Lyocell Fiber Webs Filtration Low Alpha Pulp
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Solution Overview
Problem
The high cost of producing commercial dissolving grade pulps for lyocell fibers limits the availability of affordable and effective biodegradable filter media for air and liquid filtration, as these pulps require extensive processing to remove non-cellulose components like hemicellulose, increasing production costs.
Innovation Solution
The use of low alpha pulps with low copper, lignin, and transition metal content, and broad molecular weight distribution, such as Peach® pulp, which maintains high hemicellulose content for enhanced interfiber bonding, is explored to produce nonwoven lyocell fiber webs with varying fiber diameters and basis weights, suitable for filtration products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high alpha dissolving grade pulps are used to produce lyocell fibers, then fiber quality and biodegradability are improved, but production cost increases significantly
Solution Approach 1:
The patent applies this principle by using low alpha pulps (less processed, lower cost raw materials) instead of expensive high alpha dissolving grade pulps. The invention demonstrates that lower quality raw materials can still produce functional filter media that meets performance requirements, sacrificing some fiber quality for significant cost reduction.
Solution Approach 2:
The patent changes the key parameter of alpha cellulose content from the conventional high alpha (requiring extensive processing) to low alpha pulps. This parameter change allows the use of less processed, lower cost raw materials while still achieving acceptable fiber quality through optimized web structure and hemicellulose content.
2Reliability
If hemicellulose is removed from pulp during processing, then fiber purity is improved, but interfiber bonding capability deteriorates
Solution Approach 1:
The patent applies this principle by converting hemicellulose, which is typically considered an impurity to be removed, into a beneficial component. The invention retains hemicellulose in the low alpha pulps and demonstrates that it provides excellent interfiber bonding capabilities, turning what is conventionally viewed as a harmful impurity into a useful bonding agent that enhances web strength and filtration performance.
Solution Approach 2:
The patent uses low alpha pulps that maintain a more homogeneous composition including hemicellulose, rather than creating heterogeneous high alpha pulps requiring extensive processing to remove non-cellulose components. This homogeneous composition with retained hemicellulose simplifies processing and improves bonding.
3Reliability
If extensive processing is applied to remove non-cellulose components, then pulp purity is improved, but production complexity and cost increase
Solution Approach 1:
The patent inverts the conventional approach by not removing hemicellulose and other non-cellulose components from low alpha pulps, but rather retaining them as beneficial constituents. This inversion of the standard purification process simplifies manufacturing while maintaining adequate pulp quality for filter media production.
Solution Approach 2:
The patent accepts lower pulp purity from low alpha pulps as acceptable for the intended application, avoiding the need for extensive and expensive purification processes. The invention demonstrates that high purity dissolving grade pulps are not necessary for filtration applications, allowing use of cheaper, less processed pulps.
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 reduces production costs while maintaining the biodegradability and performance of lyocell fibers, offering a cost-effective solution for high-quality filtration products with improved bonding and filtration efficiency.
Implementation Method 1
Fibers made from pulp with a high hemicellulose content are particularly suited for this application because of the added interfiber bonding attributed to hemicellulose
Implementation Method 2
Lyocell is made by dissolving cellulose in a mixture of N-methylmorpholine-N-oxide (NMMO) and water
Implementation Method 3
Lyocell is a generic term for a fiber composed of cellulose precipitated from an organic solution
Data Source
AI summary
Cellulose filtration products comprising nonwoven lyocell fiber webs in which the fibers have a diameter of from 3 to 12 microns, the largest pore diameter of less than about 300 microns and a mean flow pore diameter of less than about 150 microns are disclosed. Multilayer nonwoven lyocell fiber webs are also disclosed which have lower mean flow pore diameters and lower pore sizes.