Quaternized Cellulose Ether Thickening Personal Care Formulations
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Solution Overview
Problem
Current rheological modifiers for personal care products exhibit poor thickening efficiency, surfactant compatibility, and undesirable characteristics such as reduced spreadability and viscosity loss at increased temperatures, which affect consumer perception and product differentiation.
Innovation Solution
A combination of surfactants including ammonium laureth sulfate, ammonium lauryl sulfate, sodium laureth sulfate, decylglucoside, and cocamidopropyl betaine, with a derivatized quaternized hydroxyethyl cellulose ether having fewer than 4000 anhydroglucose repeat units, an average substitution level of hydrophobic substituents from 0.005 to 0.3 moles per mole of anhydroglucose unit, and a nitrogen percentage from 0.3 to 3.0, where the average substitution level of hydrophobic substituents is less than cationic substituents, is used to enhance viscosity without increasing stringiness or reducing spreadability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If known polymeric thickeners are used, then viscosity is increased, but thickening efficiency is poor and surfactant compatibility is poor
Solution Approach 1:
The patent applies parameter changes by modifying the chemical structure of cellulose ethers through specific quaternization and hydroxyethylation degrees, molecular weight ranges (50,000-5,000,000 g/mol), and substitution patterns to achieve both high viscosity and surfactant compatibility. The cationic charge density and hydrophobic substituent levels are precisely controlled to optimize performance with anionic surfactants.
Solution Approach 2:
The invention uses composite materials by creating quaternized hydroxyethyl cellulose ethers that combine cationic charged groups with hydrophobic substituents on a cellulose backbone. This composite structure enables simultaneous interaction with surfactant molecules through electrostatic attraction and hydrophobic association, resolving the compatibility issue while maintaining thickening efficiency.
2Reliability
If associative thickeners are used, then surfactant compatibility is improved, but spreadability is reduced and lather/foam is reduced
Solution Approach 1:
The patent applies local quality by creating specific regions on the cellulose polymer chain with different functional characteristics - cationic charged regions for surfactant binding and controlled hydrophobic regions for moderate association. The substitution levels are locally optimized to provide surfactant compatibility in micellar regions while maintaining adequate spreadability in the bulk polymer structure.
Solution Approach 2:
The invention uses partial action by implementing moderate quaternization and hydroxyethylation rather than complete substitution. The controlled substitution levels (specific ranges of cationic charge and hydrophobic content) provide sufficient surfactant compatibility without excessive associative thickening that would harm spreadability and lather performance.
3Quantity of substance
If rheological modifiers are used to increase viscosity, then thickening efficiency is improved, but viscosity maintenance at increased temperatures deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-establishing strong electrostatic interactions between cationic cellulose ether groups and anionic surfactant head groups, forming stable complexes before temperature increases occur. These pre-formed associations create a robust network structure that resists thermal disruption, maintaining viscosity at elevated temperatures.
Solution Approach 2:
The invention utilizes the three-dimensional network structure formed by the quaternized cellulose ether, where the polymer chains adopt curved, space-filling conformations that create a gel-like matrix. This curved architecture provides thermal stability by distributing stress uniformly throughout the structure, preventing collapse at elevated temperatures.
4Quantity of substance
If quaternized cellulose ether with high substitution level is used, then thickening efficiency is improved, but stringiness increases
Solution Approach 1:
The patent replaces mechanical entanglement-based thickening with electrostatic and hydrophobic interactions. The cationic charged groups and hydrophobic substituents create non-mechanical association points that thicken the formulation through molecular attraction rather than physical chain entanglement, reducing stringiness while maintaining thickening efficiency.
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 provides high thickening efficiency, maintains viscosity at elevated temperatures, and improves sensory appeal and lather performance of personal care products, including enhanced skin and hair feel, while being cosmetically acceptable and non-toxic.
Implementation Method 1
an average substitution level of hydrophobic substituents from about 0.005 to about 0.3 moles of substituent per mole of anhydroglucose unit
Implementation Method 2
a nitrogen percentage from about 0.3 to about 3.0, provided that the average substitution level of hydrophobic substituents is less than the average substitution level of cationic substituents
Implementation Method 3
maintains viscosity at elevated temperatures
Implementation Method 4
improves sensory appeal and lather performance of personal care products
Data Source
AI summary
Quaternized cellulose ethers suitable for personal care products are described.