engleski

The rub resistance of printed papers with variable content of wheat pulp

In European countries newsprint is predominantly made from recovered fibres, while other graphic papers contains considerably lower share of recovered paper. Newsprint is a lower grade paper because it has already been recycled numerous times, while other papers are categorized as higher grade papers. During recycling process fibre length become shorter and the length of the fibre defines the grade of paper. After five to seven cycles of recycling process, the fibres become too short for producing new paper and it is necessary to mixed them with virgin fibres. As the demand for paper products nowadays is still high, different types of conifers and deciduous trees become insufficient raw material for paper production. This lack of raw material is the result of irrational exploitation of the natural resources for different purposes (lumber, heating material, pulpwood). Therefore, the utilization of alternative sources of virgin cellulose fibres as agricultural residues, whose potential is not sufficiently exploited, is of great importance for papermaking industry. The idea is how various field crop species could represent an alternative to using hardwoods in some lower grade papers and graphic products as newsprint ie newspaper. The aim of this research was to explore the reproduction quality of printed laboratory papers made of variable content of wheat pulp. The reproduction quality of prints was observed through rub resistance analysis. The rub resistance tests were made 6 and 24h after printing. Analysed papers were printed with carbon black ink by Prufbau Printability Testing Machine, which simulates coldset offset printing process. The reproduction quality of the prints before and after rub resistance tests were analysed by spectrophotometric values (L*a*b*). Based on provided measurements the Euclidean colour difference, ∆E00*, was calculated. The results have presented how with the increasing the portions of wheat pulp in laboratory papers is achieved a better rub resistant. Wheat pulp provides good rub resistance of newsprint which means that the ink will not come off onto the reader’s hands if wheat pulp will be used in commercial newsprint sector.

Euclidean color distance; newsprint; rub resistance; wheat pulp

Ovaj rad je u sklopu SuZ financijske potpore istraživanju:“Kemijska stabilnost otisaka na podlogama iz ne-drvnih vlakanaca”(voditeljica: dr. sc. Ivana Plazonić).