Organosilicon Interlayer for EVA-POE Adhesive Film Delamination
Solution Overview
Problem
The existing hot melt adhesive films with an EVA/POE/EVA structure face delamination issues due to differences in crosslinking reactivity, melt viscosity, and melt shear heating rate between the non-polar POE and polar EVA copolymer layers, leading to reduced bonding force and shortened service life in packaging materials like solar panels and touch screens.
Innovation Solution
A hot melt adhesive film with a five-layer composite structure, featuring a POE inner layer, EVA copolymer outer layers, and organosilicon polymer intermediate layers, where the siloxane with a special polar structure undergoes an addition reaction upon UV irradiation to form an organosilicon polymer, enhancing the bonding force between layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If POE and EVA copolymer are co-extruded to form a three-layer adhesive film, then water vapor-proof characteristics and anti-PID characteristics are improved, but delamination occurs between layers due to differences in crosslinking reactivity, melt viscosity, and melt shear heating rate
Solution Approach 1:
A polar resin master batch is introduced as an intermediary component in the POE inner layer. This master batch contains polar groups that can interact with both the non-polar POE and the polar EVA copolymer, acting as a mediator to improve interfacial adhesion. The polar resin master batch includes functional additives such as silane coupling agents or phosphoric acid esters that create chemical bridges between the two resin systems, preventing delamination while maintaining the three-layer structure's protective characteristics.
Solution Approach 2:
The chemical composition parameters of the POE inner layer are modified by incorporating a polar resin master batch at specific concentrations (typically 1-5 wt%). This parameter change alters the surface energy and chemical reactivity of the POE layer, enabling better compatibility with EVA copolymer. The polar resin master batch adjusts the melt viscosity and crosslinking reactivity parameters to match between layers, preventing delamination during the co-extrusion process and long-term aging.
2Reliability
If POE and EVA copolymer are co-extruded with different crosslinking reactivity and melt viscosity, then functional performance is improved, but delamination risk increases during long-term aging
Solution Approach 1:
The polar resin master batch serves as a long-term mediator that maintains bonding between layers during aging. It contains hydrolyzable groups that gradually react with moisture to form stable crosslinked structures, creating a self-healing effect that compensates for initial bonding deficiencies. This intermediary component ensures that the bonding force does not deteriorate over time, extending the service life of the adhesive film while maintaining its functional performance.
Solution Approach 2:
The polar resin master batch is pre-incorporated into the POE inner layer before co-extrusion, performing preliminary chemical preparation for interfacial bonding. The polar groups are pre-positioned at the interface region, ready to interact with EVA copolymer chains during and after extrusion. This preliminary action ensures that bonding mechanisms are activated immediately, preventing delamination initiation during the aging process and extending the adhesive film's operational lifespan.
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 organosilicon polymer improves the bonding force and stability of the adhesive film, preventing delamination and extending the service life of packaging materials, while maintaining excellent light transmittance, water vapor barrier performance, and insulation.
Implementation Method 1
subjecting the three-layer co-extruded film to ultraviolet (UV) irradiation, such that the siloxane with a special polar structure in the POE undergoes an addition reaction to form an organosilicon polymer
Data Source
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AI summary
A hot melt adhesive film, and a preparation method, use, and an organosilicon polymer thereof are provided. The hot melt adhesive film includes: an inner layer, which is a polyolefin elastomer (POE); outer layers, which are an ethylene-vinyl acetate (EVA) copolymer on two surfaces of the inner layer; and intermediate layers, which are an organosilicon polymer between the inner layer and the outer layers. As intermediate layers, the organosilicon polymer plays the role of connection and transition, improves a bonding force between EVA and POE layers, and improves the stability of the hot melt adhesive film during long-term use. The hot melt adhesive film can be used as a packaging material for solar panels, touch screens, and the like.