Semi-Aromatic Polyamide Hook-and-Loop Fastener for Automotive

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Solution Overview

Problem

Shaped hook members of hook-and-loop fasteners made from semi-aromatic polyamide resins experience a decrease in engaging force under high temperature conditions, and are prone to hook-type engaging element cutting and crack generation during repeated engaging and peeling.

Innovation Solution

A shaped hook member with tapered and curved hook-type engaging elements, formed from a semi-aromatic polyamide resin blended with 2-20% elastomer, specifically maleic anhydride-modified polyolefin elastomer, and carbon black, to prevent cutting and cracking, and a method involving injection molding with a metal roll having opposite curving directions in adjacent rows of cavities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a shaped hook member is made from semi-aromatic polyamide resin, then heat resistance is improved, but engaging force decreases under high temperature conditions

Engineering Contradiction:

Improveheat resistanceVSAvoidengaging force

Core Design Contradiction:

TemperatureVSForce

Solution Approach 1:

The patent uses a composite material consisting of semi-aromatic polyamide resin blended with elastomer (specifically polyolefin elastomer). This composite maintains the heat resistance of the semi-aromatic polyamide while the elastomer component prevents brittleness and maintains engaging force under high temperature conditions. The blend ratio is controlled to achieve optimal balance between heat resistance and flexibility.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent modifies the chemical composition parameters of the resin by controlling the blend ratio of semi-aromatic polyamide and elastomer. It also controls the molecular weight and intrinsic viscosity of the semi-aromatic polyamide to optimize both heat resistance and engaging force retention at elevated temperatures.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If hook-type engaging elements are made with curved portions, then engaging performance is improved, but cracks are generated in curved portions during molding

Engineering Contradiction:

Improveengaging performanceVSAvoidcrack generation

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent controls the radius of curvature of the curved portions to be 0.3mm or more, and controls the molding temperature and resin flow parameters to prevent crack generation. By optimizing these parameters, the hook-type engaging elements maintain their curved shape for improved engaging performance without developing cracks during the molding process.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The elastomer component in the composite material increases the toughness and flexibility of the hook-type engaging elements, allowing them to form curved portions without cracking during molding. The elastomer absorbs stress concentrations at the curved portions, preventing crack initiation and propagation.

Inventive Principle:

Principle #40Composite materials

3Productivity

If hook-type engaging elements are pulled out of cavities, then production efficiency is improved, but elements are cut in the cavities

Engineering Contradiction:

Improveproduction efficiencyVSAvoidelement integrity

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

The patent controls the cavity design parameters including the radius of curvature and the pull-out force parameters by adjusting molding conditions. The elastomer content and molecular weight of the resin are optimized to ensure that the hook-type engaging elements can be pulled out cleanly without being cut, while maintaining high production efficiency.

Inventive Principle:

Principle #35Parameter changes

4Adaptability or versatility

If engaging and peeling are repeated, then fastener usability is improved, but loop-shaped engaging elements are cut and engaging force decreases

Engineering Contradiction:

Improvefastener usabilityVSAvoidengaging force retention

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The elastomer component in the composite material provides flexibility and resilience to the hook-type engaging elements, allowing them to withstand repeated engaging and peeling cycles without cutting. The elastomer absorbs the mechanical stress from repeated operations, preventing fatigue failure and maintaining engaging force retention over time.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS11425971B2Shaped hook member of hook-and-loop fastener with excellent heat resistance, process for producing said shaped hook member of hook-and-loop fastener, and method for fixing interior automotive material with said shaped hook member of hook-and-loop fastener

Publication Date: 2022.08.30 KURARAY FASTENING CO LTD

AI summary

A shaped hook member of hook-and-loop fastener including a base plate and a plurality of hook-type engaging elements that rise from a surface of the base plate. The hook-type engaging elements are each tapered from the proximal end to the distal end, and are each curved from a point in the course from the proximal end to the distal end, and the distal end is directed toward the base plate. The plurality of hook-type engaging elements are arranged in rows extending in the same direction as the curving direction of the hook-type engaging elements, and the curving directions of the hook-type engaging elements in two adjacent rows or two adjacent units each of two or more rows are opposite to each other. The base plate and the hook-type engaging element are formed of a semi-aromatic polyamide resin containing a semi-aromatic polyamide and an elastomer.