Solar Cell Back Sheet Copolymer Adhesion Without Corona Treatment
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Solution Overview
Problem
Existing back sheets for solar cell modules with fluorine-containing polymer films exhibit poor adhesiveness to other materials, leading to challenges in bonding with water-impermeable sheets and ethylene/vinyl acetate copolymer (EVA) encapsulant layers, which affects the durability and protection of solar cell modules.
Innovation Solution
A back sheet configuration featuring a water-impermeable sheet with a film formed from a specific fluorine-containing copolymer composition, including C2-C3 perhaloolefin, vinyl acetate, hydroxy-containing vinyl monomer, and carboxy-containing monomer units, which enhances adhesiveness to both the water-impermeable sheet and the EVA encapsulant layer without requiring corona discharge treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fluorine-containing polymer film is used in the back sheet, then weather resistance is improved, but adhesiveness to water-impermeable sheet and EVA encapsulant layer deteriorates
Solution Approach 1:
The patent applies local quality by creating a fluorine-containing copolymer with non-uniform functional distribution, where specific monomer units (carboxy-containing and hydroxy-containing) are incorporated at controlled ratios to provide localized adhesion promotion while maintaining overall weather resistance from the fluorine-containing backbone structure
Solution Approach 2:
The patent uses composite materials by combining multiple monomer types (C2-C3 perhaloolefin, vinyl acetate, hydroxy-containing vinyl monomer, and carboxy-containing monomer) into a single copolymer system, where each component contributes different properties: fluorine units provide weather resistance while carboxy and hydroxy units provide adhesion to water-impermeable sheets and EVA encapsulant layers
2Strength
If corona discharge treatment is applied to improve adhesiveness, then bonding strength is improved, but process complexity and treatment time increase
Solution Approach 1:
The patent applies self-service by incorporating adhesion-promoting functional groups (carboxy and hydroxy groups) directly into the polymer chain structure during manufacturing, enabling the material to provide its own bonding capability without requiring external surface treatment processes like corona discharge
Solution Approach 2:
The patent uses preliminary action by pre-introducing carboxy-containing and hydroxy-containing monomer units into the copolymer structure during film fabrication, so that adhesion functionality is built into the material before assembly, eliminating the need for subsequent corona discharge treatment
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 improved adhesiveness between the water-impermeable sheet and film, and the film and EVA encapsulant layer results in enhanced durability and protection for the solar cell module, ensuring better weather resistance and longevity.
Implementation Method 1
a film, the film being disposed on at least one side of the water-impermeable sheet and being formed from a coating composition containing a fluorine-containing copolymer... the water-impermeable sheet and the film are firmly bonded to each other and the back sheet therefore has excellent durability. In addition, the back sheet exhibits excellent adhesiveness to an EVA encapsulant layer
Data Source
Figure 1~3
AI summary
The invention provides a back sheet including a water-impermeable sheet and a film firmly bonded to each other and exhibiting excellent adhesiveness to an EVA encapsulant layer of a solar cell module even without corona discharge treatment on the film surface. The back sheet of the invention is a back sheet for solar cell module, including a water-impermeable sheet and a film. The film is disposed on at least one side of the water-impermeable sheet and is formed from a coating containing a fluorine-containing copolymer. The fluorine-containing copolymer contains a C2-C3 perhaloolefin structural unit, a vinyl acetate structural unit, a hydroxy-containing vinyl monomer structural unit, and a carboxy-containing monomer structural unit.