Water-in-oil Antiperspirant Emulsion Stability

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Solution Overview

Problem

Water-in-oil emulsion antiperspirant compositions often face challenges in achieving effective antiperspirancy performance and storage stability, particularly when using activated basic aluminium chloride (BAC) antiperspirant actives.

Innovation Solution

A water-in-oil emulsion antiperspirant composition is developed using aluminium sesquichlorohydrate (ASCH) with a specific molar ratio of calcium to aluminium and an amino acid, such as glycine, which is heat-activated to enhance antiperspirancy performance and storage stability, incorporating a silicone oil continuous phase and non-ionic emulsifier system for improved stability and sensory properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If water-in-oil emulsion compositions are formulated with activated BAC antiperspirant actives, then antiperspirancy performance is improved, but storage stability deteriorates

Engineering Contradiction:
Improveantiperspirancy performanceVSAvoidstorage stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent changes the chemical parameters of the BAC salt by selecting specific aluminium to chloride molar ratios (1.25:1 to 1.82:1, preferably 1.54:1 to 1.82:1) and controlling the activation conditions (temperature, time, calcium to aluminium molar ratio of at least 1:20). These parameter changes optimize both the antiperspirancy performance (Band III content of at least 30%) and storage stability of the composition simultaneously.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If heat activation is applied to enhance antiperspirancy performance, then Band III content increases, but manufacturing complexity increases

Engineering Contradiction:
Improveantiperspirancy performanceVSAvoidmanufacturing process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent performs preliminary heat activation of the BAC salt with calcium salt and amino acid before formulating the final water-in-oil emulsion. This preliminary action converts the BAC salt into its activated form with enhanced antiperspirancy properties, simplifying the overall manufacturing process by separating the activation step from the emulsion formulation step.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The activation process uses controlled parameter changes including heating to specific temperatures, maintaining specific molar ratios (calcium to aluminium at least 1:20, amino acid to aluminium at least 1:10), and controlling activation time to achieve the desired Band III content while managing process complexity.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If amino acid and calcium salt are added to activate BAC, then antiperspirancy performance is improved, but formulation complexity increases

Engineering Contradiction:
Improveantiperspirancy performanceVSAvoidformulation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the activation components (calcium salt and amino acid) with the BAC salt in a single activation step before emulsion formulation. This combining approach simplifies the overall formulation process by integrating multiple functions (activation, stabilization) into unified steps rather than separate operations.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent optimizes the concentrations and molar ratios of the added components (calcium to aluminium molar ratio at least 1:20, amino acid to aluminium molar ratio at least 1:10) to achieve effective activation while controlling formulation complexity. These parameter optimizations ensure enhanced antiperspirancy performance without excessive complexity.

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 achieves high antiperspirancy performance and remarkable storage stability, maintaining effectiveness for several months, with a Band III content of at least 30% and viscosity optimized for flow and stability, significantly outperforming comparative examples in sweat weight reduction and high-temperature stability tests.

Implementation Method 1

The activation mixture is heated to a temperature of from 65°C to 95°C for a period of from 1 hour to 24 hours

Methodology Applied
Scientific EffectHeat treatment: Heating

Implementation Method 2

emulsifying the resulting solution into an oily continuous phase

Methodology Applied
Scientific EffectEmulsion: Emulsion

Data Source

PatentEP3399958B1Antiperspirant compositions
Publication Date: 2020.05.06 UNILEVER PLC

AI summary

Water-in-oil emulsion antiperspirant compositions and their method of manufacture wherein a basic aluminium chloride salt of formula Al2OH4.4Cl1.6 to Al2OH4.9Cl1.1 is heat activated with a water-soluble calcium salt and amino acid, and the resulting solution is emulsified into an oily continuous phase.