High Shrinkage PTT Copolyester via Spiral Chain Conformation
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Solution Overview
Problem
Current PTT polyester fibers have limitations in shrink performance, which hinders their full utilization in high-density fabric production, where they lack the desired high shrinkage rate and stability compared to conventional PET polyester fibers.
Innovation Solution
A method for preparing high shrinkage PTT copolyester by adjusting the molecular structure through specific esterification and polymerization reactions using 1,3-propylene glycol, terephthalic acid, non-para aromatic dicarboxylic acids, branched aliphatic dihydric alcohols, and aliphatic polyalcohols, with catalysts like titanate and antimony acetate, to enhance chain movement and crystallization, resulting in improved spinnability and dyeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional PTT polyester is used, then good elasticity and softness are achieved, but shrinkage rate is insufficient for high-density fabric production
Solution Approach 1:
The patent modifies the molecular structure parameters of PTT polyester by incorporating copolymer units (cyclohexanedimethanol and isophthalic acid) to change the chain conformation from linear to spiral, thereby achieving high shrinkage rate while maintaining the material's elastic properties
Solution Approach 2:
The patent creates a composite polyester structure by combining PTT base polymer with copolymer units containing cyclohexanedimethanol and isophthalic acid, resulting in a material that exhibits both the inherent elasticity of PTT and the desired high shrinkage behavior for high-density fabric applications
2Strength
If PTT fiber is used to substitute PET fiber, then good elastic recovery and bulkiness are achieved, but high shrinkage performance is lacking
Solution Approach 1:
The patent changes the molecular conformation parameter from linear (PET) to spiral (PTT with copolymer units), which enables the fiber to exhibit both superior elastic recovery and high shrinkage performance simultaneously through the spiral chain structure's ability to expand and contract
3Ease of operation
If PTT polyester with lower glass-transition temperature is used, then low temperature dyeing and phase transition are improved, but shrinkage stability under external stress is reduced
Solution Approach 1:
The patent creates a composite polyester structure that balances the low glass-transition temperature benefit for dyeing with the structural stability needed for shape retention, using copolymer units that modify the molecular conformation to spiral shape while maintaining processing advantages
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 PTT polyester fibers exhibit excellent boiling water and dry hot shrinkage rates, maintaining shape under external forces, with enhanced elasticity and stress relief, suitable for high-density fabric production, offering improved properties over conventional PTT fibers.
Implementation Method 1
esterification reaction: add starting raw materials into a reaction kettle and add an esterification catalyst to carry out esterification reaction at 220℃～260℃ under 0.05～0.30 MPa
Implementation Method 2
polymerization reaction: add polymerization catalyst into the reaction system after step (1) and carry out the polymerization reaction at 240℃～280℃ to get polytrimethylene terephthalate
Implementation Method 3
molecular conformation of PTT polymer is spiral, which will allow PTT fiber to be highly 'puffed' and endow its fiber with good elasticity
Implementation Method 4
PTT polyester has a lower glass-transition temperature and thus apt to take low temperature phase transition, which can effectively eliminate influence on fabric by external stress
Data Source
AI summary
A method for preparing high shrinkage PTT copolyester, includes adding starting raw materials into a reaction kettle and adding an esterification catalyst to carry out esterification reaction at 220° C.-260° C. under 0.05-0.30 MPa and completing the reaction when there being no water produced; and adding polymerization catalyst into the reaction system and carrying out the polymerization reaction at 240° C.-280° C. to get polytrimethylene terephthalate. The starting raw materials consists of 1,3-propylene glycol, terephtalic acid, a third monomer, a forth monomer and a fifth monomer. Polytrimethylene terephthalate prepared by the invention shows good spinning behaviour, of which the crystallization speed is noticeably lower than that of conventional polytrimethylene terephthalate, thus, fibers made of them has high boiling water shrinkage rate and ideal shrink property.