Sizing Agents

Sizing agents are applied into the paper to impart certain desirable qualities. The main function of sizing agent is to increase the resistance to penetration of water or other liquids into the paper so that the paper is suitable for printing, writing and other purpose. It can be achieved either by using wet-end additives or by applying a suitable coating to the surface of the dried paper. Sometimes a combination of treatments is required. The wet-end Sizing agents also decrease dusting, control spreads of inks, improve dewatering, retention of filler and fibers, improve paper quality, smoothness, dimension stability, abrasion, decrease porosity and improve paper machine runnability.

Types of Sizing Agent
There are two types of sizing agents; internal sizing agents and surface sizing agents.

Internal Sizing Agents
Internal sizing agents are used in papermaking process at the wet end. The most important internal sizing chemicals are alkyl ketene dimer (AKD), rosin and alkyl succinic anhydride (ASA). The internal sizing agents should have some basic characteristics such as high hydrophobicity, good retention on fibers, uniform distribution throughout the fiber surfaces, and must strongly bonded with fibers.
The internal sizing agents can also be classified into acidic type sizing chemical and basic or neutral type sizing chemical. Rosin and its derivatives are acidic type sizing agent. On the other hand AKD and ASA are basic or neutral type sizing agent.

Surface Sizing Agents
Surface sizing agents have both hydrophilic and hydrophobic ends. It is forms a thin film on paper web, the hydrophilic tail of it joined with the fiber, whereas hydrophobic tail facing outwards. The thin film reduces paper dust; improve surface strength, printability and water resistance of the paper. There are different chemicals are used as surface sizing agent such as modified starches, Styrene Maleic Anhydride (SMA), Styrene Acrylic Emulsion (SAE), Styrene Acrylic Acid (SAA), Ethylene Acrylic Acid (EAA), gelatin and Polyurethane (PUR). It is normally applied in a paper mill though the size press at dry end section.

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14 Responses to Sizing Agents

  1. Baramki says:

    We are producer of carton board from recycle paper. It is used for shoe insole , we call it insole carton board , thickness about 1 to 1.5 mm. In our production we used a recycle paper : duplex ( the one side white and the other side grey ) , some times we add some SBR liquid , and sometimes no. We have a problem that this carton board we are producing is easy to broke , and also easy absorb water. So , what is your suggestion to can modify our formulation ?
    We wait your soon answers and technical data and uses.
    Rgds. Baramki

  2. amol patil says:

    how to reduce sizing (cobb vaulue) in recycle kraft paper mill our cpacity 30 ton/day in reainy season cobb value increased to 150 to 175 our acidity of water 400 approximate
    plz suggest

  3. By making the paper web more hydrophobic, the sizing agents influence dewatering and retention of fillers and fibers in the paper sheet.

  4. Elius says:

    How many have process in courting paper sizing increase

  5. tippy says:

    In recycled paper mill have a problem that split paper.I want to know its cause and how improvement it not have these problem ,thank you.

  6. Pagare says:

    How to achieve suitable IGT in board paper GSM 250 TO 400 by surface sizing.

  7. Pranav manjunath says:

    We are getting low burst strength factor and also worst sizing (cobb values) although we are using rosin with alum(al2so4).. I’m cordially requesting you to give your suggestions. Please help us.

  8. pradyuman patel says:

    we are manufacturing Water dispersible polyesters resine for paper wet end sizing to Water dispersible polyesters are used to treat and size paper by applying them at the wet-end of the paper process. The water dispersible polyesters can be used alone or with other chemicals typically used to treat or size paper in order to increase the paper’s dry strength, wet strength, stiffness, water repellency, water resistance, and sizing properties
    pl contact

  9. zenebe says:

    we are manufacture carton and white bond paper in acidic media buy using rosin internal sizing agent but know we need to replace rosin by other type of chemical and we need Sapporo if you maind

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