Epoxy-Acrylic Hybrid Adhesive with Core-Shell Rubber for High Heat Resistance
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Solution Overview
Problem
Current epoxy acrylic structural adhesives used in the automobile industry are brittle and fail to meet the required T-peel strengths and heat resistance, especially when exposed to high-heat conditions during manufacturing and painting processes.
Innovation Solution
A two-component adhesive composition comprising an A-side with acrylate-capped polyurethane, core/shell graft copolymer, phosphorous compounds, olefinically-unsaturated carboxylic acids, and a B-side with epoxy resin, oxidizing agent, stabilizer, and filler, which are mixed and cured to form a robust bond with improved T-peel strength and heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If epoxy acrylic hybrid adhesives are used to achieve rapid cure and heat resistance, then heat resistance is improved, but the adhesive becomes brittle and T-peel strength deteriorates
Solution Approach 1:
The patent creates a composite adhesive system by incorporating a core-shell rubber particle suspension into the epoxy acrylic hybrid adhesive. The core-shell rubber particles act as a secondary phase that provides toughness and flexibility, while the epoxy acrylic matrix provides heat resistance and rapid cure. This composite structure allows the adhesive to simultaneously achieve high heat resistance (withstanding 177°C paint oven conditions) and high T-peel strength (exceeding 40 pli), resolving the contradiction between heat resistance and peel strength.
2Strength
If structural adhesives are used to provide high strength and modulus bonds, then bond strength is improved, but the adhesive fails to withstand high-heat conditions during manufacturing
Solution Approach 1:
The patent changes the chemical composition parameters of the adhesive by selecting specific epoxy resins (such as diglycidyl ether of bisphenol A) and acrylic components with appropriate glass transition temperatures. The epoxy acrylic hybrid system is formulated to maintain its mechanical properties and crosslink density at elevated temperatures, allowing the adhesive to provide high bond strength while withstanding the thermal conditions of vehicle manufacturing and painting processes (up to 177°C).
3Strength
If polyurethane adhesives are used to provide flexibility and impact strength, then impact strength is improved, but thermal stability deteriorates under high-heat conditions
Solution Approach 1:
The patent extracts the polyurethane component from the adhesive system and replaces it with an epoxy acrylic hybrid system. The core-shell rubber particles are then added to provide the necessary flexibility and impact strength that would otherwise require polyurethane. This extraction and replacement strategy allows the adhesive to achieve impact strength through the rubber particle suspension mechanism while the epoxy acrylic matrix provides the thermal stability needed to withstand high-heat manufacturing conditions.
4Loss of time
If conventional acrylic structural adhesives are used to achieve rapid cure, then cure speed is improved, but heat resistance and bond strength deteriorate
Solution Approach 1:
The patent merges the epoxy resin system with the acrylic structural adhesive system to create an epoxy acrylic hybrid adhesive. The epoxy component contributes rapid cure capability through its reactivity with the acrylic monomers and oligomers, while simultaneously providing enhanced heat resistance and bond strength. The core-shell rubber particles are incorporated into this hybrid system to further improve toughness and T-peel strength. This merging of two different adhesive chemistries allows the final product to achieve rapid cure (within 15-30 minutes at room temperature), high bond strength (exceeding 40 pli T-peel), and excellent heat resistance (withstanding 177°C paint oven conditions).
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 adhesive composition demonstrates enhanced T-peel strength and cohesive failure mode, effectively withstanding high-heat conditions and rapid curing, making it suitable for bonding diverse substrates in the automobile industry.
Implementation Method 1
Conventional acrylic structural adhesives typically comprise a mixture of one or more olefinic reactive monomers such as methyl methacrylate and methacrylic acid, toughener(s) and redox initiator system
Implementation Method 2
A) the A-side comprising, consisting essentially of, or consisting of: i) an acrylate-capped polyurethane, preferably wherein the acrylate-capped polyurethane is be obtained by reacting a polyol with a multifunctional isocyanate to complete reaction of the isocyanate to obtain a pre-polymer, and capping the pre-polymer with acrylate groups
Implementation Method 3
the adhesive must be able to withstand the high-heat conditions (e.g., 177° C.) of the paint ovens during the assembly of the vehicle
Data Source
AI summary
The invention relates to a two-component adhesive based on hybrid urethane-acrylate epoxies comprising a core/shell rubber demonstrating good T-peel strength. The adhesives are suitable for use in industry, e.g., as adhesives for transportation industry applications.