Flushable Tampon Applicator Using Water-Dispersible PVA
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Solution Overview
Problem
Current plastic tampon applicators are not biodegradable or renewable, leading to disposal challenges and potential health hazards, and attempts to use biodegradable materials like polyvinyl alcohol have been unsuccessful due to processing difficulties and high costs.
Innovation Solution
A thermoplastic composition comprising 50-98 wt.% partially hydrolyzed polyvinyl alcohols and 2-50 wt.% plasticizer, which can be injection molded into a flushable tampon applicator that disintegrates in water, addressing the need for a water-dispersible and comfortable product.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If biodegradable polymers are used in injection molded parts, then environmental friendliness is improved, but processing difficulty and cost increase
Solution Approach 1:
The patent changes the molecular weight parameters of polyvinyl alcohol by using a blend of high molecular weight (providing strength and elasticity) and low molecular weight (providing flow and meltability) PVA. This parameter optimization enables the biodegradable material to be successfully processed by injection molding while maintaining environmental friendliness.
Solution Approach 2:
The patent creates a composite material system by blending polyvinyl alcohol with plasticizers and optionally with water-soluble or biodegradable polymers. This composite approach combines the water-solubility and biodegradability of PVA with the processability and mechanical properties of complementary materials, resolving the contradiction between environmental friendliness and ease of manufacture.
2Object-affected harmful factors
If polyvinyl alcohol is used in tampon applicators, then water-dispersibility is improved, but solution processing is slow and costly
Solution Approach 1:
The patent replaces the slow solution processing method with injection molding, a rapid thermal processing method. By formulating PVA with appropriate plasticizers and molecular weight blends, the material becomes thermoplastic and suitable for injection molding, dramatically increasing production speed while maintaining water-dispersibility.
Solution Approach 2:
The patent modifies the thermal and rheological parameters of polyvinyl alcohol through plasticizer addition and molecular weight blending, transforming it from a material requiring slow solution processing to one suitable for rapid injection molding, thereby improving productivity while preserving water-dispersibility.
3Object-affected harmful factors
If solution processing is used for polyvinyl alcohol, then water-dispersibility is achieved, but energy requirements increase
Solution Approach 1:
The patent substitutes the energy-intensive solution processing method with injection molding, which uses thermal energy more efficiently. The formulated PVA composition allows direct melting and molding without requiring large volumes of solvent and extended processing time, thereby reducing overall energy consumption while achieving water-dispersibility.
Solution Approach 2:
The patent utilizes the phase transition properties of polyvinyl alcohol, exploiting its ability to transition from solid to melt phase under controlled heating during injection molding. This phase transition approach eliminates the need for solution processing and associated high energy requirements, while the resulting molded part retains water-dispersibility.
4Object-affected harmful factors
If cardboard is used for applicators, then biodegradability is improved, but coating is required to decrease friction
Solution Approach 1:
The patent extracts the coating step from the manufacturing process by formulating polyvinyl alcohol with plasticizers and lubricants that provide the necessary low-friction surface properties intrinsically. This eliminates the need for separate coating operations, reducing device complexity while maintaining biodegradability.
Solution Approach 2:
The patent merges the functions of structural material and surface treatment by incorporating lubricating agents and plasticizers directly into the polyvinyl alcohol formulation. This combination provides both the biodegradable structure and the low-friction surface properties in a single material system, eliminating the need for separate coating layers.
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 solution enables the creation of a flushable tampon applicator that is both environmentally friendly and comfortable to use, with improved mechanical properties and disintegration in water, overcoming the limitations of existing materials.
Implementation Method 1
injection molding a pelletized, water-dispersible, thermoplastic composition into a mold cavity and shaping the thermoplastic composition into a molded part within the mold cavity
Implementation Method 2
a water-dispersible applicator that is comfortable to insert and that does not begin to break down upon insertion
Data Source
AI summary
A tampon applicator that is water-sensitive (e.g., water-soluble, water-dispersible, etc.) in that it loses its integrity over time in the presence of water is provided. The tampon applicator can be discreetly disposed of in a toilet without the risk of clogging sewer pipes. The tampon applicator includes a molded thermoplastic composition containing at least one partially hydrolyzed polyvinyl alcohol a plasticizer. The desired water-sensitive characteristics of the tampon applicator may be achieved in the present invention by selectively controlling a variety of aspects of the thermoplastic composition from which the applicator is formed, such as the nature of the components employed, the relative amount of each component, the manner in which the composition is formed, and so forth.