Screen printing decoration process of UV imitation metal etching ink
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UV imitation metal etching printing, also known as matte or sand surface printing, is a UV-transparent (UV) after printing a layer of uneven translucent ink on a substrate with a metallic mirror gloss (such as gold or silver cardboard). Curing produces an etched or matte finish similar to a shiny metal surface.
The imitation metal etching ink printing products have obvious etching effect, the ink film is full, and the three-dimensional feeling is strong, and the packaged products are all high-grade, and have been widely used in the packaging color printing industry such as cigarette labels, wine labels, cosmetics, health products and the like. Can also be used for greeting cards, calendars, brand names, tags, advertisements, and for use. Can also be used for greeting cards, calendars, brand names, hangtags, advertisements, art paintings, etc.; UV-like eclipse remembers that screen printing inks can also produce suede and matt effects, making prints soft, solemn, elegant, luxurious, to the general The effect that inks are difficult to achieve, for which it has been rapidly promoted and applied.
First, UV curing ink
The ink of the ink is short and thick, wherein the additive particles have a diameter of about 15 to 30 μm. After printing, due to the rough surface of the ink film, under the illumination, the reflection is diffuse reflection, and the gloss of the film surface is dark. There is a metallic luster-free surface. Under illumination, the reflection is positive reflection, and the gloss is strong. Therefore, the place with the film surface is gray and concave, and the place without the film surface is bright and convex. The effect of the two is completely opposite. In order to reflect the inherent luster of the substrate, the ink should be transparent, and the hiding power is not suitable for use. The UV imitation metal etching ink generally stirs a plurality of materials such as a photosensitive resin into a light transparent paste; and can also be used as a color etching ink. Its components are as follows.
UV etching ink: main agent (silicone 15~30μm); binder (photocurable resin or prepolymer, crosslinker, photosensitizer, polymerization inhibitor).
Second, UV imitation metal etching ink screen printing points
1. Plate making operation quality control
(1) The mesh size and the thickness of the photosensitive film have a certain thickness. If the mesh is too high, the mesh is small, the ink is not easy to pass or pass through during printing, and the ink is uneven. The phenomenon of whitening leads to poor etching. If the screen mesh is too low, the mesh is too large, and the ink transmission amount is too large, which causes the paste to affect the printing effect.
· Scrub rough grain: screen 100~180 mesh; photosensitive film thickness 10μm or less.
· Scrub in the grain (or ice flower in the flower): screen 150~250 mesh; photosensitive film thickness 12~14μm.
· Scrub fine text (or ice flower small flowers): screen 200~300 mesh; photosensitive film thickness 14~16μm.
(2) Because the imitation metal etching ink has a certain thickness, the printing is most commonly carried out by using an aluminum alloy frame and a screen printing machine to prevent the screen from being deformed and making the pattern overprinting difficult.
(3) Stretching operation When using the stretcher, the skewer is used to minimize the sawtooth and improve the plate making precision.
(4) Determination of tension The magnitude of the tension is directly related to the flatness and print quality of the photosensitive film. The tension is too large, the screen becomes brittle, the reaction force on the squeegee is large when printing, and the screen is easy to tear; the tension is too small, the screen is soft, the necessary resilience to the squeegee can not be generated during printing, and the squeezing point or Neem outlets. Only moderate tension can ensure the dimensional accuracy of printing and printing, make the overprinting accurate, and the mesh resilience is good, the dots are clear and resistant to printing, and it is not easy to break under normal conditions.
(5) When making the screen plate, use solvent-resistant or water-resistant type photosensitive glue, develop with water, no pollution, solvent-resistant sexy light-made plate, and can be reused after printing and film removal.
(6) Since the photosensitive film is thick, the screen requires a long exposure time to completely harden the photosensitive layer, and at the same time, the development time is appropriately lengthened to make the effect more sufficient. It is preferable to perform double exposure to sufficiently cure the photosensitive film to enhance the printing durability of the screen.
2. Print operation quality control
The imitation metal etching ink should be fully stirred before printing, and during the printing process, the stirring should be timely to prevent the ink layer from being uneven or not. Imitation metal etching inks, like ordinary screen printing inks, can be printed either by screen printing or by hand. Considering the characteristics of the etching ink itself, such as the ink itself is thicker, the printing resistance is larger, the pattern registration requirement is high, and the printing ink layer is required to be uniform, so it is generally printed by a screen printing machine. At the same time, attention should be paid to the corresponding adjustment of printing pressure, squeegee angle, screen height, etc. to control the printing quality and prevent premature damage of the screen.
(1) Use of additives
.When the imitation metal etching ink is used in the initial printing, do not add other solvents at will. Only when the ink is not printed in the printing process, a small amount of thinner can be added and stirred before printing. Excessive addition of diluent or insufficient agitation will greatly affect the metal texture and also affect its fastness and dryness on the aluminum film. Therefore, when the ink is being compounded, various additional materials must be stirred evenly.
· In order to reduce the leveling of the ink on the film surface after printing, no dilution or leveling agent is used in the dosing to promote the formation of the uneven surface.
. Dilute and clean with special thinner or industrial alcohol.
(2) Scraper selection
UV inks cannot be made of polyurethane squeegees, and special rubber squeegees are used.
·Scratch strip: its hardness should not be too high, generally with a Shore hardness of 65.
·The shape of the scraper: the substrate is flat, and a right-angle scraper should be used; when the substrate is convex, a tapered scraper is used;
.The length of the squeegee is required. Generally, the squeegee is slightly wider than the printed frame, so that when the ink is pushed back, no residual film remains on both sides.
·The quality of the scraper is also an important factor that cannot be ignored. Because the ink is short and thick, the pressure is small, the ink is not smooth through the net; the pressure is large, and the amount of ink passing through the mesh will be too much. Both will affect the printing quality and imitation metal etching printing effect, and the squeegee pressure should be controlled to be slightly larger than the pressure of printing ordinary color ink.
·The pressure should be the same when printing, to avoid the thickness of the ink layer which is imitation metal etching due to the different pressures, which affects the uniformity of the rough surface.
(3) During the printing process, the wetting state of the imitation metal etching ink should be maintained to ensure the uniform effect of the printed matter. The degree of wetting is determined based on user experience. When the ink is dry, add special thinner in time, and continue to use after stirring.
(4) The drying of the imitation metal etching ink should be selected within the range of 80W~6.4kW of the UV lamp of the UV curing machine according to the thickness of the ink and the speed of the light-solid machine. The light-solid machine must be equipped with a cooling device to prevent the composite paper from undergoing thermal deformation failure when passing through the light-solid machine.