Adhesive Film for Reflection Sheet with Controlled Heat Shrinkage
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Solution Overview
Problem
Conventional adhesive films for reflection sheets suffer from heat-induced deformation and degradation of reflection characteristics, leading to partial detachment and instability at high temperatures, which complicates the manufacturing process and affects the performance of backlight units in displays.
Innovation Solution
An adhesive film with a plastic base film exhibiting minimal heat shrinkage (−0.1 to 0.5% at 150°C) and an anchor coating layer, combined with a metal thin film layer, ensuring dimensional stability and excellent workability during lamination, allowing for multiple attachments and releases without curing, and maintaining stable physical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the base film is stretched to form fine micro voids for high reflectance, then the reflection characteristic is improved, but the thermo-formability is degraded
Solution Approach 1:
The invention divides the film structure into multiple functional layers: a base film providing mechanical strength and thermal stability, an adhesive layer for bonding, and a reflection layer with micro-voids for high reflectance. This segmentation allows each layer to be optimized independently - the base film maintains thermo-formability while the reflection layer provides high reflectance through its micro-void structure.
Solution Approach 2:
The invention creates a composite film structure combining different materials with complementary properties: the base film (providing thermal stability), the adhesive layer (providing bondability), and the reflection layer (providing high reflectance). This composite structure resolves the contradiction by assigning different functions to different layers, allowing the reflection layer to have micro-voids for high reflectance while the base film maintains thermo-formability.
2Illumination intensity
If the number of lamps or driving power is increased to improve luminance, then the reflection characteristic is improved, but the temperature increases causing malfunctions and failures
Solution Approach 1:
The invention converts the harmful effect of heat into a beneficial one by using heat-shrinkable adhesive layers that activate at elevated temperatures. The adhesive layer is designed to remain stable at normal temperatures but becomes highly bondable when exposed to heat from the backlight unit, ensuring strong adhesion under the actual operating conditions where the backlight generates heat.
Solution Approach 2:
The invention changes the temperature parameter of the adhesive layer from normal operating temperature to elevated temperature (near the glass transition temperature of the base film). This parameter change enables the adhesive to achieve optimal bonding characteristics at the actual operating temperature of the backlight unit, resolving the contradiction between high luminance (requiring high power lamps) and temperature control.
3Ease of manufacture
If an adhesive layer is formed on a release film by coating and drying, then the adhesive layer is formed, but partial detachment occurs when the adhesive layer is detached from the adherent at high temperature
Solution Approach 1:
The invention performs preliminary action by pre-forming the adhesive layer on the release film before final assembly, and designing the adhesive to remain stable during storage and handling. The adhesive layer is formulated to maintain its bonding properties throughout the product lifecycle, preventing partial detachment during normal operation or temperature variations.
Solution Approach 2:
The invention uses a composite adhesive system combining the adhesive layer with the release film and base film in a multi-layer structure. This composite structure ensures that the adhesive remains bonded to both the release film and the adherent under varying temperature conditions, preventing partial detachment while maintaining ease of manufacture through the coating and drying process.
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 provides superior dimensional stability and workability at high temperatures, preventing partial detachment and ensuring stable physical properties, simplifying the manufacturing process and enhancing the reliability of reflection sheets in backlight units.
Implementation Method 1
a plastic base film having a heat shrinkage of −0.1 to 0.5% at 150° C. in machine direction and transverse direction
Implementation Method 2
an adhesive layer formed on one side of the base film by applying an adhesive composition
Implementation Method 3
an anchor coating layer formed on the other side of the base film, opposite to the side on which the adhesive layer is formed
Data Source
AI summary
An adhesive film for a reflection sheet and a reflection sheet using the adhesive film is provided. The adhesive film comprises a plastic base film having a heat shrinkage of −0.1 to 0.5% at 150° C. in machine and transverse directions; an adhesive layer formed on one side of the base film by applying an adhesive composition; and an anchor coating layer formed on the other side of the base film, opposite to the side on which the adhesive layer is formed. The adhesive film for a reflection sheet according to the present invention is manufactured by applying an adhesive composition on a plastic base film where heat shrinkage is controlled. Thus, the adhesive film has superior dimensional stability at a high temperature and excellent workability in a post process for laminating a reflection layer. Partial detachment does not occur when an adhesive layer is detached from an adherent, and stable physical properties can be achieved.