Starch Cooking
Starch is a carbohydrate, a high molecular weight polymer of glucose, that is produced and used by all plants to store energy. It is widely used in the production of paper and board as a retention aid, dry strength additive, internal sizing agent, surface sizing agent, and as a binder in coating formulas. This course discusses how starch is used in the paper and board production process, the hazards it presents, as well the equipment and process variables of starch cooking.
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Learning Objectives
• Identify the hazards present around starch cooking and make-down systems • Define “starch,” “internal sizing,” “surface sizing,” “amylose,” and “amylopectin” • Identify and describe the uses of starch in paper and board production processes • Describe cationic, anionic and amphoteric starches • List the ways starch can be delivered to a site • List the four things necessary to cook starch • Identify the equipment used in batch and continuous starch cooking processes • Identify key process variables for cooking starch • Identify and describe the primary process flows
Specs
| Course Level | Intermediate |
| Languages | English, Portuguese, French, Polish, Russian |
| Compatibility | Audio, Video |
| Based on: | Industry Standards and Best Practices |
Key Questions
How is starch used in the production of paper and board?
Starch can be used as an internal sizing, dry strength, or surface sizing additive, as a binder in coating formulas, or as an adhesive in corrugated board.
What four things are required to cook starch and prepare it for use at a mill?
Water, time, temperature and agitation
Describe how starch can be cooked using a batch process.
Steam is used to heat a starch-water slurry in an agitated tank for at least 20 minutes at 200 to 210 degrees F
Describe how the continuous jet cooking process can be used to cook starch
Steam is injected into a starch-water slurry as it travels through a mixing device and the temperature is usually around 250 degrees F
How can the cooking method affect the viscosity (or flow resistance) of the starch solution?
When more thermal or mechanical energy is put into the starch cooking, the starch molecules will be less entangled and so the viscosity will be lower (it will flow more easily)
Sample Video Transcript
Starch is sometimes used to help form stable emotions with internal sizing agents, and improve their retention in the sheet. Internal sizing increases the resistance of the sheet to penetration by water and water-based solutions. It is used in grades which will be printed, coated, glued, or used for food packaging. Starch is often applied to the surface of the partially dried sheet at a size press to help control penetration of water and water-based solutions into the fully dried sheet. This surface sizing also tends to improve the strength and stiffness of the sheet. Starch is often used as a binder encoding formulas to bind or hold the pigment particles to the sheet surface. In corrugating and other converting operations, starch is used extensively as an adhesive.
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