PRESS ARTICLES

Converting Technology International, "Add value through mold resistance"

The addition of a carefully selected fungicide can overcome the disadvantages of paper and paperboard packaging for applications requiring resistance to decomposition and mold growth.

Paper and paperboard are particularly well-suited to point-of-sale advertising and attractive, creative packaging. The surface characteristics of paper and paperboard can vary from bright gloss to soft mat, and modern printing techniques can produce an infinite variety of colors. New types of plastic packaging and plastic/paper composites have also forged strong inroads in packaging applications. The great advantage of plastics is that they can provide a barrier to moisture and odor and they do not degrade or become discolored in damp conditions.

However, plastics and plastic/paper composites have an inherent disadvantage as opposed to paper and paperboard: they are very difficult to recycle. The increasing importance of environmental issues has made paper and paperboard a more attractive alternative. New developments in barrier coatings and mold protection are allowing paper and paperboard packaging materials to overcome the advantages of plastic.

The phenomenon of mold growth on cellulose substrates is well-known. Fungal spores, that are present in the paper either at the time of its production or later when it has come into contact with a contaminated environment, may develop active molds in the presence of both water and moderate-to-warm temperatures (10-50°C). Although paper machine systems contain bacteria, yeast and fungi, the bacteria and yeasts are generally killed by the high temperatures (90-100°C) used to dry the paper sheet. However, fungal spores may survive the drying process and remain alive but dormant in the paper until favorable growing conditions develop. Once these conditions are achieved, the fungi (molds) grow rapidly, feeding on the cellulose fibers and whatever other nutrients may be present.

The principal applications for mold resistant paper and paperboard are bar soap packaging, labels for bottles of mineral water, beer and soft drinks, and certain types of food packaging. However, with the increasing emphasis on packaging as a medium for advertising and publicity, there is a growing need for mold resistant paper and paperboard to preserve the quality of the package.

The most important characteristics of fungicides used in mold resistant papers, other than the fact that they must be effective against a wide range of fungi, are:

Water insolubility, so that they will not be leached out of the paper and will not migrate from the packaging to the paper contents

Thermal stability, so that they will not decompose in the drying process

Chemical and physical stability, enabling them to remain active in the paper for at least two years and producing a very low level of toxicity

Originalmente, los fungicidas usados en este tipo de embalajes eran relativamente tóxicos. Estos productos fueron reemplazados por otros menos pero debido a la resistencia de los mohos a los mismos, se requirieron nuevos fungicidas.

Para obtener el mayor espectro de actividad, los nuevos fungicidas normalmente incorporan dos o tres diferentes ingredientes activos. Esta nueva formulación ha probado una gran efectividad contra una gran cantidad de bacterias y mohos incluidos aquellos resistentes al carbenzalim y thiabendazole.

Como una parte de su servicio, INTACE identifica los tipos de hongos encontrados en papel contaminado y los testea con papeles tratados con los diferentes fungicidas para determinar que producto es más efectivo para cada aplicación en particular.