Non-wood Pulp Mechanical Refining Brightness
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Solution Overview
Problem
Conventional pulping processes for non-wood biomasses often result in pulps with excessive depolymerization of cellulose and hemicellulose, leading to weak and low-brightness products, particularly when processing materials like leaves or stems with an epidermal layer, which are challenging due to their non-fibrous nature.
Innovation Solution
A novel mechanical pulping process involving the use of alkaline peroxide chemicals during refining, with optional bleaching steps to produce non-wood pulps with improved properties such as long fiber length, low coarseness, low fines content, and high brightness, by preprocessing the biomass to remove water-soluble extractives and debarking to enhance pulp quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If chemical pulping processes are used to increase brightness and remove lignin from non-wood biomasses, then brightness is improved, but excessive depolymerization of cellulose and hemicellulose occurs causing weak pulps
Solution Approach 1:
The patent replaces chemical pulping processes with a mechanical pulping system that uses refiners to separate fibers. This mechanical approach avoids the harsh chemical treatments that cause depolymerization, thereby maintaining pulp strength while still achieving brightness improvement through physical fiber separation and removal of non-fibrous materials.
Solution Approach 2:
The patent changes the operating parameters of the mechanical pulping process, specifically controlling refiner plate speed, feed rate, and moisture content, to optimize fiber separation without excessive mechanical degradation. This parameter optimization allows brightness improvement while preserving cellulose integrity and pulp strength.
2Ease of manufacture
If conventional pulping processes are applied to non-wood biomasses with epidermal layers, then processing is simplified, but fiber quality deteriorates due to non-fibrous nature of epidermal material
Solution Approach 1:
The patent segments the pulping process into distinct stages: preprocessing to remove epidermal layers, mechanical refining to separate fibers, and optional bleaching. This segmentation allows targeted treatment of different biomass components, improving fiber quality by selectively removing non-fibrous epidermal material while preserving desirable fiber characteristics.
Solution Approach 2:
The patent applies preliminary preprocessing steps including size reduction, epidermal layer removal, and moisture adjustment before the main mechanical pulping operation. This preliminary action prepares the biomass for optimal fiber separation, improving final fiber quality by eliminating problematic epidermal components before they can interfere with the pulping process.
3Strength
If mechanical pulping is used to preserve fiber strength, then pulp strength is maintained, but brightness and fiber separation are insufficient
Solution Approach 1:
The patent merges mechanical pulping with optional bleaching operations in an integrated process flow. The mechanical refining stage provides initial fiber separation and brightness improvement, followed by controlled bleaching to enhance brightness further while maintaining the fiber strength benefits of the mechanical approach. This combination achieves both strength preservation and brightness enhancement.
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 yields non-wood pulps with enhanced fiber length, porosity, and brightness, suitable for producing high-quality wet-laid paper products, while reducing the fraction of very long fibers and debris, thereby improving dispersibility and reducing stringing or clumping issues.
Implementation Method 1
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 2
In certain instances, the pulping chemicals comprise an oxygen based composition, such as hydrogen peroxide
Implementation Method 3
mechanical pulping process in which 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 4
a portion of the water soluble extractives are removed to produce a bagasse
Data Source
AI summary
Disclosed are non-wood pulps having a fiber length greater than about 1.70 mm and a porosity of about 100 cfm or greater. The relatively high degree of porosity is achieved without a loss in tensile strengths. The high degree of porosity and strength makes the pulps well suited for the manufacture of wet-laid fibrous products, particularly wet-laid tissue products. The pulps may be prepared from plants of the family Asparagaceae by mechanical pulping and more preferably by a chemi-mechanical pulping using a sodium hydroxide alkaline peroxide solution where the plant biomass is cut to size prior to pulping.