Phosphorus Polyester Curing Agent for Epoxy Resins

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Solution Overview

Problem

Thermosetting resins, such as epoxy resins, used in electronic applications are flammable and existing flame retardants often compromise mechanical and electrical properties, making it difficult to achieve both flame resistance and desirable properties like high glass transition temperature and low dielectric loss tangent simultaneously.

Innovation Solution

Phosphorus-containing aromatic polyesters are used as polyfunctional curing agents for thermosetting resins, reducing the formation of undesirable hydroxyl groups and increasing cross-linking density, thereby providing high thermal stability and excellent electrical properties while functioning as both flame retardants and curing agents.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If halogen-free flame retardant compounds are used, then flame resistance is improved, but manufacturing difficulty increases and acceptable properties are hard to achieve

Engineering Contradiction:
Improveflame resistanceVSAvoidformulation difficulty
Core Design Contradiction:
Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The phosphorus-containing aromatic polyester compound serves dual functions as both a flame retardant and a curing agent for epoxy resins. The compound contains reactive ester groups that enable it to cure epoxy resins while simultaneously providing flame retardant properties, eliminating the need for separate formulation components and simplifying the manufacturing process.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The invention combines the flame retardant function and the curing agent function into a single phosphorus-containing aromatic polyester compound. This merging of functions allows the compound to both protect against flame and cure the resin system, reducing formulation complexity and improving ease of manufacture.

Inventive Principle:
Principle #5Merging (Combining)

2Strength

If phosphorus-containing flame retardants are used as curing agents, then cross-linking density increases and glass transition temperature improves, but hydroxyl group formation increases causing poor electrical properties

Engineering Contradiction:
Improvecross-linking densityVSAvoidelectrical properties
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The invention changes the chemical structure parameters of the phosphorus-containing compound by using aromatic polyester backbones with specific reactive ester groups. This structural modification allows the compound to achieve high cross-linking density through ester exchange reactions while minimizing hydroxyl group formation, thereby maintaining good electrical properties.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The phosphorus-containing aromatic polyester combines multiple functional groups within a single molecular structure: phosphorus for flame retardancy, aromatic rings for structural stability, and reactive ester groups for curing. This composite molecular structure enables simultaneous achievement of high cross-linking density and good electrical properties.

Inventive Principle:
Principle #40Composite materials

3Device complexity

If monofunctional or bifunctional flame retardants are used, then formulation is simpler, but cross-linking density decreases and glass transition temperature is reduced

Engineering Contradiction:
Improvemolecular functionalityVSAvoidglass transition temperature
Core Design Contradiction:
Device complexityVSStrength

Solution Approach 1:

The phosphorus-containing aromatic polyester is designed with multiple reactive ester groups (polyfunctionality) within a single molecule, enabling it to participate in multiple cross-linking reactions. This polyfunctionality allows the compound to simultaneously achieve high cross-linking density and high glass transition temperature while maintaining formulation simplicity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 use of phosphorus-containing polyesters as curing agents for epoxy resins results in materials with high glass transition temperature, low water absorbance, and low dielectric loss tangent, offering enhanced thermal stability and electrical insulation while maintaining flame retardancy.

Implementation Method 1

phosphorus-containing aromatic polyesters are used as polyfunctional curing agents for thermosetting resins

Methodology Applied
Scientific EffectEster curing reaction: Chemical Bonding

Implementation Method 2

When they are used as curing agents, it is possible to reduce the formation of undesirable hydroxyl groups during the curing reaction

Methodology Applied
Scientific EffectCondensation reaction: Chemical Bonding

Data Source

PatentEP3374414B1Active ester curing agent compound for thermosetting resins, flame retardant composition comprising same, and articles made therefrom
Publication Date: 2020.04.22 ICL IP AMERICA INC
  • EP3374414B1 patent drawingFigure 1
  • EP3374414B1 patent drawingFigure 2
  • EP3374414B1 patent drawingFigure 3

AI summary

There is provided herein a flame retardant and curing agent compound for curing thermosetting resins, e.g., epoxy resins, a composition comprising a thermosetting resin, e.g., epoxy resin and the curing agent, an article comprising the curing agent, and a method of making the curing agent.