Two Screen Printing New Technologies for High-end Packaging Boxes

Imitation metal etching screen printing process

The so-called imitation metal etching screen printing is the use of screen printing methods to print imitation metal etching inks on substrates with metallic luster such as gold and silver cards, and obtain a similar smooth metal processed by etching, engraving or frosting. Unique visual effect.

1. Imitation metal etching screen printing plate
(1) The choice of wire mesh. Should use a large tension, uniform mesh, small rate of expansion and contraction of the screen, the general choice of plain weave thin polyester screen. As the imitation metal etching ink particles are coarse, the diameter of about 15 ~ 30μm or so, platemaking should use 180 ~ 240 mesh / inch screen, the width of the mesh can reach 60 ~ 90μm best.

(2) The selection of the frame and the stretching of the net. The frame should be selected aluminum alloy mesh frame with good strength, heat resistance, corrosion resistance, light weight, durability and no distortion. In order to ensure the quality of the stretch net, a stretcher or pneumatic stretcher may be used to stretch the net. The tension of the stretch net should be controlled between 16 and 18 N/cm.

(3) Apply a photosensitive liquid. Photosensitive adhesive can use diazo photosensitive adhesive, coating slot is mostly stainless steel, the photosensitive liquid into the slot about 1/2, the stretched screen version tilted 70 °, the coating slot and the bottom of the screen surface contact, And slowly upwards, coating from the bottom up along the mesh surface. Note that the speed should not be too fast, so as to avoid blistering of the photosensitive liquid and pinholes on the film surface. Afterwards, the screen plate was reversed and applied once, and then dried in a drying oven at 40°C. After drying, the squeegee side of the screen plate may be applied 2 to 3 times in the same manner, and the film thickness may be 10 to 30 μm.

(4) Shaiban. The film surface of the positive image is sealed on the surface of the stencil-printed sensitized adhesive and placed in a vacuum stencil machine for exposure. Exposure light source can use 3kW iodine lamp, exposure time can be determined according to the specific circumstances.

(5) Development. The exposed screen plate is immersed in water for 1 minute so that the unexpanded film absorbs water and expands, and then the water is developed from both sides of the screen by a spray gun with a pressure of 3.5-5.5 kg/cm2, until the aperture of the unexposed image part is completely opened. Throughout. Afterwards, drying and revision processing are also required.

2. Imitation metal etching screen printing
(1) Printing materials. The surface of the printing material should be a metallic shiny surface, such as aluminum foil paperboard, electrochemical aluminum foil surface. In screen printing, the glossy film surface contrasts sharply with the rough surface of the printed etching ink. Under the irradiation of sunlight, the greater the contrast between the two, the stronger the imitation metal etching effect. This effect is the other printing materials. Unable to reach.

(2) Imitation metal etching ink. This ink is widely used in advanced tobacco, wine, tea, cosmetics, gifts and pharmaceutical packaging. After printing this kind of ink on the surface coated vacuum coated paper (commonly known as gold, silver cardboard), it will produce an effect similar to metal etched sand surface, so it is also called matte ink. The original ink can only be imported from Japan and South Korea, has now fully realized the localization, and the quality can also be comparable with imported products, is the current one of the largest amount of ink used in cigarette packs, wine bags screen printing. The ink is a transparent, viscous liquid, and its appearance is grayish white. There are three kinds of specifications: coarse sand, medium sand, and fine sand, and the printability is good.

At present, special inks for imitation metal etching screen printing are UV curable inks composed of a photopolymerizable resin, a photopolymerization initiator, a pigment, an auxiliary agent, and a polymerization inhibitor. When curing, the curing light source can use a metal halide lamp with a power intensity of 120W/cm, a focal length of 10cm, and a curing speed of 10-15m/min (the light source and the lamp distance are different, and all have differences). Imitation metal etching ink is characterized by fast curing, easy sealing, easy to clean.

Ice Screen Printing Process
Ice screen printing is to print ice ink on gold and silver card paper. After UV curing, the surface of the printed product will show a crystal clear and dense “ice flower” pattern, which shines under the illumination of light, like the winter glass window. Blossoming ice flowers. Ice screen printing can make cigarettes, wine, gifts and other packaging more innovative and unique.

1. Screen making points
(1) Screens are generally 100-300 mesh/inch monofilament polyester mesh. Among them, screen printing ice silk with 100 to 180 mesh/inch works best. The number of meshes is low, and the pattern of ice flower effect is rough. When the number of meshes is high, the ice pattern is delicate and detailed.

(2) The screen tension is 16 to 20 N/cm, and the thickness of the film coated with the photoresist is generally 12 to 14 μm.

2. Requirements for printing materials
Screen printing ice paper is coated with a high gloss vacuum aluminum coating on the surface of high-smooth paperboard. The quality of coating is one of the key factors to determine the quality of ice screen printing. The surface gloss of the coating has a great influence on the product quality. The higher the surface gloss, the stronger the reflection, the better the ice flower effect, and the more flashing and brighter the pattern. As the printed product immediately after printing UV curing, which requires the film has a certain degree of light resistance, heat resistance, that is, in the entire curing process, the film can not be bubbled, and can not be separated from the underlying cardboard.

3. Ice flower ink
Ice flower ink is a special UV ink, its printing patterns can be divided into large, medium and small three kinds. The large pattern is approximately 6 to 8 mm, the medium pattern is approximately 4 to 6 mm, and the small pattern is approximately 2 to 4 mm. If you mix these three patterns of ice-ink ink, you can create a new surface decoration effect of large flowers.

Ice flower ink is transparent, not only does not cover the underlying ink, but can also play a role in the rendering of the underlying ink color, so that the printed pattern presents a colorful visual effect.

4. Ice screen printing
The hardness of the printing squeegee is from HS65 to 75, and the squeegee and printing effects are better. In the printing, the ice printing ink adopts the discontinuous solidification method, the transmission speed of the printing material on the belt of curing machine is 25- 35 meters/ minute. The curing light source consists of six UV lamps arranged side by side with a power density of 60-80 W/cm. When curing, after passing through the first 3 UV lamps, the printed product should be blown in the cooling zone, then enter the curing zone of the rear 3 lamps, and then blown with cold air, so that the curing effect is better.