Oil-in-Water Emulsion with Cationic Surfactant for Stability and Low Irritation

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Solution Overview

Problem

Existing oil-in-water Pickering emulsions face challenges in achieving stability against temperature and agitation variations, often resulting in sticky textures and skin irritation, especially when used in cosmetic applications.

Innovation Solution

An oil-in-water emulsion composition is developed, comprising a powder component, a water phase, and a specific amount of a cationic surfactant with two alkyl chains of a certain length, where the cationic surfactant is adsorbed on powder particles, enhancing emulsion stability and reducing skin irritation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a Pickering emulsion is prepared without surfactant by allowing powder to adsorb on the interface, then skin irritation is reduced, but emulsion stability against temperature and agitation is insufficient

Engineering Contradiction:
Improveskin irritationVSAvoidemulsion stability
Core Design Contradiction:
Object-affected harmful factorsVSStability of the object's composition

Solution Approach 1:

The invention changes the chemical composition parameters by introducing a cationic surfactant with specific alkyl chain lengths (12-22 carbon atoms) into the Pickering emulsion system. This parameter change resolves the contradiction by providing both the stability enhancement needed for temperature and agitation resistance and the low irritation profile required for cosmetic safety.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite emulsion system combining powder particles, cationic surfactant, oil phase, and water phase. This composite approach allows the surfactant to adsorb onto powder particles and stabilize the oil-water interface, achieving both stability and low irritation through synergistic interactions between components.

Inventive Principle:
Principle #40Composite materials

2Stability of the object's composition

If amphiphilic substance is blended to obtain Pickering emulsion, then emulsion stability is improved, but sticky feeling is caused in use

Engineering Contradiction:
Improveemulsion stabilityVSAvoidsticky feeling
Core Design Contradiction:
Stability of the object's compositionVSEase of operation

Solution Approach 1:

The invention changes the surfactant structure parameters by specifying cationic surfactants with two alkyl chains of 12-22 carbon atoms. This structural parameter change provides adequate emulsion stability while avoiding the excessive stickiness associated with other amphiphilic substances, achieving a balance between stability and sensory comfort.

Inventive Principle:
Principle #35Parameter changes

3Stability of the object's composition

If cationic surfactant with two alkyl chains of certain length is used, then emulsion stability is improved and sticky feeling is reduced, but precise control of surfactant amount and structure is required

Engineering Contradiction:
Improveemulsion stabilityVSAvoidsurfactant specification complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The invention defines specific parameter ranges for the cationic surfactant (two alkyl chains with 12-22 carbon atoms each) and optimizes the surfactant concentration (0.001-0.5 mass%). These parameter specifications provide a clear framework that balances emulsion stability requirements with ease of formulation, avoiding overly complex constraints while achieving reliable performance.

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 excellent emulsion stability, low sticky feeling, and low skin irritation, making it suitable for cosmetic applications such as sunscreens, makeup, and hair styling products.

Implementation Method 1

the (b) cationic surfactant is adsorbed on the (a) powder particles

Methodology Applied
Scientific EffectAdsorption: Adsorption

Implementation Method 2

powder particles are adsorbed on the oil droplets dispersed in the water phase

Methodology Applied
Scientific EffectAdsorption: Adsorption

Data Source

PatentEP2149361B1Oil-in-water emulsion composition and method for producing the same
Publication Date: 2014.07.23 SHISEIDO CO LTD
  • EP2149361B1 patent drawingFigure 1
  • EP2149361B1 patent drawingFigure 2
  • EP2149361B1 patent drawing

AI summary

The present invention provides an oil-in-water emulsion composition having excellent emulsion stability, low sticky feeling, and low skin irritation. The oil-in-water emulsion composition according to the present invention comprising (a) 1 to 20 mass % of a powder component, (b) 0.001 to 0.5 mass % of a cationic surfactant having two alkyl chains with 12 or more and 22 or less carbon atoms, (c) an oil phase component, and (d) a water phase component, having a structure wherein (a) powder particles are adsorbed on the oil droplets dispersed in the water phase.