Adipic Acid pH Regulator in Incontinence Products

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Solution Overview

Problem

Existing incontinence products face challenges in precisely and effectively applying pH regulators like citric acid, which can lead to skin irritation and uneven pH regulation due to particle size issues and high production speeds.

Innovation Solution

The use of adipic acid as a pH regulator, combined with a melting point depressant such as polyethylene glycol or glycerin, allows for the application of adipic acid in a molten state, ensuring precise targeting and improved depot effect without the need for hot solvents or complex evaporation processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If citric acid or monosodium citrate are used as pH regulators in dissolved form, then precise and targeted application is achieved, but the process complexity increases due to solvent evaporation requirements and heat provision

Engineering Contradiction:
Improveprecision of pH regulator applicationVSAvoidcomplexity of evaporation process
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent changes the physical state of the pH regulator from dissolved (requiring evaporation) to molten (applicable as hot melt). By using adipic acid with a melting point of 152°C, the pH regulator can be applied in a molten state that solidifies in place, eliminating the need for solvent evaporation and heat provision while maintaining precise targeted application.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs a disposable incontinence article where the pH regulator is integrated into the product structure. The adipic acid is incorporated into the absorbent body or distribution layer during manufacturing, serving its pH regulation function throughout the product's service life without requiring complex recovery or evaporation processes.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Productivity

If citric acid is provided in particle form for high-speed production, then production speed is improved, but manufacturing precision deteriorates due to difficulty in precise and targeted application

Engineering Contradiction:
Improveproduction speedVSAvoidprecision of pH regulator application
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent changes the physical state of the pH regulator from solid particles to molten adhesive. The adipic acid is applied as a hot melt that is liquid during application and solidifies in place, enabling precise targeted application even at high production speeds of 200-400 m/min. The molten state allows for continuous application while maintaining precision.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite material system where adipic acid is combined with a polyvinyl acetate-ethylene emulsion copolymer latex binder. This composite allows the pH regulator to be applied as a unified molten adhesive that solidifies, combining the precision of targeted application with the efficiency of high-speed production.

Inventive Principle:
Principle #40Composite materials

3Manufacturing precision

If citric acid is applied in dissolved form, then precise application is achieved, but harmful factors increase due to solvent evaporation causing corrosion and safety issues

Engineering Contradiction:
Improveprecision of pH regulator applicationVSAvoidcorrosion and safety hazards from solvent evaporation
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent extracts and eliminates the solvent component from the pH regulator application system. Instead of using dissolved citric acid requiring evaporation, the invention uses adipic acid in molten form that solidifies in place, removing the harmful evaporation step entirely and eliminating corrosion and safety hazards associated with hot steam.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent employs a disposable incontinence article where the pH regulator is integrated into the product structure. The adipic acid is incorporated into the absorbent body or distribution layer during manufacturing, serving its pH regulation function throughout the product's service life without requiring complex recovery or evaporation processes.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

4Reliability

If adipic acid is used as pH regulator without melting point depressant, then pure pH regulation effect is achieved, but application difficulty increases due to high melting point of 152°C

Engineering Contradiction:
ImprovepH regulation effectivenessVSAvoidease of application process
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent introduces a melting point depressant as an intermediary substance that modifies the physical properties of adipic acid. The depressant lowers the melting point of adipic acid from 152°C to a more manageable range, enabling easier application while the adipic acid maintains its pH regulation function. The depressant acts as a mediator that facilitates processing without compromising the pH regulation effectiveness.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

This approach enables a stable and efficient pH regulation in incontinence products, reducing the risk of skin irritation, improving the distribution of the pH regulator, and facilitating production at high speeds while maintaining product quality and safety.

Implementation Method 1

a melting point depressant, in particular polyethylene glycol or glycerin, which lowers the melting temperature of the adipic acid

Methodology Applied
Scientific EffectMelting point depression: Melting

Implementation Method 2

at least one of the aforementioned components comprises a pH regulating agent with adipic acid

Methodology Applied
Scientific EffectpH regulation: Chemical Bonding

Data Source

PatentEP4302738B1Absorbent incontinence article as disposable product and method of manufacturing the incontinence article
Publication Date: 2025.06.11 PAUL HARTMANN AG
  • EP4302738B1 patent drawingFigure 1
  • EP4302738B1 patent drawingFigure 2
  • EP4302738B1 patent drawingFigure 3

AI summary

Absorbent incontinence product (10) as a single-use product, comprising a fluid-permeable topsheet (14), an absorbent core (16) arranged underneath for the absorption and permanent storage of fluid bodily excretions, a backsheet (18) arranged underneath which is fluid-impermeable at least in a central area, and preferably a fluid absorption and distribution layer (20) arranged between the topsheet (14) and the absorbent core (16). At least one of the aforementioned components (12) comprises a pH regulator (22) with adipic acid.