Dual-Cure Structural Adhesive Precursor for Automotive Bonding
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Solution Overview
Problem
Current structural adhesive compositions for bonding metal parts, particularly in the automotive industry, face challenges such as insufficient elasticity, tackiness, and corrosion resistance, especially when dealing with complex three-dimensional configurations and oily contaminated substrates.
Innovation Solution
A partially cured precursor composition utilizing a dual curing system with a cationically self-polymerizable monomer and a curable monomer, combined with a thixotropic agent, which allows for a two-stage curing mechanism to form an interpenetrating network, providing excellent adhesion, flexibility, and corrosion resistance without interfering with the initial shape of the precursor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a structural adhesive film is used to bond metal panels, then bonding strength is improved, but elasticity and tackiness are insufficient
Solution Approach 1:
The patent uses a composite adhesive system combining thermosetting resin (for strength) and thermoplastic polymer (for elasticity and tackiness). This composite formulation allows the adhesive to simultaneously achieve high bonding strength and the required flexibility for hem flange bonding applications.
Solution Approach 2:
The patent modifies the physical and chemical parameters of the adhesive by controlling the glass transition temperature (Tg) of the thermoplastic component and the curing characteristics of the thermosetting resin. This enables the adhesive to exhibit appropriate tackiness at application temperature while maintaining bonding strength after curing.
2Strength
If a structural adhesive composition is used for metal bonding, then adhesive strength is improved, but corrosion resistance is insufficient
Solution Approach 1:
The patent formulates a composite adhesive composition that includes corrosion inhibitors and rust preventive agents combined with the thermosetting/thermoplastic matrix. This composite approach provides both strong bonding and enhanced corrosion resistance for metal substrate protection.
Solution Approach 2:
The patent introduces intermediary substances such as coupling agents and corrosion inhibitors that mediate between the adhesive and metal substrate, improving both adhesion strength and corrosion resistance by preventing direct corrosive interactions while maintaining bonding performance.
3Strength
If a structural adhesive film is used for bonding, then bonding capability is improved, but handling and automation are difficult
Solution Approach 1:
The patent adjusts the viscosity and open time parameters of the adhesive composition to optimize handling characteristics. The thermoplastic component provides appropriate viscosity for application while the controlled curing kinetics enable sufficient open time for positioning and automation processes.
Solution Approach 2:
The patent creates a dynamic adhesive system that transitions from a flexible, handleable state during application to a rigid, strong bond after curing. The thermoplastic component provides initial flexibility for handling and automation, while the thermosetting resin develops final bonding strength.
4Area of stationary object
If a structural adhesive composition is used for complex three-dimensional configurations, then bonding coverage is improved, but manufacturing precision is insufficient
Solution Approach 1:
The patent employs a flexible adhesive composition that can conform to complex three-dimensional surfaces and irregular geometries. The thermoplastic component provides the necessary flexibility to wrap around and adhere to complex shapes while maintaining precise positioning and coverage.
Solution Approach 2:
The patent utilizes the dynamic flow and curing characteristics of the adhesive to achieve precise placement on complex geometries. The adhesive flows to conform to the surface during application, then固化 to maintain precise shape and position, enabling both comprehensive coverage and manufacturing 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 solution achieves enhanced adhesion, flexibility, and corrosion resistance, enabling near-net shape application and efficient bonding of complex metal parts with improved handling and automation capabilities, while maintaining the initial shape and reducing the need for further processing.
Implementation Method 1
a polymeric material comprising the self-polymerization reaction product of a polymerizable material comprising a cationically self-polymerizable monomer
Implementation Method 2
a curable monomer which is different from the cationically self-polymerizable monomer, wherein the curable monomer comprises at least one functional group selected from the group consisting of epoxy groups
Implementation Method 3
combined with a thixotropic agent, which allows for a two-stage curing mechanism to form an interpenetrating network, providing excellent adhesion, flexibility, and corrosion resistance without interfering with the initial shape of the precursor
Data Source
AI summary
The present disclosure relates to a curable precursor of a structural adhesive composition, comprising: a) a cationically self-polymerizable monomer; b) a polymerization initiator of the cationically self-polymerizable monomer which is initiated at a temperature T1; c) a curable monomer which is different from the cationically self-polymerizable monomer; and d) a curing initiator of the curable monomer which is initiated at a temperature T2 and which is different from the polymerization initiator of the cationically self-polymerizable monomer; and e) a thixotropic agent. According to another aspect, the present disclosure is directed to a partially cured precursor of a structural adhesive composition. According to still another aspect, the present disclosure relates to a method of bonding two parts. In yet another aspect, the disclosure relates to the use of a curable precursor or a partially cured precursor as described above, for industrial applications, in particular for body-in-white bonding applications for the automotive industry.