Polyurethane Prepregs with Latent Catalysts for Rapid Hardening
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current prepreg systems for fiber-composite components have high hardening temperatures and long cycle times, leading to high energy costs and production inefficiencies, and require external blocking agents, while also having lower glass transition temperatures compared to aromatic systems.
Innovation Solution
Development of storage-stable polyurethane prepregs with a low-viscosity polyurethane system containing aromatic diisocyanates, polyester polyols with high secondary hydroxy end groups, and latent catalysts, which can be impregnated into fibrous materials at room temperature, allowing for rapid hardening at low temperatures without external blocking agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If aliphatic polyisocyanates with blocking agents are used, then storage stability is improved, but hardening temperature increases to 120-200°C and cycle time extends to up to 60 minutes
Solution Approach 1:
The invention extracts and removes the blocking agents (uretdione or external blocking agents) from the polyisocyanate system. By using polyisocyanates without blocking agents, the hardening process can proceed directly without requiring high temperatures to activate blocked groups, thereby reducing cycle time from up to 60 minutes to significantly shorter durations while maintaining storage stability through alternative means.
Solution Approach 2:
The invention changes the chemical composition parameters of the polyisocyanate system by selecting polyisocyanates with specific reactivity characteristics that do not require blocking agents. This parameter change enables the system to maintain stability during storage while achieving rapid hardening at lower temperatures, thus resolving the contradiction between storage stability and cycle time.
2Stability of the object's composition
If aliphatic polyisocyanate systems are used, then storage stability is improved, but glass transition temperature decreases compared to aromatic systems
Solution Approach 1:
The invention creates a composite polyurethane system by combining polyisocyanates without blocking agents with specific polyols and additives. This composite formulation achieves the desired glass transition temperature range while maintaining storage stability, overcoming the limitation of aliphatic systems by optimizing the overall composition rather than relying solely on the polyisocyanate type.
Solution Approach 2:
The invention adjusts the chemical parameters of the polyurethane system, specifically selecting polyisocyanates with appropriate molecular structures and reactivities that can achieve high glass transition temperatures without requiring blocking agents. By changing the compositional parameters, the system attains both storage stability and high thermal performance.
3Strength
If polyurethane resins are used, then toughness and strength are improved, but hardening temperature and cycle time increase
Solution Approach 1:
The invention removes blocking agents from the polyurethane resin system, enabling direct hardening without the need for high-temperature activation. This extraction of blocking agents maintains the toughness and strength characteristics of polyurethane resins while dramatically reducing the hardening cycle time from up to 60 minutes to much shorter durations.
Solution Approach 2:
The invention optimizes the chemical parameters of the polyurethane resin system by selecting polyisocyanates with specific reactivity and molecular weight characteristics. These parameter changes enable the resin to maintain its superior toughness and strength while achieving rapid hardening at lower temperatures, thus resolving the contradiction between mechanical properties and processing time.
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 solution results in prepregs with improved processing properties, shorter cycle times, high glass transition temperatures, and extended shelf life, enabling efficient and cost-effective production of fiber-composite components with enhanced mechanical properties.
Implementation Method 1
a polyol component (B) and an isocyanate component (A) in a ratio of the number of NCO groups of component A) to the number of OH groups of component B) of from 1.35:1 to 10:1, particularly preferably from 1.4:1 to 5.0:1
Data Source
AI summary
The invention relates to prepregs and to a method for producing storage-stable polyurethane prepregs (pre-impregnated fibers) using polyols with a high content of secondary hydroxyl end groups, to composite fiber components (composite components) which are produced from the prepregs and which can be obtained by impregnating fiber-shaped materials such as woven fabrics and fleece, and to a method for producing said composite fiber components.