Substrate-Based Depilatory Article With pH Control

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Solution Overview

Problem

Substrate-based depilatory products face challenges in achieving effective hair removal while minimizing skin irritation, as they often provide lower doses of active ingredients and can cause harsh chemical conditions due to pH changes and water loss, leading to reduced efficacy and irritation.

Innovation Solution

A depilatory article with a water-impermeable substrate and an aqueous depilatory composition containing a water-soluble silicate and thioglycolate salt, which enhances hair removal efficacy while maintaining skin safety by controlling pH and preventing water loss, using a combination of monovalent and divalent metal cations to optimize the depilatory action.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If substrate-based depilatory products use low doses of active ingredients, then handling is improved and mess is reduced, but depilatory efficacy is reduced

Engineering Contradiction:
ImprovehandlingVSAvoiddepilatory efficacy
Core Design Contradiction:
Ease of operationVSProductivity

Solution Approach 1:

The patent changes the chemical parameters of the active ingredient by using a specific salt form (ammonium thioglycolate) with controlled pH (8.5-10.5) and concentration (0.1-10%). This allows the substrate-based product to maintain effective depilatory action while using low doses of active ingredients, resolving the contradiction between ease of operation and productivity

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite depilatory composition containing ammonium thioglycolate salt combined with buffering agents and conditioning ingredients. This composite formulation enhances the effectiveness of low-dose active ingredients on substrate, enabling both easy handling and adequate depilatory efficacy

Inventive Principle:
Principle #40Composite materials

2Productivity

If monovalent metal cations are used in thioglycolate salts, then depilatory efficacy is improved, but skin irritation increases due to pH increase and faster skin penetration

Engineering Contradiction:
Improvedepilatory efficacyVSAvoidskin irritation
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent uses ammonium ion as an intermediary cation in the thioglycolate salt. Ammonium acts as a buffer that controls pH levels and moderates the interaction with skin tissue, providing effective depilatory action while reducing skin irritation compared to monovalent metal cations like potassium

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent carefully controls the pH parameter of the composition (8.5-10.5) and the concentration of ammonium thioglycolate (0.1-10%). By optimizing these parameters, the patent achieves effective hair removal while minimizing skin penetration and irritation, resolving the contradiction between productivity and harmful factors

Inventive Principle:
Principle #35Parameter changes

3Productivity

If water is lost from the composition before or during use, then concentration of active ingredients increases and depilatory action is enhanced, but skin irritation is exacerbated

Engineering Contradiction:
Improvedepilatory actionVSAvoidskin irritation
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent incorporates buffering agents and pH-controlled formulations beforehand to cushion against pH increases that would result from water loss. This pre-protection mechanism ensures that even if water evaporates during storage or application, the pH remains within safe ranges (8.5-10.5), preventing excessive skin irritation while maintaining depilatory efficacy

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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 provides a desirable level of depilatory efficacy while being mild on the skin, reducing irritation and maintaining the effectiveness of the depilatory action, as demonstrated by increased hair removal and controlled pH levels.

Implementation Method 1

a water-impermeable substrate and an aqueous depilatory composition

Methodology Applied
Scientific EffectWater impermeability: Physical Containment

Implementation Method 2

comprise reducing agents to degrade keratin in the hair and thus weaken the hair strands

Methodology Applied
Scientific EffectChemical reduction: Reduction

Implementation Method 3

aqueous depilatory composition containing a water-soluble silicate and thioglycolate salt, which enhances hair removal efficacy while maintaining skin safety by controlling pH

Methodology Applied
Scientific EffectpH buffering:

Data Source

PatentEP2356968B1Substrate-based depilatory article
Publication Date: 2012.06.20 PROCTER & GAMBLE CO
  • EP2356968B1 patent drawingFigure 1~2
  • EP2356968B1 patent drawingFigure 3

AI summary

A depilatory article comprising a water impermeable substrate and an aqueous depilatory composition, the aqueous depilatory composition being in physical contact with the water impermeable substrate, forming a coated region of the water impermeable substrate and comprising a thioglycolate salt, a water-soluble or colloid-forming silicate, and a divalent metal cation.