Recycled Polyester Color Stability via Polyamide and Colorant Balance

Solution Overview

Problem

Polyester resin compositions containing polyamides are prone to yellowing during heat history, which reduces the product value of recycled packaging containers, and existing solutions that add yellowing-suppressing compounds can compromise physical and barrier properties.

Innovation Solution

A single-layer container formulation comprising a polyester resin, a specific amount of polyamide resin, a blue colorant, and a red colorant, where the polyamide resin content is between 0.05 and 7.0 mass% and the blue colorant content is between 1 to 40 ppm, effectively suppressing hue changes and maintaining high colorlessness in recycled polyester.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a polyamide resin is added to improve gas barrier properties, then barrier performance is improved, but yellowing occurs during heat history

Engineering Contradiction:

Improvegas barrier performanceVSAvoidyellowing

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful yellowing effect of polyamide during heat history into a beneficial outcome by adding specific colorants (blue colorant at 1-40 ppm and red colorant at 1-40 ppm) that counteract the yellowing. The polyamide's yellowing tendency is transformed into a controlled color adjustment mechanism, where the colorants compensate for and neutralize the undesired hue changes, thereby maintaining both barrier performance and color stability in recycled polyester.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent optimizes the content of polyamide resin within a specific range (0.05-7.0 mass%) to balance gas barrier performance and yellowing suppression. By precisely controlling the polyamide concentration and combining it with controlled amounts of blue and red colorants, the patent achieves the desired barrier properties while minimizing hue changes during recycling and heat history.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If a large amount of yellowing-suppressing compound is added to suppress hue changes, then colorlessness is improved, but physical properties and barrier performance decrease

Engineering Contradiction:

Improvehue changeVSAvoidphysical properties and barrier performance

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent optimizes the content of polyamide resin within a specific range (0.05-7.0 mass%) to balance gas barrier performance and yellowing suppression. By precisely controlling the polyamide concentration and combining it with controlled amounts of blue and red colorants, the patent achieves the desired barrier properties while minimizing hue changes during recycling and heat history.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite resin composition combining polyester resin with small, optimized amounts of polyamide resin (0.05-7.0 mass%) and specific colorants. This composite approach allows the system to achieve both gas barrier performance and color stability without relying on large amounts of single additives that would compromise physical properties.

Inventive Principle:

Principle #40Composite materials

3Reliability

If polyamide resin is used to enhance barrier properties, then gas barrier performance is improved, but yellowing occurs during recycling process

Engineering Contradiction:

Improvegas barrier performanceVSAvoidyellowing during recycling

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful yellowing effect of polyamide during heat history into a beneficial outcome by adding specific colorants (blue colorant at 1-40 ppm and red colorant at 1-40 ppm) that counteract the yellowing. The polyamide's yellowing tendency is transformed into a controlled color adjustment mechanism, where the colorants compensate for and neutralize the undesired hue changes, thereby maintaining both barrier performance and color stability in recycled polyester.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS20230356450A1Single-layer container, manufacturing method thereof, and recycled polyester manufacturing method

Publication Date: 2023.11.09 MITSUBISHI GAS CHEM CO INC

AI summary

Provided is a single-layer container containing a polyester resin (X), a polyamide resin (Y), a blue colorant (A), and a red colorant (B). The content of the polyamide resin (Y) is from 0.05 to 7.0 mass%, and the content of the blue colorant (A) is from 1 to 40 ppm.