Flushable Tampon Applicator Using PVOH-PEG Composite

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Solution Overview

Problem

Current tampon applicators are not biodegradable, pose disposal challenges, and can clog sewer systems when flushed, with previous attempts at flushable materials like PVOH being brittle and unsuitable for injection molding due to high energy and cost requirements.

Innovation Solution

A thermoplastic composition comprising partially-hydrolyzed polyvinyl alcohol (PVOH), polyethylene glycol (PEG), and a hydrophobic polymeric component, which is water-dispersible and can be injection molded, delaying water dispersion during insertion and maintaining integrity for use.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If biodegradable polymers are used in injection molded tampon applicators, then environmental sustainability is improved, but manufacturing cost increases and thermal processing becomes difficult

Engineering Contradiction:

Improveenvironmental sustainabilityVSAvoidmanufacturing cost and thermal processing

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent uses a composite material system combining PVOH (water-soluble polymer) with plasticizers and stabilizers to create an injection-moldable formulation that maintains biodegradability while achieving suitable processing characteristics and mechanical properties for applicator manufacturing

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent modifies the physical and chemical parameters of PVOH by adjusting molecular weight, degree of hydrolysis, and adding plasticizers to achieve the appropriate melt flow index (5-180) and glass transition temperature for successful injection molding while maintaining water dispersibility

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If PVOH is used to make flushable applicators, then disposal convenience is improved, but the material becomes brittle and unsuitable for injection molding

Engineering Contradiction:

Improvedisposal convenienceVSAvoidmaterial brittleness

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The patent introduces plasticizers as intermediary substances that mediate between the brittle PVOH polymer chains, increasing flexibility and ductility while maintaining the water-soluble nature that enables flushability

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the glass transition temperature and mechanical properties of PVOH by adding plasticizers and adjusting molecular weight parameters, transforming the material from brittle to sufficiently flexible for injection molding while preserving water dispersibility

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If solution processing is used for PVOH applicators, then water dispersibility is achieved, but the process becomes slow, costly, and energy-intensive

Engineering Contradiction:

Improvewater dispersibilityVSAvoidmanufacturing speed and cost

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The patent replaces the slow solution processing method with injection molding, using thermal energy and mechanical injection pressure to form the applicator directly from melted PVOH, dramatically increasing production speed while maintaining water dispersibility through controlled formulation

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Object-affected harmful factors

If cardboard applicators are used, then biodegradability is improved, but the coefficient of friction is too high for comfortable insertion

Engineering Contradiction:

ImprovebiodegradabilityVSAvoidinsertion comfort

Core Design Contradiction:

Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The patent modifies the surface properties of the PVOH applicator by controlling crystallinity, adding lubricants, or creating surface coatings that reduce the coefficient of friction to levels comparable with or lower than plastic applicators, ensuring comfortable insertion while maintaining biodegradability

Inventive Principle:

Principle #35Parameter changes

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 allows for the production of a flushable tampon applicator that is comfortable to insert, does not break down during use, and can be disposed of without clogging issues, addressing the biodegradability and disposal challenges of traditional applicators.

Implementation Method 1

a hydrophobic polymeric component, wherein the composition has a melt flow index of 5-180

Methodology Applied

Scientific EffectHydrophobic interaction: Hydrophobe

Implementation Method 2

water-dispersible and can be injection molded, delaying water dispersion during insertion and maintaining integrity for use

Methodology Applied

Scientific EffectDispersion: Dispersion (of waves)

Data Source

PatentUS11124641B2Thermoplastic injection molded and flushable material

Publication Date: 2021.09.21 KIMBERLY CLARK WORLDWIDE INC

AI summary

A water-dispersible injection-moldable composition includes partially-hydrolyzed polyvinyl alcohol (PVOH), polyethylene glycol (PEG), plasticizer, and a hydrophobic polymeric component, wherein the composition has a melt flow index of 5-180. The hydrophobic polymeric component can be a colorant within an ethylene matrix or polyethylene. The composition is flushable according to Guidance Document for Assessing the Flushability of Nonwoven Consumer Products (INDA and EDANA, 2006); Test FG 522.2 Tier 2—Slosh Box Disintegration Test. The PVOH has a hydrolysis of 87% to 89%.