Branched Diol Modified Polyester for Low-Temperature Dyeing
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Solution Overview
Problem
Polyethylene terephthalate (PET) fibers have high crystallinity and a symmetrical linear molecular structure, making it difficult for dye molecules to penetrate the fiber, resulting in poor dyeing properties and high energy consumption due to the need for high temperature and pressure during the dyeing process, as well as high melt viscosity that complicates processing.
Innovation Solution
Introducing a branched diol segment into the molecular chain of a modified polyester, which increases the spatial gap between molecular chains and reduces melt viscosity, allowing for improved dye penetration and processing efficiency without compromising the structural regularity of the polyester.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high temperature and high pressure are used for PET dyeing, then dye molecules can penetrate the fiber, but energy consumption increases and processing becomes complex
Solution Approach 1:
The invention modifies the molecular structure of PET by introducing a cyclic carbonate group, which changes the physical and chemical parameters of the polymer. This structural modification increases the spatial gap between molecular chains and creates free volume, allowing dye molecules to penetrate at lower temperatures and pressures, thereby reducing energy consumption while maintaining dyeing quality
Solution Approach 2:
The invention creates a composite structure by incorporating a cyclic carbonate group into the PET molecular chain. This composite modification introduces polar groups that interact with dye molecules and creates channels for dye penetration, enabling effective dyeing under milder conditions with reduced energy input
2Reliability
If high temperature and high pressure are used for PET dyeing, then dye molecules can penetrate the fiber, but the processing complexity increases
Solution Approach 1:
By modifying the PET molecular structure to include a cyclic carbonate group, the invention changes the physical parameters of the material to enable dyeing at lower temperatures and pressures. This simplifies the processing equipment and operational procedures required, reducing processing complexity while achieving good dyeing results
3Strength
If PET maintains its regular molecular chain structure, then mechanical properties are excellent, but dye molecules cannot penetrate the fiber
Solution Approach 1:
The invention applies local modification by introducing a cyclic carbonate group at specific positions along the PET molecular chain. This local structural change creates spatial gaps and polar groups that facilitate dye penetration, while the majority of the molecular chain maintains its regular structure to preserve excellent mechanical properties
Solution Approach 2:
The cyclic carbonate group modification changes local physical parameters such as molecular chain spacing and polarity, enabling dye penetration without disrupting the overall molecular regularity that provides mechanical strength
4Strength
If PET has high crystallinity and dense structure, then mechanical strength is high, but dye molecules are difficult to enter the fiber interior
Solution Approach 1:
The invention introduces a cyclic carbonate group that creates local spatial gaps and free volume within the dense crystalline structure. These local modifications provide channels for dye molecule entry while maintaining the overall dense structure and high mechanical strength of the PET fiber
Solution Approach 2:
By incorporating the cyclic carbonate group into the PET structure, the invention creates a composite material with enhanced properties. The cyclic carbonate component provides pathways for dye penetration while the PET matrix maintains mechanical strength, achieving both high strength and good dye uptake
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 modified polyester exhibits enhanced dyeing properties with increased dye uptake and reduced processing temperatures, improving the overall processing and dyeing efficiency while maintaining the excellent mechanical properties of PET fibers.
Implementation Method 1
introduces a branched diol segment into a molecular chain of a modified polyester. Under the circumstance, the increase of the spatial gap between the molecular chains of the modified polyester is far greater than that of the unbranched polyester at the same temperature
Implementation Method 2
The melt viscosity of modified polyester relative to unbranched polyester can also be reduced, which is helpful to reduce processing temperature, reduce degradation rate and facilitate processing
Implementation Method 3
the diffusion of dye molecules into the fiber inside under high temperature conditions, and complete the dyeing step
Data Source
AI summary
A method for preparing the modified polyester. The modified polyester segments include terephthalic acid segment, ethylene glycol diol segment and branched diol segment, in which the branched diol segment refers to a diol segment in which a branch is located on a non-terminal carbon in the glycol segment and the branch is a linear carbon chain having 5 to 10 carbon atoms. The method includes preparing terephthalic acid glycol ester through the esterification of terephthalic acid and branched diol using the concentrated sulfuric acid as the catalyst. Then get ethylene terephthalate through the esterification of terephthalic acid and ethylene glycol. After stirring and mixing the two, the modified polyester can be obtained through polycondensation reaction of a low vacuum stage and a high vacuum stage using the catalyst and stabilizer.