
1. Single film:
It is required to be transparent, non-toxic, impermeable, with good heat
sealing and bag making properties, heat and cold resistance, mechanical
strength, grease resistance, chemical resistance and adhesion resistance. It can
be prepared by extrusion blowing, extrusion tape casting, calendering, solvent
tape casting and other methods.
The heat sealing performance of the monolayer film is not only related to
the relative molecular weight distribution and molecular disproportionation of
the resin, but also related to the process conditions during film preparation,
such as temperature, cooling rate, blowing ratio, etc.
2. Aluminum foil:
99.5% pure electrolytic aluminum is melted and pressed into foil by
calender, which is ideal as the base material for soft plastic packaging. It has
good gas barrier, water vapor barrier, light shielding, thermal conductivity and
shielding.
3. Vacuum evaporation aluminum film:
Under high vacuum, the metal with low boiling point, such as aluminum, is
melted, vaporized and stacked on the plastic film on the cooling drum to form an
aluminized film with good metallic luster. When the aluminum plating thickness
reaches certain requirements, the oxygen resistance and moisture resistance of
the substrate can be greatly improved. The substrate shall be corona treated and
coated with sol.
4. Silicon coating:
It is also called ceramic coating. No matter how high the temperature and
humidity are, the performance will not change. It is suitable for making
high-temperature cooking bags. There are two kinds of coatings: one is silicon
oxide SiOx, the smaller the X is, the better the barrier is; The second is
Al2O3. The coating methods include physical evaporation and chemical
evaporation.
5. Gluing (dry/wet) composite film:
Single layer films have certain advantages as well as inherent
disadvantages. They are often difficult to meet a variety of packaging
performance requirements. Multiple layers of different substrates can complement
each other and give full play to their comprehensive advantages.
6. Extrusion coating composite film:
On an extruder, thermoplastic is streamed on the paper, foil, and plastic
substrate to be covered through a T-shaped die, or the extruded resin is used as
the intermediate binder, and other film substrates are pressed together while
hot to form a sandwich type composite film.
In order to improve the composite fastness, it is necessary to conduct
corona treatment and apply anchor paint. The extruded composite film can be
reverse printed, the thickness of each layer can be precisely controlled, the
residual amount of solvent is small, and the price is cheap.
7. Co extruded composite film:
Two or three extruders are used to use a common composite die to laminated
several compatible thermoplastics to produce multilayer films or sheets. Co
extruded composite film can only be printed on the front, not on the back.
It is difficult to control the thickness of each layer compared with dry
composite film and extruded cast film. No adhesive and anchor paint are used,
which is pollution-free and sanitary. Co extruded composite membrane has the
lowest cost.
8. High barrier film:
It is a multilayer structure film. It can effectively prevent the
infiltration of oxygen and other gases, thus causing the propagation of
microorganisms; Prevent the wrapped articles from oxidation; Prevent the outflow
of fragrance, solvent, etc.
The commonly called high barrier and high-strength materials, such as EVAL,
PVDC, PET, PAN, self PA, can be made into packaging films, which can
significantly extend the shelf life of food, or replace the traditional rigid
packaging materials with good barrier performance.
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