Polyurethane Matrix with Internal Mold Release for Fiber Composites
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Solution Overview
Problem
Current fiber composite production methods require external mold release agents, have low heat distortion resistance, long curing times, and high energy costs due to the use of reactive resin mixtures that are not phase-stable and have limited pot life, leading to inefficiencies and increased production costs.
Innovation Solution
Development of polyurethane matrix materials with internal mold release agents, featuring thermolatent reaction characteristics that allow for long pot life and rapid viscosity increase, enabling efficient impregnation and curing at low temperatures without external mold release agents, and achieving high NCO conversion directly after demolding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If external mold release agents are used for demoldability, then the fiber composite components can be produced, but the production process becomes laborious and costly due to repeated cleaning and priming of molds
Solution Approach 1:
The polyol component is modified to contain internal mold release properties through the addition of specific additives (5-50 wt% relative to polyol weight), enabling the resin mixture to self-release from the mold surface without requiring external mold release agents. This eliminates the need for repeated cleaning and priming operations, allowing continuous production without interrupting the mold preparation process.
2Duration of action of moving object
If reactive resin mixtures with long pot life are used, then fiber impregnation is improved, but curing time increases leading to low productivity
Solution Approach 1:
The patent employs a two-component polyurethane system where the polyol component contains specific additives that modify the reaction kinetics. The mixture maintains low viscosity and long pot life at ambient temperature for complete fiber impregnation, then undergoes rapid curing when exposed to elevated temperatures (80-100°C), achieving full cure within minutes rather than hours.
3Productivity
If high curing temperatures are used to reduce cycle time, then productivity increases, but energy costs increase
Solution Approach 1:
The modified polyol system enables curing at relatively low temperatures (80-100°C) while maintaining short cycle times. The internal mold release additives and catalyst system are designed to accelerate the polyaddition reaction at these moderate temperatures, achieving full cure without requiring the high temperatures (100-200°C) that would consume excessive energy.
4Ease of manufacture
If polyisocyanurate systems with internal mold release agents are used, then external mold release agents are eliminated, but phase instability occurs preventing RTM method production
Solution Approach 1:
The patent carefully controls the composition and concentration of internal mold release additives within the polyol component (5-50 wt% relative to polyol weight). This optimized formulation provides sufficient mold release properties to eliminate external agents while maintaining phase stability of the polyurethane system, enabling successful production by the RTM method unlike previous polyisocyanurate systems.
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 approach allows for the production of fiber composite components with improved mechanical properties, reduced cycle times, and increased productivity by eliminating the need for complex aftertreatments and external mold release agents, while maintaining high glass transition temperatures and surface tension for direct painting and lamination.
Implementation Method 1
The polyurethane is obtainable from a polyaddition reaction mixture consisting of polyisocyanates, polyols, thermolatent catalysts and optionally additives
Implementation Method 2
thermolatent reaction characteristics at elevated temperatures, i.e. at first is mobile for long period (has a long pot life), in order to enable good impregnation and wetting of the fibers, but then very quickly gains in viscosity ('snap-cure')
Data Source
AI summary
The present invention fiber composite components obtainable, for example, by impregnating fibers with a reactive polyurethane resin mixture of polyisocyanates, polyols, thermo-latent catalysts and optionally additives, and to a method for the production thereof.