COATING STARCH IN PAPER APPLICATION

Theoritical of Advantages and Disadvantages of coating starch

Advantages:

Lower total coating cost ( about 15%)
Improved board stiffness (good for packaging)
Better water holding for coatings
Improved holdout of top coat

Disadvantages:
Higher viscosity of coating and lower coating solids (may affect drying load)
Potential decrease in quality of fold (cracking due to stiffness)
Potential poorer wet pick (must use more crosslinker to offset this)

Some benefit of coating starch are :

• High Binding power and comparable with standard SBR latex
• High dry solid coating
• Good water retention
• Improve paper stiffness compared to all-latex
• Optimal run ability at high speed.
• Printability improvement.
• Less downtime.
• Cost Reduction

Characteristic of coating starch product needed :

1. Has good viscosity stability after storage , event was store for 24 hours the viscosity stay stable.
2. Coating starch product has to in very narrow viscosity specification
   No viscosity fluctuation results in highest latex replacement at high dry solid coating
   – To be cooked at high dry solids
   – To be used in high dry solid coatings
3. Low Mottling tendency (Molecular weight distribution)
   Molecular weight of starch molecules have influence on the migration of the starch through a coating layer.
   Small starch molecules migrate more, resulting in higher mottling tendency
4. High dry solid coating
   Coating starch product can be cooked at max. 40% dry solid

High dry solid coating will:
- decrease binder consumption

• decrease drying energy
• Improve Pick up Coating Colour (gr/m2)
• Reduced Over all cost of Coating Colour

1. As a retainable starch binder
   Retainable starches have following advantages
   • low BOD/COD values of waste water
   • less bacteriological- and pH- control problems
   • less problems with enzymatic degradation of wet-end starch

reff : (https://steemit.com/coating/@deviasyifak)