Characteristics of Sticker Label Substrate

Pressure-sensitive adhesive (PSA) materials are a type of composite material, and die-cutting is different from the die-cutting of traditional printing materials. For example, die-cutting paper involves cutting through the entire material; whereas for PSA materials, die-cutting only cuts through the face material and the adhesive layer, leaving the backing paper and its silicone coating intact. This results in the die-cut label being adhered to the backing paper for later use. When considering whether a label can be accurately die-cut, whether the edges are smooth and neat, or whether the backing paper is pierced or rough edges remain, the characteristics of the PSA label face material play a very important role.

This article explains the relationship between the characteristics of PSA label face materials and die-cutting from the perspectives of the classification and characteristics of PSA label face materials, as well as how to optimize the die-cutting process, for the reader's reference.

Classification and Characteristics of PSA Label Face Materials

In the field of PSA labels, commonly used face materials can generally be divided into two categories: paper face materials and film face materials.

01

Paper Facestock

Paper adhesive labels are suitable for various printing methods, easy to tear, breathable, and more suitable for use in dry environments. Paper materials themselves do not have waterproof or oil-proof properties, but processes such as lamination can make paper water-resistant and oil-resistant to some extent. Common paper facestocks include offset paper, coated paper, holographic paper, aluminum foil paper, security paper, kraft paper, and textured paper.

Among them, coated paper has a smooth surface, strong color reproduction, and good printing adaptability, but the texture is relatively brittle, and edge damage or fraying may occur during die-cutting; kraft paper, on the other hand, has high strength and toughness, is wear-resistant, but its surface is rough, ink absorption is strong, and paper debris may be generated during die-cutting, blocking the die-cut and affecting cutting accuracy.

02

Film Facestock

Film materials have good water and oil resistance, a smooth surface, and are easy to print. They have high weather resistance and corrosion resistance, ensuring 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 little deformation during die-cutting, but due to its high hardness, it causes greater wear on die-cutting tools; PP facestock is soft, flexible, and has good fold resistance, but may stick during die-cutting, causing difficulties in waste removal; PE facestock has low surface tension and poor adhesion, requiring special treatment after die-cutting to ensure label adhesion performance.

Specific Impact of Facestock Properties on Die-Cutting Quality

The physical and chemical properties of the facestock affect die-cutting quality in multiple aspects.

01

Thickness and Uniformity

The thickness of the face material directly affects the depth of die cutting. The thicker the face material, the easier it is to die cut. Conversely, the thinner the material, the more likely it is to cut 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 a PET face material with a thickness of 0.1mm, it is necessary to choose a die-cutting blade with a smaller blade angle and higher hardness, and 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 the die-cutting process and the wear on the tools. For instance, the flexibility of PP face material makes it easy to produce uneven edges when die cutting labels with complex shapes; whereas the high hardness of PET face material causes the die-cutting blade to dull more quickly, requiring more frequent tool replacement.

03

Surface Smoothness

The surface smoothness of the face material affects the friction and waste removal during die cutting. Smooth surface materials, such as coated paper, have lower friction with the cutting tools and are relatively easy to cut, but may cause issues with label separation from the backing paper. Rough surface materials, like kraft paper, help with waste removal, but can produce paper debris during cutting, affecting the quality of die cutting and the cleanliness of equipment.

Optimizing Die-Cutting Processes Based on Face Material Characteristics

To address the impact of different face material characteristics on die-cutting quality, targeted optimization adjustments to the die-cutting process should be made based on the specific properties of the face material.

01

Tool Selection

Choose the appropriate die-cutting tool based on the hardness and thickness of the facing material. For paper facings, carbon steel knives can be selected, as their sharpness and wear resistance can meet the die-cutting requirements of general paper materials; for film facings, harder knives with sharper edges, such as carbide knives or tungsten steel knives, should be chosen to ensure cutting accuracy and tool lifespan. At the same time, when cutting more flexible facings, the blade angle can be slightly reduced to improve cutting performance.

02

Die-Cutting Pressure and Speed

Accurately controlling die-cutting pressure and speed is key to ensuring die-cutting quality. For example, when die-cutting PET facings, the die-cutting pressure can be set at 8–10 MPa, and the die-cutting speed controlled at 20–30 m/min to achieve better die-cutting results.

03

Waste Disposal

Adopt corresponding waste disposal processes according to the characteristics of different facings. For films that are prone to sticking, apply an anti-adhesive coating on the waste disposal rollers to improve waste removal efficiency; for paper facings that generate paper scraps easily, add a vacuum device to promptly remove paper scraps produced during die-cutting.

In summary, in actual production, it is necessary to pay attention to the compatibility of facing material characteristics and die-cutting processes, continuously summarize experience, and improve the quality and efficiency of label production.