The hot stamping machine process can greatly increase the added value of packaging products, and it is widely used in the production process of printing enterprises. In response to some technical issues related to this process, this article was compiled through interviews with printing factories, hoping to provide reference for packaging and printing enterprises.
1. Q: Hot stamping can be divided into round stamping and flat stamping. What is the difference between the two?
Answer: The difference between circular hot stamping and flat hot stamping is that the general circular hot stamping method can be applied to both large area hot stamping and small area hot stamping. The reason is that circular hot stamping is a line contact hot stamping method with high hot stamping speed. Flat pressing and hot stamping belong to surface contact, which is not easy to exhaust air and can easily lead to inaccurate hot stamping. The flat stamping method is suitable for stamping small areas of patterns, lines, or text, and has a low stamping speed.
2. Q: What is the difference between hot stamping on composite cardboard and hot stamping on white cardboard?
Answer: The main difference lies in adhesion. The bonding layer of anodized aluminum is related to the affinity of the hot stamping material, and the hot stamping effect on white cardboard is better than that on composite cardboard because of the high surface tension on white cardboard.
White cardboard usually uses ordinary ink, but UV ink can also be used. Composite cardboard generally uses ink for composite material printing (such as the offset printing JP series ink from Hanghua Ink Chemical Co., Ltd.) or UV ink. The surface of composite cardboard is smooth and dense, and choosing a flat pressing square hot stamping machine is not easy to exhaust air. It is best to use a circular pressing line contact hot stamping machine.
3. Q: What should be paid attention to when printing on hot stamping foil?
Answer: It is best not to apply polish, as the ink will not transfer. When hot stamping, it is important to first test print and carefully study the properties of the materials and ink.
(1) Before printing, attention should be paid to the compatibility between anodized aluminum and ink. If allowed, the hot stamping area can be hollowed out.
(2) Select surface tension between (4.0~4.6) × 10-2N/M anodized aluminum ensures good ink adhesion.
4. Q: What should be paid attention to when conducting electrochemical aluminum hot stamping on UV varnish?
Answer: Generally, solvent based and water-based varnish products are not prone to problems, and UV is the most prone to problems. This is mainly related to affinity and is closely related to the surface tension of the printing material.
(1) Ordinary anodized aluminum stamping on UV varnish may result in inaccurate stamping, so it is necessary to ensure that the surface tension of anodized aluminum is greater than that of UV varnish;
(2) If allowed, the hot stamping area can be hollowed out, or it can be gilded first and then coated with UV varnish;
(3) It is best to try printing first and then determine the hot stamping process and materials.
5. Q: What are the reasons for inaccurate hot stamping and overprinting? What is the solution?
Answer:
(1) The paper has deformed. Solution: It can reduce the drying temperature or UV curing temperature during printing (excessive temperature can cause paper shrinkage).
(2) The hot stamping plate expands when heated. Solution: Determine several hot stamping points on a hot stamping plate, grasp the expansion law of the hot stamping plate with temperature changes, and compensate before production.
(3) Plate making