Films commonly used for printed layers
Polyester (BOPET), Nylon (BONY or BOPA), Biaxially oriented polypropylene (BOPP), Pearlescent film (foamed BOPP), Cellophane (PT), Polyethylene (PE), Paper
1. Polyester (PET)
Density is 1.35-1.39
Main performance:
High mechanical strength. Its tensile strength is comparable to that of aluminum foil, 3 times that of nylon, and 9 times that of PE film.
Heat resistance, good cold resistance. The melting point of PET is 260°C, and the softening point is 230-240°C. The film can be used for a long time at -70 ~ 150 ℃
Good oil resistance and chemical resistance. Except for nitrobenzene, chloroform, and benzyl alcohol, it is insoluble in most solvents. But it will be attacked by strong alkali.
Good water resistance and low water absorption. Immersion in water, good dimensional stability
Excellent barrier properties. The oxygen barrier rate is about 140cm3/m2·24h·0.1MPa.
Good transparency, gloss. The transparent rate of visible light is more than 90%, and it can absorb light (ultraviolet) with a wavelength below 320nm.
2. Nylon (NY or PA)
Density is 1.13-1.14
Main performance:
Nylon film is a tough film. Have good tensile strength, elongation, tear length and abrasion resistance;
Excellent puncture resistance;
Excellent low temperature retention. Has a wide operating temperature range: -60~200°C;
Excellent oil resistance, organic solvent resistance, chemical resistance and alkali resistance;
Excellent gas barrier properties, but easy to absorb water.
The film itself is not easy to generate static electricity, but the oven-dried NY will also generate static electricity during high-speed printing;
The friction coefficient is small, and NY itself has good self-lubricating properties.
3. Biaxially oriented polypropylene (BOPP)
Density is 0.9-0.91
Main performance:
Has good strength and excellent moisture resistance;
Good heat resistance. The long-term use temperature is -50C～120°C;
Excellent chemical stability. It is resistant to acid and alkali corrosion at room temperature, and almost no organic chemical solvent can dissolve it;
Great breathability;
good transparency;
Non-toxic, tasteless, odorless. Can be used directly in contact with food and medicine;
Tear strength is very low. Therefore, the knife edge must be sharp when cutting.
4. Special BOPP film
Co-extruded BOPP (MB400, MATOPP)
MB400 is a copolymer of PE and PP extruded on both sides of BOPP, so that both sides are heat-sealable;
MATOPP is a BOPP (matte film) that has a special look and feel through the atomization effect when the copolymer of PE or PP is extruded on BOPP.
Coated BOPP
That is, the BOPP film is coated with PVDC and other materials to make it heat-sealable, and at the same time improve its printability and barrier properties.
5. Pearlescent film (foamed BOPP)
It is a foamed BOPP formed by adding pearlescent masterbatch into PP particles, and fine CaCO3 is powder, rubber and other materials, and has a special pearlescent effect. The density is only 0.7 to 0.72. The heat sealability is not very good, but it can still be heat sealed.
6. Cellophane (PT)
Specific gravity: 1.4-1.55
Main performance:
It has excellent transparency, good gloss and beautiful appearance. Resistant to sunlight, no yellowing, no aging;
Has good printability;
High tensile strength, low elongation, good cutability, but high brittleness and easy to break;
No or little static electricity, not easy to stick to dust;
Small tear strength, easy to tear;
Oil resistance, good grease resistance, not easy to be stained;
It has a good barrier to the aroma of gas.
7. Paper
Paper is one of the oldest and most versatile packaging materials and is produced from wood fibers. Its features are:
Non-toxic,
Flammable,
Easy to print,
Opaque, good stiffness,
Easy to absorb moisture,
Poor barrier property,
Environmental protection.