The factor why paper that has actually been printed on one side with an inkjet printer begins to curl after several hours or days– in spite of at first being flat following printing and drying– was formerly unknown.Alexander Maaß and Ulrich Hirn from the Institute of Bioproducts and Paper Technology at Graz University of Technology (TU Graz) have actually now discovered the factor. While paper sprayed with water did not curl any more after 24 hours, the process continued for a week with paper sprayed with the water-glycerol mix. The reason for this is that the glycerol, which unlike water just vaporizes at extremely high temperature levels, gradually but steadily moved from the sprayed side of the paper to the other side.Paper separated into thin layersThe researchers were able to demonstrate this procedure by splitting the paper samples into thin layers and determining their particular glycerol material.
Alexander Maaß (front) and Ulrich Hirn have actually discovered that solvents in the ink move through the paper towards the unprinted side over time. This causes the cellulose fibers on the unprinted side to swell and the paper to curl. Credit: Lunghammer– TU GrazPaper printed on one side begins to curl with a delay of approximately a couple of days. Scientists at TU Graz have found that this is because of solvents in the ink that over time migrate towards the unprinted side of the paper.Although humanity has actually been utilizing paper for at least 2000 years, it still presents us with one or 2 secrets. For example, the reason that paper that has been printed on one side with an inkjet printer starts to curl after numerous hours or days– despite initially being flat following printing and drying– was formerly unknown.Alexander Maaß and Ulrich Hirn from the Institute of Bioproducts and Paper Technology at Graz University of Technology (TU Graz) have actually now found the factor. The cause lies in solvents contained in the ink, which move with time through the paper towards the unprinted side. This triggers the cellulose fibers on the unprinted side to swell and the paper begins to curl.The degree of paper curl determined with a laser scannerFor their experiments, the researchers sprayed standard A4 printer paper on one side with a model ink including water and the solvent glycerol. They then observed the curvature of the sheets of paper for a week utilizing a laser scanner. While paper sprayed with water did not curl any additional after 24 hours, the procedure continued for a week with paper sprayed with the water-glycerol mixture. The factor for this is that the glycerol, which unlike water only vaporizes at really heats, gradually however gradually moved from the sprayed side of the paper to the other side.Paper separated into thin layersThe scientists were able to show this procedure by splitting the paper samples into thin layers and identifying their particular glycerol content. They found that the glycerol continually decreased in the upper, sprayed layers and increased in the lower ones. Because glycerol, like water, triggers cellulose fibers to swell, the volume of the different paper layers changed during the test period. The layers near the sprayed side diminished, while the deeper layers swelled up. The noticeable outcome was that the paper curled, and did so continuously for a week.Replacing glycerol with other solvents”To solve the issue, glycerol could be replaced by other solvents. However, this is not so simple because glycerol offers the inkjet ink important residential or commercial properties that make it ideal for inkjet printing in the very first place,” says Ulrich Hirn. Additionally, the reverse side of the paper might also be printed or treated with a proper amount of glycerol.Reference: “Long term curl of printing paper due to ink solvent migration” by Alexander Maass and Ulrich Hirn, 20 December 2023, Materials & & Design.DOI: 10.1016/ j.matdes.2023.112593 The outcomes are based upon work brought out at the Christian Doppler Laboratory for Fibre Swelling and Paper Performance, in which, in addition to TU Graz, the companies Kelheim Fibres, Mondi Uncoated Fine & & Kraft Paper, Canon Production Printing and SIG Combibloc Systems were included.
