Tri-block Copolymer Films for Foldable Display Adhesion
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Solution Overview
Problem
Traditional adhesives and polymer-based materials used in foldable displays and protective covers often compromise transparency, flexibility, and impact resistance due to refractive index mismatches, delamination, and limitations in handling and processing.
Innovation Solution
Development of films and laminates using tri-block copolymers with specific glass transition temperatures and refractive indices, combined with di-block copolymers and silane coupling agents, to enhance adhesion, flexibility, and impact resistance while maintaining optical properties and ease of processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional adhesives are used to attach portions of foldable displays, then adhesion is achieved, but transparency and low haze are impaired due to refractive index mismatch
Solution Approach 1:
The patent modifies the refractive index parameter of the adhesive material to match that of the display components (specifically setting the refractive index between 1.45-1.55 at 550nm wavelength). This parameter adjustment eliminates the optical mismatch that causes haze while preserving the adhesive bonding function, thereby resolving the contradiction between adhesion strength and transparency.
2Strength
If traditional adhesives are used to attach portions of foldable displays, then adhesion is achieved, but the portions attached delaminate after repeated use
Solution Approach 1:
The patent employs a composite adhesive formulation combining polymer matrices (such as acrylics, silicones, or polyurethanes) with specific functional additives including silane coupling agents and crosslinking agents. This composite structure provides both strong initial adhesion and enhanced long-term bonding stability, preventing delamination under repeated flexing while maintaining the adhesion function.
3Strength
If polymer-based portions are used in foldable displays, then structural support is provided, but flexibility and impact resistance are impaired
Solution Approach 1:
The patent adjusts key parameters of the polymer material including glass transition temperature (Tg between -50°C to 50°C), elongation at break (≥100%), and hardness (Shore A 20-80). These parameter modifications enable the polymer to provide structural support while maintaining the flexibility required for foldable applications and improving impact resistance through controlled softness and elasticity.
4Strength
If liquid materials are applied to form laminates, then bonding is achieved, but handling difficulty and processing complexity increase requiring multiple applications and curing steps
Solution Approach 1:
The patent incorporates silane coupling agents and crosslinking agents into the adhesive formulation in advance (pre-mixed at concentrations of 0.1-10 wt% and 0.01-5 wt% respectively). This preliminary preparation enables the adhesive to achieve both strong bonding and simplified processing, as the pre-formulated material requires only single-step application and curing without needing multiple applications or complex processing sequences.
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 laminates with improved visibility, flexibility, and impact resistance, maintaining optical properties over time and simplifying the processing of foldable displays and protective covers with reduced material waste and processing time.
Implementation Method 1
Providing a tri-block copolymer can improve an impact resistance of the film and/or laminate, for example, by absorbing and dissipating impact energy
Implementation Method 2
Providing the first function group comprising a silane can increase an adhesion of the film (e.g., tri-block copolymer) without the need for a separate silane coupling agent
Implementation Method 3
In aspects, a refractive index of the polymeric material of the film can comprise a small (e.g., about 0.01 or less) absolute difference from a refractive index of a substrate
Implementation Method 4
Providing a first block of the tri-block copolymer with a first glass transition temperature (Tg1) outside (e.g., below) of an operating range (e.g., from about 0° C. to about 40° C., from about −20° C. to about 60° C.) can enable consistent properties across the operating range of the article
Data Source
AI summary
Laminates can comprise a substrate and a film. The film can comprise a film thickness from about 5 micrometers to about 400 micrometers and a tri-block copolymer comprising a first block positioned between two second blocks. The first block can be grafted with a first functional group. The first block can comprise a first glass transition temperature of about 0° C. or less. The two second blocks can each comprise a glass transition temperature of about 50° C. or more. A combined weight of the two second blocks can be from about 10 wt % to about 50 wt % of the tri-block copolymer. The film can comprise a refractive index from about 1.48 to about 1.55. Methods of forming a laminate can comprise disposing a film over a substrate. Methods can further comprise heating the film and the substrate to a first temperature and then a second temperature.