Hair Coloring Method Using Sequential pH Agents

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Solution Overview

Problem

Acid dyes used for hair coloring often result in significant skin coloring due to their acidic pH requirements, which can be undesirable and damaging to hair.

Innovation Solution

A method involving a sequential treatment process where a hydrous pre-treatment agent with an acidic pH is applied to hair, followed by a hydrous coloring agent with a neutral to basic pH containing acid dyes, minimizing skin coloring while achieving intense hair color.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If acid dyes with low pH (less than 5, preferably less than 3) are used for intense hair coloring, then the hair color intensity is improved, but skin coloring becomes pronounced and harmful

Engineering Contradiction:

Improvehair color intensityVSAvoidskin coloring

Core Design Contradiction:

Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

The patent divides the coloring process into two separate agents: a pre-treatment agent (applied first) and a coloring agent (applied second). The pre-treatment agent creates acidic conditions on the hair surface, while the coloring agent contains the acid dyes at neutral to basic pH. This segmentation allows the harmful low-pH environment to be confined only to the hair treatment zone, preventing skin coloring while maintaining intense hair coloration.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention creates a localized acidic environment on the hair surface through the pre-treatment agent, rather than applying acid throughout the entire coloring system. This local quality change ensures that the acidic conditions necessary for intense acid dye uptake are present only where needed (on the hair), while the surrounding skin areas remain unaffected by low pH.

Inventive Principle:

Principle #3Local quality

2Device complexity

If a single coloring agent containing acid dyes at low pH is used, then the process simplicity is maintained, but the skin coloring effect is pronounced

Engineering Contradiction:

Improvecoloring process complexityVSAvoidskin coloring

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent segments the single coloring agent into two separate agents: a pre-treatment agent and a coloring agent. While this increases the number of components, it eliminates the harmful skin coloring effect while maintaining the simplicity of application (both agents are applied in sequence without complex equipment).

Inventive Principle:

Principle #1Segmentation

3Stability of the object's composition

If oxidation dyes are used for permanent coloring, then the color stability is improved, but hair damage increases

Engineering Contradiction:

Improvecolor stabilityVSAvoidhair damage

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The patent changes the pH parameter of the coloring environment to achieve stable acid dye fixation without requiring oxidation. By maintaining acidic conditions on the hair surface through pre-treatment, the acid dyes can penetrate and bind to the hair keratin effectively, providing permanent coloring results similar to oxidation dyes but without the harsh chemical damage associated with peroxide-based oxidation systems.

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

This approach allows for intense hair coloring with reduced skin coloring and potentially less hair damage by controlling the pH environment for optimal dye uptake.

Implementation Method 1

the coloring effect of acid dyes depends heavily on the pH value. In order to achieve an intense color result, the agents applied on the keratinous fibers must usually have a pH value of less than about 5.

Methodology Applied

Scientific EffectpH-dependent dye uptake: Absorption (physical)

Implementation Method 2

The pre-treatment agent is acidified, whereas the colorant contains at least one acid dye and has a neutral to basic pH. Use of the new method enables a reduction of skin coloring during dyeing with acid dyes.

Methodology Applied

Scientific EffectpH gradient control: Diffusion

Data Source

PatentUS10632055B2Method and kit for coloring of hair with acid dyes

Publication Date: 2020.04.28 HENKEL KGAA

AI summary

The subject of the present disclosure is a method for coloring of keratinous fibers, particularly human hair, including the following steps in the specified sequence:A) Treatment of the fibers with a hydrous pre-treatment agent (V),B) Treatment of the fibers with a hydrous coloring agent (F),whereinthe pre-treatment agent (V) has a pH value of from about 1.0 to about 5.0 andthe coloring agent (F) has at least one partially-oxidizing acid dye and a pH value of from about 5.0 to about 9.5. An additional subject of the present disclosure is a multi-component package unit (kit) including a pre-treatment agent (V) and a coloring agent (F).