Polymeric Microcapsules for Cetylpyridinium Chloride Stability

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Solution Overview

Problem

Polymeric microcapsules used in dentifrices do not effectively protect active ingredients like cetylpyridinium chloride (CPC) from incompatible ingredients such as sodium lauryl sulfate, and they lack sufficient mechanical, temperature, and chemical stability to maintain integrity during toothpaste production and storage, while also failing to provide extended release profiles.

Innovation Solution

Encapsulating quaternary ammonium salts, such as CPC, within polymeric microcapsules of specific diameters (5-50 microns) using a water-in-oil emulsion method, which involves dissolving the salt in an aqueous phase, dispersing it in a hydrophobic solvent, and evaporating the solvent to form stable microcapsules that remain intact under shear forces, temperature variations, and chemical interactions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If polymeric microcapsules are used to encapsulate quaternary ammonium salt, then protection of active ingredient from external environment is improved, but mechanical stability to sustain shear forces during mixing and filling deteriorates

Engineering Contradiction:

Improveprotection of active ingredientVSAvoidmechanical stability

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent modifies the chemical composition parameters of the polymer shell by incorporating specific functional groups and adjusting polymer molecular weight and crosslinking density. These parameter changes enable the shell to achieve both protective encapsulation and mechanical stability under shear forces during toothpaste manufacturing processes.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If polymeric microcapsules are designed for chemical stability in presence of sodium lauryl sulfate, then chemical stability is improved, but temperature stability at elevated temperatures deteriorates

Engineering Contradiction:

Improvechemical stabilityVSAvoidtemperature stability

Core Design Contradiction:

Stability of the object's compositionVSTemperature

Solution Approach 1:

The patent employs composite polymer shell structures combining multiple polymer components with complementary properties. The composite material design provides resistance to sodium lauryl sulfate while maintaining thermal stability during high-speed filling processes that generate heat and expose capsules to elevated temperatures.

Inventive Principle:

Principle #40Composite materials

3Duration of action of moving object

If microcapsules are made to break during brushing for release, then release of active ingredient is improved, but protection during storage and manufacturing deteriorates

Engineering Contradiction:

Improveextended release profileVSAvoidintegrity during storage

Core Design Contradiction:

Duration of action of moving objectVSReliability

Solution Approach 1:

The patent creates a dynamic shell structure with controlled mechanical properties that responds differently to sustained versus transient stresses. The shell maintains integrity under storage conditions and manufacturing shear forces but is designed to fracture under the specific mechanical action of toothbrush bristles during brushing, enabling extended release while preserving protection during storage.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent introduces spatial variations in shell properties, creating regions of different thickness, crosslinking density, or polymer composition within the microcapsule shell. This local quality differentiation allows the shell to maintain overall structural integrity for protection during storage while having specific vulnerable regions that facilitate controlled breakage and extended release during brushing.

Inventive Principle:

Principle #3Local quality

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 encapsulation method provides stable CPC release over 24 hours, prevents adverse interactions with dentifrice ingredients, and ensures mechanical and chemical stability, allowing for effective antimicrobial delivery during brushing.

Implementation Method 1

dispersing the aqueous phase within a hydrophobic organic solvent having a dissolved polymer to form a solution

Methodology Applied

Scientific EffectEmulsion: Emulsion

Implementation Method 2

removing the solvent from the external aqueous phase of step (c) to form quaternary ammonium salt encapsulated polymeric microcapsules

Methodology Applied

Scientific EffectEvaporation: Evaporation

Implementation Method 3

stirring the emulsion of step (b) at elevated temperatures to evaporate the aqueous phase and form quaternary ammonium salt encapsulated polymeric microcapsules

Methodology Applied

Scientific EffectEvaporation: Evaporation

Data Source

PatentUS8178483B2Polymeric encapsulates having a quaternary ammonium salt and methods for producing the same

Publication Date: 2012.05.15 COLGATE PALMOLIVE CO

AI summary

A quaternary ammonium salt encapsulated by a polymeric microcapsule and methods for manufacturing such microcapsules are described. The quaternary ammonium salt can be cetylpyridinium chloride. The polymeric microcapsule encapsulating the quaternary ammonium salt can be used as an ingredient in a dentifrice.