Polyamide Resin Composition for Slide Fastener Strength After Dyeing
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Solution Overview
Problem
Small parts of slide fasteners, such as pull tab covers, pull tabs, top stops, and elements, made from polyamide resin compositions combining aliphatic polyamides and reinforcing fibers, experience a significant reduction in strength after dyeing due to water absorption, which affects the overall mechanical properties of the fastener.
Innovation Solution
A polyamide resin composition with a higher proportion of aromatic polyamides having a melting point of 200 to 250°C and incorporating reinforcing fibers, where the aromatic polyamide content is 70% or more by mass, is used for small parts, while the slider body is made from a composition with a higher aliphatic polyamide content, maintaining strength and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If aliphatic polyamide and reinforcing fibers are combined to produce small parts, then strength is improved, but strength significantly reduces after dyeing due to water absorption
Solution Approach 1:
The invention changes the chemical composition parameter of the polyamide resin by incorporating aromatic polyamide (20-70 mass%) in addition to aliphatic polyamide. This compositional parameter change reduces water absorption during dyeing while maintaining the reinforcing effect of fibers, thereby preserving strength after the dyeing process.
Solution Approach 2:
The invention creates a composite resin system combining aliphatic polyamide, aromatic polyamide, and reinforcing fibers (glass fibers, carbon fibers, or aramid fibers). This multi-component composite material leverages the strength-providing capability of fibers and the low water-absorption characteristic of aromatic polyamide to maintain strength during and after dyeing.
2Strength
If aromatic polyamide with melting point of 200-250°C is used in small parts, then strength after dyeing is maintained, but processing temperature range is limited
Solution Approach 1:
The invention specifies a narrow melting point range (200-250°C) for the aromatic polyamide component, which corresponds to a specific structural parameter of the polymer. This parameter selection optimizes the balance between maintaining strength after dyeing and enabling practical injection molding processing.
3Reliability
If aromatic polyamide content is increased to 70% or more, then strength retention after water absorption is improved, but cost and processing difficulty increase
Solution Approach 1:
The invention optimizes the aromatic polyamide content parameter to a specific range (20-70 mass%). Below 20%, water absorption and strength loss are problematic. Above 70%, processing difficulty and cost increase significantly. This parameter optimization achieves the best balance between performance and manufacturability.
Solution Approach 2:
The invention applies different polyamide types in different proportions based on the specific part requirements. Small parts that require dyeing use higher aromatic polyamide content (20-70%) for low water absorption, while other parts can use different compositions, optimizing both performance and processing for each application.
Data Source
AI summary
Provided is a polyamide resin composition that is suitable as a material for slide fastener parts having good strength after being dyed. A polyamide resin composition for a slide fastener, comprising a polyamide resin and reinforcing fibers, wherein a total mass of the polyamide resin and the reinforcing fibers is 90% by mass or more of the composition; wherein a proportion of an aromatic polyamide having a melting point of from 200 to 250° C. in the polyamide resin is more than 70% by mass; and wherein a content of the reinforcing fibers in the total mass of the polyamide resin and the reinforcing fibers is from 45 to 70% by mass.