How do the characteristics of adhesive label face materials affect die-cutting quality?
Self-adhesive materials are a type of composite material, and die-cutting differs from that of traditional printing materials. For example, die-cutting paper involves cutting through the entire material, whereas die-cutting self-adhesive materials only cuts through the face stock and the adhesive layer, leaving the backing paper and its silicone coating intact, ultimately allowing the die-cut labels to remain on the backing paper for later use. When considering if a label can be precisely die-cut, whether the edges are clean and smooth, or if the backing paper might be cut through or leave rough edges, the characteristics of the self-adhesive label face stock play a crucial role.
This article explains the relationship between the characteristics of self-adhesive label face stocks and die-cutting from the perspective of their classification, properties, and how to optimize the die-cutting process, for the benefit of readers.
Classification and Characteristics of Self-Adhesive Label Face Stocks
In the field of self-adhesive labels, commonly used face stocks can generally be divided into two categories: paper face stocks and film face stocks.
01Paper Facestock
Paper adhesive labels are suitable for various printing methods, easy to tear, and breathable, making them more suitable for use in dry environments. Paper materials themselves do not have waterproof or oil-resistant properties, but these can be achieved through processes such as lamination, which provide the paper with certain water and oil resistance. Common paper facestocks include offset paper, coated paper, holographic paper, aluminum foil paper, tamper-evident paper, kraft paper, and textured paper.
Among them, coated paper has a smooth surface, strong color reproduction, and good printability, but it is relatively fragile, and during die-cutting, issues such as edge damage and fraying can occur. Kraft paper, on the other hand, has high strength and toughness, is wear-resistant, but has a rough surface, strong ink absorbency, and during die-cutting, paper dust can form, clogging dies and affecting cutting accuracy.
02
Film Facestock
Film materials have good water and oil resistance, a smooth surface, and are easy to print on. They have high weather resistance and corrosion resistance, ensuring the long-term stability and clarity of labels, making them ideal for high-end products and long-term storage labels. Common film facestocks include PET (polyethylene terephthalate), PP (polypropylene), and PE (polyethylene).
Among them, PET facestock has excellent chemical resistance, high-temperature resistance, and mechanical strength, with good dimensional stability, and is not easily deformed during die-cutting. However, due to its high hardness, it causes greater wear on cutting tools. PP facestock is soft, flexible, has good fold resistance, but can stick during die-cutting, making waste removal difficult. PE facestock has low surface tension and poor adhesiveness, requiring special treatment after die-cutting to ensure label adhesion performance.
Specific Effects of Facestock Characteristics on Die-Cutting Quality
The physical and chemical properties of the facestock can affect die-cutting quality in multiple ways.
01Thickness and Uniformity
The thickness of the face material directly affects the depth of die cutting. The thicker the material, the easier it is to die cut. Conversely, thinner materials are more prone to cutting through the backing paper. Therefore, the thickness of the face material directly influences the selection of die cutting tools and the setting of die cutting pressure. For example, when die cutting PET face material with a thickness of 0.1mm, it is necessary to choose a die with a smaller blade angle and higher hardness, and to precisely control the die cutting pressure to ensure cutting quality.
02
Flexibility and Hardness
The flexibility and hardness of the face material determine its deformation during die cutting and the wear on the tools. For instance, the flexibility of PP face material can cause uneven edges when die cutting labels with complex shapes; whereas the high hardness of PET face material can dull die blades more quickly, requiring more frequent blade replacements.
03
Surface Smoothness
The surface smoothness of the face material affects the friction and waste removal during die cutting. Smooth-faced materials, such as coated paper, have less friction with the die during cutting and cut relatively easily, but it may be difficult to separate the label from the backing paper. On the other hand, rough-faced materials, such as kraft paper, help with waste removal but tend to produce paper debris during cutting, affecting die cutting quality and equipment cleanliness.
Optimizing Die Cutting Process Based on Face Material Characteristics
To address the impact of different face material characteristics on die cutting quality, it is necessary to make targeted optimizations to the die cutting process based on the specific properties of the face material.
01Tool Selection
Select the appropriate die-cutting tools based on the hardness and thickness of the substrate material. For paper substrates, carbon steel blades can be chosen, as their sharpness and wear resistance can meet the die-cutting requirements of general paper materials. For film substrates, however, tools with higher hardness and sharper edges, such as carbide or tungsten steel blades, should be used to ensure cutting precision and tool longevity. Additionally, when cutting more flexible substrates, the blade angle can be slightly reduced to improve cutting performance.
02
Die-Cutting Pressure and Speed
Precisely controlling die-cutting pressure and speed is key to ensuring die-cutting quality. For example, when die-cutting PET substrates, the die-cutting pressure can be set to 8–10 MPa and the die-cutting speed controlled at 20–30 m/min to achieve better cutting results.
03
Waste Removal
Adopt appropriate waste removal processes according to the characteristics of different substrates. For film substrates that tend to stick, an anti-stick coating can be applied on the waste removal rollers to improve efficiency. For paper substrates that generate paper debris, a dust collection system can be added to promptly remove scrap produced during die-cutting.
In summary, in actual production, attention should be paid to the compatibility between substrate characteristics and die-cutting processes, while continuously summarizing experience to improve the quality and efficiency of label production.