Both manufacturers and users pay more and more attention to the outer packaging of products, and the market demand for a variety of high-end packaging and personalized packaging is growing. In the post-press processing of products, UV frosted printing has attracted great attention for its unique printing visual effect, and has been widely used in packaging color printing industries such as cosmetics and health care products. This article shares the relevant content of UV frosted printing process, for friends’ reference:
UV frosted printing
Frosted printing is to print a layer of transparent UV frosted ink on a substrate with mirror-like luster, which is cured by UV to form a rough surface like ground glass, and mostly adopts screen printing method. Because the printed pattern is similar to the effect of metal corrosion, it has a special rough feeling.
Printed with UV imitation metal frosted ink picture and text part under the light point-blank, ink in sharp contrast to the small particles in diffuse light, like a smooth surface after grinding the dent feeling instead of part of the ink, because of paper and high gloss effect produce specular reflection and feel out it still has the gold and silver cardboard metallic luster.
2 Printing materials
Gold, silver cardboard and vacuum aluminized paper are generally used, and the surface is required to be smooth, with high smoothness, and the mirror metal effect can be produced after printing.
You can also use the method of printing color paste on white cardboard, that is, using coating equipment to print gold or silver color paste on cardboard, but the color paste is required to have high coloring force, uniform coating color, plain clothes, and good glossiness. Compared with composite gold and silver card paper, the effect of coated gold and silver card paper is slightly worse.
3 UV frosted ink
In the process of frosted printing, the frosted effect depends on the special properties of UV frosted ink. The printing frosted ink is a kind of colorless and transparent one-component UV light curing ink with particle size of 15 ~ 30μm. The products printed with it have obvious frosted effect, and the ink film is full, the three-dimensional sense is strong, which can improve the product grade.
UV frosted ink relative to the traditional solvent-based ink, has distinct advantages: fine printing patterns, strong three-dimensional sense; No solvent, high solid content, little environmental pollution; Fast curing, energy saving, high production efficiency; The ink film has good friction resistance, solvent resistance and heat resistance.
4 Key points of printing process
01 The printer
In order to ensure the accuracy of registration, it is best to use automatic screen printing equipment with UV curing device.
02 Printing environment
Temperature: 25±5℃; Humidity: 45%± 5%.
03 Set the standard
The printing plate graphic and text should be consistent with the previous colors to ensure the accuracy of overprinting, and the error of overprinting should be less than or equal to 0.25mm.
04 Printing color sequence
Frosted printing belongs to high-grade trademark printing, which not only requires rich colors, but also needs to have a certain anti-counterfeiting function, so it often adopts the method of combining multi-color printing and a variety of printing methods.
When arranging the printing color sequence, the frosted ink should be arranged in the last color printing. Such as printing a white, red, pattern hot stamping and frosted effect, the general color sequence is to first print white and red ink, then hot stamping, and finally print frosted ink. Because frosted ink is colorless and transparent, printed on the surface of gold and silver cardboard, it can transmit the inherent metallic luster of printing materials, so as to achieve the printing effect of imitating metal etching. Moreover, the final printing of frosted ink, but also the previous printing ink color.
05 Curing way
Cured by high pressure mercury lamp. The lamp life is generally 1500 ~ 2000 hours, need to be replaced frequently.
06 Printing pressure
When printing frosted ink, the pressure of the scraper should be slightly larger than that of ordinary ink, and the pressure should be consistent.
07 Printing speed
The particle size of the frosted ink is larger. In order to make the frosted ink fully penetrate the mesh, the printing speed should be lower than that of other inks. Generally other color ink printing speed of 2500 ± 100 / h; The printing speed of frosted ink is 2300±100 sheets/hour.
08 Screen requirements
Generally, about 300 mesh imported plain nylon mesh is selected, and the tension of the tension network is uniform. In the printing process, the deformation of the printing plate should be strictly controlled.
5 Common faults and solutions
01 The metal texture is poor
Causes: ink to add thinner is not appropriate; UV lamp power is insufficient; The quality of the substrate material is poor.
Solution: Before printing, add diluent matching with frosted ink; Accurate dosage of diluent and sufficient stirring. During the curing process, the power range of the light source should be selected according to the thickness of the ink layer and the speed of the light solid machine, and the power of the light source should be 0.08 ~ 0.4KW. In addition, but also to choose a higher metallic luster of the substrate material, the surface can not have scratches, and has the appropriate tensile strength and high temperature resistance.
02 The abrasive surface is rough and the particle distribution is uneven
Cause: printing pressure is not consistent.
Solution: the length of the scraper should be slightly greater than the width of the printing substrate. Right Angle scraper can be selected for printing, but the rubber scraper hardness should not be too high, the general hardness is HS65.
03 The ink is dry on the screen
Cause: direct natural light screen. Because of the natural light contains a lot of ultraviolet light, easy to trigger the ink in the photosensitizer curing reaction. A paper surface or ink containing impurities.
Solution: Try to avoid direct exposure to natural light; Choose paper with high surface strength; The printing environment should be kept clean.
04 Printing matter adhesion
Cause: the ink layer on the printed matter is not fully cured.
Solution: improve the power of the light solid machine lamp tube; Reduce the belt speed of the light machine; Reduce the thickness of ink layer while meeting the printing requirements.
05 Stick version
Causes: paper positioning is not allowed, imprint drum paper teeth improper adjustment.
Solution: Calibrate the paper positioning system, adjust the position of the paper teeth, to avoid the paper with the drum rotation.
06 The printing plate is broken
Causes: printing pressure is too large, the tension of the stretching network is not uniform.
Solution: adjust the pressure of the scraper evenly; Keep the tension of the tension network uniform; It is best to choose imported mesh cloth.
The edges of text and text are hairy
Cause: ink viscosity is too large.
Solution: add appropriate diluent, adjust the viscosity of ink; Avoid ink drawing.
Company Name: Fuzhou Huaguang Color Printing Co., Ltd.
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Address:Building 4, No. 20, Zhaoyu Road, Gaishan Town