Types of films and their properties

Application of polyolefin film

Due to its competitive advantages: low specific gravity, resistance to acids, chemicals, low cost of packaging, pof film takes an increasing share of the packaging materials market. Polyolefin films were widely used where heat-shrinkable PVC was used.

Applications:

• Packaging for raw and prepared food products - fish or sausage cuts, chilled or smoked chicken, kupat or ready-made ham.
• The chemically aggressive environment of brines and marinades does not affect it. Therefore, it perfectly preserves the quality, taste and aromas of pickled cheeses, salted herring with spices, marinated meat, which is to become a shish kebab.
• It preserves the softness and aroma of different types of bread, the freshness of fragile cookies and buns, the beauty of pastries. The properties of this package are such that even hot, freshly baked bread will not damage the micro-perforated version of the pof film and will not suffer from contact with it. The boxes of easily absorbing the smells of tea and chocolates are sealed into it, sheltered from extraneous odors.
• Shrink polyolefin (pof) film will not allow melted, hard or aristocratic mold cheese to deteriorate.
• It will preserve the freshness of ripe fruits, delicate greens and juicy vegetables.
• Will save magazines, photo albums, wallpapers, books, printer paper and other stationery from any troubles during delivery, for example, scratches and accidental wetness.
• Some auto parts, toys, household and cultural items are packed in it.
• Glass bottles with juice, beer cans, rolls of disposable towels, sets of disposable dishes are packed, wrapped in several pieces.
• Colorful waterproof labels for some drinks, such as juices, yoghurts, shampoos, also help create pof films. The shrink polyolefin wrap is suitable even for protecting control panels of household appliances. You can also find such offers in stores.

Advantages

• Elasticity and resistance to tear (puncture), thereby reducing the risk of deformation of the packaged products and ensuring the resistance of the packaging material to minor mechanical damage.
• The transparency of the film allows you to visually evaluate the packaged product, and also allows you to increase the attractiveness of the product.
• Suitable for packaging hot and frozen food, as well as industrial goods.
• Provides product protection against moisture, dirt and dust.
• Good adhesion, high-quality cling film adheres to the surface of the product and packaging, the layers adhere to each other, which eliminates the need to use adhesive tape. Adheres best to smooth surfaces.
• This material is chemically inert and safe for human health, does not emit harmful substances.
• Low cost makes cling film an affordable yet effective packaging material.

What is the pof film made of. What it is?

The production is based on the polymerization of olefins - substances isolated from oil or natural gases. The structure of polyolefins is a kind of strong "network". Compounds in those places of monomeric molecules, from which hydrogen ions have separated, seem to "cross-link" a large polymer molecule.

With the help of catalysts from homogeneous monomers or copolymerization of different monomeric molecules, film and fiber thermoplastics, rubbery elastomers are obtained.The most large-scale production of film thermoplastic polyethylene, polybutylene, polypropylene and their various copolymers has been established.

Finished products can be single-layer or multi-layer. The multilayer, cross-cut or bi-oriented structure of the polyolefin film gives it optimal strength characteristics. The ability to withstand loads is not lost even at a thickness of 10 microns. The maximum pof film thickness is up to 200 microns.

High pressure polyethylene (LDPE)

High pressure polyethylene (decoding LDPE or LDPE - abbreviations) is a thermoplastic polymer obtained by polymerization of the hydrocarbon compound "ethylene" (ethene) under the action of high temperatures (up to 1800), pressure up to 3000 atmospheres and with the participation of oxygen.

LDPE is a lightweight, durable, elastic material used in many areas of modern human activity. It can also be referred to as low density polyethylene (LDPE or LDPE), as it has relatively weak intramolecular bonds and, therefore, a lower density than other types of polymers.

Also, the abbreviation LDPE is used for its designation - the English equivalent of LDPE.

