State-of-the-art production lines are available, ensuring the hygienic filling of bulk material. Photo: AZO Group.

High level of product protection for bulk materials

Paper bags are highly tear-resistant

Dangerous goods such as chemical products and indeed also substances from the metal processing and pharmaceutical industries pose substantial demands on packaging. To protect products, humans and nature, manufacturers are subject to a higher level of product liability, covering the filling, shipping and storage. Manufacturers often use paper bags to prevent packaged goods from coming into contact with moisture, oxygen or indeed light. Such bags are especially tear-proof and have good storage properties.

Any bags that are made especially for dangerous goods have at least three coats. They are totally dust-proof and made of special paper with long fibres to ensure excellent tear resistance and sturdiness. The filling volume of a bag usually varies between 25 and 50 kilograms. To add special protection against moisture and oxygen, various films are added to the material.

A paper bag weighs around 130 grams and can comprise between one and six coats. Photo: RAND

Anyone wanting to package dangerous goods needs to have their products tested and must obtain a licence. The licensing procedure is based on European and international legislation and agreements. In Germany licences are issued by the Federal Institute for Materials Research and Testing (BAM) which conducts so-called drop tests. This involves filling specimen bags with substitute materials, sometimes after storage in a conditioning cabinet. They are then dropped from a height of 80 to 120 cm, depending on the relevant product requirements. In addition, special labelling requirements must also be met. According to BAM, the font size must be at least 12 millimetres, both on the front and on the reverse.

State-of-the-art production, filling and safety

Powdered products are particularly suitable for paper bags, e.g. cement. But food, too, is often given such a breathable skin. The Viennese company Constantia Flexibles has understood the need for paper bags on the packaging market and has recently invested in two new and fully automatic paper bag production lines in South Africa. One line exclusively serves the production of cement bags. To add further functions, Kraft paper bags can be coated or laminated in a variety of ways. They are available either in brown or bleached and allow up to eight different printing inks.

Paper bags can be kept together securely, using special adhesives. Photo: RAND

The filling of bags, too, involves state-of-the-art engineering. The AZO Group, which specialises in raw material and process automation, offers its customers special funnels to prevent dust formation while pouring. The suction device within the funnel stops dust from escaping. Some bulk solids do not flow very easily, and to channel them in the right direction, AZO provides knockers, vibrators and ventilation nozzles. In addition, there are vibrating screens, preventing, for instance, residual packaging material from contaminating products during the manufacturing process.

Paper bags are superbly suited for shipping not only cement, but also laptops. Photo: TheWrenDesign

Safety is equally paramount during shipment. To avoid any accidental toppling of paper bags on their way to their destination, it is possible to use adhesives in the palletising process. H. Rand GmbH makes a product called GRIP FIX™ for this purpose. The adhesives, which are water-soluble and solvent-free, are applied to the packages during palletisation and then stabilise the cargo until it is unloaded. In particular, the adhesives have high shearing forces and low peeling forces, thus making the bags slip-proof, yet easily detachable.

Side

UN numbers
Dangerous goods are globally classified and identified under so-called UN numbers which contain details of the gross weight and the licensing authority. Each number must be printed on a paper bag together with the relevant danger symbols, ensuring that all details are clearly visible and unchangeable.