Wavelength Conversion Film Light Diffusion and Adhesion
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Solution Overview
Problem
Existing wavelength conversion films for LCDs face issues with brightness reduction due to yellowing of light diffusion layers under UV exposure and inadequate adhesiveness between gas barrier films and quantum dot layers, leading to peeling and moisture penetration, which affects the durability and performance of the films.
Innovation Solution
A functional composite film with a light diffusion layer formed by dispersing light diffusing agents in a graft copolymer binder and an adhesive layer using an ultraviolet-curable urethane polymer, which is thermally cured to enhance adhesiveness and prevent yellowing, is used to improve the brightness and handleability of wavelength conversion films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a light diffusion layer is provided to improve brightness, then the brightness of LCD can be improved, but the light diffusion layer yellows under UV exposure reducing effectiveness
Solution Approach 1:
The patent uses a composite binder system comprising both a polymerizable compound (acrylic resin) and a curable compound (epoxy resin) in the light diffusion layer. This composite material approach allows the layer to maintain both brightness enhancement capability and resistance to UV-induced yellowing, as the two resin systems work synergistically to provide both optical performance and durability.
Solution Approach 2:
The patent specifies precise compositional parameters for the binder, including the weight ratio of polymerizable compound to curable compound (0.3 to 2.0), and the content of each component. By optimizing these parameters, the light diffusion layer achieves the desired balance between brightness improvement and yellowing resistance under UV exposure.
2Reliability
If gas barrier films are laminated on quantum dot layer to protect from moisture and oxygen, then protection is improved, but adhesiveness between layers deteriorates causing peeling
Solution Approach 1:
The patent introduces an intermediate adhesive layer between the gas barrier film and the quantum dot layer. This intermediate layer acts as a mediator that provides both moisture barrier functionality and strong adhesion to the quantum dot layer, preventing peeling while maintaining protection against moisture and oxygen.
Solution Approach 2:
The adhesive layer uses a composite formulation combining polymerizable compounds and curable compounds, similar to the light diffusion layer. This composite material approach enables the adhesive layer to achieve both strong bonding strength and resistance to environmental degradation, solving the adhesion problem while maintaining long-term reliability.
3Adaptability or versatility
If quantum dots are dispersed in binder to form quantum dot layer, then wavelength conversion is achieved, but quantum dots deteriorate due to photo-oxidation reaction
Solution Approach 1:
The patent creates a protective environment for quantum dots by enclosing them between gas barrier films that prevent contact with oxygen and moisture. This inert environment protection strategy allows the quantum dot layer to maintain its wavelength conversion capability while resisting photo-oxidation deterioration during operation.
Solution Approach 2:
The use of composite resin systems (acrylic + epoxy) in the light diffusion layer and adhesive layer creates a chemically stable environment that protects quantum dots from degradation, while maintaining the optical properties necessary for efficient wavelength conversion.
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 enhances the brightness of LCDs by optimizing the light diffusion and adhesiveness, preventing yellowing and peeling, and ensuring the durability of the wavelength conversion films, thereby improving the overall performance and reducing material usage.
Implementation Method 1
a light diffusion layer on the opposite surface to the surface of the support on which the organic layer and the inorganic layer are formed
Implementation Method 2
an adhesive layer using an ultraviolet-curable urethane polymer, which is thermally cured to enhance adhesiveness
Implementation Method 3
the quantum dots are excited to emit fluorescent light
Implementation Method 4
quantum dots which emit light by conversion of the wavelength of an incidence ray
Implementation Method 5
an oxide layer expressing gas barrier properties, such as silicon oxide, titanium oxide, and aluminum oxide, is formed on a resin film
Data Source
AI summary
Provided are a functional composite film having one or more combinations of an inorganic layer and an underlying organic layer on one surface thereof, and having a light diffusion layer on the opposite surface, in which the light diffusion layer is formed by dispersing a light diffusing agent in a binder formed using a graft copolymer having a molecular weight of 10,000 to 3,000,000 and an acryl equivalent of 500 g/mol or more, which has an acrylic polymer as the main chain and at least one of a urethane polymer with an acryloyl group at a terminal or a urethane oligomer with an acryloyl group at a terminal in the side chain; and a wavelength conversion film using the same. Using these, a functional composite film and a wavelength conversion film, having good light diffusion performance and light transmittance are provided.