Structured Surfactant Suspensions for Personal Care
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Solution Overview
Problem
Formulating suspensions of water-insoluble solids and oils in personal care compositions, such as shampoos and body washes, poses challenges due to sedimentation issues, and existing solutions like gums and polymeric thickeners either fail to prevent sedimentation or make compositions unpourable, while high foaming surfactant systems require high surfactant and electrolyte concentrations that are undesirable.
Innovation Solution
A transparent structured surfactant system is developed using a mixture of surfactants with specific HLB values, forming multilamellar vesicles without electrolytes or carbohydrates, which provides stable suspension and transparency, allowing for the immobilization of particles and maintaining a pourable consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gums or polymeric thickeners are used to raise the viscosity of the liquid medium, then the sedimentation of particles is retarded, but the composition becomes harder to pour and does not provide stable suspensions
Solution Approach 1:
The patent changes the physical-chemical parameters of the suspending medium by using structured surfactant systems with specific HLB values (11-13) to form liquid crystalline phases. This approach provides stable suspension without requiring high viscosity, thus maintaining pourability while achieving reliable particle immobilization through the structured mesophase formation.
Solution Approach 2:
The patent employs composite surfactant systems combining multiple surfactants with complementary HLB values to create structured suspending systems. This composite approach allows the system to provide both suspension stability and pourability by forming liquid crystalline structures that can immobilize particles while maintaining fluidity for easy pouring.
2Reliability
If conventional Lα-phase structured surfactants are used to form suspending systems, then particles can be immobilized, but the systems become unpourable with useful quantities of solid or experience sedimentation with smaller amounts
Solution Approach 1:
The patent optimizes the HLB parameter of the surfactant system (specifically 11-13) to achieve the right balance between particle immobilization and pourability. This parameter optimization allows the structured system to maintain liquid crystalline phases that can suspend particles effectively while remaining pourable, overcoming the limitations of conventional Lα-phase systems.
Solution Approach 2:
The patent creates a multi-functional surfactant system that simultaneously provides particle immobilization, suspension stability, and pourability. The structured surfactant system with HLB 11-13 performs multiple functions: forming liquid crystalline phases for particle entrapment, maintaining system stability, and ensuring easy pouring, thus resolving the contradiction between immobilization and operability.
3Reliability
If high foaming surfactant systems are used to suspend particles, then good skin feel and dense stable foams are achieved, but high concentrations of surfactant and electrolyte are required which are undesirable
Solution Approach 1:
The patent changes the HLB parameter to a specific range (11-13) that enables high foaming surfactant systems to form structured liquid crystalline phases at lower concentrations. This parameter optimization allows the system to achieve both good foam stability and skin feel while reducing the required surfactant and electrolyte concentrations to desirable levels.
Solution Approach 2:
The patent uses composite surfactant systems with complementary HLB values that synergistically enhance foam stability and structured phase formation. This composite approach allows the system to achieve high foaming performance and particle suspension at reduced surfactant concentrations, eliminating the need for high electrolyte levels and providing a more desirable formulation.
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 achieves stable suspension of solid, liquid, or gaseous particles without sedimentation, maintaining transparency and pourability, and is suitable for personal care compositions, offering aesthetically pleasing visual effects and improved skin and hair compatibility.
Implementation Method 1
Surfactants and water interact to form phases that are neither liquids nor crystals; these are usually termed 'liquid crystal phases,' or alternatively 'mesomorphic phases' or 'mesophases.'
Implementation Method 2
structured surfactant systems that are capable of suspending solid particles and oils without sedimentation
Implementation Method 3
the structured surfactant system is comprised of multilamellar vesicles with a droplet size of less than 2500 angstroms and a bilayer spacing below 60 angstroms
Data Source
Figure 1
AI summary
A structured surfactant system with a very high degree of clarity. The system comprises water and a mixture of at least one surfactant having a HLB (Hydrophilic Lipophilic Balance) value of less than 10, and at least one surfactant having an HLB value of 10 or greater. The structured surfactant system forms multilamellar vesicles and has suspending properties without added electrolytes, carbohydrates, or polymeric thickeners. This makes the structured surfactant system particularly useful in personal care compositions.