Co-refined Cellulose Ester Fiber Composition for Wet Laid Paper Drainage
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Solution Overview
Problem
Wet laid paper production faces challenges such as slow water drainage rates, which limit production speed and increase energy consumption, and the use of synthetic fibers can lead to web breaks and operational issues, while maintaining desired properties like tensile strength and permeability is difficult without adding complexity or cost.
Innovation Solution
A composition of cellulose fibers and co-refined cellulose ester staple fibers with specific characteristics, such as denier per filament less than 3, cut length less than 6 mm, crimping, or non-round shape, is used to enhance drainage rates and mechanical properties, allowing for increased production speed and reduced energy consumption while maintaining web integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If more refining energy is applied to improve web strength, then the wet tensile strength of the web is improved, but the freeness of the pulp is reduced resulting in a slower drainage rate of water from the web
Solution Approach 1:
The invention changes the physical parameters of the synthetic fibers by using ultrafine denier fibers (less than 3 denier per filament) with specific cut lengths (less than 6 mm) and cross-sectional shapes (non-round, crimped). These parameter changes allow the fibers to be sufficiently fine to not interfere with drainage while still providing the necessary web strength when co-refined with cellulose fibers.
2Productivity
If synthetic fibers are added to improve drainage rate, then the drainage rate of water from the web is improved, but the synthetic fibers can be damaged or melted or rolled into agglomerates or bundles in the refiner causing web breaks and operational issues
Solution Approach 1:
The invention uses synthetic fibers with ultrafine denier (less than 3 df) and specific physical characteristics that prevent them from being damaged or agglomerating in the refiner. The fine denier and controlled cut length ensure the fibers remain dispersed and intact during the refining process, maintaining web integrity while still improving drainage rates.
3Productivity
If machine line speed is increased to boost production, then the production rate is increased, but the drying energy input must be increased to maintain product quality
Solution Approach 1:
The invention performs preliminary water removal action by incorporating drainage-enhancing synthetic fibers in the web formation stage. This preliminary drainage action reduces the water content before the web enters the drying section, allowing increased machine speed without proportionally increasing drying energy input.
4Productivity
If consistency of stock to headbox is increased to reduce water content, then the drainage rate is improved, but the web may not have sufficient liquidity to form properly
Solution Approach 1:
The invention changes the consistency parameter of the stock fed to the headbox, using a thicker stock composition. The ultrafine synthetic fibers facilitate water drainage even at higher consistencies, allowing the web to form properly while maintaining improved drainage rates and reducing overall water content in the finished web.
Data Source
AI summary
A wet laid process includes a method for making paper in which a composition containing co-refined cellulose fibers and cellulose ester fibers made into a thick stock composition in a machine chest, the thick stock is fed to a cleaning/screening zone through a device that regulates the flow rate of thick stock, the consistency of the thick stock fed to the screening/cleaning zone is reduced to form a thin stock composition; the thin stock composition is subjected to a process for cleaning the thin stock and feeding the cleaned thin stock through screens to form a cleaned and screened thin stock composition, and the cleaned and screened thin stock composition is fed to a headbox.