High pressure polyethylene (LDPE) is produced in the form of LDPE granules. It has a density of 900-930 kg / m3, a melting point of 100-115 ° C and a brittleness temperature of up to -120 ° C, as well as low water absorption (about 0.02% per month) and high plasticity. These physicochemical characteristics of LDPE as a substance explain the following properties of objects and materials made from it:

• Softness and flexibility of low density polyethylene products,
• The ability to create especially smooth and shiny surfaces from LDPE granules,
• Resistance of LDPE objects to mechanical damage by rupture and impact, as well as to tensile and compressive deformations,
• High strength of LDPE (LDPE) when exposed to low temperatures,
• Moisture and air tightness of LDPE products,
• Resistance of LDPE to light, in particular to solar radiation.

IMPORTANT! The use of high-pressure polyethylene (LDPE) is absolutely safe for both humans and the environment, since it does not emit any toxic substances. That is why LDPE can be used even for contact with food and in the manufacture of children's products.

The difference between LDPE and other polymers

Polyethylenes (LDPE, HDPE, etc.) are materials that are made from one monomer, but can be of different density depending on the manufacturing characteristics.

This indicator strongly affects the properties of polyethylene: an increase in density leads to an increase in rigidity, hardness, strength of products and their chemical resistance.

But at the same time, other indicators fall: impact resistance, the possibility of stretching at break, permeability to liquids and gases. So, LDPE has significant differences from other similar polymers:

• LDPE and HDPE High pressure polyethylene is also called low density polyethylene (LDPE or LDPE) for a reason. Compared to it, hard polymers such as HDPE (low pressure polyethylene) are more susceptible to rupture under the impact of impact, more likely to break in the cold and crack with increasing load, although they are more resistant to radiation, alkalis and acids. LDPE granules and products made from them tolerate ultraviolet radiation much better, and also have a more beautiful glossy surface.
• LDPE and LDL. Another polymer - LDL (linear polyethylene), like HDPE, has a rigid structure, but its technical characteristics are between LDPE and HDPE. It is more resistant to chemically aggressive media than LDPE and has better puncture and cracking resistance than HDPE.

Types of polyethylene LDPE

Additional processing of high-pressure polyethylene gives qualitatively new materials that differ in chemical and physical properties.In particular, there are modifications of LDPE with improved adhesion to paints and other materials (for example, to metal) and with reduced flammability. At the moment, polyethylene is distinguished:

• foamed LDPE,
• sewn LDPE,
• copolymers of low density polyethylene (LDPE) with other monomers or with other types of polyethylene.

Scope of LDPE

High-density polyethylene (LDPE) currently occupies a leading position in world production volumes among many other polymers. Due to a successful set of chemical and physical properties, LDPE granules are used in the manufacture of:

• LDPE films, open and in the form of a LDPE sleeve for sacks and bags,
• LDPE plastics by injection molding (polymer pipes, technical parts, etc.),
• blown products (bottles, cans, etc.),
• foam insulation materials,
• electrical insulating materials (cable sheaths, etc.),
• LDPE hot melt glue in the form of a powder prepared by crushing LDPE granules.

INTERESTING! LDPE was the first polymer to be used as an insulating material in the electrical industry for insulating submarine cables and later for radars.

The largest manufacturers in Russia

There are quite a few manufacturers of shrink films in Russia. Also, new companies are constantly appearing on the market for the production of packaging materials. The largest of these are the following:

1. Don-Polymer LLC. It has been working for over 15 years.
2. LLC "EXIMPAK", St. Petersburg.
3. LLC "Polymer-Group +". It is engaged in the production of shrink film in Tatarstan.
4. Sealed Air Corp.
5. LLC "Pandeko", Shchelkovo.
6. OJSC "Plastic". It manufactures products both for the Russian market and for export.

In addition to the above, there are a number of other companies specializing in the production of packaging materials. Due to the relative ease of production and high demand for finished products, their number is growing from year to year. In addition to Russian-made products on the packaging materials market, one can find Chinese and Israeli-made products. Its share in the total volume of polyethylene is insignificant.

