Microfibrillated Cellulose Wet-Laid Sheet for Flushable Wet Strength
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional wet wipes are not biodegradable, contribute to environmental concerns, and may cause skin rashes due to preservatives like methylchloroisothiazolinone, while traditional manufacturing methods are costly and result in products that clog sewage systems.
Innovation Solution
A wet laid sheet material composed of >50% microfibrillated cellulose with high moisture content (>30 wt.-%) is produced using a conventional paper making machine, eliminating the need for additives and allowing for high wet tensile strength, improved runnability, and biodegradability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If air-laid paper is used for wet wipes, then softness and strength are improved, but biodegradability deteriorates and sewage system clogging occurs
Solution Approach 1:
The patent changes the fundamental parameter of fiber composition from synthetic blends to 100% cellulose fibers, and controls fiber length distribution to achieve both high wet strength and biodegradability. The specific parameter change involves using predominantly short fibers (5-20 mm) with some longer fibers (20-40 mm) to create a matrix that provides strength while maintaining disintegration capability in sewage systems.
Solution Approach 2:
The patent creates a composite fiber structure combining different fiber lengths and types (wood pulp, straw, reed, bagasse) to achieve synergistic properties. The composite consists of a matrix of short fibers providing strength and a network of longer fibers providing structural integrity, all while maintaining biodegradability unlike synthetic fiber composites.
2Reliability
If conventional wet wipes with preservatives are used, then hygiene and shelf life are improved, but skin irritation and environmental harm occur
Solution Approach 1:
The patent extracts and eliminates harmful preservatives (methylisothiazolinone, methylchloroisothiazolinone, formaldehyde donors) from the wet wipe composition entirely. Instead, it relies on the inherent biodegradability and natural antimicrobial properties of cellulose fibers to maintain hygiene without requiring chemical preservatives that cause skin irritation.
Solution Approach 2:
The patent embraces the disposable nature of wet wipes by using 100% biodegradable cellulose fibers that can be safely discarded after use. This eliminates the need for long-term preservative systems, as the product is designed for single use followed by complete biological degradation, removing the source of preservative-related skin irritation.
3Ease of manufacture
If traditional paper making process is used, then manufacturing cost is reduced, but moisture retention and wet properties deteriorate
Solution Approach 1:
The patent modifies the paper making process parameters by using a refined slurry consistency (1-5% solids) and controlling the beating/refining degree to achieve optimal fiber bonding. The moisture retention is enhanced by adjusting the drying parameters and using specific fiber length distributions that create a more open, porous structure capable of holding moisture while maintaining strength.
Solution Approach 2:
The patent uses a composite fiber composition combining different cellulose sources (wood pulp, straw, reed, bagasse) with varying fiber lengths and lumen structures. This composite structure creates a network that retains moisture more effectively than conventional single-fiber papers, while still being manufacturable using standard paper making equipment and processes.
4Strength
If high fiber content is used in air-laid paper, then strength is improved, but softness deteriorates
Solution Approach 1:
The patent applies local quality by creating zones of different fiber densities and lengths within the paper structure. Longer fibers (20-40 mm) provide strength in specific directions while shorter fibers (5-20 mm) create a softer, more uniform matrix in other areas. This spatial distribution of different fiber characteristics allows simultaneous achievement of strength and softness.
Solution Approach 2:
The patent changes the fiber length parameter distribution to optimize the balance between strength and softness. By using a bimodal distribution with predominant short fibers and a minority of longer fibers, the paper achieves high tensile strength through the longer fiber network while maintaining softness through the short fiber matrix, unlike conventional papers that use uniform fiber lengths.
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 microfibrillated cellulose-based sheet maintains moisture and wet properties, is flushable, and reduces production costs, offering a cost-efficient, environmentally friendly, and allergen-safe alternative for hygiene tissues.
Implementation Method 1
supplying a stock suspension onto a wire in a forming section of a paper machine in such a way that an initial wet web is formed and dewatered
Implementation Method 2
initial wet web is formed and dewatered
Implementation Method 3
pressing the wet web in a press section of the paper machine
Implementation Method 4
wet web is pressed in a press section of the paper machine
Data Source
AI summary
A wet laid sheet material formed from a fibrous web, characterized in that the initial fibrous web contains >50% a calculated dry microfibrillated material composition by weight of the total fiber material content in the web, wherein the fibrillated material composition has a SR value of >70; and in that the moisture content in the sheet material is >30 wt.-%.