Study on Compound Transfer Gravure Printing Process

Prepress process formulation

The preparation of the prepress process is a clear path for printing production. All matters are connected and interlocked. Errors within the process of manipulative or accidental errors are not allowed in every small part of the process. Once an error occurs, it will cause irreparable damage. loss. The requirements for the production of gravure cylinders by ordinary gravure printing have been quite strict, and the requirements for the prepress production process for wired compound transfer gravure printing are more stringent. It is necessary to be cautious when formulating prepress processes.

1, the determination of raw and auxiliary materials

(1) Transfer film: PET is generally used as the base film, because the stretching range of PET film is smaller than that of OPP film, and the stability is good. See Table 1:

Table 1 Comparison of Performance of PET and OPP Films

(2) bottom paper: select the bottom paper to refer to the sample or according to customer requirements. It is required that the surface of the paper be smooth, smooth, and soft (paper fibers should not be too hard). In this way, when the die-cutting and indentation of the subsequent process is performed, it can be ensured that the indentation line is full and the box sheet has no burrs.

(3) Adhesives: At present, adhesives used in composite products in China are solvent-based adhesives, water-based adhesives, and UV adhesives. Their performance varies.

Solvent-based adhesives have a fast drying speed and good release properties, but they have a bad odor and are not conducive to environmental protection. Moreover, composite products have a large amount of curling. After a long storage time, the color will be yellow, and there are white fog spots (caused by large rosin content).

Water-based adhesives have no solvent evaporation problems, are non-toxic and environmentally friendly. Especially when the film is laminated with the paper, the glue liquid is a naturally flowing liquid and can quickly and fully fill the concave surface of the paper surface. Therefore, the composite product has a good smoothness and a high composite fastness, and the composite product has no warping phenomenon. Flat and beautiful, excellent overall performance.

UV adhesives have fast drying speed, soft gel, good adhesion performance, high bonding strength, high temperature resistance and good freezing performance, and composite products do not burst or crisp.

In actual use, adhesives with different properties can be selected according to different equipment performances, drying methods, gluing methods, product requirements, etc. in order to achieve an ideal composite effect.

(4) Varnish, also known as resin oil, is used to coat composite or transferred gold, silver and laser paperboard surfaces to make them more ink absorbent during printing. There are currently two types of varnish available. select.

The first kind: oily varnish (volatile drying type), the main ingredient is synthetic resin (nitrocellulose, acrylic resin), and contains some additives. The advantage is that the coating is thick and the drying speed is fast. The disadvantage is that it is easily miscible with the resin ink of the same type in the printing process.

Second: water-based varnish, the main ingredient is acrylic emulsion, and add some defoamers and additives. The advantage is that the amount of coating is small, the varnish coating is thin, the cost can be saved, and the ink is not easily miscible with the ink during the printing process. The disadvantage is slow drying.

(5) Printing inks: At present, domestic paper gravure printing generally uses volatile drying type oily inks. The solvent is ethyl acetate, ethyl alcohol (isopropanol), butyl acetate, or even toluene, which is harmful to the human body and is not conducive to environmental protection. The environment-friendly water-based gravure ink is still immature and still under development.
The connection compound transfer gravure printing should choose benzene-free ink, its volatile drying speed is medium, the pigment particle size is 3-5μm, the color concentration, color saturation, high temperature performance, adhesion, printing ink surface easy hot stamping , The printing surface is not easily scratched, the diluent is ethyl acetate, more than 98.5% of anhydrous ethanol or isopropyl alcohol, slow-drying agent can be butyl ether, its toxicity is small.

(to be continued)