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Raw materials for paper products |
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| Release time:2013-09-23 Source:admin Reads: | |
| Paper products are widely seen in many occasions, most of them are used to show the products such as display hang cards. The pulp is fed to a paper machine where it is formed as a paper web and the water is removed from it by pressing and drying. Pressing the sheet removes the water by force. Once the water is forced from the sheet, felt is used to collect the water. When making paper by hand, a blotter sheet is used. Drying involves using air and or heat to remove water from the paper sheet. In the earliest days of papermaking this was done by hanging the paper sheets like laundry. In more modern times, various forms of heated drying mechanisms are used. Paper at this point is uncoated. Coated paper has a thin layer of material such as calcium carbonate or china clay applied to one or both sides in order to create a surface more suitable for high-resolution halftone screens. Coated papers are divided into matte, display hang cards. Gloss papers give the highest optical density in the printed image. Textured finishes, watermarks and wire patterns imitating hand-made laid paper can be created by the use of appropriate rollers in the later stages of the machine. Handmade paper similarly exhibits "deckle edges", or rough and feathery borders. Paper made from wood pulp, is not necessarily less durable than a rag paper. The ageing behavior of a paper is determined by its manufacture, not the original source of the fibers. Furthermore, tests sponsored by the Library of Congress prove that all paper is at risk of acid decay, because cellulose itself produces display hang cards. Some manufacturers have started using a new, significantly more environmentally friendly alternative to expanded plastic packaging made out of paper, known commercially as paper foam. The packaging has very similar mechanical properties to some expanded plastic packaging, but is biodegradable and can also be recycled with ordinary paper. |
