Q & A on the most common problems of post heat pri

2022-10-16
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Post press Expo: Q & A on bronzing process

hot stamping process can greatly increase the added value of packaging products. It is widely used in the production process of printing enterprises. Aiming at some technical problems of this process, this article is sorted out by interviewing the printing factory, hoping to provide reference for packaging and printing enterprises

1. Question: bronzing can be divided into round pressing and flat pressing. What is the difference between the two

answer: the difference between round stamping and flat stamping is that the general round stamping method can be applied to both large-area stamping and small-area stamping. The reason is that round stamping is a hot stamping method with wire connection. Everyone often has a certain degree of preference for some testing instrument brands, and the hot stamping speed is high. Flat pressing and hot stamping belong to surface contact, which is not easy to exhaust the air, and is prone to the failure of false hot stamping. The flat stamping method is suitable for stamping small areas of patterns, lines or words, and the stamping speed is low

2. Q: what is the difference between hot stamping on composite paperboard and white paperboard

answer: the main difference is adhesion. The bonding layer of electrochemical aluminum is related to the affinity of the hot stamping material. The hot stamping effect on white cardboard is better than that on composite cardboard, because the surface tension on white cardboard is large

ordinary ink is usually used for white cardboard, and UV ink can also be used. Composite paperboard generally adopts composite printing ink (such as offset JP series ink of HANGHUA ink Chemical Co., Ltd.) or UV ink. The surface of composite paperboard is smooth and dense, and it is not easy to exhaust the air by selecting flat pressing square hot stamping. It is best to choose circular pressing line contact hot stamping machine

3. Q: what should be paid attention to when re printing on hot stamping foil

answer: it is better not to polish, so the ink will not be transferred. When hot stamping, please be sure to try printing first, and carefully study the performance of materials and inks

(1) after hot stamping and printing, pay attention to whether the electrochemical aluminum is compatible with the ink. If allowed, the hot stamping part can be hollowed out

(2) select electrochemical aluminum with surface tension of (4.0 ~ 4.6) 10-2n/m to ensure good adhesion of the ink

4. Q: what problems should be paid attention to when anodizing on UV varnish

answer: general solvent type and water-based 4 This system is fully microcomputer controlled varnish products are not easy to have problems, and UV is the most prone to problems. This is mainly related to affinity and is inseparable from the surface tension of printing materials

(1) if ordinary anodized aluminum is scalded on UV varnish, there will be the failure of false hot 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 part can be hollowed out, or bronzed first and then applied with UV varnish

(3) it is best to try printing first, and then confirm and determine the hot stamping process and materials for high-performance and hard-working hot stamping

5. Q: what are the reasons for inaccurate gilding overprint? What is the solution

answer:

(1) the paper is deformed. Solution: reduce the drying temperature or UV curing temperature during printing (too high temperature will shrink the paper)

(2) the bronzing plate expands when heated. Solution: determine several hot stamping points on a hot stamping plate, master the expansion law of the hot stamping plate with the change of temperature, and compensate it before making

(3) scaling of hot stamping patterns, words or lines was not considered during plate making

(4) previous process. Solution: for the problems of the previous process, ensure that the front gauge and side gauge (the distance from the paper edge to the finished product line) are consistent

in addition, the unsteady ambient temperature, human factors and the accuracy of the equipment will also cause inaccurate overprint during bronzing, so the influence of these factors should be considered in the production process

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