Duplex paper quality depends on many factors, including the addition of certain materials. Starch is an example of one of these materials which can improve the bonding of fibres within the paper sheet. This can give good performance when printing or packaging. It may be necessary to have some variation in starch properties depending on the grade of paper being used and conditions in the paper mill.
Starke Adhesive manufactures starches for industrial applications. Understanding the specific requirements of a paper mill helps in selecting the right product. Using the appropriate Cationic starch for Duplex Paper can support consistent production and paper quality.
Role of Cationic Starch in Duplex Paper Quality
Duplex paper can have many layers and often is made from recycled fibres. The cationic starch has a positive charge so it binds well to the negative charges on the fibres and fine particles. This helps improve fibre retention.
Depending on the grade of paper, they can use different quantities and types of starch. Packaging boards will have different requirements than printing quality boards. Knowing what the paper is going to be used for helps the mills decide what materials they will need to use.
Important Factors Affecting Starch Performance
- Charge Level and Degree of Substitution : The degree of substitution (DS) is an indication of how many cationic groups have been added to the starch. This will affect interactions between starch, fibre and other components in the pulp. The correct level of charge depends on furnish and conditions at the mill. A high level will not necessarily improve performance.
- Viscosity and Handling : High viscosities can cause problems when feeding starch into the production process. It can be difficult to pump and dose if the viscosity is too high. Ensuring the correct viscosity will help ensure a consistent flow. Before adding to your process, make sure you are using starch with the correct viscosity for your process. This will depend on the concentration and temperature.
- Raw Material Composition : Different ratios of recycled fibres, virgin pulps and mineral fillers can be used in duplex paper making. Cationic starch for Duplex Paper should be tested with the actual furnish. This is especially important if you have variable amounts of recycled fibres and/ or fillers in your paper making process.
- Finished Board Requirements : Depending on the application, duplex paper can be required to have high surface strength and printing performance or rigidity and internal adhesion. By understanding the needs at an early stage, manufacturers will know if they need a specific starch grade to meet their end-use requirements.
Wet-End and Surface Applications
Cationic starch can be used in a variety of ways in paper manufacture. Firstly, at the wet end, starch is added to the pulp system to help retain fibres and fillers while improving sheet strength.
After sheet formation, starch can be applied on the surface to improve surface strength and aid print-related properties. Due to these differing uses, the correct type of product needs to be selected depending on what the application will be.
Grade Evaluation Before Regular Production
Papermakers can run lab tests and controlled trials on the new grade to see how it will perform in real life.
They can monitor:
- Retention – How much fines and fillers are retained.
- Paper strength – Results from relevant testing i.e tensile and internal bonding.
- Surface quality – Picking and printability.
- Machine run ability – Drainage, formation and stability.
- Chemical compatibility – How the product interacts with other chemicals currently being used.
This can then be compared to existing production data so they can see if they product will work for them. They can also see if they need to make any changes to their starch preparation, dosing or application.
FAQ’s
1. What does Cationic Starch do in Duplex Paper?
It helps improve fibre and filler retention. It also improves bonding within the paper.
2. What factors influence cationic starch performance?
Factors such as charge, viscosity, pulp make-up, method of application and required end-board properties will affect cationic starch performance.
3. Is wet-end applied cationic starch the same as surface applied starch?
No, wet-end starch is applied to the pulping system, whereas surface starch is applied after sheet formation. Ensure that the correct product is being used for the intended application.
Conclusion
The consistency of duplex paper relies on using the correct materials. The charge, viscosity, fibre composition and application method are all important to consider when finding the correct starch grade. Further testing can be carried out in the laboratory and on the machine.
Starke Adhesive Pvt. Ltd. offers modified starch products for use in paper manufacture. If you are a manufacturer looking to understand how Cationic starch for Duplex Paper can be used, please contact us to discuss your requirements and learn more about our range of products.
