Helpful guide to selecting the right waste sacks
The waste sacks in the KAISER+KRAFT product range are all characterised by high quality material processing, a prerequisite that is essential for any functioning waste disposal system.
Types of material
Rubbish sacks and waste sacks are made of polyethylene. The major difference between HDPE and LDPE films, each having its own specific characteristics, has to do with the difference in the pressure used in the manufacturing process.
HDPE = high density polyethylene
HDPE can be recognised by the crackling sound it makes when moved. It is resistant to higher temperatures and is typically used for thin material applications (e.g. rubbish sacks). Due to its high density, it is also extremely tear resistant in thinner sacks. However, it is less resistant to tearing once punctured.
LDPE = low density polyethylene
LDPE is softer to the touch, and due to its molecular structure, significantly more stretchable than HDPE. This translates into greater tear resistance after initially punctured or torn. LDPE is thus advantageous for sharp, heavy and pointed rubbish, which is why it is the preferred material for waste sacks.
Bio film is ideal for the composting of biodegradable waste. The film is compostable due to its special material composition of maize starch and a biodegradable polymer. It is placed in the compost waste bin together with other bio-waste.
The optimum size for your waste sack
During everyday use, the question of which waste sack is the right size for your waste collector frequently comes up. In order to quickly and easily answer this question, you can use the following formulas to determine the optimum size for your collector:
Width of waste sack = (circumference of container/2) + 10 %
Length of waste sack = height of container + (width of base/2) + 10 %
Sack thicknesses and versions
Different sacks should be used depending on which type of material is being disposed of. The thickest sack is not necessarily always the best choice. Both film quality, as well as intended use, are much more important factors to take into account when deciding which sack to purchase.
PREMIUM - Comparably high quality from select recyclable material
PREMIUM rubbish sacks are made of 100 % recyclable high pressure polyethylene. Only select regrind (largely from manufacturing waste) is used for this. The above average puncture and tear resistance ensures that PREMIUM products will also meet extremely high requirements.
UNIVERSAL - The quality brand for HDPE items
UNIVERSAL rubbish sacks and waste sacks are manufactured from high density polyethylene (HDPE). The use of this type of material allows for reductions in thickness while simultaneously ensuring high quality film. Thanks to its physical characteristics, a UNIVERSAL rubbish sack offers a high degree of puncture resistance as well as a high degree of tear resistance with minimal film thickness. Depending on the requirements for a waste sack and its type of use, UNIVERSAL is an excellent all-round choice of sack.
The production of rubbish sacks and waste sacks
The raw material
Every rubbish sack begins with a raw material, from which it is manufactured. Crude oil or natural gas is heated to such an extreme that ethylene is produced. Heat and pressure are applied to this gas in a reactor to convert it into polyethylene powder. The powder is then melted in an extruder and pressed through perforated discs to create polyethylene granulate. These small granules are the starting point for the production of new (virgin) material. In addition to new material, there are also recycled products. Regrind, which is needed for the production of these products, is reclaimed from previously used plastic through the processes of shredding, washing, drying and pelletising of pre-prepared material. The colour of the regrind is ultimately determined by the colour of the films from which it was reclaimed.
From granules to film
In a process called extrusion blow-moulding, the granules are heated and compressed in different stages to form a viscous material, which is subsequently pressed upwards through a film blowing die where it is blown-up like a bubble of chewing gum and drawn-off from the top.
Image: Extrusion blow-moulding
- Cooling air
- Moulding material
- Heating process
- Screw conveyor
Packaging of the film
In the final step of the production process, the bottom seam and a tear-off perforation are integrated into the film. This step is referred to as finishing. Depending on the type of fold a sack is supposed to have, another finishing process must be carried out. In general, there are two main types - flat bags and side gusseted sacks.
Ill.: Flat bag
Ill.: Side gusseted sack