Evaluation of the line and edge quality of printed letters on recycled paper with straw pulp

Abstract

Traditional papermaking is based on the use of an aqueous suspension consisting of cellulose fibres obtained by processing wood, non-wood plants or waste paper. With growing environmental concerns regarding deforestation and CO2 production, the paper industry has been always looking for new sources of non-wood pulp that would produce papers of similar quality to those made from wood pulp. Cereal straw from wheat, barley or triticale crops that remains on fields as a residue after grain harvesting has proven to be a good substitute for virgin wood fibres needed in the production of recycled paper. In this study, the quality of printed text on recycled paper with added straw pulp is evaluated mainly based on the line and edge characteristics of the printed letters. For this purpose, three types of laboratory paper substrates were first prepared using recycled wood pulp with the addition of 30% wheat, barley, or triticale straw pulp. The same letter pattern was printed with black ink on each paper substrate at a standard size of 12 pt with two common typefaces: Arial and Times New Roman. The quality of the printed letters was assessed through the measured print quality parameters such as blurriness, raggedness, fill and contrast. The resulting measurements were compared with the results obtained on the reference and control samples made exclusively from recycled wood pulp as a substrate from laboratory and commercial production. In terms of fill and contrast values, the uniformity of lines printed on the recycled papers with added straw pulp is the same or very similar to the reference and control papers. Letters printed in Arial (sans-serif) typeface show slightly better reproduction quality than letters printed in Times New Roman (serif) typeface. The measured parameters blurriness and raggedness of all laboratory-made paper substrates (with and without straw pulp) had similar values between 0.17 mm and 0.20 mm, resulting in a very similar reproduction quality compared to the reference paper substrate.

Towards Expanding the Use of Paper Made from Recycled and Non-Woody Plants: Enhancing the Print Quality through the Application of Nano-Modified Offset Inks

“…Papers made from recycled wood fibers and non-woody plants, such as straw from wheat, barley, and triticale crops, show promise for applications in graphic technology and design. These papers can be used as printing substrates for different printing techniques, including digital UV inkjet, gravure printing, flexographic, and offset printing [5,13]. The quality of printed motifs on papers made from non-woody plants is comparable to those made on papers made exclusively from recycled wood pulp, with a similar reproduction quality and optimal reproduction of details [13].…”

“…These papers can be used as printing substrates for different printing techniques, including digital UV inkjet, gravure printing, flexographic, and offset printing [5,13]. The quality of printed motifs on papers made from non-woody plants is comparable to those made on papers made exclusively from recycled wood pulp, with a similar reproduction quality and optimal reproduction of details [13]. Furthermore, the development of reusable and recyclable paper from natural materials, such as pollen, offers a sustainable alternative to conventional wood-based paper [7].…”

“…The challenges in using paper made from recycled and non-woody plants for application in graphic technology and design include the need for an even density over the entire sheet, the availability of raw materials and environmental protection, and the influence of the fiber type on the vapor barrier properties and migration to foodstuffs [16][17][18]. Ensuring an even density in the paper is influenced by various parameters such as the pulp preparation technology, equipment, and selection of optimal raw materials [13]. The availability of raw materials, especially non-wood materials, is a challenge due to the pressure on forests and the decline in capacity utilization in the paper industry [6].…”