What are the factors that affect folding endurance?

① relative humidity. When changing from low humidity to high humidity, the folding endurance increases accordingly, reaches the maximum value after reaching a certain humidity, and then the folding endurance decreases with the increase of humidity.

② temperature. As the temperature rises, the fiber strength inside the folded area of the paper decreases, resulting in a sharp drop in the folding endurance, sometimes down to 1/3 of the original. Most of the folding Testers currently used are equipped with a small fan to blow air on the folding area, so that the temperature rise in the folding area is limited, thereby ensuring the stability of the test results.

③ Instrument tension. The paper folding test is actually a paper under the condition of changing tension, which periodically measures the knife-edge tensile force of the sample that is gradually damaged by folding. The greater the tension, the smaller the number of times the paper is folded.

④The folding blade and jaw of the instrument. The smoothness and wear of the folding blade of the instrument and the arc of the jaw also have a significant impact on the number of folds.

⑤The quality of corrugated base paper and cardboard paper.

⑥ The initial tack and cohesive force of the adhesive are the key factors affecting the flexibility of the adhesive surface after drying and the folding endurance of the cardboard.

⑦Indentation process in box making process. During the manufacturing process of the carton, the offset of the center line of the upper and lower rollers makes the thickness of the indentation part uneven, or due to the improper adjustment of the distance between the upper and lower rollers, the force on the corrugated cardboard is too small or too large, resulting in If the indentation part is too thick or too thin, it will affect the folding resistance of the carton.