Multilayer Metal-Polypropylene Composite Adhesion via Modified Polyolefin
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Solution Overview
Problem
The existing methods for creating multilayer composite bodies of metals and polypropylene-based resins face challenges in achieving sufficient adhesive strength between the metal and the polypropylene injection-molded articles, particularly with polypropylene resins, which have poor adhesion to metals due to their nonpolar nature.
Innovation Solution
A multilayer composite body is formed by laminating a thermosetting resin layer, a modified polyolefin resin layer, and a polypropylene-based resin composition on a shaped metal article, where the modified polyolefin resin has a specific molecular weight and melting point range, and includes graft polymerization of α,β-unsaturated carboxylic acids or their derivatives with (meth)acrylic acid esters, enhancing the adhesion properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a primer layer of polyolefin resin is formed on the metal surface to enable polypropylene injection molding, then the polypropylene can be joined to the metal, but the bond strength between the metal and polypropylene is insufficient for practical use
Solution Approach 1:
The primer layer is divided into two distinct layers: a lower adhesive layer containing polar resin components that bond to the metal surface, and an upper polypropylene layer that provides compatibility with the injection-molded polypropylene. This segmentation allows each layer to perform its specific function optimally, resolving the contradiction between manufacturability and bond strength.
Solution Approach 2:
The primer layer is formulated as a composite material containing both polar resin components (for metal adhesion) and polypropylene resin components (for compatibility with the injection-molded polypropylene). This composite structure enables the primer to simultaneously achieve strong metal bonding and effective stress transfer to the polypropylene, thereby improving overall bond strength while maintaining ease of manufacture.
2Productivity
If polyolefin-based resins such as polypropylene are used due to their excellent mechanical properties and cost-effectiveness, then the material is inexpensive and weather-resistant, but the adhesion to metals is poor making multilayer composite bodies difficult to produce
Solution Approach 1:
The primer layer acts as an intermediary between the metal surface and the polypropylene resin. It contains polar resin components that provide strong adhesion to the metal surface, while also incorporating polypropylene resin components that ensure compatibility and bonding with the injection-molded polypropylene. This intermediary structure resolves the adhesion problem while maintaining the cost-effectiveness and weather resistance of polypropylene.
Solution Approach 2:
The primer layer's composition is specifically designed with controlled ratios of polar resin to polypropylene resin, and its thickness is optimized to balance adhesion performance with compatibility. By adjusting these parameters, the primer achieves both strong metal adhesion and effective stress transfer to the polypropylene, enabling easy manufacture of high-strength composite bodies.
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
This approach results in a multilayer composite body with improved shear breaking stress, achieving a bond strength of 13 MPa or more between the metal and the polypropylene-based resin, and when combined with glass fiber reinforced thermoplastic plastic, it enhances the mechanical properties and productivity.
Implementation Method 1
the modified polyolefin resin layer includes a modified polyolefin resin which has a weight-average molecular weight of 100,000 to 200,000 and a melting point of 70° C. to 110° C., as determined with a differential scanning calorimeter (DSC), and in which two or more selected from an α,β-unsaturated carboxylic acid or a derivative of the α,β-unsaturated carboxylic acid (B) and a (meth)acrylic acid ester (C) are graft polymerized onto a copolymer-type polyolefin (A) as a base material
Implementation Method 2
a thermosetting resin layer, a modified polyolefin resin layer, and a polypropylene-based resin composition are laminated on a shaped metal article
Data Source
AI summary
A multilayer composite body in which a shaped metal article, a thermosetting resin layer, a modified polyolefin resin layer, and a polypropylene-based resin composition, or a PP-based GFRTP are laminated in the order of description. A multilayer composite body of a metal and a resin is obtained which excels in a fixing strength (shear breaking stress) between the shaped metal article and the molded article of the polypropylene-based resin composition. The thermosetting resin layer is composed mainly of a urethane resin or an epoxy resin. The polypropylene-based resin composition is molded by an injection molding. The modified polyolefin resin forming the modified polyolefin resin layer includes one or two or more of non-chlorinated modified polyolefin resins having a weighted average of melting points of 70° C. to 110° C., as determined with a differential scanning calorimeter (DSC).