There are only twelve types of structures for composite films!

Today, Advanced Institute Technology will introduce single-layer film, aluminum foilVacuum evaporated aluminum filmLet's take a look at the performance and advantages of twelve types of flexible packaging materials, including silicon coating, adhesive (dry/wet) composite film, extrusion coating composite film, and co extrusion composite film!

1. Single-layer film

Require transparency, non toxicity, non permeability, good heat sealing and bag making properties, heat and cold resistance, mechanical strength, oil and grease resistance, chemical resistance, and anti adhesion properties. It can be produced by various methods such as extrusion blown film method, extrusion casting method, rolling method, solvent casting method, etc. The heat sealing performance of single-layer thin films is not only related to the relative molecular weight distribution and molecular disproportionation degree of the resin, but also to the process conditions during film formation, such as temperature, cooling rate, blowing ratio, etc

2. Aluminum foil

99.5% purity electrolytic aluminum is melted and pressed into foil using a rolling mill, making it an ideal substrate for soft plastic packaging. It has good gas barrier properties, water vapor barrier properties, light shielding properties, thermal conductivity, and shielding properties.

3. Vacuum evaporated aluminum film

Under high vacuum, low boiling point metals such as aluminum are melted, vaporized, and deposited onto a plastic film on a cooling drum to form a layer with good metallic lusteraluminizerWhen the aluminum plating thickness meets certain requirements, it can greatly improve the oxygen and moisture resistance of the substrate. The substrate needs to undergo corona treatment and be coated with sol.

4. Silicon coating

Also known as ceramic coating, its performance will not change no matter how high the temperature and humidity are, making it suitable for making high-temperature cooking packaging bags. According to Coating Online, there are two types of coatings: one is silicon oxide SiOx, the smaller the X, the better the barrier properties; Two is Al2O3. There are physical vapor deposition and chemical vapor deposition methods for coating.

5. Adhesive coated (dry/wet) composite film

Single layer films have certain advantages as well as inherent disadvantages, often unable to meet various packaging performance requirements. By combining multiple layers of different substrates, they can complement each other's strengths and weaknesses, and fully leverage their comprehensive advantages.

6. Extrusion coated composite film

On an extruder, thermoplastic is cast through a T-shaped die onto paper, foil, or plastic substrates that are ready to be coated, or extruded resin is used as an intermediate adhesive to press other film substrates together while hot, forming a "sandwich" composite film. To improve the composite fastness, corona treatment is required and anchor coating agent is applied. Extrusion composite film can be reverse printed, with precise control of layer thickness, low solvent residue, and low price.

7. Co extruded composite film

Using two or three extruders, sharing a composite die, laminating several compatible thermoplastic materials to produce multi-layer films or sheets. Co extruded composite film can only be printed on the front and cannot be printed on the back. Compared with dry composite film and extrusion cast film, it is difficult to control the thickness of each layer. No use of adhesives and anchor coatings, no pollution, good hygiene, and the lowest cost of co extruded composite film.

8. High barrier film

It is a thin film with a multi-layer structure. This film can effectively prevent the infiltration of gases such as oxygen, which can cause the proliferation of microorganisms; Prevent oxidation of wrapped items; Prevent the leakage of fragrance, solvents, etc. from the product. The commonly known high barrier and high-strength materials, such as EVAL, PVDC, PET, PAN, selar PA, etc., can be used to make packaging films, which can significantly extend the shelf life of food or replace traditional rigid packaging materials with good barrier properties.

9. Preservation and sterilization film

① Ethylene gas adsorption membrane, by adding substances such as zeolite, quartz, silica, etc. to the film, can absorb the ethylene gas exhaled by fruits and vegetables and inhibit their rapid maturation.

② Anti condensation and fogging film, the inner surface of packaging film for water green fruits is prone to condensation and fogging, which can easily cause food to become moldy. Adding anti fog and anti drop agents such as stearic acid monoglycerides, polyol fatty acid derivatives, and sorbitan stearate to film materials, as well as waterproof agents such as fluorine-containing compounds, can effectively prevent food mold.

③ Antibacterial membrane is made by adding synthetic zeolite (SiO2 Al2O3) with ion exchange function to plastic materials, followed by inorganic fillers containing silver ions. After silver sodium ion exchange, it becomes silver zeolite with antibacterial properties on its surface. According to Coating Online, the use of co extrusion composite technology can make the film have a 6 μ m silver zeolite inner layer. When the silver ion concentration reaches 10-50ppm, it can completely kill bacteria on the surface of the green fruit.

④ Far infrared preservation film, mixed with ceramic filling agent in plastic film, has the function of producing far-infrared radiation, which can not only kill bacteria but also activate cells in green fruits, thus having preservation function.

10. Aseptic packaging film

Mainly used in the production of sterile packaging for food and medicine, it is required to have: sterilization resistance; High barrier properties and strength; Good heat and cold resistance (no brittleness at -20 ℃); Good resistance to needle puncture and bending; Printed patterns will not be damaged during high-temperature sterilization or other sterilization methods.

11. High temperature resistant steaming bag

High temperature steaming bags can be divided into transparent types (with a shelf life of over one year) and non transparent types (with a shelf life of over two years), high barrier types, and ordinary types. According to the sterilization temperature, it is divided into low-temperature cooking bags (100 ℃, 30min), medium temperature cooking bags (121 ℃, 30min), and high-temperature cooking bags (135 ℃, 30min).

The inner layer of the steaming bag is made of various cast and blown PE (LDPE, HDPE, MPE) films, high-temperature cast CPP or blown IPP. EVAL、 Aluminum foil and PVDC film are suitable as intermediate layers. Biaxially oriented PET, nylon 6, and other materials are suitable for use as surface layer materials. Polyester based two-component polyurethane adhesive is suitable for use as a dry composite film adhesive.

The main advantages of high-temperature steaming bags are:

① High temperature steaming can kill all bacteria, and 121 ℃/30 minutes can kill all Clostridium botulinum;

② Can be stored at room temperature for a long time without refrigeration, can be eaten cold or warm;

③ The packaging material has good barrier properties, no less than canned goods;

④ Reverse printing, beautiful printing decoration;

⑤ Waste is easily incinerated for disposal.

12 temperature pack, high resistance film sheet

The melting point of the material is above 200 ℃, suitable for making high-strength hard/soft containers.