How to choose shrink wrap

First, decide on the type. PVC film is very popular, which is distinguished by excellent gloss, transparency, and a wide temperature range. The polyolefin analogue, even at small dimensions, is able to withstand significant weights. The polyethylene version is the most popular - it is dense, elastic and inexpensive. The modified material with additives is denser and more heat-resistant. Also, decide between sleeve, half sleeve and canvas.

Choose a single or multi-layer option - the latter can be more durable even with a lower thickness. To make the purchase optimal, choose its thickness wisely. So for souvenirs, flour products, etc. choose a 20-50 micron film. For packing goods in groups, an analogue with a thickness of 50-100 microns is perfect. There is also a material of 100-250 microns, which is suitable for massive packaging of products.

Types of food films and their properties

Depending on the composition, the possibility of shrinkage and application, the following types of cling film are distinguished:

1. Plastic cling film is the most popular type today. Well suited for packaging products with a short shelf life (fruits, butter, cheese, cold meats). Very tacky, elastic and durable enough.

2. Stretch film PVC (PVC), also called hot table, food stretch - is made of polyvinyl chloride. Its properties are similar to those of polyethylene, but unlike it, PVC is breathable, it is also called "breathable" film. Usually, bread, fresh poultry, meat and fruits of those types that slowly spoil are packed in food stretch.The material allows air vapors to pass through, products in PVC film can be wrapped directly hot.

3. Shrink PVC film - when heated, it shrinks. Such material is used to pack not only food, but also other non-food products. The heat-shrinkable variety is made of PVC, but has the greatest gloss, unsurpassed transparency and the highest strength characteristics.

4. Vacuum food film (barrier) - consists of several different layers (OPA / PE, EVOH / PA / PE, PET / PE, PA / PE, etc.), has high gas tightness, prevents fogging, products packed in it, have a higher shelf life. Sausages, fish, semi-finished meat products and vegetables are packed in such material.

Vacuum food wrap

What it is?

It's hard to imagine an industry today that doesn't use polymers. Polyethylene turned out to be one of the most convenient, therefore it quickly and firmly entered everyday life. It also transfers its unusual properties to shrink film - the most popular packaging option.

The chemical industry is on a special account, therefore the production of products and materials from polyethylene is regulated by separate norms. The manufacture, use and storage of shrink film is described in the document GOST 25951-83. For example, the composition, temperature characteristics, properties of certified materials, the packaging method of the film itself, and even storage features are described.

The composition of polyethylene affects its density, transparency and strength. The name "shrinkable" film is due to its specific temperature properties. For example, it remains stable at + 30º-50º С - it does not decompose or deform. It is to this level that the air is sometimes heated in the hot season. If the film is exposed to a high temperature (shrinkage in industrial conditions is achieved by heating + 120º-150º С), then the material begins to change its shape. It becomes plastic and shrinks or shrinks. With this effect, polyethylene repeats the contours of objects, wrapping them like a dense knitted fabric, and not in contact with these very objects. Thanks to this effect, it is possible to tightly pack goods of various shapes and characteristics.

The packaging has unique properties: it is sealed, resistant to mechanical damage, forms a dense and strong frame, inside which, if necessary, you can securely fix such items as cans, bottles or bags. Through transparent polyethylene, it is easy to see the contents without opening the protective container, to see the marking, color, condition.

The only drawback - long-term decomposition - is compensated by the fact that polyethylene is recycled and reused in production.

Manufacturing notes:

Film roll width Film thickness Film roll lengthAny large deviations in thickness, length and width of the film do not increase the cost of a roll of film with the stated dimensions. The stated dimensions are guaranteed. Each roll has two labels

• The commercial label is on the outside of the box.
• The label on the inside of the sleeve contains manufacturing information.

Quality control

Storage and transportation conditions:

• Transportation must be carried out on pallets in the original packaging.
• It is necessary to store and transport films in an upright position.
• Pallets can be stacked one on top of the other, but no more than two rows.
• The transshipment should be carried out by mechanized means adapted for the transshipment of goods on pallets.
• Storage conditions: in a closed dry room at temperatures from +5 to + 25C, excluding direct sunlight and heating devices.
• Shelf life - 1 year from the date of manufacture.

