Water-Disintegrable Paper Mandrel to Prevent Wastewater Plugs
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Solution Overview
Problem
Conventional cardboard mandrels used in roll packaging for sanitary products, such as toilet paper, are not easily disposable and can form plugs when exposed to water, making them difficult to evacuate through waste systems.
Innovation Solution
A water-disintegrable paper sheet with a basis weight of 80-400 g/m², formed by dry process papermaking fibers bonded with a water-soluble starch-based binder, which disintegrates within 10-40 seconds, providing controlled crumblability and strength comparable to cardboard.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a cardboard mandrel is used to maintain roll structural integrity, then the roll resists crushing forces during transport and handling, but the mandrel cannot be easily evacuated with waste water and forms plugs
Solution Approach 1:
The mandrel material parameters are changed from traditional cardboard to a specialized paper with basis weight of 80-400 g/m² and specific fiber composition (40-60% cellulose fibers, 20-40% recycled paper fibers, 10-30% other fibers). The binder system is modified to use water-soluble binders (starch, carboxymethyl cellulose, or their derivatives) at concentrations of 5-20%, which enables the mandrel to disintegrate in water within 10-60 seconds while maintaining adequate mechanical strength during handling.
Solution Approach 2:
The mandrel is constructed as a composite material system combining multiple fiber types (cellulose, recycled paper, and other fibers) with water-soluble binders. This composite structure provides both the mechanical strength needed for transport and handling, and the water-solubility required for easy evacuation. The synergistic combination of hydrophobic fibers (for strength) and hydrophilic binders (for water solubility) resolves the contradiction between structural integrity and disposability.
2Object-generated harmful factors
If the mandrel disintegrates quickly in water, then it can be evacuated before forming a plug, but it may lose structural integrity during handling and transportation
Solution Approach 1:
The disintegration time parameter is precisely controlled within the range of 10-60 seconds through adjustment of binder type and concentration. Faster-disintegrating binders (such as modified starch at 10-20% concentration) prevent plug formation, while the fiber matrix maintains structural integrity during the brief handling period. The water contact triggers rapid binder dissolution, causing immediate disintegration before the mandrel can travel far through the waste system.
Solution Approach 2:
The mandrel exhibits dynamic behavior: it maintains stable structural integrity under dry conditions during handling and transportation, then transitions to rapid disintegration upon water contact. This dynamic response allows the mandrel to fulfill its structural function when needed and eliminate itself when no longer required, resolving the contradiction between durability and disposability.
3Object-generated harmful factors
If a water-soluble binder is used to enable mandrel disintegration, then the mandrel can be easily evacuated with waste water, but the manufacturing complexity and cost increase
Solution Approach 1:
The mandrel is designed as a disposable component using inexpensive, readily available materials: common fibers (cellulose, recycled paper) and water-soluble binders (starch, carboxymethyl cellulose) that are already widely used in the paper industry. The simple pulping and molding process eliminates the need for complex manufacturing equipment, making the disposable mandrel economically viable despite its short service life.
Solution Approach 2:
The binder concentration parameter is optimized to balance performance and cost. At 5-20% concentration, water-soluble binders provide sufficient water-solubility for disintegration while minimizing material costs and processing complexity. This parameter optimization allows the use of simple, well-established manufacturing processes rather than requiring complex new technologies.
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 water-disintegrable paper mandrel effectively disintegrates in water before forming a plug, maintaining structural integrity during handling and transportation, while being environmentally friendly and cost-effective, thus addressing the challenge of easy disposal and environmental impact.
Implementation Method 1
a water-soluble binder used is a mono-, di- or trisaccharide, preferably sucrose, mixed with the starch
Implementation Method 2
The starch-based binder is capable of imparting both dry strength and water solubility to the sheet
Implementation Method 3
The mandrel should disintegrate on contact with water. The material must disintegrate in the water at a sufficient rate for it to be evacuated before forming a plug
Implementation Method 4
Dry process paper is known per se. It is made by depositing a sheet of paper fibers on a canvas
Data Source
AI summary
The present invention relates to a water-degradable paper sheet. The sheet has a basis weight of 80 to 400 g/m2 and is characterised in that it is dry-formed from paper fibres bound together by a water-soluble binder including starch, the amount of binder in the sheet being 30 to 70%. The invention also relates to a mandrel formed by a cylinder having a wall that includes at least one dry-formed paper sheet including paper fibres bound together by a water-soluble binder.