Problems and Countermeasures of UV Abrasive Printing in Printing

1. The sand is not good, but it does not show a strong sense of roughness. The main reasons are as follows: 1 The fillers in the matte ink are not properly selected, and the particle size is too small; 2 The amount of the filler added is improper; 3 The doctor blade is selected improperly; 4 The mesh number is not properly selected.

Solution: According to the sand sensation requirements of the printed matter, select the appropriate diameter of the filler; appropriate increase in the amount of filler; use the appropriate hardness of the scraper. In general, the higher the hardness of the blade, the clearer the printed pattern, the lower the hardness of the blade, the more likely the printed pattern is imaginary, resulting in reduced sand sensation. At the same time, adjusting the mesh number of the screen can also significantly improve the sand feel of the printed sample. In general, for the same type of matte ink, the lower the mesh number, the stronger the sand feel.

2. The effect of mirror contrast is not obvious. Main reasons: 1 The gloss of the substrate itself is not high; 2 The amount of filler added to the matte ink is too large to completely cover the substrate; 3 The degree of matteness of the filler is not high, resulting in the contrast between the mirror substrate and the ink film surface. strong.

Solution: At the same time as selecting suitable fillers, choose a high-gloss mirror substrate as much as possible.

3. The surface of the printed material is white and non-inking. The main reasons are as follows: 1 improper selection of screen mesh number; 2 oil stain on the substrate surface; 3 oil containing low volatile oil impurities in the matte ink.

Solution: In general, for a filler with a large particle diameter, if a mesh with a high mesh number is selected, since the mesh is small, the ink is not easily passed or passes through during printing, so that the ink is uneven and a white phenomenon occurs. The presence of oil stains makes the ink difficult or spots or whitening phenomenon. This situation can be solved by selecting the appropriate screen and corresponding cleaning measures.

4. Paste printing occurs during printing. Main reasons: 1 The viscosity of the matte ink is too large; 2 The mesh distance is too small; 3 The number of screen meshes selected is too low; 4 The printing pressure is not suitable.

Solution: Minimize the viscosity of the photo-setting resin in the matte ink, adjust the distance between the screen plate and the substrate, select an appropriate mesh screen or adjust the printing pressure.

5. Penetration occurs when prints are stacked. Main reasons: 1 The curing speed of the materials in the matte ink is not enough; 2) The printing substrate has moisture or other solvents; 3 The curing time is too short.

Solution: Select a photocurable resin with a fast curing speed, or increase the amount of photoinitiator or photosensitizer, and extend the curing time appropriately to keep the substrate dry and clean.

6. There are moire patterns in prints. Main reasons: 1 The curing time is too long; 2 The resin itself in the matte ink is not good; 3 The stretching mode is not appropriate.

Solution: Due to excessive cure time, excessive cure and post-cure can occur, resulting in cracking. Therefore, the curing time should be controlled. Selecting photohardening resins and reactive monomers with good flexibility can also improve the moire phenomenon. The use of oblique stretch nets instead of positive stretch nets also avoids the occurrence of moire.

7. The adhesion of printed matter is not good. Main reasons: 1 As the photo-curable resin and reactive monomer will inevitably undergo volume shrinkage after UV curing, it will inevitably affect the adhesion of the matte ink on low surface energy, non-polar substrates; 2 The surface of the substrate has silicone oil , dusting, dust and other impurities.

Solution: For low surface energy, non-polar substrates such as PE, PP, PET, etc., should be corona treatment or other chemical and physical treatment in advance, before commissioning, while maintaining the clean printing substrate.

8. The print has poor toughness. Mainly reflected in the folding and cutting after the process is prone to cracking, the main reasons are: 1 matte ink itself is not good toughness; 2 printed frosted ink ink layer thickness is too large.

Solution: Select tougher photo-curable resins and reactive monomers, and select a higher mesh screen to print thinner patterns to improve toughness.