Polyolefin Substrate Coating Adhesion via Additive Mediation
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Solution Overview
Problem
Conventional polyolefin resin compositions for automotive materials face challenges in achieving sufficient coating adhesion, particularly when containing elastomers and fillers, and hindered amine compounds can bleed, leading to poor weatherability and coatability.
Innovation Solution
Incorporating an aromatic phosphoric ester metal salt and a hindered amine compound into a polyolefin resin composition, along with a benzoate light stabilizer, to enhance coating adhesion and weatherability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If surface modification such as sanding or flame/corona treatment is applied to enhance coating adhesion, then coating adhesion is improved, but physical properties of the substrate are unintentionally reduced and equipment investment is required
Solution Approach 1:
An additive serving as an intermediary substance is incorporated into the polyolefin resin composition. This additive contains functional groups that interact strongly with both the substrate and coating material, facilitating adhesion without requiring surface modification. The additive acts as a molecular bridge between the low-surface-energy polyolefin and the coating composition.
Solution Approach 2:
The chemical composition parameters of the polyolefin resin are modified by incorporating specific additives with controlled amounts. This changes the surface chemistry and bulk properties of the resin, enabling improved coating adhesion while maintaining the integrity of physical properties without mechanical or chemical surface treatment.
2Strength
If additives are added to increase coating adhesion, then coating adhesion is improved, but the functions of other additives such as pigments and antioxidants are impaired and cost increases
Solution Approach 1:
The additive is designed with localized functional groups that perform specific functions at different locations within the molecule. One part of the additive interacts with the polyolefin resin, another part interacts with the coating material, allowing it to enhance adhesion without interfering with the functions of other additives like pigments and antioxidants dispersed in the resin.
Solution Approach 2:
The additive serves as a mediator that facilitates coating adhesion through its dual-functional structure, while being compatible with other necessary additives. It provides the adhesion function without displacing or deactivating pigments, antioxidants, and other functional additives required for aesthetic quality and weatherability.
3Reliability
If hindered amine compound is incorporated to improve weatherability, then weatherability is improved, but bleeding occurs leading to poor coatability
Solution Approach 1:
The invention uses a composite resin composition that combines polyolefin resin with hindered amine compounds and other stabilizers in specific proportions. This composite formulation maintains weatherability while preventing bleeding through proper compatibility management. The composite structure allows the hindered amine to remain dispersed and functional without migrating to the surface.
Solution Approach 2:
The concentration and type of hindered amine compound are optimized within specific ranges to achieve the desired balance between weatherability and coatability. By controlling the amount and selecting appropriate molecular structures, the invention prevents bleeding while maintaining UV resistance and overall weatherability performance.
Data Source
AI summary
A substrate excellent in weatherability and adhesion to a coating applied thereon is provided. The substrate contains (a) 100 parts by mass of a polyolefin resin, (b) 0.01 to 0.5 parts by mass of an aromatic phosphoric ester metal salt having general formula (1), and (c) 0.02 to 0.5 parts by mass of a hindered amine compound, preferably a compound having general formula (2), and optionally preferably (d) 0.02 to 0.5 parts by mass of a benzoate light stabilizer having general formula (4). The structures of general formulae (1), (2), and (4) are as defined in the description.