Non-Wood Pulp Brightness via Mechanical Refining
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Solution Overview
Problem
Existing pulping processes for non-wood biomasses often result in pulps with excessive weakness and low brightness, particularly due to the high concentration of lignin in woody biomasses and the depolymerization of cellulose and hemicellulose in non-wood biomasses.
Innovation Solution
A novel mechanical pulping process involving the treatment of non-wood biomass with alkaline peroxide chemicals before or during refining, which includes steps such as cutting the biomass, extracting water soluble solids, and refining the impregnated bagasse to produce a pulp with improved properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If chemical pulping processes are used to increase brightness and remove lignin from woody biomasses, then brightness is improved, but the process becomes highly chemically intensive and causes significant depolymerization of cellulose and hemicellulose leading to weak pulps
Solution Approach 1:
The patent replaces chemical pulping processes with a mechanical pulping process. Specifically, it uses a refiner with rotating discs to mechanically separate fibers from the non-wood biomass, eliminating the need for harsh chemical treatments while maintaining pulp strength and achieving acceptable brightness through physical means alone
Solution Approach 2:
The patent extracts and removes lignin and other components from the non-wood biomass through mechanical action in the refiner, separating them from the cellulose fibers without using chemical reagents. This mechanical extraction achieves the separation function of chemical pulping while preserving fiber integrity
2Ease of manufacture
If conventional pulping processes are applied to non-wood biomasses, then processing is simplified, but the pulps produced have excessive weakness due to depolymerization of cellulose and hemicellulose
Solution Approach 1:
The patent uses a mechanical refining process instead of chemical pulping to process non-wood biomasses. The refiner applies mechanical shear forces to separate fibers while preserving the polymer structure of cellulose and hemicellulose, achieving both process simplicity and pulp strength
Solution Approach 2:
The patent changes the processing parameters by using controlled mechanical refining conditions (rotational speed, disc spacing, feed rate) to optimize fiber separation while minimizing depolymerization, thereby maintaining pulp strength without complex chemical treatments
3Illumination intensity
If chemical pulping is used to achieve high brightness in woody biomasses, then brightness is improved, but the process becomes highly chemically intensive requiring extensive chemical inputs
Solution Approach 1:
The patent replaces chemically intensive pulping processes with a mechanical refining process that uses physical forces to separate fibers and achieve brightness improvement without requiring large quantities of chemical reagents, thereby eliminating the trade-off between brightness and chemical consumption
4Ease of manufacture
If non-wood biomasses with epidermal layers are processed using conventional processes, then processing is straightforward, but the resulting pulps have poor dispersibility and high coarseness due to the non-fibrous nature of epidermal layers
Solution Approach 1:
The patent uses mechanical refining with rotating discs to effectively break down and separate the non-fibrous epidermal layers from the fibrous content of non-wood biomasses. This mechanical action improves dispersibility by physically separating components that conventional processes cannot adequately separate, while maintaining process simplicity
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 process achieves pulps with desirable properties like long fiber length, low coarseness, low degree of fines, good dispersibility, high brightness, and low debris content, making them suitable for the manufacture of wet-laid paper products.
Implementation Method 1
treatment of non-wood biomass with alkaline peroxide chemicals before or during refining
Implementation Method 2
chemicals, such as alkaline and hydrogen peroxide, are added to the bagasse before or during one or more stages of mechanical refiner pulping
Implementation Method 3
mechanical refiner pulping
Implementation Method 4
refining the impregnated bagasse under first refining conditions to produce pulp
Data Source
AI summary
Disclosed are non-wood pulps having a fiber length greater than about 1.70 mm and a Very Long Fiber (VLF) content of about 0.50% or less. The fibers are readily dispersible in water and useful in the formation of fibrous sheets, particularly wet-laid sheets and more particularly wet-laid tissue sheets having a relatively low basis weight. In addition of having a relatively long fiber length and a low VLF content, the pulps may also have a Dispersivity Index of about 2.00 or less, which is indicative of a relatively narrow fiber length distribution. The pulps may be prepared from plants of the family Asparagaceae by mechanical pulping and more preferably by a chemi-mechanical pulping process using an alkaline and hydrogen peroxide where the plant biomass is cut to size prior to pulping.