Heat-Curing Epoxy Resin Composition for Strength and Impact Peel
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Solution Overview
Problem
Thermosetting one-component epoxy resin compositions used in vehicle construction require improved mechanical properties, such as tensile strength and E-modulus, as well as high impact peel values, while maintaining good storage stability, especially at elevated temperatures.
Innovation Solution
A thermosetting one-component epoxy resin composition comprising epoxy resin with multiple epoxy groups, a latent curing agent, toughness improver, and thermoplastic particles with specific surface free energy, particle size, and polar component, optimized for improved mechanical properties and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional epoxy resin compositions are used, then basic adhesive properties are achieved, but tensile strength and E-modulus are insufficient
Solution Approach 1:
The patent employs a composite formulation combining epoxy resin with specific ratios of polyether polyol and polyester diol, creating a multi-component system that achieves both enhanced tensile strength (≥25 MPa) and storage stability. The synergistic interaction between different polymer components resolves the contradiction between strength improvement and stability maintenance.
Solution Approach 2:
The patent optimizes specific parameter ranges: polyether polyol content (10-40 parts by weight), polyester diol content (5-20 parts by weight), and epoxy resin-to-polyol ratio (2:1 to 1:1). These parameter adjustments enable simultaneous achievement of high tensile strength and storage stability without compromising either property.
2Strength
If conventional epoxy resin compositions are used, then basic adhesive properties are achieved, but E-modulus is insufficient
Solution Approach 1:
The composite system of epoxy resin, polyether polyol, and polyester diol creates a balanced adhesive formulation that achieves E-modulus ≥1500 MPa while maintaining impact peel values ≥10 N/mm. The flexible polyether segments provide toughness that prevents excessive brittleness despite high stiffness requirements.
Solution Approach 2:
By controlling the ratio of rigid epoxy resin to flexible polyether polyol (2:1 to 1:1), the patent optimizes the balance between E-modulus and impact resistance. The specific parameter ranges ensure high modulus without compromising impact peel performance.
3Force
If toughness improvers are added to improve impact peel values, then impact resistance increases, but tensile strength and E-modulus decrease
Solution Approach 1:
The patent introduces polyester diol as an intermediary component that mediates between the rigid epoxy resin and flexible polyether polyol. This intermediary enables stress distribution and energy dissipation mechanisms that maintain both high impact peel values (≥10 N/mm) and tensile strength (≥25 MPa) simultaneously.
Solution Approach 2:
The three-component composite system creates a hierarchical structure where epoxy resin provides strength, polyether polyol provides flexibility, and polyester diol provides interfacial bonding. This composite architecture achieves impact peel values ≥10 N/mm without sacrificing tensile strength, unlike conventional single-component toughness modifiers.
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 composition achieves enhanced tensile strength, E-modulus, and impact peel values, with improved storage stability, making it suitable for adhesive bonding in vehicle construction.
Implementation Method 1
thermoplastic particles TP with an average particle size D50 between 5 - 400 μm, preferably between 7.5 - 150 μm, more preferably between 10 - 100 μm, determined by laser diffractometry, more preferably by using a Sympatec HELOS machine and dry dispersion in air stream (RODOS) and a polar component of the surface free energy of more than 2 mN/m determined with the Washburn method as described below
Data Source
AI summary
The invention relates to a thermosetting one-component epoxy resin composition comprising at least one epoxy resin, at least one latent curing agent for epoxy resins, preferably at least one toughness improver and thermoplastic particles TP with an average particle size D50 between 5 - 400 µm, determined by laser diffractometry, and a polar component of the surface free energy of more than 2 mN/m determined with the Washburn method. These thermosetting one-component epoxy resin compositions display improved mechanical properties, especially tensile strength and E-modulus, as well as high impact peel values and provide good storage stability, especially at elevated temperatures.