Current situation of new screen printing technolog

2022-08-20
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Current situation of new printing technology for high-end packaging boxes (II)

refractive printing process

the rising refractive printing technology in recent years is a new star in the printing family that produces the best and safest products in packaging. The traditional refractive effect is generally to make a copper zinc plate with refractive texture first, and press lines with different angles on gold and silver card paper with a circular press or a circular press relief press to produce a refractive texture effect. The disadvantage of this method is that the plate making cost is high and the effect is not ideal. Printing can easily print ultra-fine concave convex lines on mirror gold and silver card paper, which will produce colorful refraction effect after light irradiation, making the silk printed packaging box more noble and gorgeous

the process flow of refractive printing is: refractive original design → stretching → cleaning the roughened silk plate → the coating sense cannot be changed. The range selection knob photoresist → exposure → development → revision → secondary exposure → printing

1. Refractive manuscript design

the key points of refractive manuscript design are as follows: draw the parts in the image that need refractive dots into a millimeter bisector, divide the length of each millimeter into 5 ~ 8 bisectors, and each bisector is divided into 10 ~ 16 bisectors with black and white. Taking 16 as an example, it can be designed as black 4, white 12, or black 8, white 8. Its lines are divided into straight lines, arcs and ellipses. Lines and arcs kiss each other with the changes of the image

the appearance of the refraction pattern is fine and complex, and its internal structure cannot be seen through with the naked eye. Under a microscope of more than 40 times, it can be seen at a glance that the refraction diagram is composed of several or dozens of lines arranged at equal distance but with different angles and radians. The thickness of the refraction line should be 0.10 ~ 0.15 μ This article is just a simple explanation m with 300KN as an example, which can be produced by a high-resolution laser Imagesetter

2. Making refractive version

(1) selection and stretching of silk. To make the refracting plate, we must choose the appropriate wire, which is required to have good elasticity, friction resistance, very small expansion rate, large holes and thick printing ink layer. Polyester filament is an ideal choice, generally 390 ~ 420 mesh/inch

when stretching, choose the oblique stretching method with an angle of 22.5 °, and the tension of the plate is required to be 18 ~ 22n/cm. The newly stretched silk plate must be cleaned and roughened, which has a very important impact on the quality of the plate

(2) apply photosensitive adhesive. Whether automatic gluing or manual gluing is adopted, the gluing must be uniform and flat. The number of gluing times of the refractive plate depends on the thickness of the photosensitive glue, which generally takes 4 times. For the first time, scrape the glue applicator repeatedly and evenly on both sides of the plate to make the photosensitive glue fill the holes evenly, and then dry it in a drying oven at 40 ℃. For the second and third times, only glue and dry the printing surface, and for the fourth time, glue and dry the ink scraping surface

(3) exposure. The refraction lines are fine, many and dense. In order to ensure the quality of printing, we must use a printing machine with a vacuum adsorption device to print. When printing, the film should fit closely with the photosensitive film surface of the plate, and the printing time should be appropriate. If it is too long, the roughness will affect the accuracy; The latter use servo electromechanical cost is high, and it is difficult to develop. Too short will affect the printing resistance of the version, and the refraction line will become thicker. The required accurate exposure time can be measured with the test strip

(4) development. Put the sun dried version into a blackout pool with a water depth of 20 ~ 30cm. Soak the version in the water for 1 minute, then press the version into the water repeatedly, squeeze out the photosensitive glue of the image part with water pressure, and clean it. In order to ensure the uniformity of the photosensitive film of the refractive plate, it is necessary to wash it with a low-pressure water gun during development. Dry after sufficient development

(5) revision. Check the layout for pinholes, bubbles and other defects, and repair them

(6) secondary exposure. After the plate is dried, it needs a second exposure to completely solidify the photosensitive film of the plate and improve the printing resistance of the plate

refractive ink

uv refractive ink can produce unique refractive effect only when it is printed on the surface of the mirror substrate. When printing, you can add an appropriate amount of diluent to dilute as needed

4. Refraction printing

if the area of refraction printing is large, in order to ensure the quality, it must be completed with a high-precision silk screen printing machine, and manual printing can be adopted for small areas. Refractive printing requires operators to understand the production of high-quality version, the hardness, angle and pressure of scraper, as well as the performance of UV refractive ink, so that they can take corresponding countermeasures against various problems in the production process

precautions

1 The same type of printing ink produced by different manufacturers also has certain differences in quality and performance. Generally, it is necessary to go through trial printing first, and then carry out mass production after confirming that the quality is stable and reliable

2. The ink must be fully stirred before use, especially when several kinds of ice flower ink with patterns are mixed, it is best to use bamboo board to stir, and it is best to use a wide leaf mixer to stir when used in large quantities

3. Pay attention to check the curing condition of the ink, so as not to affect the hardness and adhesion fastness of the ink layer due to incomplete curing

4. Temperature change will change the viscosity of the ink, resulting in the difference of printing effect. Therefore, the ink should be put into the printing workshop in advance to adapt to the temperature of the workshop and ensure the stability of quality

the ink is irritating to the skin. Be careful when taking it and avoid contact with the skin. If the skin is stained with the ink, wash it immediately with soapy water

6. The ink should be sealed and stored at low temperature (2 ~ 18 ℃), away from light and heat. The storage period is generally 6 months to avoid changes in the performance of the ink

source: keyin

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