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Jiuheng label | Why is the die-cutting of hot melt adhesive self-adhesive materials “ridden with problems”? These features and methods must be mastered!Jiuheng label |

Die-cutting hot melt adhesive non-drying label materials pose a common challenge for label printing factories. When processed on the same die-cutting equipment alongside commonly used water-based adhesive materials with identical dimensions, waist width, and liner thickness, labels made of water-based adhesives perform smoothly. However, hot melt adhesive labels often encounter issues, leading to reduced efficiency and increased waste in label printing factories. This may necessitate adjustments such as enlarging waist width or switching to water-based adhesive materials. Some have attempted to improve the die-cutting process by altering the hot melt adhesive formula, achieving improved die-cutting performance but at the cost of reducing the initial viscosity of the adhesive, overshadowing the advantages of hot melt adhesives. Explore effective solutions with these insights.

Sailing Label delves into the analysis of die-cutting characteristics and temperature adaptability of hot melt adhesive non-drying label materials in this article. We address common issues encountered during the die-cutting of these materials in customer interactions and production practices, offering practical solutions. Explore valuable insights to optimize your experience when die-cutting hot melt adhesive non-drying label materials.

Table of contents

  • Die-cutting characteristics of hot melt adhesive self-adhesive materials
  • Die-cutting characteristics of hot melt adhesive self-adhesive materials

The die-cutting principles of hot melt adhesive non-drying label materials are similar to those of water-based adhesive materials, as depicted in Figure 1. In the case of die-cutting hot melt adhesive non-drying label materials, it is crucial to ensure that both the face stock and the adhesive are completely severed. This is because the adhesive used in hot melt adhesives is a rubber-based adhesive with strong cohesion, similar to the resilience of chewing gum (difficult to tear apart). Incomplete cutting during die-cutting can lead to issues such as waste edge breakage or the waste edge peeling off along with the label, resulting in die-cutting quality problems.

In contrast, the die-cutting process for water-based adhesive materials is different. The cohesion of water-based adhesive is relatively weaker, so as long as the face stock is cut, the adhesive, even if not completely severed, will not hinder the normal waste removal along the paper edge. Explore the intricacies of die-cutting hot melt adhesive non-drying label materials versus water-based adhesive materials for optimal results.

  • Temperature suitability of hot melt adhesive self-adhesive materials

The resistance generated when the face stock is peeled off from the liner in hot melt adhesive non-drying label materials is referred to as peel force or release force. Release force is a key indicator affecting the performance of hot melt adhesive non-drying label materials. Excessive release force increases the waste removal resistance, leading to waste edge breakage. On the other hand, insufficient release force reduces the bonding strength between the label and the liner, resulting in issues such as misalignment or detachment during die-cutting waste removal or automatic label application.

Therefore, it is essential to control the release force of non-drying label materials within a reasonable range. Explore the nuances of release force in hot melt adhesive non-drying label materials and optimize your label production for superior results.

The viscosity of hot melt adhesive varies with temperature, a characteristic known as temperature sensitivity. The temperature-dependent viscosity of the hot melt adhesive significantly influences the release force of non-drying label materials. Another crucial factor impacting release force is the surface energy of the liner. Adjusting the surface energy of the liner, achieved by altering the silicone oil formulation, allows for control of the release force within a reasonable range, facilitating a smooth die-cutting process.

The relationship between the release force of hot melt adhesive non-drying label materials, adhesive viscosity, and liner surface energy is illustrated in Figure 2. In the ideal scenario, the release force of hot melt adhesive non-drying label materials should remain constant, forming a straight line regardless of temperature changes (depicted in yellow). The initial increase in adhesive viscosity with rising temperature is represented in red, while the decrease in liner surface energy with temperature rise is shown in blue.

It is evident that the final stability of the release force of non-drying label materials is achieved only when the liner’s surface energy changes in tandem with adhesive viscosity variations. This ensures the stability of die-cutting and application characteristics. Therefore, suppliers of hot melt adhesive non-drying label materials must adapt the release agent coating formulation for the liner to accommodate temperature changes, especially during different seasons. Explore the intricacies of temperature sensitivity and surface energy for optimal performance.

Due to the distinct physicochemical and die-cutting characteristics of hot melt adhesive non-drying label materials compared to water-based adhesive materials, the die-cutting process for hot melt adhesive non-drying labels imposes stringent requirements on various factors. These include the uniformity of the liner in non-drying label materials, the stability of surface energy, the precision of the die-cutting machine, the angle, and sharpness of the die-cutting blade, as well as the size design of label waste edges, choice of face material strength, die-cutting speed, and environmental temperature.

Meeting these requirements and ensuring correct equipment adjustments are crucial to effectively guarantee the die-cutting quality and production efficiency of hot melt adhesive non-drying label materials. Explore the intricacies of die-cutting these materials and optimize your production process for superior results.

