Plastic gravure spot color printing common fault solution

In order to increase the overall effect of packaging, many customers will design a larger area of ​​the spot color in the design of the packaging, if not well controlled in the printing process, will greatly reduce the product's grade, thus affecting the product in the market competition The status. Therefore, from the quality control of the raw materials and the technical quality of the operators during printing, strict requirements are imposed.

1, each batch or the same batch of color is not

(1) At the time of the first proofing, it is necessary to make a detailed record of the blade angle, ink viscosity, and ink ratio.

(2) Pre-press control. Since the spot color ink is generally self-aligned, it is necessary to ensure that the used ink is not biased and the proportioning accuracy is correct. The ink tray, ink stick, and ink pump should be cleaned. The previous use of the remaining ink should be added to the new ink in an appropriate amount to adjust the blade angle and ink viscosity.

(3) It is necessary to control the ink viscosity in printing. It is recommended to increase the number of manual measurements or to prepare the viscosity with the automatic regulator.

2, uneven ink transfer

(1) When coloring, the type of ink should be reduced as much as possible. The three colors that can be used in two colors can be used. The inks of different manufacturers cannot be mixed, and the blending should be done well for a good amount of years, and the proper amount of butanone should be added to dissolve. The addition of the solvent should be slowly added and stirred so as not to cause the solubility to deteriorate due to the impact with the solvent, destroying the ink structure, thereby causing poor transfer.

(2) Reduce scraper pressure (more applies to transitional spot colors)

3, water lines

Increase the viscosity of the ink. Because the spot color version is darker, it is generally 30-35μm, so the ink viscosity will appear over the bottom of the ink. It is recommended that the speed of 120-150m/min be used for 22 seconds to 20 seconds (the Zahn No. 3 cup).

4, indentation and twill

(1) Reduce the pressure of the embossing roller.

(2) Compared with the software package of the embossing roller, the replaced embossing roller has a hardness of 75 Shore.

5, peel strength is not enough and adhesion

Because spot colors generally account for 40% to 60% or more of the entire package, the peel strength of spot colors must be better, and can be controlled from the following aspects:

(1) The substrate surface tension must meet the requirements and must not be less than dyne/cm.

(2) Choose the ink that is suitable for the village material model.

(3) Select a solvent with a lower surface tension to reduce the surface tension of the entire open car system, thereby improving the wettability of the substrate.

(4) Increase the heat and air volume of the oven. If the heat and air volume of the oven are too small, the amount of ink on the spot color is large, which may cause insufficient adhesion and peel strength.

In short, to control the printing of spot colors, it is also necessary to concisely sum up and improve the awareness of the operators on product quality, and earnestly improve each gate to achieve excellence.