Paper & Board

Paper & Board

Production of Wood pulp
1. Mechanical
  1. Coniferous Trees ground down
    1. Softens lignin, separating fibres
      1. Groundwood pulp
        bleached with peroxide or sodium hydroxide
  2. low-grade paper
    1. newspaper
2. Chemical
  1. De-barked hard and softwood
    1. Cut to 2cm chips
      1. stored & treated
        acid or alkali
        break down lignin
        Less fibre produced
        longer
        stronger
        fewer impurities
    2. Alkaline kraft process
      1. Cooks wood
    3. Sulphate process
3. Waste
  1. Recycled paper and board
    1. mixed with virgin fibres
      1. Bonding agents
      2. coloured pigments
        different qualities
        better surface finish
        sizing agents
        water resistance
Foundrinier Process
1. Wet end
  1. 99% water
  2. 1% fibre
  3. slurry pumped from head box to wire belt
    1. vibrates to drain
      1. fibres interweave
        raised gauze
        watermark
  4. high-quality writing paper
2. Calender section
  1. rollers
    1. uniform thickness
      1. pressure determines finish
        wound onto web
3. Press section
  1. rollers/nip pressers
    1. wring out water
      1. rough paper
        adjusted for thickness
        160gsm+ is card
4. Dryer section
  1. steam heated rollers
    1. removes moisture
      1. water content
        4-6%
  2. starches & resigns
    1. enhance properties
Look at book table for different types of paper (pg32-33)
weight and size
1. mertic 'A' sizes
2. gsm (grams per square metre
3. 220gsm+
  1. board
4. card and board
  1. micrometres (microns)
cartonboards
1. Retail packaging
2. high-speed/high-quality
  1. printing
  2. cutting
  3. creasing
    1. gluing

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	Criado por hwhitehorne aproximadamente 11 anos atrás