Foam Coating Starch Suspension for Paperboard
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Solution Overview
Problem
Current methods for applying starch in paper or paperboard manufacturing, such as spray and curtain coating, face challenges with low solid content, contamination, and uneven distribution, particularly when using uncooked starch particles, which affect adhesion and drying costs.
Innovation Solution
A method involving an aqueous suspension of starch particles with an amphiphilic polymer to create a foam, allowing for high solid content application via foam coating, reducing the need for surfactants like SDS and enabling wet-on-wet dosing, thereby improving interply strength and reducing drying costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If spray or curtain coating of liquid starch solutions is used, then starch can be applied to the paper or paperboard web, but the solid content is low and a large amount of liquid medium is required
Solution Approach 1:
The patent applies foam coating technology where starch is applied in foam form rather than liquid solution. The foam structure allows high solid content starch to be applied with minimal liquid medium, as the starch is carried in bubbles that collapse upon contact with the substrate, leaving behind concentrated starch deposits without excessive liquid residue.
Solution Approach 2:
The invention changes the physical state and concentration parameters of starch application from dilute liquid solutions (typical spray/curtain coating) to concentrated foam formulations. This parameter change enables solid content to be increased from typically low percentages in liquid solutions to much higher concentrations in foam form, reducing liquid medium by a factor of 5-10 times.
2Strength
If uncooked starch particles are applied in the wet-end, then interply strength is improved, but contamination and microbial growth occur due to spray application causing dust
Solution Approach 1:
The patent uses foam coating which delivers uncooked starch particles through a foam matrix that collapses on contact with the substrate. This pneumatic-hydraulic delivery method prevents dust generation and aerosolization that occurs with spray application, while still enabling uncooked starch to reach the wet-end paper or paperboard web for improved interply strength.
Solution Approach 2:
The foam acts as an intermediary carrier that protects uncooked starch particles during application. The foam matrix encapsulates the starch particles, preventing them from becoming airborne dust or contaminants, while still delivering them effectively to the substrate where the foam collapses and releases the starch for bonding.
3Ease of operation
If dilute starch solutions are used for dosing, then application is easier, but cost efficiency decreases and distribution becomes uneven
Solution Approach 1:
The invention changes the concentration parameter from dilute solutions to concentrated foam formulations. This allows easier application (maintaining operability) while dramatically improving cost efficiency through reduced starch and liquid medium consumption. The foam structure enables uniform distribution of the concentrated starch without the wasteful dilution required by spray or curtain coating methods.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method achieves higher solid content starch application, enhancing interply strength and surface integrity, while minimizing contamination and energy consumption, and allowing for cost-effective and even starch distribution between paperboard plies.
Implementation Method 1
creating a foam of the aqueous suspension
Implementation Method 2
an aqueous suspension comprising starch particles and at least 1 wt %, based on the dry solid content of the suspension, of an amphiphilic polymer
Implementation Method 3
applying the foam to the paper or paperboard web
Data Source
AI summary
The invention relates to a method for applying starch to a paper or paperboard web, the method comprising the steps of: providing an aqueous suspension comprising starch particles and at least 1 wt %, based on the dry solid content of the suspension, of an amphiphilic polymer, creating a foam of the aqueous suspension, and applying the foam to the paper or paperboard web. The invention further relates to a paper or paper board product obtained by the method.