Know-how

Polyethylene

Polyethylene is the most produced plastic in the world. Used in its early days primarily as insulation for electrical wiring, its solidity and almost unlimited uses today make it a popular material for many other applications.

Polyethylene can be processed into hard and firm, but also soft and flexible products. Cling film, bottles, bin bags, pipes, toys, etc. – it is almost impossible to narrow down its applications. Whatever its use, there is complete agreement on the excellent characteristics of this material. It is a good insulator, resistant to aggressive substances, tough and hard-wearing, almost unbreakable, and kind to the environment.

Production

Crude oil is used to produce naphtha, which is another term for petroleum spirit. When naphtha is heated to a high temperature (a process called cracking), a gas is released, called ethylene. In the next step, this gas (ethylene) is passed through another reactor and transformed into polyethylene (which basically means many ethylene particles); it now looks like a warm, liquid pulp. Before it solidifies, the pulp is pushed through a plate with small holes in a constant stream. The result is a mass of polyethylene granules. These granules then go to companies as raw material, where they are melted and processed into all kinds of products.

Qualities
The granules can be processed in various ways depending on the required application:

LDPE: low density polyethylene
This is a soft, tough and flexible polyethylene type used primarily for strong consumer items such as caps or lids. It is also used as insulation material. Today, however, its most popular application is plastic film (e.g. for carrier bags, packaging material or agricultural sheeting).

HDPE: high density polyethylene
The sturdiest and most inflexible type, it is ideal for applications such as organic waste containers and a large number of common household products (clothes pegs, bottles, etc.). Although HDPE is quite heavy, it can also be used to produce paper-thin film with a crinkly feel. It is often found in supermarkets where it is used for fruit and vegetables, or in the form of bin bags.

LLDPE: mixture of LDPE and HDPE
LLDPE is used to produce both flexible and sturdy products. It is extremely tough and rigid and allows even thinner films to be produced with the same tear resistance. Other known uses include multi-layer packaging.

Processing
For most processing methods, the polyethylene granules are funnelled into a cylinder, where they are heated. The molten mass is pressed via a “conveyor” through an opening. The cylinder with the conveyor is called an extruder. Depending on how it is pressed, the mass can be turned into different types of film:

Blown film:
The molten material is blown through an opening using compressed air and rises as a thin walled tube. Once cooled, this tubular film is flattened and wound onto reels. This method is suitable for the production of carrier bags, tubular film, etc.

Flat film:
The molten material is pressed through a very thin slot. This results in a single layer of very thin film that is rolled up after cooling off.

PE tubular film products

Environment

Under ecological aspects, polyethylene is one of the most environmentally friendly materials:

• Its production is relatively clean and efficient; the emission of harmful substances is minimal and there is virtually no waste
• It is a highly efficient material. Not even 1% of the total oil and gas is used per year for its global production
• Polyethylene is extremely suitable for recycling, as it can be melted down an unlimited number of times. Many bin bags today are already made of recycled polyethylene
• If polyethylene is no longer recycled, it makes an excellent fuel for power supply.

Recycling system

Steinbach AG has been participating in the Dual System Interseroh since January 2019.

We are a licensed partner with the following registration number: DE5475909545402-V