The elasticity and hardness performance of flexographic printing are key factors affecting printing quality.
1. Elasticity performance
Definition of elasticity: Elasticity is an important characteristic of flexographic printing plates, which determines the recovery ability of the plates after being pressed. Plates with good elasticity can better adapt to the surface of the substrate during the printing process, thereby ensuring the uniform transfer of ink.
Relationship between elasticity and substrate: The surface characteristics of the substrate have different elasticity requirements for the printing plate. For example, substrates with smooth surfaces require printing plates with less elasticity to ensure the clarity of printing; while substrates with rough surfaces require printing plates with greater elasticity to ensure sufficient transfer of ink.
Changes in elasticity: During the printing process, the elasticity of the printing plate will change to a certain extent. Especially after high speed and long-term continuous printing, the elasticity of the printing plate may decrease, resulting in insufficient rebound. Therefore, it is necessary to maintain a light printing pressure state during printing to reduce damage to the elasticity of the printing plate.
2. Hardness performance
Definition of hardness: Hardness refers to the ability of the printing plate to resist external pressure into its surface. The size of the hardness directly affects the printing resistance and printing effect of the printing plate.
Factors affecting hardness: The hardness of the printing plate is affected by many factors, such as temperature, pressure, and pressing time during sulfur curing. For photosensitive resin plates, their hardness also depends on the hardness of the photopolymer, which can be adjusted by adding a hardness control agent.
Matching hardness with substrates: Different substrates have different hardness requirements for printing plates. For example, when printing solids or text, a printing plate with a higher hardness is required to ensure the clarity of printing; while when printing dots or fine lines, a printing plate with a lower hardness is required to prevent dot expansion.
Hardness and printing effect: The hardness of the printing plate will also affect the layer reproducibility and dot expansion of the printed product. A printing plate with high hardness is not easy to deform during the printing process, which can ensure the clear layering of the printed product; while a printing plate with low hardness is prone to dot expansion, affecting the quality of the printed product.
3. Relationship between elasticity and hardness
Inverse index relationship: Elasticity and hardness are two important performance indicators of the printing plate, and there is a certain inverse index relationship between them. That is, the higher the hardness, the lower the elasticity; the lower the hardness, the greater the elasticity. Therefore, when selecting a printing plate, it is necessary to balance these two performance indicators according to specific printing needs.
