One-Part Curable Resin Composition Impact Peel Performance
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Solution Overview
Problem
One-part curable resin compositions containing epoxy resins and dicyandiamide exhibit low fracture toughness and brittle behavior, limiting their impact peel performance in applications such as adhesives and structural materials.
Innovation Solution
A one-part curable resin composition is developed by blending epoxy resin with core-shell-structured polymer particles and/or blocked urethane, a phenolic compound having one to three phenolic hydroxy groups, and dicyandiamide, optimizing the mole ratio of phenolic hydroxy groups to cyanamide groups to enhance impact peel performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If epoxy resin is blended with dicyandiamide to produce a one-part curable composition, then the composition can be stored and cured on-demand, but the cured product exhibits low fracture toughness and brittle behavior
Solution Approach 1:
The patent applies composite materials by combining epoxy resin with core-shell polymer particles (rubber core with plastic shell) and phenolic compounds. This composite structure allows the cured product to maintain the ease of one-part storage while significantly improving fracture toughness. The rubber core provides elasticity and crack resistance, while the phenolic compound enhances crosslinking density, creating a composite material that resolves the contradiction between storability and toughness.
Solution Approach 2:
The patent changes the chemical parameters of the curing system by introducing phenolic compounds with specific hydroxyl group counts (1-3 per molecule) and controlling the molar ratio of phenolic hydroxy groups to cyanamide groups (0.01-1.5). This parameter optimization modifies the crosslinking structure to achieve both adequate storage stability and improved fracture toughness, resolving the contradiction through precise compositional control.
2Strength
If core-shell polymer particles are added to improve impact resistance, then fracture toughness increases, but the composition complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies local quality by using core-shell polymer particles where the rubber core provides localized elasticity and shock absorption, while the plastic shell provides localized structural support and compatibility with the epoxy matrix. This localized functional differentiation allows impact resistance improvement without requiring complex bulk compositional changes, thereby managing composition complexity while enhancing toughness.
3Strength
If phenolic compound is added to enhance crosslinking and toughness, then mechanical strength improves, but the curing process control becomes more difficult
Solution Approach 1:
The patent uses phenolic compounds as intermediary substances that mediate between the epoxy resin and dicyandiamide curing system. The phenolic compound with 1-3 hydroxyl groups per molecule acts as a bridge, participating in crosslinking reactions while controlling the reaction kinetics. This intermediary role allows mechanical strength enhancement while maintaining manageable curing process control through the specific hydroxyl group count and molar ratio parameters.
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 cures into a product with significantly improved impact peel performance, offering high bond strength and toughness, suitable for structural adhesives and laminates.
Implementation Method 1
Dicyandiamide forms cyanamide when heated. This enables dicyandiamide to function as a latent curing agent that exhibits activity as a curing agent.
Implementation Method 2
Cured products of epoxy resins excel in many properties such as dimensional stability, mechanical strength, electrical insulation performance, heat resistance, water resistance, and chemical resistance.
Data Source
AI summary
A one-part curable resin composition contains 100 parts by weight of an epoxy resin (A), 1 to 100 parts by weight of core-shell-structured polymer particles and/or blocked urethane as a component (B), a compound (C) having one to three phenolic hydroxy groups per molecule, the compound (C) not being a compound having an amino group; and dicyandiamide (D). The ratio of the number of moles of the phenolic hydroxy groups of the compound (C) to the number of moles of CN groups derived from the dicyandiamide (D) is from 0.01 to 0.39 when the compound (C) has one phenolic hydroxy group per molecule and from 0.01 to 1.5 when the compound (C) has two or three phenolic hydroxy groups per molecule.