With an increase in the ambient temperature, depending on the time the film is in extreme conditions, one can expect a process of forced shrinkage of the material from 5% of its uneven distribution over the expanded surface of the film to sintering on the outer sections of the roll and complete unsuitability in the future.

Storage.

• Store rolls in their original packaging in an upright position. Do not place more than three pallets in height. The height of rolls on a pallet should not exceed 900 mm.
• Limits of temperature and humidity must be avoided. The optimum storage temperature is 15-21C.
• It is recommended to use the film within 12 months from the date of manufacture.

When transporting and storing shrink films, consider their sensitivity to temperature. With an increase in the ambient temperature, depending on the time the film is in extreme conditions, one can expect a process of forced shrinkage of the material from 5% of its uneven distribution over the expanded surface of the film to sintering on the outer sections of the roll and complete unsuitability in the future.

Combustion.

• The film burns in direct contact with a source of ignition.
• Combustion produces HCl and other decomposition products.
• Use CO for extinguishing₂, dry chemical compounds, foam or water extinguishers.

Recommendations for use.

• It is recommended to install a ventilation system in the packaging area.
• It is necessary to regularly remove film residues from the heating elements, which can cause unpleasant odors and the formation of a bad seam.
• Do not use film if flammable substances are present in the air.
• The packaging equipment must be grounded.

Material production

Manufacturing methods for each type of material have their own characteristics. So, BOOP film (biaxially oriented) is produced by the method of flat-slit extrusion. The technology involves the distribution of hot melt evenly over the surface of a rotating drum, which is placed in a bath of cold water for cooling. The film is formed in the casting device. At the initial stage, it turns out to be quite thick, but then it is stretched horizontally due to rolling with hot rollers, and in the transverse direction - due to the capture of the edges with special klups. After that, the film web is cooled, the edge is cut, the thickness and other parameters are checked for compliance with the requirements. For this, the film is X-rayed, a corona discharge is applied to the edge, which affects the surface of the film.

In order for the polypropylene film to acquire the required properties, special additives are added to the melt. With their help, it is possible to reduce the coefficient of friction of the material, increase its transparency, and achieve an antistatic effect.

Films used for vapor barrier are made using membrane technology. To create such a material, the film is first irradiated with heavy charged particles, then treated with organic solvents, dried and heat treated. As a result, the production rate of semi-permeable membranes is significantly increased.

Various technologies and methods for the manufacture of polymeric materials make it possible to impart various properties to them. Depending on the purpose of using the polypropylene film, you can select the required variety.

BOPP is made from polypropylene, which contains only carbon and hydrogen atoms. Bopp production is considered safe, the material is clean and easy to handle. The processing technology includes alternate stretching of the produced film in two transverse directions (axes). The BOPP film produced in this way has increased strength and low density in comparison with other polymer films. This gives the advantage of BOPP - with the same thickness, it weighs less than the rest of its competitors, which makes the use of bopp more profitable.

Polypropylene films are:

1. biaxially oriented or biaxially oriented;
2. oriented (ORR / RPO);
3. undirected (CPP / Cast).

Biaxially oriented polypropylene (BOPP) is the most durable because it stretches in opposite directions during production.

Product description

Color: all films are transparent, in a roll they are yellow.
Film width: from 150 mm to 680 mm
deviation from the indicated dimensions: +10 mm
Film thickness: 12.5 to 40 microns.
Film length: depends on thickness.
Sleeve diameter: 76 mm.
Equipment: manual and semi-automatic shrink machines of chamber or tunnel type.
Standard positions:

Film type: CF DB 4UL (half sleeve)

Thickness, micron: 12.5

Film roll width, mm: 150, 200, 250, 300, 350, 400, 450, 500, 550,620.

