Closed-Cell Foam Sheet for Touch Display Pooling Suppression
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Solution Overview
Problem
Touch-sensitive display devices face issues with liquid crystal pooling due to strong pressing forces, requiring a foam sheet with high shock-absorbing properties and rapid recovery to prevent pooling, while also needing durability and reduced thickness for portable devices.
Innovation Solution
A closed cell foam sheet with specific thickness, compressive stress, tensile strength, and recovery time is developed by foaming and crosslinking a polyolefin-based resin, optimizing cell structure and density to achieve high durability and pooling resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the foam sheet thickness is reduced for downsizing portable devices, then the device size is reduced, but the shock-absorbing properties and durability deteriorate
Solution Approach 1:
The invention changes the physical and chemical parameters of the foam sheet by controlling the crosslinking degree (5-60%) and using specific polyolefin-based resins to achieve optimal balance between thickness (0.05-0.35mm) and mechanical properties, including tensile strength (1,800-15,000 kPa) and compressive stress (30-100 kPa at 25% strain)
Solution Approach 2:
The invention uses composite material structure with polyolefin-based resin as the base material, incorporating crosslinked networks and controlled cell structures (80% or more closed cells) to create a multi-phase composite that achieves high durability and shock absorption in thin configuration
2Object-affected harmful factors
If the foam sheet is made with high shock-absorbing properties to prevent pooling, then pooling resistance is improved, but the thickness increases which conflicts with downsizing requirements
Solution Approach 1:
The invention optimizes parameters including recovery time (0.1 seconds or less after 5N pressing), compressive stress (30-100 kPa at 25% strain), and cell structure to achieve rapid recovery from deformation, enabling thin foam sheets (0.05-0.35mm) to effectively suppress pooling
3Strength
If the tensile strength is increased to improve durability, then the foam sheet can withstand repeated pressing, but the flexibility and comfort decrease
Solution Approach 1:
The invention controls the crosslinking degree within 5-60% to optimize the balance between tensile strength (1,800-15,000 kPa) and flexibility, ensuring the foam sheet can withstand repeated pressing while maintaining comfort and ease of operation
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 foam sheet effectively suppresses pooling and maintains high durability and flexibility, ensuring the display device's performance and longevity despite repeated strong presses, while being thin enough for modern portable device designs.
Implementation Method 1
the foam sheet is prepared by foaming and crosslinking a resin material comprising a polyolefin-based resin
Implementation Method 2
the foam sheet is prepared by foaming and crosslinking a resin material comprising a polyolefin-based resin
Implementation Method 3
a shock-absorbing sheet may be arranged at the back side of a display device for preventing breakage and failure
Implementation Method 4
increasing the recovery rate thereof when the foam sheet is pressed and then released from the pressing
Data Source
Figure 1(A)~1(C)
AI summary
The closed cell foam sheet of the present invention is a closed cell foam sheet having a thickness of 0.05 to 0.35 mm, wherein the foam sheet has a 25% compressive stress of 30 to 100 kPa, a tensile strength in MD of 3,000 to 15,000 kPa, a tensile strength in TD of 1,800 to 9,800 kPa, and a recovery time of 0.1 seconds or less after the foam sheet is pressed for 5 seconds by 5 N and then released.