Kraft carton plays an important role in logistics, transportation and product packaging, and its folding resistance is crucial for frequent handling scenarios.
First of all, the selection of paper raw materials is a key factor. High-quality kraft paper with long fibers should be preferred. Long fibers can provide better toughness and tensile resistance. For example, kraft paper made from kraft wood pulp has longer fiber length and higher strength. In comparison, cartons made from recycled pulp with shorter fibers are much less durable in terms of folding resistance. When purchasing paper, fiber length, strength and other indicators are strictly controlled to ensure the high quality of raw materials.
Secondly, the number of cardboard layers and structural design of the carton have a significant impact. Increasing the number of cardboard layers can effectively improve the overall strength and folding resistance. Common three-layer, five-layer or even seven-layer cartons are common. For frequently moved items, five-layer or seven-layer cartons are more suitable. At the same time, the corrugated structure of the carton should be reasonably designed, such as using high-strength corrugated types, such as B-type or C-type corrugated corrugations, which have better buffering performance and folding resistance. In terms of structural design, optimize the corners of the carton, add reinforcing ribs or special folding methods to evenly distribute stress and reduce local breakage.
Furthermore, the production process of cartons cannot be ignored. During the cardboard production process, the amount and uniformity of glue application must be controlled to ensure firm bonding between the various layers of cardboard. Too much or too little glue will affect the performance of the carton. Too much may cause the cardboard to become hard and brittle, while too little may cause the bond to be weak. In addition, an advanced cardboard drying process is used to avoid stress concentration inside the cardboard and reduced folding resistance due to uneven or too fast drying.
Surface treatment is also one of the means to improve folding resistance. Coating the surface of kraft carton, such as plastic film coating, can enhance the wear resistance and waterproofness of the carton surface, and indirectly improve the folding resistance. Or use special moisture-proof agent treatment to prevent the carton from softening and reducing its strength due to moisture, so as to maintain good folding resistance during frequent transportation.
In the carton forming process, precise die-cutting and folding processes are crucial. The die-cutting size must be precise to avoid burrs or uneven edges, which may affect the folding effect. Advanced folding equipment and technology are used to ensure that the folding lines of the cartons are straight and flat, making the cartons less likely to break during repeated folding processes.
In addition, the finished kraft carton is inspected and screened for quality. Through professional folding endurance performance testing equipment, we can simulate the folding situation during frequent transportation and detect the folding endurance and strength of the carton. Screen out unqualified products, further analyze the causes and improve the production process.
Finally, during storage and transportation, proper stacking of kraft carton can also protect its folding resistance. Avoid excessive extrusion and store according to the prescribed number and method of stacking to prevent cartons from deformation and damage due to long-term pressure and ensure that they can withstand the test of frequent handling in actual use.