NCC-Polymer Additives 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 dry strength agents often interfere with other additives or degrade their effectiveness.
Innovation Solution
The introduction of NCC-polymers, specifically polymers bonded to a nano-crystalline cellulose core with various monomers, is added to the paper substrate in the wet end of the papermaking process, improving wet strength and retention of solids during drainage, and can be used as coatings or dispersed within the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional retention aids and dry strength agents are added to the slurry, then drainage retention and dry strength are improved, but they interfere with other additives and degrade their effectiveness
Solution Approach 1:
The patent uses cationic starch as an intermediary substance that bridges the interaction between nanocrystalline cellulose and other additives in the slurry. The cationic starch modifies the surface properties of nanocrystalline cellulose, enabling it to retain solids during drainage without interfering with the effectiveness of optical brighteners, fillers, and other strength agents. This intermediary approach resolves the contradiction by mediating the interactions between multiple components in the papermaking slurry.
2Loss of substance
If retention aids are added to facilitate drainage retention, then solid matter retention is improved, but water drainage freedom is restricted
Solution Approach 1:
The patent changes the physical and chemical parameters of the retention system by using nanocrystalline cellulose with specific surface properties and charge characteristics. The nanocrystalline cellulose, when modified with cationic starch, creates optimal retention conditions that allow high solid matter retention while maintaining adequate water drainage freedom. This parameter optimization resolves the contradiction between retention effectiveness and drainage efficiency.
3Strength
If surface strength agents are applied as coatings to increase resistance to abrasive forces, then surface strength is improved, but flexibility of the paper product is impaired
Solution Approach 1:
The patent creates a composite system where nanocrystalline cellulose, cationic starch, and paper fibers form an integrated reinforcement structure throughout the paper matrix. This composite approach distributes strength enhancement throughout the paper rather than applying a separate coating layer, thereby improving surface strength and overall durability while preserving the natural flexibility and drape of the paper product. The composite structure avoids the rigidity problems associated with surface 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
The NCC-polymers significantly enhance wet strength, improve drainage retention, and increase dry strength, reducing material waste and costs, while maintaining the flexibility and optical properties of the paper, outperforming conventional polymers in retention and strength enhancement.
Implementation Method 1
The NCC-polymer may comprise a polymer chain bonded to an NCC core
Implementation Method 2
the retention aid function to retain solid matter within the slurry as water is drained out of the slurry
Implementation Method 3
the NCC-polymer is substantially distributed throughout the paper substrate
Data Source
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.