Chemistry in the paper mill


The criticalities of food contact and its needs put a strain on paper makers. The use of chemical additives with a barrier effect is of fundamental importance to guarantee the performance requested by the market and the norms. An Italian company, which is the branch of an international group, has developed and tested ad hoc products.

The capacity of paper to serve as a barrier has always been a critical and delicate issue for all paper makers, specifically when talking about packaging designed for food contact.

Paper production for food packaging is the main area of growth for the supply of chemical additives in Europe. This is the reason why Protex International, with Proxitalia Prodotti chimici Srl as its Italian branch, is investing large resources in this field.

«Supplying such a competitive market means working with the aim of constantly improving ourselves», as explained in the company. «Paper makers are the most demanding customers, as they expect the utmost and constant quality, as well as efficient and innovative chemical additives».

Barrier products

If chemicals generally have a significant impact on the good quality of the paper product, increasingly stricter requirements are posed to food contact paper. Especially in Italy, very strict norms are posed to food contact paper.

The first step, therefore, lies in the identification of possible hazardous substances in the paper making process. In this respect, Protex International has started a pathway of actions aimed at the elimination of these very substances.

Along this pathway, the company has committed itself to develop barrier products, which can replace the perfluorinated chemicals (PFCs) used as additives to increase the barrier to water, oils and greases.

Beyond PFCs

Proxitalia representatives explain that perfluorinated chemicals (PFCs) are molecules, in which all the carbon-hydrogen bonds are replaced by carbon-fluorine bonds. «These compounds have been largely used over the last 50 years thanks to their chemical-physical characteristics. They are long carbon chains composed of, at least, 6 carbon atoms, except for the most recent compounds, which terminate with a polar group. This chemical structure provides PFCs on the one hand with a particularly high heat resistance and chemical inertia, and on the other hand with an exceptionally high hydrophobicity and lipophobicity. The latter characteristics have enabled a largely varied use of PFCs both in industrial and household settings».

The issue with these molecules is, however, linked with their environmental contamination, which is the main problem they are normally associated with. In order to make up for these inconveniences, Protex International has recently developed new dedicated products for the paper market, with the aim of enhancing some of the barriers requested by paper and with quality and performance characteristics that might be even better than the ones currently demanded by market standards.

«Protex International’s objective has been to replicate the performance of a C6 perfluorinated chemical with a product that does not contain any fluorine, after careful comparison with the products already available on the market».

Conceived for paper

Products have been developed to equip paper with a barrier against several types of elements: water, oils and greases, steam and Mosh. I.e. Mineral oil saturated hydrocarbons. The latter «are the category of saturated aliphatic hydrocarbons, which are normally composed of linear and branched alkanes, as well as by alkil-substituted cycloalkanes and MOA, i.e. Mineral oil aromatic hydrocarbons, which represent the category of hydrocarbons possessing from 1 to 4 aromatic rings. These constitute a much larger and complex group compared to the Mosh, however this group mainly includes alkil-substituted polyaromatic hydrocarbons».

Tests have been carried out on four main types of products:

– wax compounds

– silicones

– catalysers and extenders

– modified polymers.

«The research carried out has led to several interesting findings», say company representatives, «with unexpected positive performances as regards all forms of tested resistance, even after bending paper».

These new types of barrier substances have a particularly important heat-sealing property. «This characteristic is becoming indispensable and difficult to reach for the development of several new papers on the market».

Tests on catering paper

The Havi olive oil test is one of the tests carried out for the paper sector. This is an increasingly widespread test, especially for papers used in the catering sector, i.e. tapers for paper tablecloths, napkins, etc.

«This testing method has been finalized to analyse the performance of new barrier products, as it offers a good correlation with the results observed during the live assessment of caterers. The test has not been developed to determine the success/fail criteria for new additives, but rather to provide a preliminary indication of the performance of the barrier substance and the suitability for a further assessment of the caterer».

The pictures of the samples (pictures no. 2, 3, 4 and 5) show the result obtained with the Havi olive oil test on a reference paper treated with a new-generation barrier product, compared to the same paper treated with a C6 carbon-fluorine resin.

The value of the Kit Test is 8 for both samples.

In the sample treated with barrier product (picture no. 2), oil propagates over the surface, but it does not sink in. There is a barrier, however with a relative decrease of surface tension.

Conversely, in the sample treated with a C6 carbon-fluorine resin (picture no. 3), oil remains on the surface and in droplets. The barrier shows a significant decrease of surface tension.

Havi olive oil test: after removing the oil, the paper treated with the barrier products developed by Protex International passes the test (picture 4), while the paper treated with the C6 carbon-fluorine resin absorbs the oil and does not pass the test (picture 5).

French heart, global nationality

Proxitalia Prodotti Chimici Srl is a company of the French group Protex International, which produces and supplies industrial chemicals. The company, which has been active on the market since 1932, is a multinational with branches and production plants all over the world. The chemicals designed and produced by the company are used in various reference markets, as well as in numerous manufacturing sectors. That is the reason why the group has specialized, and it is internally organized in five separate divisions, i.e. paper; textile and leather; coating, printing inks and varnishes; agriculture; and specialty chemicals.

Besides continuing to develop new products that meet the new and increasingly demanding needs of the market, the Italian branch can offer alternatives to the use of carbon-fluorine resins for barriers against water/steam/oil/grease, also heat-sealing ones.