High-temperature resistant polyurethane adhesives are a key material in the flexible packaging industry. Through special chemical structure design, they significantly enhance the heat resistance of traditional polyurethane adhesives while maintaining their excellent performance, to meet increasingly demanding packaging processing and usage conditions.
Its main advantages are reflected in the following aspects:
1. Outstanding heat resistance: This is its most core advantage. It can withstand high-temperature sterilization processes up to 121℃ or even above 135℃ without delamination, bubbling or performance degradation. This is crucial for food, medical devices and other items that need to be stored for a long time.
2. Outstanding structural strength and toughness: Even after high-temperature and high-pressure treatment, it can still maintain extremely high bonding strength, ensuring the firm combination of each layer of materials in the composite packaging (such as plastic film, aluminum foil, etc.), effectively preventing leakage of contents and external contamination.
3. Good resistance to media: It can resist the erosion of complex contents such as oily, acidic and salty ones, maintain the stability of the bonding interface, and prevent packaging failure caused by the penetration of contents.
4. Wide processing adaptability: It can adapt to mainstream production equipment such as high-speed dry laminating machines, and has appropriate operation Windows and curing characteristics, which is conducive to improving production efficiency.
Usage in the flexible packaging industry:
High-temperature resistant polyurethane adhesives are mainly used in fields with extremely high requirements for packaging performance and are often referred to as "retort packaging" or "high-temperature retort packaging".
1. Application fields: It is most commonly found in the packaging of various high-temperature sterilized foods, such as meat cans, sauces, pet food, ready-to-eat meal packs, etc. These foods need to undergo long-term high-temperature treatment in an autoclave after packaging to kill all microorganisms, ensuring food safety and extending the shelf life. In addition, it is also used for aseptic packaging of medical devices. These devices need to undergo strict irradiation or ethylene oxide sterilization before leaving the factory, which places extremely high demands on the durability and reliability of packaging materials.
2. Packaging structure: Typical high-temperature resistant retort packaging usually adopts a multi-layer composite structure, such as: polyester film (PET)/aluminum foil (Al)/cast polypropylene film (CPP), or nylon (PA)/special polyethylene (RCPP), etc. High-temperature resistant polyurethane adhesives play the role of a "skeleton" in it, firmly bonding these materials with different functions together to form a complete packaging system that can withstand high-temperature sterilization, has high barrier properties, and is strong, tough and puncture-resistant.
High-temperature resistant polyurethane adhesives are an important technical support for promoting the development of flexible packaging towards greater safety, convenience and longer shelf life, especially in the fields of high-value food and medical sterilization packaging, they hold an irreplaceable position.
