The Paper Research Institute in Hungary tested eight papers from three Hungarian mills that had converted to alkaline. The papers, chosen by the mills and all in the 80-120 g/m2 range, were tested for conformity to ISO 9706. Artificial aging was done as well, for 24 days at 80°C and 65% RH. Tear resistance, pH, alkali reserve, kappa number plus folding endurance and brightness were measured before and after aging.
The three mills were Dunaújváros, Füzfö, and Diósgyör, and the papers they furnished were Kossuth, Helikon Specimen, Ofset, Biancoprint and Biancoprint Superwhite. All eight papers met the requirements of the ISO 9706 standard even after aging. The test results for a Biancoprint paper, 100 g/m2 (from the Dunaújváros mill) are shown in the following table.
Properties for ISO 9706 | Before aging | After aging | % Retention |
---|---|---|---|
Tear resistance, mN |
| ||
MD | 846 | 776 | 91.7% |
CD | 647 | 607 | 93.8% |
Alkali reserve, mol/kg | 2.92 | 1.80 |
|
Kappa number | 0.5 | 1.5 |
|
pH, cold water extraction | 7.8 | 8.1 |
|
Other properties |
| ||
Double folds (Schopper) | |||
MD | 75 | 54 |
|
CD | 27 | 12 |
|
Brightness % (Elrepho 2000) | |||
R 457 + | 94.9 | 82.8 |
|
R 457 - | 90.6 | 80.4 |
|