Polymer Stabilizing Composition with pH Buffering Agent

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Solution Overview

Problem

Polymers used in various applications face challenges in retaining melt flow properties, viscosity, and color stability, especially when exposed to heat for prolonged or repeated periods, due to degradation issues and interactions with traditional acid scavengers and antioxidants.

Innovation Solution

A stabilizing composition comprising a combination of phenolic, phosphite, sulfur-containing, and aminic antioxidants, along with a buffering agent that can buffer in an aqueous solution at a pH range of 4 to 8, which is a solid at 50°C or lower, is used to maintain polymer stability during heat exposure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional acid scavengers (metal salts of fatty acids, metal oxides, metal hydroxides, metal carbonates) are used to counteract acidic degradation products, then polymer stability against acid-catalyzed degradation is improved, but phenolic antioxidants discolour due to high pH

Engineering Contradiction:
Improvepolymer stabilityVSAvoiddiscolouration
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces buffering agents (such as organic carboxylic acid salts, inorganic phosphate salts, or silane-based buffers) as intermediary substances that mediate between the acid scavengers and phenolic antioxidants. These buffering agents maintain pH within a neutral range (6-8), preventing both acid-catalyzed degradation and base-induced discolouration, thus resolving the contradiction between polymer stability and colour stability

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the pH parameter control strategy by incorporating buffering agents that actively maintain pH within an optimal range (6-8). This parameter control prevents the high pH conditions that cause phenolic antioxidant discolouration while still providing adequate protection against acid-catalyzed degradation, thereby resolving the contradiction

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If phosphite antioxidants are included to reduce discolouration caused by high pH, then colour stability is improved, but the phosphite antioxidants undergo hydrolysis in high or low pH environments

Engineering Contradiction:
ImprovediscolourationVSAvoidantioxidant functionality
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent changes the pH environment parameter by introducing buffering agents that maintain pH within the range of 6-8. This optimized pH range prevents hydrolysis of phosphite antioxidants while still providing protection against discolouration, thus resolving the contradiction between colour stability and antioxidant functionality

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The buffering agents act as intermediary substances that create a stable chemical environment for phosphite antioxidants. By maintaining pH within the optimal range, these intermediaries prevent both discolouration and hydrolysis, allowing phosphite antioxidants to function effectively

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If acid scavengers are used to maintain high pH in the polymer, then acid-catalyzed degradation is prevented, but phenolic antioxidants discolour

Engineering Contradiction:
Improveresistance to acid-catalyzed degradationVSAvoiddiscolouration
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent modifies the pH parameter from high pH (maintained by traditional acid scavengers) to a neutral range (6-8) by incorporating buffering agents. This parameter change prevents acid-catalyzed degradation while avoiding base-induced discolouration of phenolic antioxidants, thus resolving the contradiction

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The buffering agents serve as intermediary substances that replace traditional acid scavengers in maintaining polymer stability. These intermediaries provide adequate protection against acid-catalyzed degradation without creating the high pH conditions that cause discolouration, thus resolving the contradiction

Inventive Principle:
Principle #24Intermediary (Mediator)

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 proposed solution significantly improves color stability and retains melt flow properties and viscosity of polymers, even under prolonged or repeated heat exposure, outperforming conventional acid scavengers and avoiding discolouration and viscosity changes.

Implementation Method 1

at least one buffering agent, wherein the buffering agent has the capacity to buffer in aqueous solution at a pH range from 4 to 8

Methodology Applied
Scientific EffectBuffering:

Implementation Method 2

a first stabilising component comprising at least one phenolic antioxidant; a second stabilising component comprising at least one phosphite antioxidant

Methodology Applied
Scientific EffectOxidation: Oxidation

Data Source

PatentEP3619260B1Stabilising composition
Publication Date: 2022.07.06 SI GRP SWITZERLAND GMBH
  • EP3619260B1 patent drawingFigure 1
  • EP3619260B1 patent drawingFigure 2

AI summary

The invention concerns a stabilising composition, comprising: at least one antioxidant comprising one or more of: a phenolic antioxidant, a phosphite antioxidant, a sulphur- containing antioxidant, and an aminic antioxidant; and at least one buffering agent, wherein the buffering agent has the capacity to buffer in aqueous solution at a pH range from 4 to 8.