How to improve the wear resistance and adhesion of UV varnish

Color box printing companies often encounter such problems: after UV varnishing of printed products, the wear resistance and adhesion of UV varnish film layer is not good, especially if the printing products are printed with metallic ink (gold ink or silver ink). This phenomenon is particularly prominent when UV glazing is performed.

In general, companies often solve this problem by replacing UV varnish. In fact, we should not only limit the idea to replacing UV varnish, but instead change the idea to change the production process of the color box or adjust the relevant process parameters.

Solutions

The conventional corrugated box production process route is: plate making and paper cutting → ordinary printing → over UV bottom oil → over UV surface oil → 裱 楞 楞 → die cutting → paste box. After many trials, the author summarizes the methods for improving the production process of corrugated box.

(1) Plate making and paper cutting → UV ink printing + online UV glazing.

Tests have shown that this production process can greatly improve the abrasion resistance and adhesion of UV varnish on metal UV inks, but metal UV inks are rare on the market, require special customization, are expensive, and must be UV-coated. The printing press has a limited limitation.

(2) Plate making and paper cutting → ordinary printing → screen printing UV glazing.

This production process can also solve the problem of poor wear resistance and adhesion of UV varnish on metal ink, but the cost of screen printing UV varnish is high, and the environmental performance is not as good as water-based UV varnish, which is not worth popularizing.

Finally, after repeated verification, the idea of ​​solving the problem was clarified: high wear resistance UV surface oil was used to improve the wear resistance, and the adhesion of the UV base oil was ensured by adjusting the process parameters or replacing the materials. Due to the two glazing, the varnish film is thicker, which makes the wear resistance of the high wear-resistant UV surface oil more secure. The next step is to solve the key factors affecting the adhesion of UV varnish - printing ink and UV base oil.

solution

Before solving the problem, you first need to understand the customer's requirements for the color box and how to detect it.

(1) To detect the abrasion resistance of the color box UV varnish, the method is as follows:

1 If the color box needs to be shipped by sea, you can install a box of actual products in the carton used in the actual customs declaration, or install a box of product models whose weight specifications are consistent with the actual products, and put them on the simulated transportation test machine (vibration test bench). More than an hour, the surface of the color box has no obvious UV varnish film layer or ink layer drop as qualified;

2 Put the sample of the color box on the anti-friction tester and rub it back and forth 80 times with the weight of 22N (weight and frequency can be determined according to customer's requirements), and it is qualified to have no obvious UV varnish or ink drop.

(2) Check the adhesion of the color box UV varnish, as follows:

1 Apply 3M transparent tape to the surface of the color box, and then tear the tape quickly and forcefully in the direction of 45 degrees to ensure that the UV film or ink layer is not adhered;

2 Use the HB pencil lead to draw back and forth on the surface of the UV varnish film layer of the color box, so as not to cross the UV varnish film layer or the ink layer.

Program summary

Finally, the author summarizes the technical points of the wear resistance and adhesion of UV varnish on metal ink.

(1) Production process route: plate making and paper cutting → ordinary printing → over UV bottom oil → over UV surface oil.

(2) Select high abrasion resistant UV surface oil and oily UV base oil.

(3) Add 10% to 20% of fast-drying varnish to the metal ink (the specific ratio is completely dried after the metal ink is dried, the finger gently strokes the surface of the printed product, and the metal powder on the finger is basically left, if the metal ink The color is diluted and can be blended by adding four-color ink). It should be emphasized that the UV ink must be passed after the metal ink is completely dried.

(4) The quick-drying varnish contains ink drier. If the metal ink is still difficult to dry after adding fast-drying varnish, the drier with the same drying property as white dry oil can be added appropriately (addition ≤ 3%) ), do not add red dry oil, because red dry oil can only accelerate the drying speed of the ink layer surface, but can not accelerate the drying speed inside the ink layer.

(5) In the process after glazing, the moisture content of the color box must be controlled to be 16% or less.

(6) The brand of various materials in the fixed production process route, and the various process parameters of ordinary printing, UV-base oil and UV-surface oil processing should be kept stable, and relevant records should be made.

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