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The Characteristics and Advantages of Shrink Film Labels and The Principle of Material Selection

Jan. 05, 2021

Shrink labels are highly adaptable, and can be decorated for plastic, metal, glass and other packaging containers. Shrink film sleeve labels are more and more popular in the market because they can combine high-quality patterns and distinctive shapes. The Shrink Film Supplier told you about the characteristics and advantages of shrink film labels and the principle of material selection. The content is for the selection of the excellent packaging material system for friends' reference:

Concepts and advantages

Shrink film sleeve label is a kind of film sleeve label printed on plastic film or plastic tube. It has the following characteristics:

1. The shrink film sleeve label is easy to process, the package is sealed, and it is anti-pollution, and it is good for product protection;

2. The film sleeve is close to the product, the packaging is compact, and the product shape can be displayed, so it is suitable for irregular products that are difficult to pack;

3. When labeling shrink film sleeves, no adhesive is needed, and the same transparency as glass can be obtained;

4. The shrink film sleeve label can provide a 360° decoration for the packaging container, and can print product information such as product descriptions on the label, so that consumers can understand the performance of the product without opening the package;

5. The printing of shrink film sleeve labels belongs to the printing in the film, which can protect the imprint, and the label has better wear resistance.

PETG Copolymer Film

PETG Copolymer Film

Design key points and material selection principles

1. Label design

The design of the decorative pattern on the film set should be determined according to the thickness of the film. When designing a pattern, we must first understand the horizontal and vertical shrinkage of the film, as well as the allowable shrinkage rate in each direction after packaging and the allowable deformation error after the decoration pattern shrinks to ensure that the shrinked pattern and text can be accurately restored.

2. Film thickness and shrinkage

The materials used for shrink film sleeve labels should focus on three factors: environmental protection requirements, film thickness and shrinkage properties.

The basis for determining the film thickness is the application field and cost factors of the label. Of course, price is not a decisive factor, because each film has its own uniqueness, users and trademark printers must clarify the film used and the most suitable material technology before signing a contract. In addition, the indicators required by the processing equipment and other process factors also directly affect the choice of thickness. Generally, the film thickness required to make shrink film sleeve labels is 30-70μm, of which 40μm and 50μm films are used more. In addition, there are certain requirements for the shrinkage of the film, and the transverse shrinkage is higher than the longitudinal shrinkage. The transverse shrinkage rate of common materials is 50%~52% and 60%~62%, and can reach 90% under special circumstances. The longitudinal shrinkage rate is required to be 6% to 8%. When making shrink film sleeve labels, try to choose materials with small longitudinal shrinkage.

film materials

The main materials for making shrink film sleeve labels are PVC film, PET film, PETG film, OPS film, etc. Its performance is as follows:

1. PVC film

PVC Film is currently the most widely used film material. It is inexpensive, has a large temperature shrinkage range, and does not require high heat sources. The main processing heat source is hot air, infrared rays or a combination of the two. However, PVC is difficult to recycle and produces toxic gas when burned, which is not conducive to environmental protection. Its use has been banned in Europe and Japan.

2. OPS film

As a substitute for PVC film, OPS film is increasingly widely used. It has good shrinkage properties and is also conducive to environmental protection. This product is in short supply in the domestic market. At present, high-quality OPS mainly relies on imports, which has become an important factor restricting its development.

3. PETG film

PETG Copolymer Film is not only environmentally friendly, but also can adjust the shrinkage rate in advance. However, due to the excessive shrinkage, it will be limited in use.

4. PET film

PET film is an internationally recognized environmentally friendly heat shrinkable film material. Its technical indicators, physical properties, application range and use methods are close to PVC heat shrinkable film, but the price is cheaper than PETG, and it is currently the most advanced unidirectional shrinkable film. Its horizontal shrinkage rate is 70%, longitudinal shrinkage rate is less than 3%, and it is non-toxic and non-polluting. It is the most ideal material to replace PVC.

In addition, the heat shrinkable film is also the material for the production of shrink film sleeve labels, and can be formed at one time without sewing in the production. Compared with the horizontally flat film, the cost of producing shrink film sleeve labels with heat shrinkable film tubes is lower, but the surface printing of the tube body is more difficult to achieve. At the same time, the graphics and text of the heat shrinkable film tube label can only be printed on the surface of the film, and the graphics and text are easy to wear during transportation and storage, which affects the packaging effect.

shrink film sleeve label printing

1. Printing

Print on selected films. At present, the printing of shrink film sleeves mainly uses gravure printing, using solvent-based inks, followed by flexographic printing. With the development of flexo printing technology, the printing color is vivid and clear, which can be comparable to gravure printing, with the thickness and high gloss of gravure. In addition, flexo printing mostly uses water-based inks, which is more environmentally friendly.

2. Slitting

Use a high-performance slitting machine to slit the printed roll film material longitudinally, and at the same time process the edge of the film to make it smooth, flat and not curled. When using the slitting machine, you should pay attention to avoiding the blade from heating, because the heated blade will cause the part of the film to be wrinkled.

3. Stitching

The slitted film is stitched at the center with a sewing machine, and the nozzles are glued to form the film sleeve required for packaging. The material allowance required for stitching depends on the stitching accuracy and the skill of the operator. The maximum stitching allowance is 10mm, usually 6mm.

4. Horizontal cutting

Pack the film sleeve on the outside of the product, and cut it horizontally according to its packaging size with a slitting machine. When the shrink film is heated at a proper temperature, its length and width will shrink sharply. Generally, the size of the film is required to be about 10% larger than the maximum size of the product.

5. Heat shrinkage

It is heated by hot aisle, hot oven or hot air spray gun. At this time, the shrink label will quickly shrink along the outer contour of the container and closely fit the outer contour of the container to form a label protection layer that is completely consistent with the outer contour of the container.

In the production process of shrink film sleeve labels, each process must be strictly inspected by a dedicated inspection machine to ensure production accuracy.

Scope of application

Shrink labels are highly adaptable, and can be used for surface decoration and decoration of packaging containers such as wood, paper, metal, glass, and ceramics. They are widely used in packaging and decoration of food, daily chemical products, and chemical products, such as various beverages and cosmetics. , Children's food, coffee, etc. In the field of pharmaceutical labeling, paper is still the main substrate, but the development of film packaging has been rapid. At present, the key to the development of shrink film sleeve labels is to reduce costs. Only in this way can we improve our competitiveness and strive for greater market share.