Polyester Copolymer Composition for One-Bath Cotton Blend Dyeing
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Solution Overview
Problem
The challenge lies in developing a polyester composition that can be dyed with cotton in a single step, as current methods require separate dyeing processes for cotton and polyester due to their differing dyeing conditions, which are costly and degrade the elasticity of stretch fibers like spandex.
Innovation Solution
A polyester copolymer composition is formulated with specific ratios of terephthalic acid, adipic acid, pentaerythritol, polyethylene glycol, and diethylene glycol, allowing for dyeing at atmospheric pressure and lower temperatures, enabling simultaneous dyeing with cotton while maintaining the desired properties of both fibers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate dyeing processes are used for cotton and polyester, then each fiber can be dyed under its optimal conditions, but the process becomes costly and time-consuming
Solution Approach 1:
The patent combines the dyeing of cotton and polyester into a single simultaneous process using a dyebath containing both reactive dyes (for cotton) and disperse dyes (for polyester). This merging of previously separate dyeing operations allows both fibers to be colored in one step, improving productivity while maintaining dyeing quality through careful selection of compatible dyes and process parameters.
Solution Approach 2:
The patent modifies dyeing parameters to enable simultaneous dyeing: using a dyebath pH range of 4.0-6.0 that allows both reactive and disperse dyes to function, controlling temperature between 130-150°C, and adjusting dye concentrations and application rates. These parameter changes create conditions where both fiber types can accept their respective dyes under the same process conditions.
2Reliability
If high temperature and pressure are used to dye polyester, then polyester can be dyed effectively, but the elasticity of spandex fibers is degraded
Solution Approach 1:
The patent changes the dyeing parameters from conventional high-temperature/high-pressure conditions to a milder regime: temperature reduced to 130-150°C, atmospheric pressure maintained, and extended dyeing time of 30-60 minutes. These parameter modifications allow polyester to be dyed effectively without exposing spandex to conditions that would degrade its elastic properties.
Solution Approach 2:
The patent introduces specific disperse dyes and reactive dyes that function as intermediaries to facilitate color uptake at lower temperatures. These dyes are selected and formulated to achieve adequate polyester dyeing at 130-150°C without requiring the conventional high-energy conditions that would harm spandex elasticity.
3Reliability
If conventional polyester dyeing conditions are used, then polyester can be dyed, but cotton and polyester require separate processing steps
Solution Approach 1:
The patent merges the dyeing of cotton and polyester into a single integrated process using a dyebath that contains both reactive dyes (for cotton) and disperse dyes (for polyester). This combination eliminates the need for separate dyeing operations, reducing process complexity while maintaining effective dyeing of both fiber types through careful control of pH, temperature, and dye ratios.
Data Source
AI summary
A copolymer composition is disclosed with advantages for textile fibers, yarns, blended yarns, fabrics, and garments. The composition includes polyester copolymer, between about 4.5 and 5.5 percent adipic acid based on the amount of copolymer, between about 630 and 770 parts per million (ppm) of pentaerythritol based on the amount of copolymer, and between about 3.4 and 4.2 percent polyethylene glycol based on the amount of copolymer.