PA6 Injection Molding Composition for Strength and Mold Release

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Solution Overview

Problem

Commercially recycled polyamide 6 materials exhibit inconsistent colors and low crystallinity, leading to mold sticking, low strength, and cosmetic issues in injection molding, while chemically recycled PA6 lacks sufficient strength for apparel trims and accessories.

Innovation Solution

A composition comprising Polyamide 6 and an inorganic nucleation agent, along with optional mould release, plasticizer, and antioxidants, is used for injection molding, enhancing smoothness and tensile strength without rigid fibers, enabling mono-material recycling of waste yarn into new apparel products.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If mechanically recycled PA6 is used, then color consistency is improved, but crystallinity remains low leading to mold sticking and weak strength

Engineering Contradiction:

Improvecolor consistencyVSAvoidtensile strength

Core Design Contradiction:

Stability of the object's compositionVSStrength

Solution Approach 1:

The patent applies parameter changes by introducing an inorganic nucleation agent that modifies the crystallization behavior of PA6. This nucleation agent changes the crystallinity parameter during injection molding, enabling the material to achieve both color consistency from mechanical recycling and sufficient crystallinity for strength and mold release.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite material system by combining PA6 with an inorganic nucleation agent. This composite approach allows the nucleation agent to enhance crystallinity while the PA6 provides the base material properties, resolving the contradiction between color consistency and strength.

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If chemically recycled PA6 is used, then color consistency is improved, but tensile strength is insufficient for apparel trims

Engineering Contradiction:

Improvecolor consistencyVSAvoidtensile strength

Core Design Contradiction:

Stability of the object's compositionVSStrength

Solution Approach 1:

The patent uses parameter changes by incorporating an inorganic nucleation agent that enhances the crystallinity of chemically recycled PA6. This allows the material to maintain color consistency while achieving sufficient crystallinity to provide adequate tensile strength for apparel trims and accessories.

Inventive Principle:

Principle #35Parameter changes

3Strength

If glass fibers or rigid fibers are added to improve strength, then tensile strength is improved, but mono-material recycling capability is lost

Engineering Contradiction:

Improvetensile strengthVSAvoidmono-material recycling capability

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The patent applies parameter changes by using an inorganic nucleation agent that enhances crystallinity without adding rigid fibers. This allows the material to achieve sufficient strength through crystallinity enhancement alone, maintaining mono-material composition for recyclability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical reinforcement approach (adding glass fibers) with a chemical/crystallization-based approach (using nucleation agents to enhance crystallinity). This substitution maintains material homogeneity for recycling while achieving the required strength properties.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Device complexity

If recycled PA6 is used without nucleation agent, then material simplicity is maintained, but injection molding smoothness deteriorates due to mold sticking

Engineering Contradiction:

Improvematerial composition simplicityVSAvoidinjection molding smoothness

Core Design Contradiction:

Device complexityVSEase of manufacture

Solution Approach 1:

The patent applies parameter changes by introducing an inorganic nucleation agent that modifies the crystallization kinetics during injection molding. This enhances mold release smoothness by controlling crystallinity development, while the agent can be easily removed or degraded during recycling, maintaining material simplicity.

Inventive Principle:

Principle #35Parameter changes

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 composition achieves improved injection molding smoothness and meets industrial standards for tensile strength, allowing for seamless production of accessories like buttons and zipper pullers without mold sticking, and supports sustainable mono-material recycling.

Implementation Method 1

The present disclosure provides a composition for injection molding, comprising Polyamide 6 (PA 6); and an inorganic nucleation agent.

Methodology Applied

Scientific EffectNucleation: Nucleation

Implementation Method 2

Pure chemically recycled PA6 directly from waste yarn is colorable, but has a low crystallinity

Methodology Applied

Scientific EffectCrystallization: Crystallisation

Data Source

PatentEP4703417A1Polyamide 6 composition and an article prepared therefrom

Publication Date: 2026.03.04 DURAFLEX HONG KONG

AI summary

The present invention relates to a composition for injection molding, comprising Polyamide 6; and an inorganic nucleation agent. The present invention also provides an injection molded accessory, such as a button, a zipper puller, a buckle, a cord lock, a cord end, and a stopper, comprising the composition. The present invention also provides a method for preparing an article, such as an accessory, comprising injection molding of the composition.