PET technologies, material features, labeling

06 November 2024

Polyethylene terephthalate (PET) is a synthetic fiber used in many industries, including the production of packaging, closures.
History of creation and development of PET

For the manufacture of unbreakable lightweight containers, bottles, PET is most often used as a raw material in modern times. The material was invented in 1941 by the British company “British Calico Printers”. Then the copyrights for this synthetic fiber were acquired by the brands “DuPont” and “ICI”, which then sold licenses to use PET to various manufacturers.

Until the sixties, the material was in extraordinary demand in the production of synthetic textiles, and in the seventies, PET was used to produce packaging film. A little later, DuPont produced the first PET bottle, which immediately became a successful competitor to glass containers.

In today’s world, PET bottles are successfully used as food containers. The first PET bottle blowing machines were produced by the French company “Sidel” and the German brand Krupp Corpoplast.

What properties PET containers have

Modern PET bottles and other forms of containers have many advantages and excellent qualities.

First of all, it is, of course, its low weight, compared to glass containers. An ordinary half-liter PET bottle has a mass of only 28 g, while a glass bottle weighs 350 g.

The second advantage is the attractive appearance. After all, this is a very important parameter for packaging containers. PET containers are transparent and look very spectacular, it can be given any shape and color.

 The third important quality of this material is that it does not break during transportation, unlike glass. PET can be recycled without harming the planet’s ecology.

The fourth undeniable plus is the affordable price of such containers, which allows the manufacturer to make its products more affordable and attractive to customers.

In today’s world, PET packaging has limitless potential for application not only in design, but also in consumer priorities.
How PET bottles are produced

     PET containers are becoming increasingly popular. Therefore, high-tech machines are created for the production of PET containers and filling of products into them.

 The technological line is equipped with various functions: automated control and culling, individual settings of production parameters and each bottle and much more. The capacity of the bottles, which can already reach 20 liters, is also increasing. PET bottles do not require great difficulty and financial costs in transportation, which is also an important advantage.

 PET Preforms

PET bottles are manufactured by the mold-inflation method. In modern equipment, the manufacturing process is well controlled, which makes it possible to produce high quality containers.

The ISBM manufacturing process is a two-stage process. First, a matrix is made, i.e. a preform, which resembles a thin transparent tube. Then a full-fledged bottle is made from it by heating and inflating it from the inside. The neck of the future container is formed when forming the preform.

The peculiarity of PET bottles is the presence of a ring on the neck, which is located just below the thread. This element is designed for convenient gripping and moving of the preform along the technological line, as well as for convenience in transportation of finished products.

Preforms are produced on multi-cell equipment, which allows for 1 cycle to produce more than 100 preforms, which will then turn into a full bottle.

 Production of preforms is a very responsible process. After all, it will depend on the quality of the bottle.
In today’s market, you can find preform manufacturers producing products with different neck diameters, different wall thicknesses and other parameters.

The weight of the future preform depends on the capacity of the future bottle and the thickness of its walls. To color bottles in different colors, dyes designed specifically for PET are used.

Modern production lines for PET containers are both single-phase and two-phase.

 When producing bottles using the single-phase method, the preform and the bottle are formed from polyethylene terephthalate in one step, using one machine. In this case, the production is a single unbroken technological process. This is not always profitable and convenient.
In two-phase production, a preform is initially produced on one machine, which is then fed to another production line for blowing the desired bottle shape, or stored. This way of manufacturing can be more rational and saves space in warehouses. After all, the preform is much smaller and more compact than the finished bottle. In addition, the same preform can be used for different designs.

The second production phase for PET containers is much faster than the first. That is, the preform takes much longer to produce than the final product, the container itself. If there are already ready preforms in stock, the manufacturer will be able to very quickly produce the required products from them upon receipt of the relevant order. On average, on quality equipment for 1 hour from preforms can make more than 1000 bottles.

In general, the productivity of the equipment depends on many factors: the number of blowing cells, the duration of the cycle, the features of the finished product and so on.

Marks on bottles
All bottles have markings, such as the recyclable plastic icon. It stands on any polymer packaging, but is subdivided into 7 varieties, depending on the type of plastics. Each is assigned its own numerical symbol, which allows you to get information about the container, such as the type of material and how it is processed.

The type of synthetic raw material is indicated by the number inside the triangle. A letter abbreviation is also used.    

1. PET(E) or PET - polyethylene terephthalate, a raw material suitable for containers for filling cold drinks, juices, water. Often it is also used for containers for various products, liquid or bulk, with a neutral environment. It is highly recyclable and recyclable.

 2. PEHD (HDPE) or LDPE is a high-pressure polyethylene. It is mainly used for molding opaque containers for food and non-food products, as well as for detergents, various oils and more. This plastic is also highly recyclable and recyclable, saving our planet's resources.

3. PVC or PVC is a material called polyvinyl chloride. It is also used for packaging various products, including those with aggressive environments. However, it is not recyclable and is not entirely environmentally friendly. It contains the harmful carcinogen vinyl chloride, which can also penetrate into products stored in such containers and then harm humans. In the production of PVC use many different additives such as phthalates, heavy metals and other things that are very harmful to humans. During processing, it also emits toxic substances, dioxins, the most poisonous gases.

4. PELD (LDPE) or HDPE is a material called low pressure polyethylene. Every person on the planet is familiar with this material. It is used for the bags we use every day, as well as plastic packaging and more. It is easily recycled and then recycled.

5. PP or PP is polypropylene. It is most commonly used to make disk covers, pipes, crates, resistant machinery parts, children's toys, bags and more. It is also well recycled without harming the environment and then used again in various production.

6. PS or PS is a synthetic substance called polystyrene. It is used quite widely in the construction industry for the manufacture of thermal insulation, sandwich panels, decorative tiles and other things. Its recycling is quite problematic, and in some countries it is banned altogether.

7. O(ther) or other. Such labeling denotes various mixed compositions containing plastics or polymers. Such packaging is not recycled.
Thus, in today’s world, PET packaging is the most environmentally friendly, safe and cost-effective in production. It expands the boundaries of creativity in the packaging industry, allowing to create the best packaging for both manufacturers and end consumers, and helps to take care of our beautiful planet.

If you have any questions about PET packaging and its production, please contact our manager. We are always ready to produce the best packaging for your products!