  • Common problems and solutions for die cutting of hot melt adhesive self-adhesive materials

Common problems with hot melt adhesive self-adhesive materials during the die-cutting process include edge breakage when waste is discharged after die-cutting, labels falling off when waste is discharged, and labels being peeled off together with the waste edges. It is very important for die-cutting workers to correctly understand the causes of these problems and find corresponding solutions.

1.Breaking edges when discharging waste

There are many reasons for the edge breakage of hot melt adhesive self-adhesive materials when they are discarded after die-cutting, and the solutions are also different. details as follows:

  • (1) The end face of the paper roll is uneven, presenting a serrated pattern with small cracks, leading to reduced paper edge strength and susceptibility to tearing.
  • Solution: Replace the non-drying label material, improve the slitting quality to ensure a neat cross-section, and reduce die-cutting speed.
  • (2) Non-drying label material exhibits serpentine swinging during die-cutting, causing variations in waste edge dimensions. When the waste edge narrows, the paper edge is prone to tearing.
  • Solution: Replace the non-drying label material, enhance slitting quality to prevent serpentine swinging, and reduce die-cutting speed.
  • (3) The waste edge of the non-drying label material is too narrow, with low tensile strength.
  • Solution: Adjust the waste edge size of the die-cut non-drying label material appropriately and reduce the die-cutting speed.
  • (4) The overall tensile strength of the die-cut non-drying label material is too low, indicating poor material quality.
  • Solution: Replace the die-cut non-drying label material with higher tensile strength and reduce die-cutting speed.
  • (5) Changes in the frictional force and diameter of the waste rewind roller result in variations in waste edge tension, making it prone to tearing.
  • Solution: Timely observe and adjust the frictional force of the waste rewind roller, correctly control waste edge tension, and reduce die-cutting speed.
  • (6) Breakage of waste edges occurs due to the influence of label shapes and the number of label columns.
  • Solution: Increase the radius of label corners where possible to facilitate waste removal; add more waste columns to enhance waste edge tensile strength.
  • (7) Adhesive seepage at the edges of non-drying label material causes waste edges to stick to the liner, leading to paper edge breakage.
  • Solution: Properly address adhesive seepage at the edges of non-drying label material using talcum powder or grease to alleviate seepage, or use tape to remove the adhesive-seeped portion.
  • (8) Operating the die-cutting machine at either too fast or too slow speeds results in paper edge breakage.
  • Solution: Adjust the die-cutting speed of the machine to an appropriate level.
  • (9) Issues with the interface of the die-cutting blades lead to paper tearing and edge breakage.
  • Solution: Change the interface position of the die-cutting blades.
  • (10) Expiration of non-drying label material causes the adhesive to bond with the liner, resulting in paper edge breakage.
  • Solution: Replace the non-drying label material.
  • (11) Uneven silicon coating on the liner, with areas lacking silicon, leads to uneven adhesive application and paper edge breakage.
  • Solution: Replace the non-drying label material.
  • Optimize your die-cutting process by addressing these issues for superior results in label

2. The label is dropped when discharging waste

The loss of standards during waste discharge mainly manifests itself in two aspects.

  • (1) As seen in Figure 2, a decrease in temperature results in a reduction in the peel force (release force) of non-drying label materials. This decrease can lead to a reduction in the bonding strength between the label and the liner, causing label detachment.
  • Solution: Preheating the non-drying label material before die-cutting or implementing in-line heating on the die-cutting machine can increase the viscosity of the adhesive, accelerate the increase in release force of the non-drying label material, and thereby enhance the bonding strength of the label.
  • (2) When the release force of non-drying label material is too low, after passing through the die-cutting machine, the label undergoes repeated deformation on the guide roller due to the long winding path, ultimately causing the label to loosen and detach.
  • Solution: Minimize the waste removal distance on the die-cutting machine to prevent label loosening on the liner, ensuring that the labels are wound promptly after die-cutting.

3. Peel off the label together with the waste edge

In the die-cutting process of hot melt adhesive non-drying label materials, the simultaneous peeling of labels and waste edges may occur due to incomplete cutting of the face stock or adhesive. This results in the adhesive not being completely severed, causing the label and waste edges to remain attached. In such cases, the ‘bottom paper dyeing method’ should be employed to confirm the precision of die-cutting, inspect the degree of adhesive stringing, and verify the cutting status of the adhesive. It is advisable to minimize the winding distance on the die-cutting machine, use new die-cutting blades with small angles, and maintain appropriate sharpness.

Furthermore, the size of the label and the number of label columns in die-cutting can also lead to the simultaneous peeling of labels and waste edges. This is particularly common with small labels and elongated labels. As the label area decreases and the label becomes more slender, the release force of the non-drying label material decreases. In such cases, adjustments to the die-cutting machine or replacement of the non-drying label material should be considered, selecting a material with a higher release force.

With the increasing prevalence and usage of hot melt adhesive non-drying label materials, printing factories encounter a growing number of challenges. We hope this publication can provide some assistance to the label industry.