Apr. 5, 2018 - Up until now, the only International Standard that specified the requirements for paper permanence was ISO 9706, developed by the Technical Committee ISO/TC 46 on Information and documentation. Although this standard is primarily intended for archival and library documents stored in protected environments, it is also applicable to all types of unprinted papers.
According to ISO 9706, in order for paper to be classified as permanent, it shall have a lignin content of less than 1 per cent. The limitation on lignin content in ISO 9706 has until now excluded the presence of modern pulps such as high-yield chemical pulps, Bleached ChemiThermo Mechanical Pulp (BCTMP), alkaline peroxide mechanical pulp (APMP) and most recycled pulps from paper products classified as “permanent” according to the requirement of ISO 9706. However, based on research findings on paper permanence over the past 20 years, we know that such pulps can be used in a wide range of paper products for general graphic applications with no significant loss of mechanical properties over long storage periods.
In order to respond to market demands for an International Standard applicable to mechanical and high-yield pulp products, Canada, through FPInnovations, has taken the initiative to develop a new ISO Standard that specifies the requirements for the stability of paper for general, graphic applications. The project was launched in October 2012 through ISO/TC6, the technical committee on paper and board. However, the draft went through several stages of review to ensure the standard was not in conflict with ISO 9706 and that there was no ambiguity to potential users when deciding which Standard is appropriate for their particular applications.
As an important part of the development of this new Standard, an international round robin study, involving accelerated aging of paper, was conducted in eight laboratories from seven different countries: Belgium, Brazil, Canada, France, Japan, Italy and the U.S. The results were consistent with previous research results, indicating that neither the mechanical nor optical properties of paper, over a 0-79 per cent range of mechanical pulp content, were significantly impaired during long-term storage, providing further evidence that papers complying with the requirements of ISO 20494 are well-suited for use in products not intended for archival storage, including magazines, books and copy paper.
The new Standard was published in December 2017 as ISO 20494: Paper – Requirements for stability for general graphic applications. One of the main aspects of this standard is that it has no restrictions with regard to wood fibre type or lignin content, as long as the pH and alkali reserve of the paper, among other specifications, are met. This new Standard will open up opportunities for mechanical and high-yield pulp producers and paper manufacturers worldwide, and particularly in Canada – a large producer of high-yield pulp – to develop and market a wide range of paper products containing mechanical fibre as well as recycled fibre. In particular, coated and uncoated printing and writing papers containing high-yield pulps, such as BCTMP or recycled fibre, will be classified as stable paper, as long as they meet the specifications described in this Standard, and the end-use performance targets are achieved.
The benefits of using mechanical fibre and/or recycled fibre in paper products range from improved paper performance – particularly paper opacity – and lower production costs, to higher sustainability and greatly reduced environmental footprint. In particular, the amount of virgin fibre, energy consumption, use of water resources, levels of GHG and other emissions, and solid discharge are significantly lower with the addition of high-yield pulp and/or recycled pulp in paper production.
This column was originally published in the Spring 2018 issue of Pulp & Paper Canada.
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