Grit-Free Solid Cleansing Bars via Fine Powder Surfactant
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Solution Overview
Problem
Conventional soap bars are highly alkaline, disrupting skin pH and causing dryness, while sulfate-based surfactants further irritate the skin, leading to the formation of 'grits' in solid cleansing compositions due to the hard nature of sodium cocoyl isethionate and its poor solubility.
Innovation Solution
A one pot process involving the blending of hydrogenated vegetable oil, glycerine, sodium O-acyl isethionates in fine powder form, polyglyceryl ester, N-acyl glycines, and minimal water to create a 'grit-free' solid cleansing composition without the need for high temperature emulsification or excess water.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If sodium O-acyl isethionate is used as the major surfactant in solid cleansing compositions, then the harshness and skin irritation caused by conventional soaps and sulfate surfactants is reduced, but the surfactant's hard nature and poor solubility lead to formation of grits on the product surface
Solution Approach 1:
The patent applies parameter changes by controlling the particle size of sodium O-acyl isethionate to be less than 250 μm (fine powder form) and maintaining processing temperature between 90-95°C. These parameter modifications enable the surfactant to soften properly without forming grits, while preserving its skin-friendly properties. The fine particle size increases surface area for better wetting and softening, and the controlled temperature ensures complete softening without degradation.
Solution Approach 2:
The patent creates a composite material system by combining sodium O-acyl isethionate with hydrogenated vegetable oil (30-40%), glycerin (4-10%), polyglyceryl ester (5-12%), and N-acyl glycine (0.4-4%). This composite formulation leverages the emollient and softening properties of the oil and humectant components to counteract the hard nature of the surfactant, preventing grit formation while maintaining skin benefits.
2Object-affected harmful factors
If high quantity of hydrophobic emollient oils is incorporated to improve skin conditioning, then the emollience is enhanced, but the solubility of sodium O-acyl isethionate is further hindered leading to increased grit formation
Solution Approach 1:
The patent maintains processing temperature at 90-95°C, which is sufficiently high to soften both the hydrophobic emollient oils and the sodium O-acyl isethionate simultaneously. This temperature parameter ensures that even with high oil content (30-40%), the surfactant particles remain soft and do not form grits during processing and application.
Solution Approach 2:
The patent adds sodium O-acyl isethionate in fine powder form (<250 μm) to the already heated mixture of hydrogenated vegetable oil and glycerin. This preliminary preparation of the oil phase at processing temperature before adding the surfactant ensures immediate softening and uniform distribution, preventing grit formation even with high emollient content.
3Manufacturing precision
If conventional emulsification process with excess water and high temperature is used to soften sodium O-acyl isethionate, then grit formation is avoided, but hydrolysis of the surfactant occurs and energy consumption increases
Solution Approach 1:
The patent optimizes the water content to a minimal amount (less than 5%) and maintains processing temperature at a moderate 90-95°C. This parameter combination is sufficient to soften the fine powder surfactant and prevent grit formation without providing excess water for hydrolysis or excessive temperature for energy waste, unlike conventional emulsification processes.
Solution Approach 2:
The patent extracts the essential function of water (to facilitate softening and processing) while removing the excessive amount used in conventional emulsification. By using only the minimum water needed for processing (less than 5%), the patent achieves grit-free production without creating conditions for hydrolysis or unnecessary energy consumption for heating and evaporating large water volumes.
4Ease of manufacture
If sodium O-acyl isethionate is used in flake or noodle form with 80-85% active matter, then the surfactant is readily commercially available, but the unsoftened particles appear as grits on the product surface
Solution Approach 1:
The patent changes the particle size parameter of sodium O-acyl isethionate from conventional flake or noodle forms to fine powder form with particle size less than 250 μm. This parameter change dramatically increases the surface area to volume ratio, enabling rapid and complete softening at 90-95°C without forming grits, while still using commercially available surfactant material.
Solution Approach 2:
The patent performs preliminary size reduction of the surfactant to fine powder form before incorporation into the formulation. This preliminary action ensures that when the surfactant is added to the heated oil-glycerin mixture, the fine particles can be completely softened and integrated without leaving unsoftened grits, while maintaining ease of manufacture through use of commercially available material that can be milled to fine powder.
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 process results in solid cleansing bars with high vegetable oil content that are free from grits, maintaining skin pH and reducing skin irritation, while also avoiding the hydrolysis of surfactants and minimizing energy consumption.
Implementation Method 1
mixing component a) and b) at temperature between 90 to 95° C., to afford a homogenous mass
Implementation Method 2
cooling the reaction mass of step B and adding components d) to f) followed by kneading to afford an amalgamated mass
Implementation Method 3
adding component c) to the homogenous mass of step A to obtain a reaction mass
Data Source
AI summary
The invention relates to a one pot process for preparing a ‘grit-free’ solid cleansing composition. The composition has pH resembling to skin pH which comprises hydrogenated triglyceride oil/s, humectant, sodium O-acyl isethionate as anionic surfactant, polyglyceryl ester, N-acyl glycine/s, water and, skin benefit agents and/or hair benefit agents. This is accomplished by a unique process using sodium O-acyl isethionates of particle size less than 250 μm.