Plastic bags: types, characteristics, purpose

2024 Author: Priscilla Miln | [email protected]. Last modified: 2023-12-16 00:21

Today let's talk about the most popular type of packaging and packaging in our country and, probably, all over the world. These are plastic bags. We learn more about their characteristics, purpose, running varieties. We will pay most attention to the classification of this type of packaging.

Bags, plastic bags

Packaging plastic bags began to be produced in the middle of the last century. They were originally used to pack fruit and bread. Currently, the production of such packaging reaches 4.5 trillion pieces annually!

The plastic, polyethylene container consists of a thin polymer base, which is synthesized from ethylene, a gaseous hydrocarbon. Judging by the conditions of the polymerization reaction, the material may be as follows:

• HDPE (PNED) - formed in the presence of catalysts, at low pressure. This bag is more opaque, rustling to the touch.
• PVD (PVED) - obtained under high pressure. The result is a substance of somewhat lower density. The finished product is transparent, soft, elastic, smooth to waxy. Another remarkable feature of it is that it is able to withstand large loads due to strong intermolecularties.
• Packaging from linear, medium density polyethylene, polyethylene mixture of different types. The final product in its properties occupies a middle position between LDPE and HDPE.

Packaging properties

There are both dense polyethylene bags and packages of lesser density. Let's highlight their common properties:

• Resistant to chemically active components - acids, fats, alkalis, etc.
• Tear and tensile strength.
• Retaining its basic properties even at low temperatures (only at -60 ° C does the material become brittle).
• Resistant to biodegradation, soaking.
• Non-toxic, which allows contact even with food contents.
• Availability due to cheap material.
• Hygienic polyethylene.
• Impervious to liquids, gases, which guarantees the protection of the contents from unwanted environmental factors.
• Polyethylene is thermoplastic - most of its varieties begin to melt at temperatures above 80-90 °C. This makes bags made of this material unsuitable for storing hot food!

Comparison with other materials

Compare opaque and transparent plastic bags with packaging made from a different kind of material.

Polyethylene	The main advantage is the cheapest packaging material.
Cellophane	Is the result ofpulp processing. The main disadvantage is that when a small tear appears, it breaks further almost instantly.
Paper	The most sustainable packaging. But absolutely not suitable for greasy or wet content.
Polypropylene	Unlike polyethylene, it can withstand even higher temperatures. But less resistant to direct sunlight, punctures. Not recommended for packing spicy items.

Go to the next topic.

Packaging production

How are plastic bags made? The heated polymer mass is extruded through an appropriately sized extruder hole. A kind of polyethylene sleeve is formed, from which packages of the desired variety are formed.

Further production is divided into the following areas:

• Rewinding into rolls for subsequent tear-off along the perforation line.
• Packing in packs of a certain number of pieces.
• Additional design of the bag - installation of accessories, handles.
• Printing images - one-, two-, multicolor.

Types of packages

Modern production of plastic bags involves the release of the following items:

• Packing bags. Transparent, thin, made of different types of polyethylene material. The main purpose is the packaging of piece goods.
• Packages-"T-shirts". They got their name due to the fact that the shape and position of the handles resemble this object.wardrobe. The main material is HDPE. Most common in supermarkets due to roominess, compactness, ease of carrying.
• Packages with handles. Outwardly similar to bags, they cost a little more than "T-shirts". Material - PVD, linear polyethylene, mixes. Handles here are very diverse - rope, plastic, slotted, loops, etc.
• Packages with fasteners, lock.
• Trash bags for technical and household needs. Material - polyethylenes of all types, recyclable. There may be tightening tapes, handles.
• Branded packages. Decorated with an image, drawing a logo, inscriptions, etc. An additional way to promote a firm, enterprise, other organization.

Classification by type of bottom

Plastic bags are also divided according to the type of their bottom:

• Flat, seamless bottom. Among folded bags, this type is very common. It is the simplest and cheapest option. The seam is observed only on the sides of the package. Packing heavy products, items with sharp edges in such a bag is undesirable. Of all the following, the most unstable when filling.
• Flat seamed bottom. The most common type. The seam strengthens the bag, which allows it to withstand a good weight. The bottom is similar to the edge of the pillowcase. It is better not to place wet contents in such a container, because water will accumulate at the bottom of the bag.
• With folds, flat seam bottom. Such packages are resistant to tearing, more dense. Bottomthe polyethylene bag is flat and soldered. Good for bulk packaging. Another plus is that it has the most presentable appearance.
• With a bottom fold (the folds are at the bottom). The main difference between such packaging is that the folds are located at the bottom, and not across the entire width of the package. This gives the container stability when filling.
• The bottom of the "star". The shape of such a plastic bag is cylindrical, which allows the weight of the cargo to be distributed evenly throughout the container. A star-shaped bottom seal prevents leakage of wet contents. These are plastic garbage bags; they are also widely used in catering establishments.

Plastic bags are produced in a large assortment in Russia and around the world, from various kinds of raw materials. They have both a number of advantages and a number of disadvantages over other types of packaging.