1. Technical Field
The present disclosure relates to an adhesive composition, more specifically, an adhesive composition that enables adhesion between metals, between a metal and an organic material, and between organic materials.
2. Background
Examples of conventional bonding methods for joining two adherends include interlocking, welding, and adhesion using an adhesive or a sticker, and these methods are frequently used in their fields depending on their uses. In recent years, in uses related to transporters such as automobiles, weight saving of the automobile body has advanced, and hybrid vehicles and electric vehicles are becoming popular as solutions to global warming by, for example, reduction of emission of the carbon dioxide gas CO2. Accordingly, aluminum, magnesium, and FRPs (CFRP: Carbon Fiber Reinforced Plastics, GFRP: Glass Fiber Reinforced Plastics) are becoming more frequently used for the automobile body because of their light weights.
In conventional welding processes, welding of different kinds of materials such as aluminum and iron is very difficult, and melding itself is impossible in cases of FRPs of glass fibers and carbon fibers. Thus, a method for bonding these materials (adherends) with a bonding strength equivalent to that achieved by welding is required. As a method for bonding materials which cannot be bonded by welding or the like, a method using an adhesive may be employed. Adhesives used for bonding such materials are required, for example, to be capable of achieving adhesion between metals, between a metal and an organic material, and between an organic material and an organic material, to achieve a bonding strength sufficient for structural uses, and to provide adhesion whose strength is not deteriorated by temperature changes.
As adhesives that satisfy the above requirements, thermosetting resins such as epoxy resins are generally used. However, although the mechanical strength of the resin itself of an epoxy adhesive after curing is high, the resin has poor toughness, and, in cases where an epoxy adhesive is used for a use such as an aircraft or an automobile, the problem of a decrease in the bonding strength sometimes occurs due to brittle fracture. In order to solve such a problem, addition of a thermo-setting resin or the like to an epoxy resin is attempted to provide an epoxy adhesive having flexibility (e.g., JP 2003-82034 A).
However, in cases where a thermo-setting resin having flexibility is used for an epoxy adhesive, thermal resistance of the adhesive is deteriorated, so that the adhesive cannot be used for uses in which thermal resistance is required, which is problematic.