Spun-dyed Polyester Monofilaments for Dimensional Stability
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Solution Overview
Problem
Monofilaments used in the construction sector face challenges in achieving high dimensional stability and low thermal shrinkage due to the limitations of existing spinning processes and the introduction of additives, which often compromise their properties.
Innovation Solution
The development of spun-dyed polyester monofilaments with specific pigment compositions, such as perylene, and the use of a modified spinning process with controlled stretching and relaxation to achieve a dimensional stability of less than 15% for reference elongation and thermal shrinkage, while maintaining a high titer and incorporating flame-retardant and friction-reducing additives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If high spinning drafts are used to achieve high modulus and low shrinkage, then dimensional stability is improved, but thermal shrinkage increases due to high molecular chain orientation
Solution Approach 1:
The patent changes the chemical composition parameters of the polyester by incorporating specific comonomers (cyclohexanedimethanol and/or 1,4-butanediol) in controlled amounts (0.5-50 mol% and 0.5-20 mol% respectively). This compositional modification alters the molecular chain flexibility and crystallization behavior, enabling the material to achieve high dimensional stability without excessive thermal shrinkage even at high spinning drafts. The specific comonomer ratios allow tuning of the force-elongation curve characteristics.
Solution Approach 2:
The patent creates a composite polyester system by combining multiple comonomers (CHDM and BDO) with terephthalic acid in specific ratios. This composite approach allows synergistic effects where the combination of different comonomers provides both the desired modulus and reduced thermal shrinkage, overcoming the limitations of single-comonomer systems when subjected to high spinning drafts.
2Strength
If extremely high stretching is applied to achieve high modulus, then elastic modulus is improved, but thermal shrinkage increases due to highly oriented molecular chains
Solution Approach 1:
The patent modifies the intrinsic viscosity parameter of the polyester to specific ranges (0.60-1.05 dl/g, preferably 0.70-0.95 dl/g) through controlled polymerization and comonomer selection. This viscosity optimization ensures that the polymer chains have appropriate entanglement and flexibility, allowing high stretching to achieve high modulus while the modified chain structure resists excessive thermal shrinkage through altered crystallization kinetics.
3Stability of the object's composition
If high spinning drafts are used to achieve high modulus, then dimensional stability is improved, but the manufacturing complexity increases due to process control requirements
Solution Approach 1:
The patent optimizes the force-elongation curve characteristics by selecting specific comonomer ratios, which inherently shapes the KD curve to have desirable properties (higher initial slope, controlled non-linearity). This material parameter optimization reduces the need for complex process control during spinning, as the material itself responds more predictably to standard spinning drafts, simplifying the manufacturing process while maintaining high dimensional stability.
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 resulting monofilaments exhibit improved dimensional stability, reduced thermal shrinkage, and enhanced flame retardancy, making them suitable for construction applications like light roof structures and facade cladding, while maintaining a high titer and incorporating additives for improved performance.
Implementation Method 1
free thermal shrinkage after 30 minutes of treatment at 180 °C
Implementation Method 2
the molecular chains are largely oriented in the longitudinal direction
Implementation Method 3
In subsequent stretching, the molecular chains are further oriented and crystallized. This achieves high moduli and, due to the semi-crystalline content, also low shrinkage values.
Data Source
AI summary
The invention relates to spun-dyed monofilaments made of polyesters having high dimensional stability, containing a selected dye. Dyes comprising perylene pigments are preferred. Polyesters that are modified to be permanently flame-retardant are especially preferred as the starting raw material. Said monofilaments can be used preferably in light-weight roof constructions, shading elements, facade claddings and other decorative textile articles in or on buildings. Said filaments are characterised by good resistance to light and low heat absorption.