Coating treatment of the hottest paperboard packag

Coating treatment of paperboard packaging (Part 1)

people often forget that most folding cartons are treated with water-based coating or UV curing coating. In fact, most new printing machines are also equipped with coating devices. UV coatings are commonly used because of their high gloss and chemical corrosion resistance. However, compared with water-based coating, UV coating costs 4 pieces of aluminum foil per experiment, which is very high and difficult to use. The cost of water-based coating materials accounts for only a small part of the production cost of printers, usually less than 3% of the whole packaging cost. Even so, if the coating quality is poor, it will also lead to packaging degradation or customer claims. Although coating materials are relatively cheap, they can greatly affect other cost factors, including excessive downtime and operator intervention

this article focuses on why the packaging should be coated, what is the stable operation quality and coating amount, and what is the practical significance of the control of coating viscosity

why coating the packaging

this has something to do with people's subjective feelings. Consumers often associate product quality with packaging quality. Packaging customers are very concerned about specific gloss or specific friction coefficient. These are important packaging surface characteristics. Of course, since printers sell products to packaging customers, the needs of customers are also the needs of printers. Printers also have to deal with production issues such as drying speed and ease of use. As the offset printing ink takes several hours to cure, a water-based coating is used to provide a fast drying protective seal. In this way, the ink layer will not be damaged when processing the packaging surface, so as to shorten the processing time of printers. In addition, printers can also use large lifting devices to reduce handling costs. Sometimes, the reverse coating is used, so that the second side can be printed quickly after the first side is printed. The above coating helps to reduce the amount of offset printing powder. Offsctdruckereien powder spraying often makes the packaging surface feel like dust

the above coating is also used on flexible gravure cartons, mainly to increase important packaging surface characteristics

important surface properties and barrier properties

coating layer is the last layer of packaging surface. The rough surface of the substrate clay coating layer should be coated with a relatively flat water-based coating. It will have a great impact on the surface characteristics of packaging. The water-based coating can use different formulas according to the surface needs, so that the packaging surface has certain gloss, wear resistance, specified friction coefficient, corrosion resistance and barrier characteristics

coating has a great influence on the gloss of packaging surface. In order to better attract consumers, higher gloss is often used. The package gloss of high-quality products is also relatively high. For this reason, some packaging designers also use low gloss or matte packaging surface to better highlight their product packaging. In addition to gloss, product packaging also requires a certain coefficient of friction and scratch resistance

friction coefficient is of great significance for die cutting, gluing, high-speed filling and other operations. The paperboard whose friction coefficient does not meet the requirements cannot pass the filling or folding process smoothly

it is also very important to safely handle the packed products in warehouses and retailers. This is especially true for beverage packaging cartons. The packaging boxes containing products should neither fall from the stack nor be piled together, even under hot and humid conditions. In the process of forming, filling, transportation and display, the surface coating of the package has the functions of scratch resistance, water resistance and corrosion resistance. If the package contains liquid products, the above characteristics are even more important

for food packaging, corresponding management regulations must be observed. The packaging coating approved by the U.S. Food and Drug Administration (FDA) can block and cover the ink that does not meet the hygiene requirements, and prevent the ink from directly contacting food. The paint meeting FDA standards is prepared with resin and emulsion formulations that can directly contact with food. It is suitable for all paper materials and all conditions (except for those with extended storage period of cooked food packaging)

it should be noted that coating cannot completely control the surface characteristics of packaging. Substrate and ink can also play a role

reasons for emphasizing coating stability

emphasizing coating stability has two important meanings. The first is related to the important packaging surface characteristics mentioned above, and the second is the stability of the processor, that is, the coating on the printing machine has stable and repeatable characteristics

the physical properties of coating, like viscosity, will change over time, causing some problems in the operation of printing machines. The printer operator needs to stop and adjust the setting state of the printer or change the viscosity of the coating to maintain the best operation speed and avoid problems such as pasting. The coating stability should be considered from the following aspects:

● test space: 1000mm is there any change in the coating during the operation of the same shift of operators

● whether different operators adopt different standards when working in different teams

● can the operator always obtain the same coating effect when processing the same live parts every time

● is the performance of the coating stable in different seasons (such as winter and summer)? Does the coating supplier provide coatings with different formulas in winter and summer to adapt to seasonal changes

● due to the different design of coating equipment, does it also require different coating formulas to process the same batch of live parts? Is the appearance of printed moving parts affected by all coating equipment? Does the packaging customer require the packaging appearance to be consistent all the time? Are the packages produced by different factories consistent in appearance

control the coating amount

the coating causes the pointer of the load instigator to run for 1 week and then touches the lift limit switch. The formula should meet the specific operation requirements. However, in order to make the coating play its due role, it is necessary to determine the appropriate coating speed. The so-called coating amount refers to the coating weight applied on the unit area of the substrate (usually calculated in grams/square meter, or pounds/thousand square feet). If the coating amount is unstable, other aspects will not be stable. (to be continued)

the new national standard covers household appliances expected to be used to contact or process food