Film length in a roll, m: 650.

Film type: CF DB 4XL (half sleeve)
Thickness, micron: 15
Film roll width, mm: 150, 200, 250, 300, 350, 400, 450, 500, 550,620.
Film length in a roll, m: 650.

Film type: CF DB 4XM (half sleeve)
Thickness, micron: 19
Film width in a roll, mm: 150, 200, 250, 300, 350, 400, 450, 500,550, 620.
Film length in a roll, m: 650.

Film type: CF DB 4XH (half sleeve)
Thickness, micron: 25
Film width in a roll, mm: 150, 200, 250, 300, 350, 400, 450, 500,550, 620.
Film length in a roll, m: 500.

Film type: CF DB 4XG (half sleeve)
Thickness, micron: 30
Film width in a roll, mm: 150, 200, 250, 300, 350, 400, 450, 500, 550, 620.
Film length in a roll, m: 400.

Properties and characteristics of BOPP

BOPP has a number of valuable properties that have ensured high growth in its consumption:

• Excellent transparency, gloss, aesthetic appearance;
• Elasticity and increased strength. Among all films, only PET can compare with BOPP in terms of rigidity and strength characteristics. This property makes it possible to use the material on high-speed packaging machines;
• Resistance to high and low temperatures: the material retains its properties at temperatures from -50 to +100 degrees Celsius. This allows it to be used for packaging deep-frozen products;
• Barrier properties - resistance to oxygen, carbon dioxide, ultraviolet radiation, water, microbes and mold. The permeability of BOPP is three times less than that of polyethylene, five times less than PET, six times less than PVC;
• Lack of your own smell;
• Convenience of processing: application of flexographic printing, metallization, lamination, cutting, welding;
• Adjustable shrinkage - bopp can be made as low shrinkage, or given the desired shrinkage when heated, ensuring the adhesion of the film to the product.

How to use?

In industrial conditions and in volumes, shrink wrap can be used with the use of special equipment - machines that provide compression at high temperatures. In this case, you can pack a separate item of different sizes, a group of items (the same size or different), or create a shape on special templates.

How to use such a machine correctly? The item to be packed is placed on a stand, wrapped in a film. Then, the sections are closed with welded seams and the shrinkage procedure proceeds by moving the packed item into the heat chambers.

The packaging equipment itself is divided into automatic and semi-automatic machines by type. The machines carry out predetermined production cycles. Power and heating are selected according to the type of film, the size of the objects.

In addition to machines, you will need a thermal knife to work with shrink wrap. It heats up to a certain temperature, under the influence of which the web is cut evenly, without tears or damage.

The film for home use does not require serious equipment. Usually it is already prepared and divided into the necessary segments, it remains only to place an object inside the package and heat it. Shrink-wrapping manufacturers are looking for new safe home applications to expand their consumer base. The production of film is closely related to the search for new solutions, since any innovation helps to improve production, expand the scope of application and increase the profit.

For shrink wrap, see the video below.

Application

The leaders in the consumption of heat shrinkage are food and construction companies. The film is used in breweries, soft drink bottling plants, canning factories, dairies, large bakery industries and other areas.

For each type of application, a different shrink film thickness is used:

• Material 20-50 microns is used for packing souvenirs, flour products, sausages, poultry;
• Film 50-100 microns is used for group packaging of the same type of products, bottles, etc.
• Heat shrinkage 100-200 microns thick is used to pack large-sized piece products or use it for stacking (grouping a batch of goods on a pallet or other basis).

The most common uses for shrink polyethylene are discussed below.

For group packaging of bottles

Group packaging of bottles into shrink film can be carried out both with the use of a cardboard backing, and without. It allows you to reliably fix a certain number of bottles during transportation and storage.

It takes from 8 to 20 bottles to form a block. Then the wrapping process takes place. After heat treatment, the film casing acquires a density that protects the bottles from damage.

