Hydrolytically Stable Polymer Compositions

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Solution Overview

Problem

Hydrolytic degradation of polymers used in medical devices, such as polyether block amide copolymers, is accelerated by additives like tungsten carbide, leading to reduced shelf life and increased costs, necessitating the development of stabilizing methods to enhance hydrolytic stability.

Innovation Solution

Incorporating a carbodiimide compound and a hindered amine into the polymer composition to form a stabilizing mixture that decreases the rate and extent of hydrolytic degradation, thereby extending the shelf life of hydrolytically unstable polymers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If stabilizing additives are added to extend polymer shelf life, then hydrolytic stability is improved, but device complexity increases

Engineering Contradiction:
Improveshelf lifeVSAvoidcomposition complexity
Core Design Contradiction:
Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The patent combines carbodiimide compound and hindered amine into a single stabilizing mixture that works synergistically to protect the polymer against hydrolytic degradation. This merging of multiple stabilizing functions into one compositional system extends shelf life while managing the complexity through integrated design.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The invention creates a composite stabilizing system by incorporating both carbodiimide compound and hindered amine into the polymer composition. This composite approach provides enhanced hydrolytic stability through the combined action of different chemical mechanisms, effectively extending the polymer's service life.

Inventive Principle:
Principle #40Composite materials

2Reliability

If carbodiimide compound and hindered amine are combined, then hydrolytic degradation is reduced, but manufacturing complexity increases

Engineering Contradiction:
Improvehydrolytic stabilityVSAvoidprocessing complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The carbodiimide compound and hindered amine are incorporated into the polymer composition during the manufacturing process, performing the stabilizing action in advance before the polymer is put into service. This preliminary incorporation ensures hydrolytic protection is already in place, reducing the need for post-manufacturing interventions.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The stabilizing mixture of carbodiimide compound and hindered amine provides self-service protection against hydrolytic degradation throughout the polymer's service life. The additives continuously perform their stabilizing function without requiring external intervention, maintaining hydrolytic stability autonomously.

Inventive Principle:
Principle #25Self-service

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 combination of carbodiimide and hindered amine additives significantly reduces hydrolytic degradation, as evidenced by sustained molecular weight and mechanical property retention over extended aging periods, particularly at 65°C/50%RH, effectively increasing the polymer's service life.

Implementation Method 1

the carbodiimide compound and hindered amine are used in amounts effective to decrease the rate and/or extent of hydrolytic degradation of the polymer

Methodology Applied
Scientific EffectHydrolysis: Hydrolysis

Implementation Method 2

a hindered amine; wherein the carbodiimide compound and hindered amine are used in amounts effective to decrease the rate and/or extent of hydrolytic degradation

Methodology Applied
Scientific EffectFree radical scavenging:

Data Source

PatentEP3448449B1Hydrolytically stable polymer compositions, articles, and methods
Publication Date: 2023.02.22 MEDTRONIC INC
  • EP3448449B1 patent drawingFigure 1
  • EP3448449B1 patent drawingFigure 2
  • EP3448449B1 patent drawingFigure 3

AI summary

A composition, article, and method for increasing the hydrolytic stability of a polymer; wherein a composition includes: a polymer comprising functional groups having hydrolyzable bonds; a carbodiimide compound; and a weak base (or hindered amine); wherein the carbodiimide compound and weak base (or hindered amine) are used in amounts effective to decrease the rate and/or extent of hydrolyic degradation of the polymer relative to either used alone in the same amount with the polymer.