Overview of varieties
There are several popular types of film.
Transparent
The high level of transparency of such material allows the consumer to examine the product from all sides and visually assess its quality. Such packaging is beneficial not only for buyers, but also for manufacturers, as they get the opportunity to demonstrate their product to customers, thereby highlighting all its advantages over the products of competing brands. Such a film is often used for packing stationery and some types of food products (bakery products, baked goods, as well as groceries and sweets).
Mother-of-pearl
Biaxially oriented pearl film is obtained by introducing special additives into the raw material. The chemical reaction produces propylene with a foamed structure that can reflect light rays. The pearlescent film is lightweight and very economical to use. It can withstand subzero temperatures, therefore, it is often used for packaging food products that need to be stored in the freezer (ice cream, dumplings, glazed curds). In addition, such a film is suitable for packaging fat-containing products.
Metallized
Metallized BOPP is usually used for wrapping waffles, crispbreads, muffins, cookies and sweets, as well as sweet bars and snacks (chips, crackers, nuts)
Maintaining maximum UV, water vapor and oxygen resistance is critical for all of these products.
Shrink
Biaxially oriented shrink film is characterized by its ability to first shrink at relatively low temperatures. This feature is often used for packaging cigars, cigarettes and other tobacco products. In terms of properties, it is as close as possible to the first type of films.
What it is?
The abbreviation BOPP stands for biaxially oriented polypropylene films. This material belongs to the category of film based on synthetic polymers from the group of polyolefins. The BOPP production method assumes bi-directional translational stretching of the produced film along the transverse and longitudinal axes. As a result, the finished product receives a rigid molecular structure, which endows the film with properties that are valuable for further operation.
This material is widely in demand for packaging toys, clothing, cosmetics, printing and souvenir products. BOPP is widely used in food packaging - this demand is due to the heat resistance of the material, due to which the finished product can be kept hot for a long time. And perishable food packed in BOPP can be placed in the refrigerator or freezer without compromising the preservation of the film.
Compared to all other types of packaging materials, biaxially oriented polypropylene film has many advantages:
- compliance with GOST;
- low density and lightness combined with high strength;
- a wide range of products offered for packaging a wide variety of product groups;
- affordable cost;
- resistance to high and low temperatures;
- chemical inertness, due to which the product can be used for packaging food;
- resistance to ultraviolet radiation, oxidation and high humidity;
- immunity to mold, fungus and other pathogenic microorganisms;
- ease of processing, in particular the availability of cutting, printing and lamination.
The product is suitable for metallized coating and printing. If necessary, during production, you can add new layers of material that increase its operational parameters, such as protection against accumulated static electricity, glossiness and some others.
The only drawback of BOPP is inherent in all bags made of synthetic materials - they decompose for a long time in nature and therefore, when accumulated, can cause harm to the environment in the future. Environmentalists around the world are struggling with the use of plastic products, but today the film remains one of the most popular and common packaging materials.
LDL properties
LDL has high physical and chemical characteristics. The properties of LDL can be called intermediate between the properties of PVP and PNP. But in comparison with LDPE, LDPE has a more uniform distribution of polymer groups by molecular weight. This material has the following properties:
Significant tensile strength, high resistance to cracking and elongation at break.
- High performance
- Quite high melting point. This allows the use of LPVD when filling hot products.
- A huge advantage of linear polyethylene is its chemical resistance in a large temperature range. LDL can withstand temperatures in the range of -45-100 ° C.
- Excellent melt elasticity. This property makes it possible to obtain a fairly thin film (from 6 to 25 microns).
- Linear polyethylene is chemically inert at room temperature, and with sufficient heating it is capable of nitriding, oxidation, and sulfonation reactions.
- LDL is perfect for storing food, because it does not affect their taste.
- LPVD is not exposed to ultraviolet rays, corrosion, does not deteriorate in extreme weather conditions. It is used at a peak temperature of 60 ° C.
- Due to its high crystallinity, linear low density polyethylene is less transparent than other types of polyethylene. To obtain a more transparent LDL, special optical additives are introduced into it.
- Externally, LPVD is a hard material with a barely noticeable pearlescent tint.
- Linear polyethylene in thin films is practically transparent, elastic, thermoplastic and flexible, easily cut with a knife. LDL in thick sheets is difficult to cut with a knife.
- LPVD lights up very slowly, burns without soot, with a weak blue flame, exuding the smell of hot paraffin.
- When melted, linear polyethylene is converted into a soft jelly-like mass with almost no fluidity.
- LDL is practically insoluble in organic liquids below 60 ° C. At higher temperatures, linear polyethylene quickly dissolves in halogen derivatives, hydrocarbons, and some other products.
- LPVD absorbs water to an extremely small extent. Absorption and its rate increase slightly at high temperatures.
- The permeability of water vapor through the linear polyethylene film is extremely low. LDL is one of the best waterproof film-forming materials.
Types of BOPP films
Often on sale you can find 5 types of these products. Films are produced with different parameters of thickness (20-40 microns) and width (10-1500 mm). Its sale is usually carried out within a predetermined length.
- BOPP transparent film consists of 3 layers: 2 of them are heat-sealable, and the central one, polypropylene, carries the main load.
It is often found in bulk food packaging, as it has excellent transparency and is also complemented by anti-reflective components. The material does not accumulate static charge and glides perfectly. In addition, it is officially approved for food packaging - from ice cream to hot products. - The mother-of-pearl BOPP film differs from the previous type by the presence of an OOP layer with a microporous structure, which gives the film a “pearl” tint.
It is used where protection from direct sunlight is needed, and also, due to its resistance to low temperatures, in the packaging of frozen foods. Like the previous one, it is protected from static charge, glare, glides well and is excellent for printing. - Metallized BOPP film - the main difference of this material is the increased barrier properties, which are provided by sputtering from aluminum.
This coating will be in close contact with the crowned layer, due to the initially high adhesion, and will perfectly tolerate not only printing, but also heat sealing, without losing its reflective properties. Excellent protection against odors, suitable for packaging fish and meat. - Shrink biaxially oriented has a high ability to shrink at relatively low temperatures.
Due to this feature, it is often used for packaging cigarettes, therefore it is sometimes called "tobacco". The properties are closest to the first type. - BOPP film for general use - the basis for the manufacture of scotch tape, as well as packaging products, labels, tapes, etc.
Unlike previous types, it cannot be used for heat sealing, since it is made without appropriate layers.
There are other types, for example, BOPP film with polyethylene lamination (packaging of large weight or packaging of products with high fat content), or perforated.