OPP, BOPP and CPP, do you know them?
OPP film, as a type of polypropylene film, has a unique production process - multi-layer extrusion, which gives it the name of co-extruded oriented polypropylene film (OPP). If the processing involves biaxial stretching, it is called biaxially oriented polypropylene film (BOPP). In contrast, cast polypropylene film (CPP) gives it different characteristics. The three films have their own advantages in performance and use.
1. OPP film
Oriented polypropylene film has excellent stretchability and is a member of the polypropylene family.
The main application areas of OPP are wide, for example:
1. OPP tape, with polypropylene film as the base material, has strong tensile force, light texture, non-toxic and odorless and environmentally friendly, and has a very wide range of uses.
2. OPP bottle, its light weight, low cost, improved transparency and excellent heat resistance make it the first choice for hot filling.
3. OPP label, compared with paper label, it has high transparency, high strength, excellent moisture resistance and is not easy to fall off. Although the cost is slightly higher, the display and use effect are excellent. With the advancement of domestic printing and coating technology, the production of self-adhesive film labels and printed film labels is no longer a problem. It can be predicted that the domestic use of OPP labels will continue to rise.
2. BOPP film
Biaxially oriented polypropylene film also belongs to the polypropylene series.
Common BOPP films include: ordinary type, heat-sealed type, cigarette packaging film, pearlescent film, metallized film and matte film. Their main uses are as follows:
1. Ordinary BOPP film is widely used in printing, bag making and composite with other substrates.
2. BOPP heat-sealed film is mainly used for printing and bag making.
3. BOPP cigarette packaging film is designed for high-speed cigarette packaging.
4. BOPP pearlescent film is often used for packaging and printing of food and daily necessities.
5. BOPP metallized film is used as a substrate for vacuum metallization, radiation, and anti-counterfeiting, and is also suitable for food packaging.
6. BOPP matte film is used for packaging boxes of soap, food, cigarettes, cosmetics, pharmaceutical products, etc.
7. BOPP anti-fog film, specially designed for packaging of vegetables, fruits, sushi, flowers, etc.
BOPP film, as an important flexible packaging material, is widely used. It is colorless, odorless, tasteless, non-toxic, and has high tensile strength, impact strength, rigidity, toughness and good transparency. However, BOPP film is easy to accumulate static electricity and does not have heat sealing properties. In high-speed production lines, static eliminators need to be installed. In order to obtain heat-sealable BOPP film, heat-sealable resin glue, such as PVDC latex, EVA latex, etc., can be coated on its surface, or extrusion coating or co-extrusion compounding methods can be used.
3. CPP film
CPP film has high transparency, good gloss, good stiffness, strong moisture barrier, excellent heat resistance, and is easy to heat seal.
After printing and bag making, CPP film is suitable for packaging of clothing, knitwear and flowers; film for documents and albums; food packaging; and metallized film for barrier and decoration. Its potential uses also include food outer packaging, candy outer packaging, pharmaceutical packaging, and the fields of replacing materials such as PVC, synthetic paper, and self-adhesive tape. CPP film has excellent heat resistance and a softening point of about 140℃, so it is suitable for hot filling, cooking bags, aseptic packaging and other fields. It has excellent acid, alkali and grease resistance and is the first choice for bread product packaging or laminating materials. It is safe to contact with food, has excellent demonstration performance, and will not affect the flavor of food. Different grades of resin can be selected according to needs to obtain the required characteristics.
The production process of CPP film usually adopts the T-die head method, which has distinct characteristics:
1. The casting method omits the film blowing stage of the tube film method, making production simpler and reducing waste.
2. During the casting method production, the chemical molecules are arranged in an orderly manner, which is conducive to improving the transparency, gloss and thickness uniformity of the film, making it an ideal choice for high-end packaging.
3. The casting part adopts an electric up and down swing and forward and backward moving structure, which is easy to operate.
4. The corona part adopts air cooling and water cooling to ensure that the product is not easy to deform.
After the extruder melts the raw resin, the molten resin is cast onto the cooling roller with a smooth surface through the die head and quickly cooled into a film. After thickness measurement, pulling, corona treatment and flattening, the thicker edge material is removed and the film is unfolded and rolled into a film roll again.
