Thermosetting Resin Processing Window Extension

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Solution Overview

Problem

The processing window for liquid composite moulding (LCM) resins with particulate hardeners is limited, making it difficult to infuse resin into large and complex structures before the resin becomes too viscous, which restricts the formation of composite structures with high strength-to-weight ratios.

Innovation Solution

Subjecting the LCM resin to a heat-treatment step at the dissolution temperature of the particulate hardener to dissolve the particles, then cooling it to form a low-viscosity resin mixture, which is maintained at a dwell-temperature below the dissolution temperature for extended infusion time before curing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the resin is heated to dissolve hardener particles, then the particles are dissolved and can be infused, but the resin gels or cures prematurely

Engineering Contradiction:

Improveparticle dissolutionVSAvoidprocessing window

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The hardener particles are dissolved in the resin before injection into the mold, during a pre-heating stage. This preliminary action ensures complete particle dissolution occurs prior to the resin entering the mold cavity, allowing the mold to be kept at lower temperatures during infusion to maintain extended processing window

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Different temperature zones are used in different locations of the processing system. The resin is pre-heated to high temperature (e.g., 150-160°C) in the injection system to dissolve particles, then injected into a mold maintained at lower temperature (e.g., 25-50°C) during infusion. This spatial temperature differentiation allows particle dissolution without premature curing

Inventive Principle:

Principle #3Local quality

2Reliability

If the mold temperature is kept high to dissolve particles, then particles are dissolved, but the resin viscosity decreases too quickly and the processing window is shortened

Engineering Contradiction:

Improveparticle dissolutionVSAvoidprocessing window

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

Particle dissolution is accomplished in advance during resin pre-heating before injection, rather than maintaining high mold temperature throughout the entire infusion process. This allows the mold to be cooled to lower temperatures during infusion, thereby extending the resin's low-viscosity state and prolonging the processing window

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The temperature parameter is dynamically changed during the process: high temperature (150-160°C) is applied briefly during pre-heating to dissolve particles, then the mold temperature is reduced to lower values (25-50°C) during infusion to maintain resin flowability and extend the processing window

Inventive Principle:

Principle #35Parameter changes

3Productivity

If the resin is injected quickly, then the processing time is reduced, but the resin cannot be uniformly infused throughout large and complex structures

Engineering Contradiction:

Improveinfusion speedVSAvoidinfusion uniformity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The resin viscosity parameter is controlled by temperature management. The resin is pre-heated to reduce viscosity for easy injection, then the mold is maintained at lower temperature during infusion to slow down the viscosity increase rate, allowing sufficient time for complete and uniform infusion of large and complex structures while maintaining reasonable productivity

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

This method significantly prolongs the processing window, allowing complete and uniform infusion of resin into fibrous structures, enabling the formation of larger and more complex composite parts by maintaining the resin's low viscosity for an extended period.

Implementation Method 1

heating the resin enough to insure particle dissolution

Methodology Applied

Scientific EffectDissolution: Solvation

Implementation Method 2

cooling it to form a low-viscosity resin mixture

Methodology Applied

Scientific EffectCooling: Cooling

Implementation Method 3

maintained at a dwell-temperature below the dissolution temperature for extended infusion time

Methodology Applied

Scientific EffectTemperature control:

Implementation Method 4

the resin is injected into a mold that contains a fibrous body. The resin infuses throughout the fibrous body and is cured within the mold to form a final composite structure

Methodology Applied

Scientific EffectCuring: Photopolymerisation

Data Source

PatentUS8747720B2Process for prolonging the processing window of thermosetting resins

Publication Date: 2014.06.10 HEXCEL COMPOSITES LTD (GB)

AI summary

The processing window for thermosetting resins that contain particulate hardeners is prolonged using the combined steps of heat-treating the resin to form a low-viscosity resin mixture in which the particles are dissolved and then molding the low-viscosity resin mixture at temperatures below the dissolution temperature of the particles to infuse a fibrous preform. The infused resin preform is heated to the curing temperature of the resin to provide final curing of the resin.