Flexible packaging is an important form of packaging for food and medicine. However, if it is not properly controlled during the gravure process of flexible packaging, it may cause excessive organic solvent residues and threaten people's health. With the gradual improvement of people's living standards and health consciousness, consumers have put forward more flexible, environmentally friendly and convenient requirements for traditional flexible packaging. Under this demand, functional co-extruded films have emerged quietly, and have achieved Successfully applied. In the following, the author will elaborate on the main characteristics and application fields of the functional coextruded film, hoping to learn together with people in the industry.

main feature

1. Structural features

The functional co-extruded film is a composite film that uses a multi-layer co-extruded composite technology to combine a variety of substrates with different properties. It is a one-time molding, which can integrate the performance of various substrates in one and can be well satisfied. Different functional requirements for flexible packaging. Common structures of functional co-extruded films 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 fragrance retention; strong mechanical properties, high drop resistance, puncture resistance, tear resistance; high temperature resistance ( 121 ℃), low temperature resistance (-40 ℃), grease resistance; non-toxic and tasteless, in line with the hygiene standards of food and pharmaceutical packaging; good heat sealability, flexibility and transparency.

From the perspective of processing technology and cost, the advantages of functional co-extruded film mainly include: not limited by product specifications, which 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 with the required performance is reduced to the minimum thickness, and the thinnest thickness of the single layer can reach 2 to 3 μm, which can greatly reduce the use of expensive resin; only one process of blow molding can be used to effectively reduce production costs.

Application field

1. Composite membrane replacing partial structure

Functional co-extruded films can be used to replace composite films with partial structures. For example, composite films with an intermediate layer of PA / PE can be replaced with PA / PE co-extruded films; composite films with high barrier structures can be replaced with co-extruded films containing EVOH. Especially for products with high barrier requirements such as fruit juice, ketchup, jelly, etc., functional co-extruded film is used for packaging, which can effectively prevent the product from changing color and taste.

The use of functional co-extruded film to replace part of the structure of the composite film has the following obvious advantages: ① can reduce the composite process, the yield can be increased by 1% to 1.5%; ② compared with traditional composite film, it can save about 10% of production Cost; ③ The physical and chemical properties of the functional co-extruded film (such as barrier properties, folding resistance, transparency, etc.) are better than traditional composite films, such as some self-standing bags that use traditional composite films to store liquid leakage, and functional co-extrusion Membrane can improve this phenomenon; ④Functional co-extruded film can simplify the production process, shorten the production cycle in the production process, and effectively guarantee the customer delivery time.

2. For automatic packaging machines

The common structure of the functional co-extruded film used under the automatic packaging machine is PA / TIE / PE / TIE / PA (EVOH) / TIE / PE / PE / PE (EVA), which is currently used in snack food packaging, medical dressing product packaging, etc. More applications in the field. In the future, it is a development trend to apply functional co-extruded film to automatic packaging machines.

First of all, the application of the functional co-extruded film with the automatic packaging machine can effectively reduce the labor intensity of manual packaging. One automatic packaging machine can be equipped with 3 production personnel, which is equivalent to 15-20 production personnel when using manual packaging. Labor intensity not only eases the difficulty of recruiting workers, but also reduces labor costs.

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.

In addition, the functional co-extruded film does not require a compounding process, and can well control the residual amount of organic solvents, providing a reliable guarantee for the safety and environmental protection of food, pharmaceuticals and other products.

3. Used as buffer packaging for electronic and electrical products

The functional co-extruded film used as a buffer package for electronic and electrical products has very outstanding advantages. The conventional structure is P E / PE / TIE / PA / TI E / PE / PE. This type of cushioning packaging is also called "inflatable packaging". The film materials used must have good mechanical properties, such as puncture resistance, extrusion resistance, good barrier properties, oil resistance, light protection, etc., which requires a variety of different The performance of polymer pellets is combined to achieve.

In the past two years, this type of buffer packaging has a large application market, mainly because: ① small size, easy to transport, can reduce transportation and storage costs to 80% of the original; ② strong comprehensive protection, such as in toner cartridges, It can play a very obvious protective role in the packaging of high-end and fine electronic products such as notebook computers.

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 actively taken action and independently developed a number of functional types for infusion bags with excellent performance. Co-extruded film, the more representative companies are Ningbo Huafeng Packaging Co., Ltd., Fuzhou Lufan Plastic Products Co., Ltd. and so on.

This type of functional co-extruded film is a mixture of various polymer pellets with special functions according to a certain ratio. These mixed pellets are extruded and granulated by an extruder under suitable conditions, and finally are cooled by water or air. Cooling and cooling, in the process of extrusion molding, some polymer pellets also need to undergo cross-linking through radiation. The air cleanliness level of this type of functional co-extruded film production workshop must reach 100, so as to ensure the cleanliness and sterility of the surface of the functional co-extruded film, so that the physical and chemical indicators of the infusion bag meet the medical requirements.

The advantages of the functional co-extruded film infusion bag are as follows: ① The infusion bag is emptied by self-flow under the action of air pressure; ② Not only eliminates the pollution of the return air, but also solves the problem of micro-leakage of the soft bag; Next, the infusion function can be restored by means of external pressure.

5. Used as a vacuum packaging 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. It has a traditional composite film Unmatched advantages, conventional structures are: 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 co-extruded films will play a greater role in the vacuum packaging bag market.