The best film for packaging PET bottles is considered, which has a multilayer structure. Sizes are commonly used:

• width 350-530 mm, depending on the capacity of the container;
• thickness 60 to 100 microns.

Brick packing

Packing pallets of bricks in industrial shrink wrap provides reliable protection during transport and storage on the construction site. Due to its high strength characteristics, it completely eliminates the possibility of stretching and tearing. In addition, this material is resistant to ultraviolet radiation, which allows you to store bricks directly in the open air.

Bulky cargo packaging

Shrink wrapping of bulky goods allows you to reliably protect objects during transportation and storage. Polyethylene tightly wraps around the surface of the products, taking their shape.

Other uses

Shrink wrap is a versatile packaging material. It is widely used for packaging stationery, book publishing, medical and perfumery products. In the food industry, it is indispensable for the packaging of semi-finished products and bakery products. Flexographic printing on shrink wrap allows you to place advertising information on the packaging, which contributes to the passive promotion of services and goods.

Film shrink labels

A separate category of shrink film material. It is a thin transparent polymeric structure in the shape of a sleeve. The wall thickness does not exceed 70 microns. A pattern is applied to the inner part of the surface with special paints, put on the product and given a heat treatment. The end result is a label. For example, almost all drinks in plastic containers are wrapped in this way.

The advantage of a film label over traditional paper labels is its durability in a humid environment and the absence of the need for glue. The applied information is not subject to fading and is clearly visible.

Types of films and their properties

Once BOPP was used, it was single-layer, but that was progress. Nowadays, multilayer is becoming more and more popular. Its characteristics are much better than single-layer, because thanks to interlayers made of different materials, it has become much more practical and protects products in many ways.

The polypropylene film must be waterproof, transparent, airtight, temperature resistant and durable. To achieve these characteristics, foil and adhesives are placed between the layers of material.Usually, when in contact, the material sticks together, this property facilitates the packaging process. But there are a huge number of types of multilayer polypropylene film and each has its own characteristics that are convenient for packaging different products.

1. Skin film - excellent protection against moisture and dust, used for packaging cardboard and paper
2. Co-extruded polyethylene is a three-layer film, resistant to tearing due to puncture or impact, very transparent.
3. Biaxially oriented polypropylene film is transparent, elastic, durable. It can be transparent, white, pearlescent, with a metallic sheen.
4. Cast film (CPP film) is durable and transparent. Not sensitive to high temperatures.

Each type of material has its own characteristics and unique properties. The scope of their application depends on this. Stronger materials are often used in construction and industry. For example, semi-permeable films are excellent for performing roof vapor barrier in the construction of buildings for various purposes. A special property of such materials is the ability to pass steam and moisture in one direction and not to pass it in the other. Thanks to this, vapors from the room leave the house outside, and moisture from the street does not penetrate into the house, does not spoil the insulation and other building materials.

Polypropylene films provide sound insulation, which allows them to be used in various residential and industrial premises.

Manufacturers

GOST 25951-83 regulates the requirements for finished products or the shrink film itself. This need arises because polyethylene is a product of the chemical industry, when working with it, you must follow the rules.

The polymer enters the production of shrink film in a granular state. Further, on special equipment, the substance is heated until a homogeneous mass is obtained and a polymer web is formed using extrusion, it is given the necessary appearance, and laid according to the established rules. The final products are packaged in boxes and double-labeled. The outer marking is applied over the packaging, and the inner one is applied to a roll of film. It contains data such as the date of manufacture, the team number, and other data necessary for the identification and control of those responsible for production.

Special industrial exhibitions such as RosUpack or TransPack (TRANSPACK) help to promote and acquire customers and contractors.

Among the most famous manufacturers of shrink films are Russian companies and joint ventures. Known joint ventures in the Russian market:

Russian-German "Südpak Rus" produces films, bags, packaging materials;

Russian manufacturers operate in almost all regions and often interact with industry institutions, introducing innovations and experimental production:

TPK Sahara works with a wide range of products from packaging films to ready-made solutions for specialized industries;