Standardised printing process and practical methods of four-colour, spot-colour ink measurement

Packaging box printing, in addition to a comprehensive packaging technology team and appropriate printing equipment, packaging boxes using standard and high stability of the material is necessary, otherwise it will disrupt the coherence of the box production and then affect the capacity and quality of the box manufacturer. Therefore, the box manufacturer’s knowledge of the material and the requirements of the particularly important, just in the purchase price of the pursuit of low-cost products, without in-depth understanding of which level of products to achieve the standard and stability, in the box printing will be more than lost.

　　There are a lot of materials needed for box printing, so in this article, we can only share with readers the seemingly simple, but in fact, quite important is the standard of four-colour and spot-colour inks and the way to distinguish between good and bad quality. Hopefully, this will give readers a basis to make a wise choice.

　　Four-colour inks

　　Problems with the colour standard ISO2846-2

　　In recent years, the colour management system used for printing standards has been based on ISO12647-2. Therefore, it is very important to use four-colour inks that comply with the ISO2846-2 standard. I have learnt that there are many four-colour inks in the market that can provide ISO2846-2 approval, but most of them cannot fully meet the requirements of ISO12647-2 on the printed matters. One of the main reasons is that in the assessment of ISO2846-2 four-colour ink of the U.S. agencies only require the four-colour ink to be sent to the approval of the four-colour ink, in its specified standard value of the paper, with the general colour spreading mechanism for the 4-colour full-page colour bar, as long as its Lab* value, transparency and ink layer thickness to its very loose range of eligibility…. . a DeltaE5 is sufficient. There is no dot gain criterion required for 4-colour inks. Therefore, 4-colour inks that do not meet the dot gain requirements can also be qualified. Generally, 4-colour inks may have excessive dot gain, and usually the printing department will make adjustments to reduce the dot gain without following the standard dot gain method when making printing plates. However, if the 4-colour inks with the high drop value Lab*DeltaE5 mentioned above are used, there is no way to adjust them when you need to print in multiple colours and have to take into account the standard dot gain. Usually, the printer will replace the iterative part with a spot colour or print the iterative part and the dot part in two parts…. It is very time-consuming and troublesome. Therefore, choosing a set of 4-colour inks with a low drop and meeting the standard can achieve the effect of smooth production and increase the capacity.

　　Chain relationship between pre-drying, full-drying and ink concentration of 4-colour inks

　　In the first hour after printing, almost all of the prints are pre-dried by osmosis, and then oxidised film is used to complete the drying. But generally cheaper ink formula concentration is low, and will be used to more appropriate linker; especially after drying will volatilize the mineral oil component is more, which will form the dry colour value of the print after drying relative to the printing of the wet colour value is very different. Ink in the formulation of the use of more cost-effective mineral oil, not only so that the V.O.C. content increases, but also will make the ink excessive penetration into the paper, the consequence is that when the print is fully dry will be found than the expected colours are much lighter. To avoid this excessive wet and dry value of the colour difference, printing technicians will only be able to adopt a curative approach to increase the amount of ink, which in addition to a large number of wasted ink and not environmentally friendly, it is not easy to dry, to use more powder, easy to back print and dot too large adverse consequences will follow. Therefore, the general printing master to feel the test just printed pieces, that feel dry faster ink is a misunderstanding, because the faster the pre-drying time is on behalf of the ink penetrates into the paper inside the rapid rather than the real fast-drying ink. As long as the ink used in printing, do not have to use more powder and prints will not back print, but also in a reasonable period of time can be fully dry. Especially the bottom of the eight-colour printing, not to use pre-drying fast ink.

　　The importance of water-ink balance when emulsifying inks

　　This is generally not often mentioned in depth is actually the decision of the ink in the printing process stability, transferability of the biggest key. Many printers think that emulsification is a scourge, but the truth is that the ink must emulsify with the sink liquid before transfer, otherwise the ink will not transfer properly. In simpler terms… Emulsification is “water mixed with oil” as long as the “water mixed with oil” ratio can be in a longer printing period to maintain its stability, the transfer performance of these inks should be the better. A set of high-quality four-colour ink in the absence of external factors such as too much lint under the influence of the continuous printing of tens of thousands of sheets without having to stop to clean the rubber blanket. The use of volatile cleaning fluids and expensive downtime each time the blankets are cleaned is equivalent to… Neither environmental protection and reduce production capacity.

　　Therefore, in addition to know how to choose a better quality of four-colour ink.