Because it is made of paper, the carton packaging also has properties such as water absorption. Therefore, the adjustment of the moisture of the paper greatly affects the quality of the product.
Paper packaging manufacturers have their techniques for regulating the moisture of paper. This helps the carton to keep its rigidity, strength, and compression … during product preservation.
The concept and standards of the moisture of carton packaging
Paper packaging moisture is the hygroscopic property of paper. Absorbent paper changes the mechanical properties and causes the cellulose fibers to become plastic. This causes the bond between the fibers to loosen and weaken. Therefore, the humidity level in the carton also changes the ability to absorb and reflect infrared and microwave bands.
Besides, humidity also affects the quality of carton packaging. Affects the process of printing, production process, and finishing section. Normally, the newly produced carton packaging paper will have a lower moisture content than the environmental humidity.
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Each type of paper packaging has a certain moisture content. The degree of difference in moisture in paper varies from 2% to 12%, depending on the water vapor, the amount of powder used, the degree of grinding, and the chemicals used in the production process.
The role of moisture index on carton packaging quality
Humidity greatly affects the quality of packaging paper. Therefore, most paper packaging enterprises have to apply many methods to regulate the equilibrium. This contributes to improving the quality of paper in offset printing.
According to research, when the roll paper is stored in humid conditions for 6 months, there will be about 12cm of paper dampened by the outside environment. Causes wavy edges of paperboard to make cartons.
Abnormal changes in moisture content will cause the paper to warp and wave, as some individual fibers swell more than others. When the moisture content of the paper making the carton is in the range of 5% – 6%, the damage of the carton is at its highest.
The porosity of an offset printed carton shows how much pressure the paper can withstand until it breaks. When the moisture content of the paper fluctuates above 18%, the damage degree value will decrease in the range of 10% or more.
Method of determining paper moisture
Currently, the optimal method to help determine the moisture of carton packaging paper is the application of the drying method in the laboratory. This method applies to most corrugated cartons.
Some equipment is necessary for testing the moisture content of carton packaging, including scales, samples, weighing cups, weighing boxes, and drying ovens… These items must meet the standards to give the most accurate results.
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Samples of carton packaging participating in the test must meet the standards of TCVN 3649:2000. Besides, the sample was torn into small pieces with a minimum weight of 1g. At the time of sampling, the test sample must have a minimum weight of 50g and be chopped or stacked for placement in the weighing box.
When experimenting, the weighing boxes were washed, numbered, opened the lid, and put in the drying oven at 105 degrees C ± 2 degrees C within 1 hour to determine the absolute dryness.
Next, the process as above until the test sample has a constant mass, this case is taken into account when the difference between two successive weighings is not more than 0.1% of the original mass.
Measures to maintain humidity to preserve cartons packaging
Typically, businesses often use the paper state conditioning method to control the humidity of carton packaging. This is the process of restoring moisture to the paper, to reduce the deformation of the paper during storage and use.
Conditioning the state of carton packaging paper is a method of preserving form in an environment with stable humidity. This environment will cause the moisture of the paper to increase, corresponding to the equilibrium of the surrounding environment. Besides, the fibers become soft and relieve the stresses inside the paper. This is a condition to reduce paper deformation during storage.
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Moreover, controlling the moisture of carton packaging is an important issue. This is to improve the quality and limit the deformation of the paper during the production process.
Therefore, companies producing carton packaging need to invest in and research the hygroscopic properties of the packaging to have a suitable preservation method.
Hope the above article has helped you gain more experience working with paper packaging manufacturers. Contact us for free product consultation.
KHANG THÀNH – HOUSE OF PACKAGING
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