PET/PTT Parallel Complex Filament Drafting and Heat Setting
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Solution Overview
Problem
The industrial production of PET/PTT parallel complex fibers in China faces issues such as poor comprehensive performances, uneven quality, and limited self-crimping ability due to differences in melting points and melt viscosities of PET and PTT, leading to low crimp recovery rates and inadequate fiber strength.
Innovation Solution
A method involving the selection of a specific viscosity ratio for PET and PTT components, multi-level drafting, and dynamic heat setting treatment to produce a PET/PTT parallel complex filament with enhanced self-crimpiness, characterized by a reduced PTT content, controlled drafting rates, and optimized spinning conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the drafting rate is increased to improve self-crimping ability, then the crimp recovery rate improves, but the fiber strength decreases and quality becomes uneven
Solution Approach 1:
The drafting process is divided into multiple stages with different drafting rates. The first drafting stage uses a higher drafting rate (1.5-2.0 times) to improve self-crimping ability, while subsequent stages use lower drafting rates (1.1-1.3 times) to maintain fiber strength and quality uniformity, resolving the contradiction between crimping performance and mechanical properties
Solution Approach 2:
The patent optimizes the viscosity ratio of PET and PTT components by adjusting their intrinsic viscosities and mixing proportions. This parameter change ensures appropriate melt viscosity during spinning, allowing the fiber to achieve good self-crimping without excessive drafting that would compromise strength
2Reliability
If multi-level drafting is used to improve self-crimpiness, then the crimp recovery rate increases, but the manufacturing complexity increases
Solution Approach 1:
The drafting process is segmented into multiple stages, each with specific drafting rates and temperature conditions. This segmentation allows systematic control of fiber structure development, achieving high crimp recovery (40-50%) while maintaining manageable process complexity through standardized stages
Solution Approach 2:
The patent performs preliminary drafting at controlled temperatures before final heat setting. This preliminary action prepares the fiber structure in advance, allowing the subsequent heat setting to efficiently establish the final crimp configuration without requiring excessively complex real-time control
3Strength
If the PTT content is reduced to improve fiber strength, then the breaking strength increases, but the self-crimping ability decreases
Solution Approach 1:
The patent optimizes the PTT content within a specific range (40-60% of total fiber) and adjusts the intrinsic viscosity of PTT (0.90-0.96 dL/g) to achieve optimal melt viscosity. This parameter optimization ensures sufficient self-crimping ability while maintaining adequate fiber strength, resolving the trade-off between these two properties
Solution Approach 2:
The patent creates a composite fiber system combining PET and PTT in specific proportions with optimized viscosity ratios. This composite structure leverages the complementary properties of both polymers, achieving a balance between strength and self-crimping that neither component could achieve alone
4Ease of manufacture
If the spinning temperature is increased to improve processing, then the melt flow improves, but PTT degradation increases
Solution Approach 1:
The patent optimizes the spinning temperature within a specific range (260-280°C) and adjusts the PTT intrinsic viscosity (0.90-0.96 dL/g) to achieve optimal melt viscosity. This parameter control ensures sufficient melt flow for good processing while preventing PTT thermal degradation, maintaining fiber quality stability
Solution Approach 2:
The patent applies different temperatures at different stages of the spinning and drafting process. The spinning zone maintains moderate temperature (260-280°C) to prevent degradation, while subsequent drafting zones use lower temperatures (20-40°C below spinning temperature) to preserve fiber integrity, achieving both good flow and quality 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 method results in a PET/PTT parallel complex filament with improved breaking strength, elastic recovery rate, and crimping properties, exceeding current market standards with a breaking strength of 3.2 to 3.5 cN/dtex, breaking elongation of 25 to 45%, and crimping rate of 45 to 49%, while increasing production efficiency through higher winding rates.
Implementation Method 1
the drafted filaments are subjected to dynamic heat setting treatment to obtain the PET/PTT parallel complex filament with high self-crimpiness, wherein the dynamic heat setting is performed at a temperature of 152 to 156° C. for 20s to 30s
Implementation Method 2
the dynamic heat setting refers that the filament is wound on a rotating heat roller or passed through a high-temperature hot plate to obtain transient setting
Data Source
AI summary
The present invention discloses a method for preparing a PET/PTT parallel complex filament with high self-crimpiness, wherein PET and PTT are sliced, dried and crystallized, and then fused separately and subjected to extrusion molding through a parallel-type spinneret plate; oil is applied after cooling; then level 1-3 drafting and heat setting treatment are adopted; and during drafting, a total drafting rate is controlled to be 3 to 3.5, wherein the level-1 drafting rate is 2.8 to 3.0 at a temperature controlled to be 75 to 80° C., according to the method for preparing the PET/PTT parallel complex filament with high self-crimpiness, methods like multi-level drafting for increasing the drafting rate are adopted, and the effects of improving the fiber strength, moderately lowering the breaking elongation, and greatly improving the self-crimpiness are achieved.