adhesion of the coating resin to the ink.

Different printing substrates have the same print adaptability. In printing, it is necessary to choose different processes for production in order to achieve better results.

1BOPP is the most commonly used substrate, and its production process is a typical plastic gravure production process: use polyamide or chlorinated polypropylene ink for printing, appropriate tension and embossing force. Drying temperature is controlled at 80%.

2BOPET printing points: Because PET is usually thin, easy to fold, printing requires greater tension, the ink has a certain degree of selectivity, easy to use the general printing ink release, easy to block version (not online), fluffing and scraping marks (Knife wire) Phenomenon, the humidity in the workshop is good for printing.

3BOPA printing points: BOPA is a film that is easy to absorb moisture and deform. Therefore, the printing machine must ensure that the environmental humidity of the printing machine cannot be too high (if it is not suitable for dehumidification and the environment with high humidity is not suitable for nylon film); the unprinted film cannot destroy its original aluminum film packaging film, and it must be printed immediately after opening. Nylon film should be preheated during printing (if the machine does not have a preheating device, the plate can be mounted on the second color, leaving the first color as a preheating). The preheating temperature is 50-80°C; printing Tension should be properly reduced; pressure should be moderate; ink adaptability, depending on the choice of different product structure, if it is a cooking bag must choose to cook ink, after printing the product must be sealed and quickly compounded.

4K coating layer (KOP, KPA, KPET) printing points: Because K coating film is roller coating type or spraying type, its thickness uniformity is not very good, the surface is uneven, and PVDC is brittle, printing at the time of printing Tension and imprinting pressure can not be too large, overprinting is difficult, the ink transferability is poor, and when the shallow web is printed, it is easy to get a dot (part of the dot is lost), and a higher hardness press roller is used for printing. In addition, the solvent is selective. If the solvent is used improperly, the coating may dissolve, the residual amount of the printing film solvent is large, and the adhesion is easy. Therefore, special attention should be paid to drying and cooling.

5 The printing of the matte film can be printed on the smooth side using the OPP process. However, because the matt layer on the surface cannot withstand high temperatures, the drying temperature needs to be controlled.

6 Pearl film uses table printing ink for surface printing, and try to use transparent printing ink.

7 Heat shrinkable film printing using a very low drying temperature, to choose a dedicated heat shrinkable ink (silver ink layer to be able to heat shrink without falling), if it is PVC heat shrinkable film also consider the solvent solubility of the film .

The tension of unstretched PP and PE films is very small, and overprinting is difficult. When designing a pattern, the amount of deformation in printing should be fully considered.

Different printing substrates should be considered in terms of ink selection, plate design, printing process, etc.

For different printing substrates, adjustment must be made from the selection of ink, plate design, and printing process to ensure that the quality of the product meets the requirements. In addition, some high barrier coating materials do not print on the coated surface as much as possible under conditions to prevent damage to the barrier coating.