Functional coextrusion film characteristics and applications
lexible packaging is an important form of packaging for foods and pharmaceuticals. However, in the process of gravure printing of flexible packaging, if it is improperly controlled, it may cause excessive residual organic solvents and threaten people's health. With the gradual improvement of people's living standards and health awareness, consumers have put forward more requirements for traditional flexible packaging, such as safer, more environmentally friendly, and more convenient. Under this demand, functional co-extruded membranes have emerged and realized in different fields. Successful application. Below, the author will elaborate on the main features and application fields of the functional co-extruded film, and hope to learn together with the industry.
1. Structural features
The functional co-extruded film is a composite film that combines a plurality of substrates of different properties by a multi-layer co-extrusion composite technology, which is a one-shot molding, which can combine the performances of various substrates and can well satisfy Flexible packaging has different functional requirements. The common structures of functional co-extruded membranes are: PE/TIE/PA/TIE/PE(PA), moderate barrier properties, moderate strength; PE/TIE/EVOH/TIE/PE, high barrier properties, moderate strength; PA/EVOH /PA/TIE/EVA, high barrier and high strength.
2. Outstanding advantages
From the performance point of view, the advantages of functional co-extruded film mainly include: high oxygen barrier, good moisture resistance, good aroma retention; strong mechanical properties, high drop resistance, good puncture resistance, tear resistance; high temperature resistance ( 121 ° C), low temperature resistance (-40 ° C), grease resistance; non-toxic and tasteless, in line with food and pharmaceutical packaging hygiene standards; good heat sealability, flexibility, transparency and so on.
From the perspective of processing technology and cost, the advantages of functional co-extruded film mainly include: it is not limited by product specifications, and can effectively meet the needs of different packaging occasions; the more layers, the more flexible the structural design, the lower the cost, such as The resin material of the required performance is reduced to a minimum thickness, and the thinnest thickness of the single layer can be 2 to 3 μm, which can greatly reduce the amount of expensive resin used; only a blow molding process is required, which can effectively reduce the production cost.
1. Substitute partial membrane composite membrane
The functional co-extruded film can be used to replace the partial structure of the composite film. For example, the composite film with the intermediate layer of PA/PE can be replaced by the PA/PE co-extruded film; the composite film with the high barrier structure can be replaced by the co-extruded film containing EVOH. In particular, for products with high barrier properties such as juice, ketchup, and jelly, packaging with a functional co-extruded film can effectively prevent problems such as discoloration and odor.
The use of functional co-extruded film to replace part of the composite film has the following obvious advantages: 1 can reduce the compounding process, the yield can be increased by 1% to 1.5%; 2 compared to the traditional composite film, can save about 10% of production Cost; 3 physical and chemical properties of functional co-extruded membranes (such as barrier properties, folding resistance, transparency, etc.) are better than traditional composite membranes, such as the use of traditional composite membranes in the standing bag storage and leakage phenomenon, and the use of functional coextrusion Membrane can improve this phenomenon; 4 functional co-extruded film can simplify the production process in the production process, shorten the production cycle, and effectively guarantee the customer delivery time.
2. For automatic packaging machines
The common structure of functional co-extruded film used under automatic packaging machine is PA/TIE/PE/TIE/PA (EVOH)/TIE/PE/PE/PE (EVA), currently in leisure food packaging, medical dressing product packaging, etc. There are many applications in the field. In the future, the application of functional co-extruded film and automatic packaging machine is a development trend.
First of all, the application of functional co-extruded film and automatic packaging machine can effectively reduce the labor intensity of manual packaging. One automatic packaging machine can be equipped with three production personnel, which is equivalent to 15 to 20 production personnel when using manual packaging. Labor intensity not only eases the difficulty of recruiting, but also reduces the cost of labor.
Secondly, the functional co-extruded film can be automatically filled on the automatic packaging machine, which effectively reduces the secondary pollution caused by manual packaging on products with high hygiene and safety requirements such as food and medicine.
Furthermore, the functional co-extruded film does not require a compounding process, and can well control the residual amount of organic solvents, and provides a reliable guarantee for the safety and environmental protection of foods, medicines and the like.
3. Used as buffer packaging for electronic and electrical products
The functional co-extruded film has a very prominent advantage as a buffer package for electronic and electrical products. The conventional structure is P E/PE/TIE/PA/TI E/PE/PE. Such cushioning packaging is also called "inflatable packaging", and the film material used must have good mechanical properties, such as puncture resistance, anti-extrusion, good barrier properties, oil resistance, light protection, etc., which requires a lot of different The performance of the polymer pellets is combined to achieve.
In the past two years, such buffer packaging has a large application market, mainly because: 1 small size, easy to transport, can reduce transportation and storage costs to 80%; 2 comprehensive protection, such as in the toner cartridge, In the packaging of high-end and fine electronic products such as notebook computers, it can play a very obvious protective role.
4. Used as an infusion bag
Functional co-extruded film is the main application material in the current infusion bag market. In the past, it was mainly imported. In recent years, some domestic material manufacturers have also taken active actions to independently develop a variety of functional infusion bags. Co-extruded film, more representative companies are Ningbo Huafeng Packaging Co., Ltd., Fuzhou Luyi Plastic Products Co., Ltd., etc.
The functional co-extruded film is prepared by mixing various polymer pellets with special functions according to a certain ratio, and the mixed pellets are extruded and granulated by an extruder under suitable conditions, and finally water-cooled or wind-driven. Cooling is carried out in the cold. During the extrusion process, some polymer pellets also need to undergo cross-linking by radiation. The air-cleaning grade of this type of functional co-extruded film production workshop must reach 100 grades, so as to ensure the cleanliness and sterility of the functional co-extruded membrane surface, so that the physical and chemical indicators of the infusion bag meet the medical requirements.
The advantages of the functional co-extruded membrane infusion bag are as follows: 1 The flow of the infusion bag is self-flowing under the action of the air pressure; 2 not only eliminates the pollution of the return air, but also solves the problem of soft bag micro-leakage; 3 in the case of inability to automatically infuse The infusion function can be restored by external pressurization.
5. Used as a vacuum bag
The packaging of aquatic products, seafood, rice and other products needs to meet the requirements of puncture resistance and drop resistance. The true rate packaging bags made of functional co-extruded film can meet the above requirements by adjusting the proportion of polymer pellets. Unmatched advantages, the conventional structure is: PA / TIE / PE / TIE / PA / TIE / PE / PE / PE (EVA), with high strength; PA / TIE / PE / TIE / EVOH / PE / PE / PE /PE (EVA), with high strength and high barrier properties. In the future, functional coextruded films will play a greater role in the vacuum packaging market.
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