What is the correlation between the characteristics of adhesive materials and die-cutting accuracy in high-speed scenarios?

In the first two articles, the author elaborated on the control logic and specific practical methods of die-cutting accuracy in high-speed scenarios from the perspectives of the performance of die-cutting equipment itself and the characteristics of die-cutting tools, which provided readers with great inspiration. In this article, let's take a look at the relationship between the physical properties of self-adhesive materials and die-cutting accuracy from the perspective of self-adhesive materials.
First article: Die Cutting Column | Control Logic and Practical Path of Die Cutting Equipment Accuracy in High Speed Scenarios
Part 2: Die Cutting Column | How to Control the Precision of Die Cutting Tools in High Speed Scenarios? Please master these key points!

Zhang Jufeng
The consistency and stable physical properties of adhesive materials themselves are the "innate conditions" for ensuring die-cutting accuracy. The thickness uniformity and mechanical performance fluctuations of the surface material, base paper, and adhesive layer can directly amplify the die-cutting error, especially in high-speed production. Insufficient material accuracy is likely to lead to batch die-cutting quality problems.
Thickness and mechanical stability of base paper
The uniformity of the thickness of the base paper is a prerequisite for controlling the depth of die-cutting. The fluctuation value of Grassin base paper with a thickness of 32-35 μ m needs to be ensured to be ≤± 1 μ m (conventional base paper is generally controlled at ± 3 μ m), otherwise the cutting depth error of labels in the same batch may exceed the allowable range, causing the surface material to be uncut in areas where the base paper is too thick, while damage to the base paper may occur in areas where the base paper is too thin.
At the same time, the tensile resistance of the base paper needs to match the tension in the die-cutting and labeling processes. For example, the tensile strength of 35 μ m thick Grassin base paper should be ≥ 2.5N/15mm, and the elongation at break should be ≥ 3%, in order to avoid the base paper from breaking due to excessive local tension during die-cutting feeding or labeling traction.
Characteristic control of surface material and adhesive layer
The thickness uniformity and ductility of adhesive surface materials directly affect the die-cutting effect. Taking 50 μ m PET surface material as an example, the thickness fluctuation needs to be ≤± 2 μ m, otherwise it will cause local insufficient cutting depth (thick areas) or over cutting (thin areas) problems. Its longitudinal elastic modulus should be ≥ 3GPa, ensuring that the elongation under feeding tension is ≤ 0.2%, to avoid deviation in die-cutting position caused by material stretching.
In addition, the uniformity of the coating of the adhesive layer is equally important. The thickness fluctuation of the dry adhesive should be ≤± 1 μ m to prevent tool adhesion caused by excessive adhesive layer or insufficient label adhesion caused by insufficient adhesive layer.
Environmental adaptability of materials
Temperature and humidity changes can cause fluctuations in the stability of adhesive material dimensions, thereby affecting die-cutting accuracy. For example, when the environmental humidity of BOPP surface material increases from 40% to 60%, the lateral dimension will expand by 0.15%. If the die-cutting equipment does not compensate for humidity, it is likely to cause a deviation of label size exceeding ± 0.05mm.
Therefore, high-precision die-cutting requires higher temperature and humidity stability for adhesive materials. Typically, under environmental conditions of 23 ℃± 2 ℃ and 50% ± 5% humidity, the thermal shrinkage rate of the surface material should be ≤ 0.1%, and the moisture absorption expansion rate of the base paper should be ≤ 0.05%.