NCC-Polymer Additive for Paper Strength and Retention
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Solution Overview
Problem
The papermaking process faces challenges in simultaneously enhancing dry strength, surface strength, and drainage retention while maintaining the quality and attributes of the paper product, as existing retention and strength agents often interfere with other additives or degrade the paper's flexibility.
Innovation Solution
The method involves adding a nano-crystalline cellulose (NCC)-polymer to the paper substrate in the wet end of the papermaking process, where the NCC-polymer comprises a polymer chain bonded to a nano-crystalline cellulose core, made from specific monomers such as vinyl acetate and acrylic acid, to improve wet strength and retention of solids during drainage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional polymers or retention aids are added to improve drainage retention and dry strength, then strength properties are enhanced, but they interfere with other additives or degrade paper flexibility
Solution Approach 1:
The invention uses composite materials by combining nanocrystalline cellulose (NCC) with polymer chains to form NCC-graft-polymer. The NCC core provides strength enhancement while the grafted polymer chains ensure compatibility with other additives in the papermaking process, resolving the contradiction between improving strength and maintaining adaptability with other chemicals.
Solution Approach 2:
The invention applies local quality by having different functional components in the NCC-graft-polymer structure serve different purposes: the NCC core provides localized strength enhancement at fiber contact points, while the polymer chains distributed throughout the structure provide overall compatibility and retention. This localized functional differentiation allows simultaneous achievement of strength improvement and additive compatibility.
2Loss of substance
If retention aids are added to retain solid matter during drainage, then drainage retention is improved, but water drainage freedom is restricted
Solution Approach 1:
The invention changes the physical and chemical parameters of retention aids by using NCC-graft-polymer with specific molecular weight, grafting density, and polymer chain composition. These parameter adjustments allow the retention aid to effectively bind solid matter while maintaining adequate water drainage capability, balancing retention improvement with drainage productivity.
3Strength
If surface strength agents are applied as coatings to increase resistance to abrasive forces, then surface strength is improved, but paper flexibility is impaired
Solution Approach 1:
The invention merges surface strength enhancement and flexibility maintenance into a single NCC-graft-polymer additive that is incorporated throughout the paper matrix during wet end addition. This combines the functions of surface strength agents and flexibility maintainers into one material, eliminating the need for separate coatings that would impair flexibility.
Solution Approach 2:
The NCC-graft-polymer acts as an intermediary that provides surface strength through the NCC core while the polymer chains mediate flexibility by creating a flexible matrix structure. This intermediary material bridges the contradiction between surface strength and flexibility that arises when using conventional surface strength coatings.
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 approach significantly improves drainage retention, wet strength, and dry strength of the paper, reducing material waste and costs, while maintaining the paper's flexibility and optical properties, outperforming conventional polymers in retention and strength enhancement.
Implementation Method 1
the NCC-polymer comprises a polymer chain bonded to an NCC core
Implementation Method 2
The retention aids function to retain solid matter within the slurry as water is drained out of the slurry
Data Source
Figure 1
AI summary
The invention provides methods and compositions for improving the characteristics of paper substrates. The method involves adding to a paper substrate an NCC-polymer. NCC-polymers have unique chemical properties which result in improvements in wet strength, dry strength and drainage retention properties of the paper substrates.