Refractive screen printing technology for packaging and printing

The refraction screen printing technology that has emerged in recent years is a new star in the packaging screen printing family. The traditional refraction effect is generally to make a copper-zinc plate with a refractive texture, using a round-pressed or round-pressed letterpress printing machine in gold. The silver card paper presses the lines at different angles to produce the refractive texture effect. The disadvantage of this method is that the plate making cost is high and the effect is not ideal. The screen printing can easily print on the mirror gold and silver cardboard. The fine concave and convex lines will produce a colorful refraction effect after being irradiated by light, making the screen printing package more noble and gorgeous.

The process of refraction screen printing process is: refraction original design; stretch net; cleaning rough screen version; coating photosensitive glue; exposure; development; revision; double exposure;

1. Refractive original design

The design points of the refraction original are as follows: the part of the image that needs to be refraction point is drawn into a millimeter aliquot, and the length per mm is divided into 5~8 bisectors, and each aliquot is divided into black and white 10~16, etc. For example, 16 can be designed as black 4 white 12, or black 8 white 8. Its lines are divided into three types: straight line, arc, and ellipse. Lines and arcs change with each other as the image changes.

The refraction pattern is fine and complex in appearance, and it cannot be seen through the internal structure with the naked eye. Under the microscope of 40 times or more, it can be seen at a glance that the refraction map is composed of several segments or tens of segments equidistantly arranged but with different angles and curvatures. The thickness of the folded light bar should be 0.10~0.15μm, and it can be produced by high resolution laser phototyper.

2. Making a refraction screen

(1) Selection of mesh and stretcher. To make a reticulated screen, it is necessary to select a suitable screen. The screen is required to have good elasticity, and it is resistant to friction. The expansion ratio is very small, the mesh is large, and the ink layer is printed. Thick. Polyester screen is an ideal choice, the general choice of mesh is 390 ~ 420 mesh / inch.

When stretching the net, select the oblique stretch net with an angle of 22.5°, and the tension of the screen is required.

18~22N/cm. For the new stretched screen version, it must be cleaned and roughened, which has a very important influence on the quality of the screen.

(2) Coating photosensitive adhesive. Whether using automatic gluing or manual gluing, it is necessary to ensure that the gluing is even and even. The number of gluing of the reticulated screen depends on the consistency of the photosensitive adhesive, generally 4 times. When the first time is applied, the glue applicator should be evenly scraped on both sides of the screen, so that the photoresist is evenly filled in the mesh, and then dried in a drying oven at 40 ° C. 2nd, 3rd Only the printing surface can be glued and dried, and the fourth time is glued on the scraping surface.

(3) Exposure. The folded light bar is more delicate and more dense. In order to ensure the quality of the printing plate, it must be printed on the plate with a vacuum adsorption device. The film should be closely adhered to the surface of the photosensitive film when printing. The time of the plate should be appropriate. If it is too long, it will be difficult to develop. If it is too short, it will affect the printing durability of the screen. The folded light bar will also become thicker. You can use the test strip to measure the accurate exposure time required.

(4) Development. Put the dried screen into the shaded pool, the water depth in the pool is 20~30cm, the screen should be soaked in water for 1 minute, then the screen is repeatedly pressed into the water, and the image is pressed with water pressure. Part of the photoresist is squeezed out and cleaned. In order to ensure that the refractive film of the refractive screen is uniform, it needs to be washed with a low-pressure water gun during development. After the development is sufficient, it is dried.

(5) Revise the plate. Check the plate for pinholes, air bubbles, etc., and repair it.

(6) Double exposure. After the screen is dried, a double exposure is also required to completely cure the photosensitive film on the plate to improve the printing durability of the screen.

3.UV refractive ink

UV refraction inks can only produce a unique refraction effect when printed on the surface of the mirror substrate. When printing, add appropriate amount of diluent to dilute as needed.

4. Refraction screen printing

If the area of ​​the refraction printed image is large, in order to ensure the quality, it must be completed with a high-precision screen printing machine. The small area can be printed by hand. The refraction screen printing requires the operator to make high-quality screen printing and scraping. The hardness, angle and pressure, as well as the performance of the UV refractive ink should be understood in order to be able to take appropriate countermeasures for various problems in the production process.

Precautions

1. The same type of screen printing ink produced by different manufacturers has certain differences in quality and performance. Generally, it must be tested first to determine the quality is stable and reliable before mass production.

2. The ink must be fully stirred before use. Especially when mixing several patterns of ice-cream ink, it is best to use bamboo plate to stir. When using in large quantities, it is best to stir with a wide-leaf mixer.

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

4. The temperature change will change the viscosity of the ink, which will cause the difference in printing effect. Therefore, the ink should be placed in the printing workshop in advance to adapt it to the temperature of the workshop to ensure the stability of the quality.

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

6. The ink should be sealed and stored at low temperature (2~18°C), protected from light and heat, and the storage period is generally 6 months to avoid the change of ink performance.