Fiber composition of packaging grade papers as determined by the Graff 'C' staining test.

摘要

A qualitative and quantitative analysis of the fibre components of 15 representative papers that are used for the production of corrugated board was carried out by the Graff 'C' staining test. Fifteen different packaging grade papers were selected to cover all the qualities of linerboard (3 kraft liners, 1 test liner and 3 recycled liners) and corrugating medium (5 semichemicals and 3 recycled medium) and to represent all the variety of papers available in the market at the moment for the production of corrugated board in Spain. The method of processing of softwood, hardwood and nonwood fibres was determined under a light microscope by their colour reactions with the stain. All papers, due to the use of recycled pulp raw materials in their manufacturing, were found to incorporate in their furnish fibres that had been produced with a variety of pulping processes: chemical, mechanical, and semi-mechanical. The recycled-based papers (recycled-liner and recycled-medium) were proved to be the most variable comprising 12-15 different fibre components, while in some of the semi-chemicals only up to 7 components were identified. The weight percentages of the fibre components calculated by the application of weight factors showed that in almost all papers the most important fibre component from a quantitative standpoint was hardwood unbleached kraft followed by softwood unbleached kraft. Besides hardwood unbleached semi-chemical pulp and mechanical softwood pulp that were also plentiful in the papers, there was a smaller number of other components which sum, however, accounted for a significant fraction in the total furnish weight. The results taken on the total softwood, hardwood and nonwood fibres content of the papers demonstrate that Graff 'C' staining test is adequate to analyse both the structure and quality of packaging grade papers in practical industrial testing..