Biphenyl-Linked Azo Dyes for Lightfast Brown Paper Coloring

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Solution Overview

Problem

Brown papers often suffer from insufficient lightfastness due to the lack of effective protection against light and weather, leading to changes in color or shade.

Innovation Solution

Azo dyes with at least two azo groups linked by a biphenyl group and attached to benzene or naphthalene rings, which are water-soluble and used to produce materials with improved lightfastness in brownish shades, allowing for single-dye production of brownish shades in organic or fiber-containing materials like paper.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional dye mixtures (e.g., C.I. Direct Brown 44 and Direct Yellow 11) are used to produce brown papers, then the desired brownish shade is achieved, but the lightfastness is insufficient and color changes occur under light exposure

Engineering Contradiction:

ImprovelightfastnessVSAvoiddyeing process complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent combines multiple azo groups and aromatic ring systems into a single complex dye molecule (formula I), merging the functions of multiple separate dyes into one compound that provides both brownish shade and improved lightfastness, eliminating the need for dye mixtures

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The dye molecule is constructed as a composite structure with multiple functional components: azo groups for coloration, aromatic rings for stability, and sulfonic acid groups for water solubility and fiber affinity, creating a molecule with superior overall performance

Inventive Principle:

Principle #40Composite materials

2Ease of operation

If dye mixtures are used to achieve brownish shades, then color requirements are met, but the complexity of the dyeing process increases

Engineering Contradiction:

Improvedyeing process simplicityVSAvoidlightfastness

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The single dye compound performs multiple functions simultaneously: it provides brownish coloration, ensures adequate lightfastness, maintains water solubility through sulfonic acid groups, and exhibits affinity for cellulose and polyamide fibers, replacing the need for multiple specialized dyes

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If papers are stored without protection from light and weather, then storage convenience is maintained, but color stability deteriorates over time

Engineering Contradiction:

Improvestorage flexibilityVSAvoidcolor stability

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The dye molecule is designed with inherent structural features (multiple azo groups linked by aromatic rings) that provide built-in resistance to light-induced degradation, cushioning against color fading before exposure occurs and reducing the need for additional protective measures

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 use of these azo dyes results in materials with enhanced lightfastness, maintaining the brownish shade effectively even when exposed to light or weather, surpassing the lightfastness of papers dyed with traditional dye mixtures.

Implementation Method 1

azo dyes containing at least two azo groups which are linked by a biphenyl group and which are attached to benzene or naphthalene rings... enable the production of materials, in particular of organic or fiber-containing materials, e.g. paper or board, in brownish shades and with high lightfastness

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentEP2457956B1Azo dyes

Publication Date: 2018.10.10 KEMIRA OY

AI summary

The present invention relates to new azo dyes, a process for their preparation, and their use for dyeing or printing fibrous materials, to produce materials with brownish shades.