Shrink labels are highly adaptable and can be used to decorate plastic, wooden, paper, metal, glass, ceramic and other packaging containers, and are widely used in beer beverages, medicine and health care, daily chemical products, Snack food, stationery and other fields.
In order to achieve the best overall sleeve labeling effect, it is not only necessary to adjust the heat shrinkage temperature of the sleeve labeling machine, but also to select the label material and design pattern. This article explains how to correctly select and use shrink film sleeves.
Design points and material selection principles
1. Label design
The design of the decorative pattern on the film sleeve should be determined according to the thickness of the film. When designing a pattern, you must first understand the transverse and longitudinal shrinkage of the film, as well as the allowable shrinkage in each direction after packaging and the allowable deformation error after shrinkage of the decorative pattern, 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 performance.
The film thickness is determined based on the label's application field and cost factors. Of course, price is not the decisive factor, because each film has its own uniqueness. Users and trademark printers must clearly understand the film used and the process that is most suitable for the material before signing a contract. In addition, the indicators required by processing equipment and other process factors also directly affect the choice of thickness. The film thickness required for making shrink film sleeve labels is usually 30 to 70 μm, among which 40 μm and 50 μm films are widely used. In addition, there are certain requirements for the shrinkage rate of the film, and the shrinkage rate in the transverse direction (TD) is higher than the shrinkage rate in the longitudinal direction (MD). The transverse shrinkage rates of commonly used materials are 50% to 52% and 60% to 62%, and can reach 90% under special circumstances. The longitudinal shrinkage requirement is 6% to 8%. When making shrink film sleeve labels, you should try to choose materials with a small longitudinal shrinkage rate.
The main materials for making shrink film sleeve labels include PVC (polyvinyl chloride) film, PET (polyester) film, PETG (modified polyester) film, and OPS (oriented polystyrene) film. The properties are as follows: 1. PVC film
PVC film is currently the most widely used film material. Its price is extremely low, its temperature shrinkage range is large, and its requirements for heat sources are not high. The main processing heat sources are hot air, infrared rays, or a combination of the two. However, PVC is difficult to recycle and produces poisonous 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 becoming increasingly widely used. It has good shrinkage performance and is also environmentally friendly. Now this product is in short supply in the domestic market. At present, high-quality OPS membranes still mainly rely on imports, which has become an important factor restricting its development.
3. PETG film
PETG polymer film is not only beneficial to environmental protection, but also can adjust the shrinkage rate in advance. However, due to excessive shrinkage, use will also be limited.
4. PET film
PET film is an internationally recognized environmentally friendly heat shrinkable film material. Its technical indicators, physical properties, application range and usage methods are close to PVC heat shrinkable film. , but the price is cheaper than PETG film. It is currently the most advanced unidirectional shrink film. Its transverse shrinkage rate reaches 70% and the longitudinal shrinkage rate is less than 3%. It is non-toxic and pollution-free. It is the most ideal material to replace PVC film.
In addition, heat shrinkable film tubes are also used in the production of shrink film sleeve labels, and they can be formed in one go without sewing during production. Compared with transverse flat film, the cost of using heat shrinkable film to cover labels is lower, and printing on the surface of the tube body is difficult to achieve. At the same time, the graphics and text of heat-shrinkable film tube labels can only be printed on the surface of the film. The graphics and text are easily worn during transportation and storage, which affects the entire packaging effect.