Ethanol-Stable O/W Emulsion via Phase Inversion
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Solution Overview
Problem
Conventional oil-in-water emulsion bases for cosmetics lack stability when a high amount of ethanol is added, resulting in inadequate water resistance after application.
Innovation Solution
Incorporating 5-50% ethanol, a polyether-modified silicone with an HLB(Si) of 5-10, a hydrophilic thickening agent, and a polyol into the emulsion to create a stable oil-in-water emulsion that phase-inverts to a water-in-oil type post-application, enhancing water resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high amount of ethanol is added to an oil-in-water emulsion base, then the composition can provide excellent water resistance after application, but the emulsified particles are disrupted and stability deteriorates
Solution Approach 1:
The patent changes the HLB parameter of the surfactant from conventional values (>10) to a specific range (5-10), which fundamentally alters the emulsion's response to ethanol. This parameter change enables the emulsion to maintain stability with up to 50% ethanol while achieving water resistance through phase inversion after application.
Solution Approach 2:
The patent uses a composite surfactant system combining polyether-modified silicone with specific HLB characteristics and conventional surfactants. This composite approach creates synergistic effects that simultaneously provide emulsion stability in high ethanol content and water resistance through controlled phase inversion.
2Ease of operation
If conventional surfactants with HLB of 10 or more are used in oil-in-water emulsion, then the emulsion provides good moistness feeling, but water resistance is not satisfactory
Solution Approach 1:
The patent fundamentally changes the HLB parameter from conventional values (≥10) to a novel range (5-10), enabling the emulsion to provide both moistness during application and water resistance after application through phase inversion mechanism.
Solution Approach 2:
The patent creates a dynamic emulsion system that can transition between different states: maintaining oil-in-water structure for moistness during application, then inverting to water-in-oil structure for water resistance after application. This dynamic behavior is enabled by the specific HLB(Si) range.
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 emulsion provides a moist feel during application and excellent water resistance post-application, along with improved UV screening when a UV absorbent is added, making it suitable for skin care and makeup compositions.
Implementation Method 1
using a polyether-modified silicone having an HLB(Si) of 5 to 10 as a surfactant
Implementation Method 2
after being applied to the skin or the like, as the composition undergoes a phase inversion to a water-in-oil type in accordance with evaporation of ethanol
Data Source
AI summary
Disclosed is an oil-in-water emulsion base which is stable even when ethanol in an amount of 50% by mass or less is blended therein and which exhibits excellent water resistance after being applied to the skin or the like. Specifically disclosed is an oil-in-water emulsified cosmetic composition which is characterized by containing (A) 0.1-10% by mass of a polyether-modified silicone having an HLB(Si) of 5-10, (B) 5-50% by mass of ethanol, (C) 0.01-3% by mass of a hydrophilic thickening agent and (D) 0.1-15% by mass of a polyol. Preferably, the oil-in-water emulsified cosmetic composition additionally contains a UV absorbent, thereby forming a sunscreen cosmetic composition.