Лако-красочные материалы — производство

Composting represents another option allowing the material loop of products made from organic materials to be closed. Biological degradation of the material allows the products to be reconveyed to a form that is useful to Nature. Especially in the packaging sector, this is an attractive option, in particular when packages are contaminated with food residues. With the development ofbiodegradable materials, for the first time in industrial development a group of materials was conceived that was specifically targeted towards reuse and recyclability. Although natural raw materials are more advantageous in terms ofbiological degradation, special synthetic polymers can also meet these requirements. Yet, natural raw materials have the advantage of renewability, which saves resources.

To ensure reliable composting, it is not only the basic material of these products which must be biodegradable, but also the processing aids such as adhesives. Adhesives based on plant or animal raw materials easily meet this requirement.

With regards to the market in Western Europe, more than 6% of the adhesives used are derived from natural polymers. Raw materials derived from plants comprise polymers such as starch, celluloses, natural latex, proteins and low-molecular-weight substances such as resins (e. g. rosin) and diols. Raw materials derived from animals particularly include proteins such as casein and hide glue.

Waterborne adhesives and hot melts exist that also meet the requirements of the packaging industry with regards to compostability. These systems can be based on natural or fossil biodegradable raw materials, such as natural polyester. Aliphatic polyesters are preferred to their aromatic counterparts because they have a higher degree of biodegradability. As shown in Figure 8.47, the biological degradation of these hot melts is comparable to that of cellulose.

As many biodegradable materials are available as films, it is hardly surprising that biodegradable multilayer films have also been developed that consist of at least two different films laminated by an adhesive. This makes it possible to combine the performances of each single film and also to save weight; moreover, if both films are biodegradable this should also apply to the adhesive. Considerable progress has been made in this field, making available biodegradable adhesives for different types of film.

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