Cationic Hair Dye Composition for Light and Shampoo Fastness

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Solution Overview

Problem

Current hair dyes, particularly cationic dyes, face challenges with color fastness to light and shampoo fastness, leading to undesirable fading and unevenness in hair color.

Innovation Solution

A hair dye composition containing a compound represented by the general formula (I), which is a blue cationic dye, offering excellent dyeing properties, light fastness, and shampoo fastness, and can be used in a wide pH range without auxiliary agents, along with optional additives like surfactants and oxidants for enhanced performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a cationic dye is used for hair dyeing, then dyeing properties and water solubility are improved, but color fastness to light and shampoo fastness deteriorate

Engineering Contradiction:

Improvedyeing propertiesVSAvoidcolor fastness to light and shampoo fastness

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent modifies the molecular structure of the cationic dye by introducing specific substituents (R1 and R2 groups) at positions 2 and 6 of the phenothiazine ring. These structural parameter changes enhance both the dyeing properties and color fastness simultaneously, resolving the contradiction between ease of manufacture and reliability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite dye molecule combining the phenothiazine core structure with specific alkyl or aryl substituents. This composite structure integrates the benefits of good water solubility and dyeing properties while adding stability for improved color fastness to light and shampoo fastness.

Inventive Principle:

Principle #40Composite materials

2Duration of action of stationary object

If an oxidative dye is used for hair dyeing, then color stability over long period is improved, but skin allergy reaction and hair damage occur

Engineering Contradiction:

Improvecolor stabilityVSAvoidskin allergy reaction and hair damage

Core Design Contradiction:

Duration of action of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The patent employs a direct-dyeing cationic dye that provides temporary coloration without the need for oxidative chemicals. This short-living coloring approach eliminates skin allergy reactions and hair damage associated with oxidative dyes, while still providing satisfactory color stability for cosmetic use.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The invention converts the typical weakness of direct dyes (poor fastness) into a benefit by using a cationic dye that specifically binds to keratin fibers. This binding mechanism provides sufficient color stability while avoiding the harmful effects of oxidative agents, effectively turning a limitation into an advantage.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Object-affected harmful factors

If an acidic dye is used for hair coloring, then allergic reactivity is reduced, but color fading occurs during washing

Engineering Contradiction:

Improveallergic reactivityVSAvoidcolor fading

Core Design Contradiction:

Object-affected harmful factorsVSDuration of action of stationary object

Solution Approach 1:

Instead of using an anionic acidic dye that fades during washing, the patent inverts the approach by using a cationic dye. The positive charge of the cationic dye enables strong electrostatic interaction with negatively charged keratin fibers, preventing color fading during washing while maintaining low allergic reactivity.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the charge parameter of the dye from negative (acidic dye) to positive (cationic dye). This parameter change fundamentally alters the interaction mechanism with hair fibers, providing both low allergic reactivity and improved color fastness during washing.

Inventive Principle:

Principle #35Parameter changes

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 hair dye composition provides superior color retention and stability against light and shampoo exposure, maintaining vibrant color and reducing unnatural fading, while being suitable for both direct and oxidative hair dyeing methods.

Implementation Method 1

a main dye of these hair manicure and color conditioner is an acidic dye used in cosmetics. Since the acidic dye has low allergic reactivity as compared with the above described oxidative dye

Methodology Applied

Scientific EffectElectrostatic attraction: Ion Repulsion/Attraction

Implementation Method 2

a colorless precursor substance is given to hair and this precursor substance is oxidation-polymerized to form a massive coloring substance

Methodology Applied

Scientific EffectOxidation-polymerization: Oxidation

Data Source

PatentEP2193781B1Hair dye and hair dye composition

Publication Date: 2014.01.22 HODOGAYA CHEMICAL CO LTD

Figure 1

AI summary

A hair dye containing a compound represented by the following general formula (I): [Chemical Formula 1] wherein R1 and R2 each independently represent a hydrogen atom or a straight chain or branched alkyl group having 1 to 5 carbon atoms, and An- represents an inorganic anion, an organic anion, or a complex salt anion, respectively.