UV-Cured Finish Coat Composition for Stronger Frame Adhesion
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Solution Overview
Problem
The existing bonding performance between plastic middle frames or battery covers and glue in electronic devices is poor due to the high crosslinking degree and non-recoatability of the finish coat layer, leading to issues like the touch screen falling off.
Innovation Solution
A finish coat composition comprising film-forming resins, acrylate monomers, photoinitiators, leveling agents, and matting powder, which are crosslinked and cured under UV light to form a finish coat with improved bonding performance, replacing the current finish coat layer without altering the production process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a finish coat layer with high crosslinking degree is used to protect the plastic middle frame or battery cover, then the protective performance and durability are improved, but the bonding performance with glue deteriorates
Solution Approach 1:
The patent modifies the chemical composition parameters of the finish coat by incorporating acrylic resins and photoinitiators that enable UV-curable formulations. This changes the crosslinking mechanism from conventional high-crosslinking systems to a controlled photopolymerization system that maintains lower crosslinking density, thereby improving glue adhesion while preserving protective functions.
Solution Approach 2:
The invention creates a composite finish coat system combining acrylic resins, polyurethane acrylate, and photoinitiators. This composite material structure allows the coating to exhibit both protective properties (through the resin matrix) and bonding compatibility (through the acrylate groups that can form weak interfacial bonds with adhesives), resolving the contradiction between protection and adhesion.
2Stability of the object's composition
If the finish coat layer is made non-recoatable to ensure durability, then the coating stability is improved, but the bonding performance with adhesive deteriorates
Solution Approach 1:
The patent adjusts the molecular weight and functional group composition of the acrylic resins to achieve an optimal balance. The resins are designed with moderate molecular weights and specific acrylate functional groups that provide sufficient coating stability while maintaining surface characteristics compatible with adhesive bonding, eliminating the need for etching processes.
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 new finish coat composition achieves a shear strength of 20 MPa or more with the adhesive, preventing the screen from falling off and enhancing the reliability of electronic devices.
Implementation Method 1
the film-forming resin is crosslinked and cured with the acrylic monomer under the action of ultraviolet light to form a finish coat
Data Source
AI summary
A finish coat composition, including: 30˜60 parts by mass of film-forming resin, where the film-forming resin includes one or more of acrylic resins and polyurethane acrylate resins; 5˜20 parts by mass of acrylate monomer; 1˜10 parts by mass of photoinitiator; 0.5˜10 parts by mass of leveling agent; 0˜20 parts by mass of matting powder; and 20˜50 parts by mass of solvent. This application further provides a composite material, a middle frame of an electronic device. The finish coat composition according to this application can be crosslinked and cured under an action of ultraviolet light to form a finish coat having good reliability and bonding performance, which is used as a finish coat layer of the middle frame of an electronic device and the battery cover of an electronic device, and has good bonding performance with glue, thereby preventing a screen of the electronic device from falling off.