Cellulose Ester Fiber Composite for Wet Laid Paper Drainage
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Solution Overview
Problem
Wet laid paper production faces challenges such as slow water drainage rates, reduced tensile strength, and increased energy consumption due to the limitations of refining cellulose fibers, which can be exacerbated by the use of synthetic fibers that may damage or agglomerate in refiners, leading to web breaks and operational interruptions. Additionally, there is a need for improved air and water permeability, reduced basis weight, and increased bulk without compromising product properties.
Innovation Solution
A composition comprising cellulose fibers and cellulose ester staple fibers, which are co-refined to enhance fibrillation and drainage rates while maintaining or improving tensile strength, and can be added post-refining to minimize process complexity and equipment costs. This composition includes fibers with specific features like non-round shapes and crimped structures to optimize web formation and drying efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If more refining energy is applied to cellulose fibers, then the strength and toughness of the web is improved, but the drainage rate of water from the web is reduced
Solution Approach 1:
The patent combines cellulose fibers with biodegradable synthetic fibers (polyester, polyamide, or acrylic) to create a composite web structure. The synthetic fibers provide structural support and strength while the cellulose fibers contribute to drainage properties. This composite approach allows the web to maintain tensile strength without requiring excessive refining energy, thereby preserving drainage rate.
Solution Approach 2:
The patent modifies the physical and chemical parameters of the fiber mixture by controlling the ratio of cellulose to synthetic fibers (typically 90:10 to 50:50 by weight), fiber length, denier, and fineness modulus. These parameter changes enable optimization of both strength and drainage characteristics without requiring high refining energy input.
2Productivity
If synthetic fibers are used to improve drainage rate, then the drainage rate increases, but the synthetic fibers may be damaged or melted in the refiner causing web breaks and operational interruptions
Solution Approach 1:
The patent specifies particular parameters for the synthetic fibers including fineness modulus between 2.0-4.0, denier per filament of 0.5-3.0, and fiber length of 1-20mm. These parameter changes make the synthetic fibers more resistant to damage during refining while maintaining their drainage-enhancing properties.
Solution Approach 2:
The patent creates a composite system where biodegradable synthetic fibers are combined with cellulose fibers in specific ratios. This composite structure allows the synthetic fibers to perform their drainage function without being overwhelmed by excessive refining energy, as the cellulose fibers absorb much of the mechanical stress.
3Strength
If cellulose fibers are heavily refined to increase tensile strength, then the wet tensile strength improves, but the air and water permeability of the web is reduced
Solution Approach 1:
The patent employs a composite fiber structure where synthetic fibers create a more open web architecture that maintains air and water permeability even when cellulose fibers are refined to achieve desired tensile strength. The synthetic fibers act as spacers that prevent complete densification of the web structure.
Solution Approach 2:
The patent applies different fiber types in specific locations and proportions within the web structure. The synthetic fibers are distributed throughout to maintain permeability pathways, while cellulose fibers are concentrated in areas requiring strength, creating local quality variations that satisfy both strength and permeability requirements.
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 composition increases water drainage rates, reduces energy consumption in drying, and enhances air and water permeability while maintaining tensile strength, allowing for increased production speeds and reduced basis weight without significant drops in product properties, thus improving operational efficiency and environmental sustainability.
Implementation Method 1
A composition comprising cellulose fiber and a staple fiber; wherein said staple fiber comprises cellulose ester; and wherein said composition exhibits a deeper texturing than a composition comprising 100% comparative cellulose fiber
Implementation Method 2
The stock is then deposited onto the forming section of a wet laid machine... One example of a forming section is a Fourdrinier wire onto which the stock is deposited through the slice of a headbox... It is necessary to refine pulp to provide necessary strength and/or toughness to the web, but as more refining energy is applied, the freeness of the pulp (typically measured as the Canadian Standard Freeness CSF) is reduced resulting in a slower drainage rate
Implementation Method 3
Water from the stock drains through the wire to increase the consistency of the web sufficiently to permit it to be processed across rolls unsupported. Water is typically removed through a combination of gravity and vacuum.
Implementation Method 4
Water is typically removed through a combination of gravity and vacuum.
Implementation Method 5
The web layer is generally pressed through the nip of press rolls to further reduced it water content by mechanical means
Implementation Method 6
after which it enters a drying zone for further removal of moisture from the web by the application of thermal energy
Implementation Method 7
The dried web can then optionally proceed through a sizing press for application of a variety of surface sizing agents. At this stage, because the web is rewet by the application of the sizing agents, the web proceeds through a second drying zone to dry the web to the desired moisture content
Data Source
AI summary
The present invention provides compositions comprising cellulose fibers and cellulose ester fibers and wet laid articles made from the compositions, as well as wet laid processes to produce these compositions. More specifically, the present invention provided compositions comprising cellulose fibers and cellulose acetate fibers and wet laid articles made from these compositions as well as wet laid processes to produce these compositions. The present invention also relates to composition, process, wet laid product, or articles exhibiting any one of many desired benefits. The invention also relates to a composition comprising cellulose fiber and a staple fiber exhibiting improved texturing.