From material selection to printing to finished products, a full set of explanations on the production process of shrink film sleeve labels
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Shrink film sleeve labels are increasingly popular in the market due to the combination of high quality patterns and distinctive shapes. What are the characteristics, advantages, design selection principles and production points of shrink film labels? This article is explained in detail for reference.
Concept and advantage
A shrink wrap label is a film set label that is printed on a plastic film or plastic tube. It has the following characteristics:
1. The shrink film sleeve label is easy to process, the package is sealed, anti-pollution, and the product is well protected;
2. The film sleeve is close to the product, the package is compact, and the product shape can be displayed, so it is suitable for irregular products that are difficult to package;
3. When labeling the shrink film sleeve label, it is not necessary to use the adhesive, and the same transparency as the glass can be obtained;
4. The shrink film sleeve label can provide 360° all-round decoration to the packaging container, and can print product information such as product description on the label, so that the consumer can understand the performance of the product without opening the package;
5. The printing of the shrink film sleeve label belongs to the film printing (the inside of the film sleeve), which can play the role of protecting the print, and the label wear resistance is better.
Design points and selection principles
1, label design
The design of the decorative pattern on the film sleeve is determined according to the thickness of the film. When designing the pattern, first understand the transverse and longitudinal shrinkage of the film, and the allowable shrinkage in each direction after packaging and the allowable deformation error after shrinking the decorative pattern to ensure accurate reduction of the pattern and text after shrinking.
2, film thickness and shrinkage
The materials used to shrink the film sleeve label should consider three factors: environmental requirements, film thickness and shrinkage properties.
The basis for determining the film thickness is the field of application of the label and the cost factor. Of course, price is not a decisive factor, because each film has its own uniqueness, and users and trademark printers must be clear about the film used and the process that best suits the material before signing the contract. In addition, the required specifications and other process factors of the processing equipment also directly affect the choice of thickness. It is generally required that the film thickness of the shrink film sleeve label is 30 to 70 μm, and 40 μm and 50 μm films are often used. In addition, there is a certain requirement for the shrinkage rate of the film, and the transverse (TD) shrinkage is higher than the longitudinal (MD) shrinkage. The transverse shrinkage of commonly used materials is 50% to 52% and 60% to 62%, and can reach 90% in special cases. The longitudinal shrinkage rate is required to be 6% to 8%. When making a shrink film sleeve label, try to choose a material with a small longitudinal shrinkage.
Film material
The materials for making the shrink film sleeve label are mainly PVC (polyvinyl chloride) film, PET (polyester) film, PETG (modified polyester) film, OPS (oriented polystyrene) film and the like. Its performance is as follows:
1, PVC film
PVC film is currently the most widely used film material. It is inexpensive, has a wide temperature shrinkage range, and is not demanding heat sources. The main processing heat source is hot air, infrared light 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. It has been banned in Europe and Japan.
2, OPS film
As an alternative to PVC film, OPS film is increasingly used. Its shrinkage performance is good and it is also environmentally friendly. The domestic market for this product is in short supply. At present, high-quality OPS mainly relies on imports, which has become an important factor restricting its development.
3, PETG film
The PETG copolymer film is not only environmentally friendly, but also capable of adjusting the shrinkage rate in advance. However, since the shrinkage rate is too large, it is also 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 usage are close to PVC heat shrinkable film, but the price is cheaper than PETG, and it is the most advanced one-way shrink film. Its transverse shrinkage rate is 70%, its longitudinal shrinkage 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 tube is also a material for producing a shrink film sleeve label, and can be molded at one time without sewing in production. Compared with the horizontal flat film, the cost of producing the shrink film sleeve label by the heat shrinkable film tube is low, but the surface printing of the tube body is difficult to realize. At the same time, the graphic of the heat-shrinkable film tube label can only be printed on the surface of the film, and the image is easily worn during transportation and storage, thus affecting the packaging effect.
Shrink film sleeve label printing
1, printing
Printing is performed on the selected film. At present, the printing of shrink film sleeves mainly uses gravure printing, using solvent-based inks, followed by flexographic printing. With the development of flexographic printing technology, the printing color is clear and clear, comparable to gravure printing, with a thick and high gloss of gravure. In addition, the use of water-based inks for flexo printing is more environmentally friendly.
2, cut
The printed web material is longitudinally slit by a high performance slitter while the edge portion of the film is treated to make it smooth, flat and non-curling. Care should be taken when using the slitter to avoid heat on the blade, as hot blades can cause the film to be partially creped.
3, stitching
The slitted film is center-stitched with a stitching machine, and the nozzles are bonded to form a film sleeve required for packaging. The amount of material required for suturing depends on the accuracy of the stitching and the skill of the operator. The maximum amount of stitching is 10 mm, usually 6 mm.
4, horizontal cutting
The film sleeve is packaged on the outside of the product, and is cut transversely according to the package size by a slitter. At the appropriate heating temperature, the shrink film will shrink sharply (15% to 60%) in length and width. Generally, the film size is required to be about 10% larger than the maximum size of the product.
5, heat shrinkage
Heated through a hot aisle, hot oven or hot air gun. At this point, the shrink label quickly shrinks along the outer contour of the container and fits snugly against the contour of the container to form a label protective layer that conforms exactly to the shape of the container.
In the production process of shrink film sleeve labels, each process must be closely tested by a special inspection machine to ensure production accuracy.
Scope of application
The shrink label has strong adaptability and can be used for surface decoration and decoration of packaging containers such as wood, paper, metal, glass and ceramics. It is widely used in the 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 drug labeling, paper is still the main substrate, but the development of film packaging has become increasingly 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 a larger market share.