Coloring composition for polyamides
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Solution Overview
Problem
Existing methods for coloring polyamide fibers, particularly in black or dark shades, rely on chromium-based dyes, which are toxic and pose environmental and health risks, and fail to achieve sufficient substantivity, ease of washing, and maintain fiber properties like elasticity.
Innovation Solution
A coloring composition comprising reactive dyes and sulfamic acid at a pH of 2 or below, preferably with sulfuric acid, is used to color polyamide fibers, avoiding chromium and ensuring efficient dye uptake without altering fiber properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chromium-based dyes are used to color polyamide fibers in black, then coloring efficiency is achieved, but toxicity and environmental harm increase
Solution Approach 1:
The invention extracts and removes chromium from the dyeing system entirely, replacing it with reactive dyes that function at low pH without requiring toxic heavy metals. This eliminates the harmful substance while maintaining the coloring function.
Solution Approach 2:
The invention changes the pH parameter from alkaline (typical for reactive dyes) to acidic (pH 2 or below), and modifies the dye chemistry to function under these conditions. This parameter change enables the use of non-toxic reactive dyes instead of chromium-based dyes.
2Object-affected harmful factors
If reactive dyes are used to color polyamide fibers, then chromium toxicity is eliminated, but substantivity and dye fixation remain insufficient
Solution Approach 1:
The invention changes the pH parameter to acidic conditions (pH 2 or below), which enhances the reactivity and substantivity of the modified reactive dyes on polyamide fibers. This parameter change enables sufficient dye fixation without chromium.
Solution Approach 2:
The invention uses a composite approach combining reactive dyes with specific chemical groups (vinyl sulfone, chlorotriazine) that are optimized for polyamide fiber interaction at low pH, creating a synergistic system that achieves both non-toxicity and sufficient substantivity.
3Object-affected harmful factors
If low pH conditions are applied to color polyamide fibers with reactive dyes, then chromium is eliminated, but fiber hydrolysis and damage may occur
Solution Approach 1:
The invention applies preliminary protection measures by using reactive dyes with specific chemical structures that are designed to be less aggressive toward polyamide fibers at low pH. The dye chemistry is pre-modified to minimize hydrolysis risk while maintaining reactivity.
Solution Approach 2:
The invention optimizes the pH parameter to a specific range (pH 2 or below) that is low enough to enable reactive dye fixation but controlled to minimize fiber damage. The process parameters are precisely tuned to balance dyeing efficiency with fiber protection.
4Ease of operation
If conventional reactive dyes designed for cotton are used on polyamide fibers, then ease of washing is improved, but coloring efficiency on polyamide remains insufficient
Solution Approach 1:
The invention modifies the reactive dye structure to have local chemical characteristics that are specifically suited for polyamide fiber interaction. The dyes contain functional groups (vinyl sulfone, chlorotriazine) that create optimal local chemical environments for bonding to polyamide at low pH, while maintaining the ease of washing properties of reactive dyes.
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 achieves effective black coloring of polyamide fibers with improved substantivity and resistance to washing, while maintaining fiber integrity and safety by eliminating chromium toxicity.
Implementation Method 1
the composition comprises sulfamic acid and a strong acid, the composition having a pH of 2 or below
Implementation Method 2
They can be classified in four categories, depending on their chemical constitution: Chlorotriazine Dyes (MCT) Vinyl Sulphone Dyes (VS) Heterocyclic Halogen Containing Dyes (HHC) Mixed Dyes (MCT-VS)
Implementation Method 3
The dyes are classified according to their chemical structure, mainly on the nature of the chromophore, which constitutes the skeleton necessary for the coloring of the molecule
Data Source
Figure 1
AI summary
The present application relates to the field of black coloring of textile fibers, and in particular polyamide fibers. A coloring composition for polyamides comprises at least one dye of the reactive type and sulfamic acid, the composition having a pH of 2 or below. It further relates to the process for coloring synthetic textile such as polyamide based textile using the coloring composition, wherein the textile is first immersed in water with the composition added in an amount equivalent to between 10 and 50% of the weight of the textile, the mixture is heated to between 70 °C and 100 °C; sulfamic acid and/or sulfuric acid may be added. Rinsing and drying steps finalize the process.