Liquid Detergent Stability via Surfactant Ratios

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Solution Overview

Problem

Existing laundry detergent compositions with higher surfactant levels are unstable, which affects their ability to provide effective softening and cleaning benefits to textiles.

Innovation Solution

A liquid detergent composition comprising 6-40 wt.% nonionic surfactant, 6-20 wt.% anionic surfactant, 2-14 wt.% fatty acid or salt, and 0.2-1.5 wt.% cationic polysaccharide-based polymer, with a weight ratio of nonionic surfactant to fatty acid between 2.5:1 and 6:1, ensuring a total surfactant level of at least 25 wt.% and improved stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If higher surfactant levels are used in laundry detergent compositions, then cleaning effectiveness is improved, but formulation stability deteriorates

Engineering Contradiction:
Improvecleaning effectivenessVSAvoidformulation stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The invention changes the concentration parameters of multiple surfactant types simultaneously, maintaining total surfactant levels at 10-40% while optimizing the individual proportions of anionic (1-20%), nonionic (5-30%), and cationic (0.1-5%) surfactants. This parameter optimization resolves the contradiction by finding the stable concentration range that delivers effective cleaning without compromising formulation stability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses a composite surfactant system combining three different types of surfactants (anionic, nonionic, and cationic) with complementary properties. This composite approach allows the formulation to achieve both high cleaning effectiveness through synergistic action and improved stability through balanced interactions between different surfactant classes

Inventive Principle:
Principle #40Composite materials

2Reliability

If cationic polymer and anionic surfactant are combined for softening, then fabric softening is improved, but formulation stability deteriorates at higher surfactant levels

Engineering Contradiction:
Improvefabric softeningVSAvoidformulation stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The invention optimizes the concentration of cationic polymer (0.1-5%) relative to anionic surfactant (1-20%), maintaining a balanced ratio that enables effective fabric softening through polymer-surfactant interactions while preventing excessive precipitation or phase separation. This parameter control resolves the softening-stability contradiction

Inventive Principle:
Principle #35Parameter changes

3Reliability

If rinse-added conditioner compositions are used to increase fabric softness, then fabric softening is improved, but the process complexity increases

Engineering Contradiction:
Improvefabric softnessVSAvoidprocess complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention merges the softening function with the detergent wash cycle by incorporating softening agents directly into the laundry detergent formulation. This allows softening to occur during the main wash process, eliminating the need for separate rinse-adding steps and reducing process complexity while maintaining effective fabric softness

Inventive Principle:
Principle #5Merging (Combining)

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 composition provides enhanced softening, antistatic benefits, reduced wear and pilling, improved color retention, and a lubricating layer for fabric, while maintaining stability over time, resulting in a preferred 'softening in the wash' effect.

Implementation Method 1

a cationic polymer and anionic surfactant... The composition provides enhanced softening, antistatic benefits

Methodology Applied
Scientific EffectElectrostatic interaction: Ion Repulsion/Attraction

Implementation Method 2

a lubricating layer for fabric, while maintaining stability over time

Methodology Applied
Scientific EffectLubrication: Lubrication

Data Source

PatentEP2366009B1Laundry compositions
Publication Date: 2012.10.24 UNILEVER PLC

AI summary

The present invention relates to a liquid detergent composition comprising at least 25 wt.% surfactant, comprising (a) nonionic surfactant, (b) anionic surfactant, (c) fatty acid or salt thereof and (d) a cationic polysaccharide-based polymer, wherein weight ratio of (a) to (c) is from 2.5:1 to 6:1; the composition being useful in providing fabric softness during laundering.