Polyurethane Prepreg Impregnation for Storage-Stable Composite Molding
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Solution Overview
Problem
The production of polyurethane prepregs is hindered by the difficulty in handling and processing due to the short processing time of 2-component polyurethane systems, which limits storage stability and handling ease, especially when dealing with complex mold geometries and the toxicity of isocyanates used in traditional methods.
Innovation Solution
A process involving the dissolution of reactive polyurethane composition components in a suitable solvent, impregnation of fibrous supports, and subsequent solvent removal at low temperatures, allowing for the production of storage-stable prepregs with improved handling and processing properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If 2-component polyurethane systems are used for prepreg production, then reactivity and crosslinking speed are improved, but storage stability and processing time are reduced
Solution Approach 1:
The polyurethane composition is divided into separate components (isocyanate component and polyol component) that are applied at different times. The isocyanate component is applied first to the fibrous support, then the polyol component is applied later during the molding process, preventing premature crosslinking and enabling long-term storage of the prepreg with the isocyanate component already in place.
Solution Approach 2:
The isocyanate component is applied to the fibrous support in advance during prepreg manufacturing, allowing the prepreg to be stored and handled before the actual molding process. This preliminary application of one component enables subsequent application of the second component (polyol) at the appropriate time without premature reaction.
2Strength
If traditional polyurethane resin systems are used, then toughness and damage tolerance are improved, but toxicity of isocyanates is increased
Solution Approach 1:
The patent removes the toxic isocyanate component from the dissolved prepreg state by applying it first as a separate layer, then removing excess isocyanate. This extraction of the harmful substance from the bulk material while maintaining its functional benefits resolves the contradiction between toughness and toxicity.
Solution Approach 2:
The patent converts the potentially harmful isocyanate component into a beneficial surface treatment layer that provides adhesion and reactivity, while the bulk of the material uses non-toxic polyol and filler components. The isocyanate's reactivity is harnessed for bonding rather than being a source of toxicity in the final product.
3Adaptability or versatility
If prepregs are cut to size for complex mold geometries, then adaptability is improved, but cutting tool contamination increases
Solution Approach 1:
The patent uses a disposable release film or transfer medium that is applied to the prepreg, allows easy cutting without contamination, and is then removed or left as a non-interfering element. This disposable layer protects cutting tools from contamination while enabling precise cutting for complex geometries.
4Manufacturing precision
If fiber reinforced materials are laid in mold with complex geometries, then manufacturing precision is improved, but handling difficulty and time increase
Solution Approach 1:
The fibrous support is pre-formed and pre-sized to match the complex mold geometry before prepreg application. This preliminary shaping of the substrate allows the reactive composition to be applied as a simple coating rather than requiring complex manipulation of the fibrous material itself during molding, greatly simplifying handling while maintaining precision.
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 process results in prepregs with enhanced storage stability, ease of handling, and improved mechanical properties, suitable for high-performance composite applications in various industries without the toxicity concerns of traditional isocyanate-based systems.
Implementation Method 1
the critical ingredient of one component is always a polyisocyanate, in the case of the second this is polyols... The two parts are only mixed together shortly before processing. Thereafter the chemical curing takes place by polyaddition with formation of a network of polyurethane or polyurea.
Implementation Method 2
by impregnation of fibre reinforced materials such as fabrics and non-wovens with the use of reactive polyurethane compositions
Implementation Method 3
removal of the solvent
Data Source
AI summary
The invention relates to a method for producing storage-stable polyurethane prepregs and molding bodies produced therefrom (composite components), which can be obtained by a method using a polyurethane composition in solution and by impregnation of fiber-reinforced materials such as of woven fabrics and laid scrim using reactive polyurethane compositions.