Screen printing process of paper packaging products (2)

Second, printing

1. The choice of paper
1) When printing paper packaging, it is usually based on the customer's requirements and the use of the product to select paper, and according to the cost to determine whether to use gold, silver paper, gold, silver paper. Gold and silver cardboard are made of vacuum aluminum on glass paper. Gold and silver paper are made of vacuum aluminum on white paper. The surface smoothness and stiffness of glass paper is better than that of white paper. The cost is also high.

2) According to the use of the product, choose face paper (250g/m2, 300g/m2, 350g/m2) and backing paper (250~350g/m2 white paper, small corrugated paper or large corrugated paper). General wine box and outer box face paper commonly used 350g/m2 gold, silver paper, wine box paste back paper commonly used 300g/m2 white paper, outer box paste back paper commonly used small corrugated paper or large corrugated paper, in order to increase strength and stiffness.

3) According to the customer's requirements to determine the color of the paper, shades of gold, silver, and paper must have high gloss, high brightness, smooth surface, no foaming, no wrinkles, tensile and flexural strength, toughness, Aluminized film has good fastness and does not fade.

2. Printing
Before the ink is used, it should be fully stirred. When mixing, an appropriate amount of thinner (less than 10%) can be added to ensure that the ink is wet. After mixing, the ink can be printed on the machine. To keep the mesh open, wipe it with a cleaning agent. The ink viscosity should be moderate, too large, easy to stick, too small, no three-dimensional. After printing, use a special washing net water for reuse. After the ink is used, it needs to be sealed immediately. Since the ink contains a photosensitizer, direct sunlight should be avoided during the printing process. It is better to operate under yellow light.

After printing, it must be cured by UV. When the curing is not complete, the ink fastness is reduced, the surface hardness is low, and the hand is touched. The light and solid are excessive, the bottom paper coating layer is easy to damage, the ink layer is resistant to folding, and the abrasion resistance is reduced. That is to say, ink drop, or even paper deformation occurs, resulting in post-processing difficulties, that is, sticking back paper and pasting paper are not close, uneven, wrinkles or open mouth phenomenon, affecting quality and beauty.

3. Meet the needs of post-press processing
The post-press processing of paper packaging includes backing, bronzing, embossing, die-cutting, and gluing.

Since the surface of the gold and silver (paper) paper is an aluminized film and aluminum is an amphoteric metal, at a certain temperature, a chemical reaction occurs between the acid and the alkali, and the aluminum particles gradually oxidize and lose luster. Therefore, from the consideration of post-process, good quality gold and silver card (board) paper should be used.

Paper and backing paper must be stored at the same temperature and humidity, otherwise the paper will be deformed and the backs will not be even. The backing adhesive must be neutral and the compounding temperature should not be too high.

In order to improve the grade of packaging, increase the three-dimensional sense, make products more eye-catching, many packaging but also use embossing process, the name of the product on the packaging box convex, and then die-cutting, therefore, requires the screen printing ink layer to have High folding and abrasion resistance.

Source: Comin Media