Solar Cell Protective Sheet UV Bleeding Control
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Solution Overview
Problem
Transparent protective sheets for solar cell modules exhibit uneven spots due to excessive bleeding of ultraviolet absorbers during roll-to-roll manufacturing, which is a result of non-uniform pressure on the base material resin layer with higher hardness and a weather-resistant resin layer with lower hardness, compromising both manufacturing efficiency and UV protection.
Innovation Solution
Incorporating an easy adhesion layer with a specific amount of wax on the surface opposite to the light-resistant adhesive layer, which contains an ultraviolet absorber, to improve sliding properties and distribute pressure evenly, thereby preventing excessive bleeding of the ultraviolet absorber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a light resistant adhesive layer containing ultraviolet absorber is used to protect the base material resin layer, then UV protection is improved, but uneven spots occur on the surface due to excessive bleeding of the ultraviolet absorber
Solution Approach 1:
The patent applies different hardness characteristics to different layers: the base material resin layer has higher hardness (R80 or more) while the weather resistant resin layer has lower hardness. This local differentiation in hardness properties prevents excessive bleeding of the ultraviolet absorber from the adhesive layer, as the harder base material layer provides structural support that limits the migration of low molecular weight components, while still maintaining adequate UV protection through the adhesive layer.
2Strength
If the base material resin layer has high hardness for durability, then mechanical strength is improved, but non-uniform pressure is applied during roll-to-roll manufacturing causing uneven spots
Solution Approach 1:
The patent creates a composite structure where a hard base material resin layer (R80 or more) is combined with a softer weather resistant resin layer. This composite material approach allows the hard base layer to provide mechanical strength and durability, while the softer outer layer acts as a buffer that distributes pressure uniformly during roll-to-roll manufacturing, preventing the non-uniform pressure application that would otherwise occur when pressing directly on the hard base material layer.
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 solution effectively prevents the occurrence of uneven spots on the transparent protective sheet surface while maintaining high UV protection and transparency, enhancing manufacturing efficiency and durability.
Implementation Method 1
the light resistant adhesive layer contains an ultraviolet absorber... it is essential to add an ultraviolet absorber to the weather resistant resin layer side... in order to protect the base material resin layer from ultraviolet rays
Implementation Method 2
Incorporating an easy adhesion layer with a specific amount of wax on the surface opposite to the light-resistant adhesive layer... to improve sliding properties and distribute pressure evenly
Data Source
Figure 1
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AI summary
Provided is a transparent protective sheet which is obtained by forming a light resistant adhesive layer on the surface of a base resin layer, wherein the occurrence of uneven spots on the sheet surface can be avoided in a roll-to-roll manufacturing line. In a transparent protective sheet 1 for a solar cell module, a weather resistant resin layer 13 is layered on one surface of a base resin layer 11 with a light resistant adhesive layer 12 therebetween, and an easily adhesive layer 14 is formed on the other surface of the base resin layer 11. The base resin layer is a resin film with a Rockwell hardness of R80 or more as measured according to JIS G 0202. The weather resistant resin layer 13 is a resin film with a Rockwell hardness which is less than that of the resin film which forms the base resin layer 11, as measured according to JIS G 0202. The light resistant adhesive layer 12 includes 0.3 to 1.3 g/m2 of an ultraviolet absorbing agent, and the easily adhesive layer 14 includes 0.07 to 0.25 g/m2 of a wax.