What Is Shrink Film?
Shrink film is a film that contracts when heat is applied, commonly used for packaging a diverse range of products due to its ability to tightly conform to their shapes.
Uses of Shrink Film
Initially used for insulating capacitors, shrink film has found widespread use in packaging, driven by the need for improved safety in food and general products. This material, typically a thermoplastic resin, is versatile, allowing multiple deformations upon heating. It boasts high gloss, transparency, water and cold resistance, and mechanical strength. These properties make it an attractive and secure packaging choice, preventing product tampering and damage.
Shrink film wraps around various products, including food bottles, toothpaste tubes, cosmetics boxes, books, DVDs, and more.
Principle of Shrink Film
Shrink film operates on a simple principle: heat application causes it to shrink and adhere to the product it encases. It comes in several types, each with specific characteristics:
1. Vinyl Chloride
Valued for its transparency, formability, and flame resistance, vinyl chloride shrinks at lower temperatures. However, its tendency for spontaneous shrinkage and lower strength are drawbacks.
2. Polypropylene
Noted for its transparency, cold resistance, and moisture resistance, polypropylene is cost-effective but has natural shrinkage and weaker strength.
3. Polyethylene
Polyethylene offers superior mechanical strength compared to polypropylene and is effective for large packaging due to its good shrinkage properties. Its disadvantages include lower transparency and slower shrinkage time.
4. Polystyrene
Polystyrene boasts excellent transparency and heat shrinkability. However, it is susceptible to impact and organic solvents, with natural shrinkage as a downside.
5. Polyolefin
Polyolefin excels with its high shrinkage rate, resistance to wrinkling and creasing, and high tear strength. It is processed at relatively low temperatures, safeguarding the wrapped product. The higher cost and difficulty in opening are its cons.
6. Polyethylene Terephthalate
Commonly known as PET, this resin features excellent transparency, mechanical strength, chemical resistance, and dimensional stability. However, it is challenging to process and open.
Features of Shrink Film
Shrink film is distinguished by its heat-induced shrinkage, conforming to the product shape, combined with excellent water and cold resistance, and mechanical strength. It’s particularly useful for packaging due to its aesthetic appeal, operational efficiency, and tamper-evident properties.
1. Design Features
With its large display area, shrink film allows for effective product promotion and multi-colored printing. It’s frequently used for packaging products like boxed tissues and instant noodles.
2. Operational Efficiency
Shrink film facilitates the bundling of products such as yogurts or beverage packs, enhancing efficiency in transportation and display.
3. Product Protection and Tamper-Resistance
Once torn, shrink film doesn’t revert to its original state, providing evidence of tampering. It’s especially useful for sealing products like jam jars, where only the lid part is wrapped, indicating if the jar has been opened.