Mondi Industrial Bags: new generation of paper bags ideal for cement

In recent years, Mondi has made major efforts in innovation.That has led to more reliable industrial bags with reduced environmental impact and attractive added-value features, matching the customer’s requirements. One of the key drivers behind this continuous innovation process is the fact that Mondi is a fully integrated supplier. All steps involved in producing an improved paper bag can be handled in close collaboration between paper mills and bag converting plants.

INITIAL STEPS TOWARDS INNOVATION

Generally, the first step towards an improved industrial paper bag is to develop new or improved grades of sack kraft paper. As part of R&D activities at Mondi’s R&D Innovation Centre in Frantschach, Austria, Mondi’s sack kraft paper and industrial bag team members analyse and assess existing and proposed materials, including kraft pulp, with a view to improving paper strength, de-aeration properties and mechanical qualities of paper and bags. These R&D activities are often oriented to achieving steady improvement, with the overall goal of taking sack kraft paper and industrial bag solutions to a whole new level. Claudio Fedalto, Deputy COO, Mondi Industrial Bags, points out the importance of co-operation among business segments within the Group:“Being in direct proximity to our sack kraft paper colleagues helps the bag development process, as we can work closely together on each project.” The launch of Mondi’s Advantage Protect sack kraft paper and the recently introduced Splash Bag, a bag developed especially for the needs of the cement and building industry that shows a higher water-resistance than normal paper bags, is just the latest example of this close internal collaboration.

RIGOROUS TESTING

The next stage of the development process involves rigorous testing. Application engineers at Mondi’s Bag Application Centre (BAC) analyse bag strength, de-aeration properties and behaviour during filling and under different storage conditions. To test bag construction, simulations of specific situations are performed using advanced technology, e.g. a high-speed camera (1,000 images per second) for observing behaviour during drop tests, and a climate chamber for measuring performance under hot, humid or other demanding conditions. In 2014, the Bag Application Centre performed drop tests for around 400 bags, the water vapour transmission rate was assessed for around 300 bags, and over 900 Mega Gurley tests were performed.

CUSTOMER FOCUSED — EVERY DAY

Collaborating with customers and listening to feedback is also important. In keeping with the Mondi initiative ‘IN TOUCH EVERY DAY’, Mondi encourages customers with specific requirements — e.g. a bag needs to be developed or adapted — to collaborate closely during the development process. Recent examples include collaborations with cement producers: one bore fruit in the shape of the world’s first biodegradable industrial bag, the Terra Bag®. Another resulted in the above- mentioned SplashBag, a bag that, thanks to the perfect combination of Mondi’s sack kraft paper and industrial bag construction and know-how, is resistant to rain for two hours and can withstand moisture ingress for up to 12 hours.

Further progress in the evolution of industrial paper bags was the launch of a bag that offers uncompromising weather protection and significantly extended shelf life of its contents. Combining the best of two worlds — paper and PE — the HYBRIDPRO bag represents a whole new concept in industrial bag design. It is particularly suitable for building materials, including gypsum and cement, as well as many other moisture- sensitive products.

Like a hybrid drive in a car, the HYBRIDPRO bag is an excellent combination of the available options: the inner ply is made of 120g/m2 Mondi Advantage ONE sack kraft paper; the outer ply is a 40μm-thick layer of high-density polyethylene (HDPE). The innovative step here is that the HDPE forms a protective layer on the outside of the paper. Other bags also use a combination of paper and plastic, but not in this way. This is a considerable technical achievement that brings a new dimension to industrial bag design. paper ply is available in a bleached or an unbleached version.