Anonymous
Anonymous asked in Education & ReferenceHomework Help · 1 decade ago

how is paper manufactured?

4 Answers

Relevance
  • inatuk
    Lv 4
    1 decade ago
    Best Answer

    Manufacturing

    International Paper Company: Kraft paper mill, located in Georgetown, South Carolina

    Enlarge

    International Paper Company: Kraft paper mill, located in Georgetown, South Carolina

    Whether done by hand or with a paper machine, the paper making process has three simple steps:

    [edit]

    Preparation of the fibers

    The material to be used for making paper is first converted into pulp, a concentrated mixture of fibers suspended in liquid. The source of fiber is often natural (softwood or hardwood trees or other plants) or recycled, such as old corrugated boxes, newsprint, or mixed paper.

    When best sheets materials are used to make paper, it is usually necessary to break down the lignin inside of the plant's cell walls. This is done via a chemical process, such as the Kraft process. These processes are not needed when breaking down recycled fibers, as the lignin has already been removed from the source material. If the lignin is retained in the pulp, the paper will yellow when exposed to air and light.

    Pulp that has been broken down mechanically is often known as "groundwood pulp." The mechanical process to break down wood chips into pulp requires no chemicals. Since the lignin is not removed from mechanical pulp, yields are relatively high, approximately 90-98%. However, due to the aging issues indicated above, mechanical pulp is most often used for newspapers and other non-permanent goods.

    Pulp that is broken down chemically is known as "chemical pulp." The main purpose of a chemical pulping process is to break down the chemical structure of lignin and render it soluble in a liquid (most often water) so it may be washed from the remaining fibers. Removing the lignin from wood chips also serves to break them apart into the fibers that compose pulp.

    Recycled fibres do not need to be pulped in the conventional sense. These fibres have already been treated once, so instead they need a more gentle process to break the fibers apart while preserving their integrity.

    Once the fibers have been extracted, they may also be bleached, dyed, or have additional ingredients added to alter the appearance of the final product. For example, Kaolin (or calcium carbonate) is added to produce the glossy papers typically used for magazines. The Kappa number indicates how much bleach is required to obtain a given whiteness.

    [edit]

    Sheet formation

    The pulp mixture is further diluted with water resulting in a very thin slurry. This dilute slurry is drained through a fine-mesh moving screen to form a fibrous web. A watermark may be impressed into the paper at this stage of the process. This mark is used on paper currency and other things. This moving web is pressed and dried into a continuous sheet of paper.

    In the mould process, a quantity of pulp is placed into a form, with a wire-mesh base, so that the fibers form a sheet on the mesh and excess water can drain away. Pressure may be applied to help remove additional water. The paper may then be removed from the mould, wet or dry, and go on to further processing.

    Most mass-produced paper is made using the continuous Fourdrinier process to form a reel or web of fibers in a thin sheet. When dried, this continuous web may be cut into rectangular sheets by slicing the web vertically and horizontally to the desired size. Standard sheet sizes are prescribed by governing bodies such as the International Organization for Standardization (ISO).

    [edit]

    Drying

    After the paper web is produced, the water must be removed from it in order to create a usable product. This is accomplished through pressing and drying. The methods of doing so vary between the different processes used to make paper, but the concepts remain the same.

    Pressing the sheet removes the water by force. Once the water is forced from the sheet, another absorbant material must be used to collect this water. On a paper machine this is called a felt (not to be confused with the traditional felt). 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. On the paper machine, the most common is the steam-heated can dryer. These dryer cans heat to temperatures above 200ºF and are used in long sequences of more than 40 cans. The heat produced by these can easily dry the paper to less than 6% moisture.

    Source(s): www.wikipedia.org
  • Whether done by hand or with a paper machine, the paper making process has three simple steps:

    1).Preparation of the fibers

    2).Sheet formation

    3).Drying

    for more info

    http://en.wikipedia.org/wiki/Paper#Manufacturing

  • 1 decade ago

    I can write a thesis but I'll make it short so it's easily understood:

    How is wood made into paper?

    1. In the papermaking process, wood is first chipped into small pieces. Then water and heat, and sometimes chemicals, are added to separate the wood into individual fibers.

    2. The fiber is mixed with lots of water (and often recycled fiber), and then this pulp slurry is sprayed onto a huge flat wire screen which is moving very quickly through the paper machine. Water drains out, and the fibers bond together.

    3. The web of paper is pressed between rolls which squeeze out more water and press it to make a smooth surface.

    4. Heated rollers then dry the paper, and the paper is slit into smaller rolls, and sometimes into sheets, and removed from the paper machine.

    Done. You got paper. Just to go further regarding recycling:

    During the paper recycling process, ink is removed from paper in a process called deinking (de-inking). After the recovered paper is chopped up (or pulped), and mixed with water to make a pulp slurry, it is put through a series of washing and/or flotation deinking processes in which water and/or soap-like chemicals called surfactants remove the ink from the paper.

    But what happens to the ink that's been removed?

    Along with clay, short fibers, and other materials removed during the deinking process, ink that is removed from recycled pulp can be burned to generate energy to run the mill, or sold to make such useful materials as compost or gravel for roads.

    How many times can you recycle paper?

    A single piece of paper may contain new fibers as well as fibers which have already been recycled once, twice, or several times. Papermaking fibers can typically be recycled 5-7 times before they become too short to be recycled again.

    You might ask, "yeah, but what if food is on paper? Well it needs to be sorted, here's how:

    Successful recycling requires clean recovered paper which is free of contaminants such as food, plastic, metal, and other trash. Contaminated paper can introduce impurities and bacteria into the recycling process. Furthermore, different grades of paper - corrugated boxes, newspapers, and office paper - must be kept separate, because the different grades of recovered paper are used to make particular types of recycled paper products

    Sorted.

  • 1 decade ago

    from the tree back , is very funny, you just see it rolled out from the soft part of the tree

Still have questions? Get your answers by asking now.