UV-curable inks are UV-cured and attached to paper. The curing time is 3 to 5 seconds. According to the size of the particle size, the matte ink is classified into three types: coarse sand, medium sand, and fine sand. Need to choose according to the fineness of the print and the customer's request. The first thing to do is to ensure that the number of screen meshes and the size of the screen are adapted to each other General coarse sand with 150-200 mesh, sand with 200-250 mesh, fine sand with 300-400 mesh screen. Second, in the printing process, the viscosity of the ink is properly selected according to the size of the ink particle size. The coarse sand is generally controlled at 2000±100CPS, the medium sand is controlled at 3000±100CPS, the fine sand is controlled at 3500cm and 100CPS, and ink additives are added as little as possible. To ensure proper printing speed.
Die-cut indentation quality is the main factor affecting the appearance of the carton. The choice of die cutter, indentation steel wire, improper use, etc. are the main causes of ink burst, such as die cutter dull.
(1) Correct choice of die cutter
Die cutters require sharpness and high hardness. The aluminized film on the gold (silver) cardboard surface and the rough particles of the matte ink increase the difficulty of die cutting and accelerate the wear of the die cutter. According to statistics, the non-gold (silver) card frosted print has a print resistance of 800,000 times, while the gold (silver) card frosted print has a significantly lower print resistance.
Different die cutters should be selected for different thicknesses of paper. BOHLER and Qingdao Sandvik Fish G1 2 die-cutting blades are better. The microscopic thickness of the tip of the G1 2 die-cutting blade is controlled within 3 μm. The sharpness and durability are very suitable for die-cutting gold (silver ) Paper jams. Hard-to-cut materials such as PET. Its height is 23.80mm and its thickness is 0,71mm. 1.07mm, 1.42mm and so on, generally use 0.71mm.
(2) Correct selection of indentation line and indentation steel wire
The high-quality indentation steel wire should have moderate hardness, strong stability, round head, circular axis symmetry, small deviation in height and thickness, and complete specifications. The selection principle is: the thickness of the indentation steel wire is not less than the paper thickness, and the height is equal to the height of the die-cutting blade minus the thickness of the die-cut material, minus the correction value 0.05 to 0.10mm. The selection principle of the indentation line is: indentation line The thickness is not less than the paper thickness, and the width is equal to 1.5 times the paper thickness plus the thickness of the indented steel wire.
For example: die-cut 0.40mm thick paper, die cutter height of 23.80mm, indentation steel wire thickness is selected as 0.71mm, then: indentation steel wire height = 23.80-0.40-0.10 (0.05 ~ 0.10) = 23.30 (mm) The thickness of the indentation line ≥ 0.40 (mm) The width of the indentation line is 0.40x1.5 + 0.71 = 1.31 (mm) For the matte product, the height of the indentation steel wire needs to be slightly reduced on the above basis, ie The indentation is lighter because the indentation is too deep and can cause blowouts. The amount of reduction is determined by the thickness of the paper, usually 0.10-0.20 mm. At the same time, when the distance between the indentation steel wire is too small, it is necessary to paste a sponge strip to play the role of back tension, press the paper tightly, and reduce the pressure.
In addition, the die-cutting plate is too thick, the die-cutting pressure is too large, the indentation die is too thick, and the indentation die is narrow and the like can easily cause bursting. In the die-cut frosted prints also have to be adjusted accordingly. In the process of die-cutting, the accumulated paper powder in the creasing mold slit is cleaned in time. Miscellaneous items, etc.
(3) Reasonably control the open point
The open point is essentially a small width of a certain width at the edge of the die cutting knife, so that the cardboard box and the waste edge after die cutting do not spread out, so that the waste can be easily discharged. Even the point is usually hidden in the product after the molding is not easy to see, and to avoid the location of the glue line. If it has to be visible after molding, it should be as small as possible, otherwise it will not be easily separated at the point of waste, resulting in tearing of the paper and bursting of the ink layer nearby. Width; paper thickness +0.20mm.
(4) Reasonably arrange the cutting time
Matte printing of gold (silver) cardboard should be performed as soon as possible after printing to prevent the ink film from drying out excessively to prevent the ink layer from bursting.