Technical film: types, characteristics, applications

The history of this material began abroad already in the middle of the last century ,. It was used to pack food products. The technical film was the result of multiple modifications of the chemical composition and production technologies, which provided it with a wide range of products and a high level of use.

Composition

The properties that the polyethylene technical film possesses, and its purpose depend on the composition:

• High pressure polyethylene, having a low density (LDPE).
• Polyethylene of low pressure, having a dense structure (HDPE).
• Linear LDPE with a modified composition.
• Compound variations: for example, LDPE and HDPE, with polypropylene.

Technical requirements

Polyethylene is not toxic, it consists of a group of flammable non-toxic materials with an ignition temperature of 300 ° C, the remaining characteristics depend on the composition:

Polyethylene film of low pressure:

• Mechanically strong material (0.94 ÷ 0.96 g / cm ² ).
• Resistant to high temperatures (flow regime at 112 ° C).
• Resistant structure to edible fats, oils. Neutral to acidic and alkaline substances.
• The disadvantage is a high level of permeability, almost 6 times higher than the HP film. The contact with hydrocarbons is inadmissible and undesirable - with easy-oxidizing substances.
• A technical film based on low-density polyethylene is indispensable for packaging products that are sterilized and a certain range of foods.

High pressure polyethylene film:

• It has a density of 0.91 ÷ 093 g / cm ² .
• Moderate tensile strength.
• A low level of fluidity allows you to weld pieces of material.
• Frost resistant: up to - 60С °.
• The surface is easy to apply paint.

Linear LDPE: the basis for creating stretch multilayer films.

Each type of produced material must comply with the requirements of state regulatory documentation:

• Polyethylene film technical - GOST 10354 - 82.
• Polyethylene thermoshrinkable - GOST 25951 - 83.
• HDPE GOST 16338 - 85.
• LDPE GOST 16337 - 77.

Production

The technical film is produced by the technology of extrusion in several stages:

• Melting and blowing a semi-liquid composition passed through the outlet through different types of nozzles:

1. Ring, giving a baggy appearance of packaging. At the exit from the nozzle, the material is blown upward and dried over the entire length, followed by tightening the rollers and winding the full rolls. A labor-intensive process that allows you to get a canvas up to 2400 mm long.
2. Flat, allowing to get a straight film sheet. After extrusion, the material is dried, stretched and cut. This is a faster technology, but polyethylene sheets do not exceed 1.5 m.

• Polyethylene is modified to produce a material with the desired properties:

1. Chemical, with the addition of certain elements.
2. Mechanical, by stretching.
3. "Stitching" with the help of ion radiation
4. Thermal stabilization. After heat treatment, the material structure becomes more resistant to mechanical damage.

Technical film: characteristics and types of finished products

Depending on the modifications of the raw materials on sale, the following types of technical polyethylene can be seen:

• Light stabilized: has great resistance to solar radiation, the service life depends on the concentration of stabilizers. Has bright colors: yellow, green and so on.
• Shrink: when heated, changes its size, tightening the object inside. The width of the canvas is up to 150 mm, the sleeves up to 2500 mm.

Shrinkage:

1. Longitudinal: from 40 to 80%.
2. Transverse: 10 ÷ 50%.

• Composite shrink: various types of coating with the addition of reagents, changing the property of the material for the necessary characteristics.
• Reinforced: a technical film with a mesh of polypropylene or polyethylene.
• Transparent: the starting material is LDPE. The copolymer ethylene vinyl acetate hydrophilic film has increased transparency.
• Color: material - LDPE, dyes, stabilizers.

Polyethylene technical film: applications

The variety of species makes it possible to use polyethylene in almost all spheres of human economic activity:

• Building: in the form of a sleeve or cloth, thickness 60 ÷ 200 microns. It is used for packing and sheltering pallets with materials and protecting surfaces from contamination.

• Agriculture:

1. Technical film with black pigment: various types of works, including covering of shoots "under steam" (thickness from 60 microns), mulching, density 10 ÷ 60 microns.
2. Hydrophilic with increased transparency: for greenhouses.

• Packing:

1. Shrink film (sleeve, linen) from primary and secondary, cheaper raw materials.
2. In the form of bags: for packing garbage and waste.

Polyethylene technical film has a large assortment, allowing to satisfy any wishes of the buyer. The main disadvantage is the high decomposition time of the material and the low level of its processing.