UV-Cured Urethane Adhesive Composition for Foldable Display Flexing
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Solution Overview
Problem
Existing adhesive resins for flexible display devices fail to provide suitable coating properties and adequate elastic modulus, leading to bonding failures and operational stress during folding or bending.
Innovation Solution
A resin composition comprising a urethane (meth)acrylate oligomer with specific viscosity and storage modulus ranges, photocured with UV light, is used to form an adhesive member with high adhesive strength and elasticity, suitable for flexible display devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing adhesive resins are used for flexible display devices, then the coating process can be completed, but the adhesive resin fails to provide suitable coating properties and adequate elastic modulus, leading to bonding failures and operational stress during folding or bending
Solution Approach 1:
The patent applies parameter changes by precisely controlling the storage modulus of the adhesive resin at different UV irradiation doses. The resin composition is formulated to achieve a storage modulus of 10³ to 10⁴ Pa at 200 mJ/cm² (for coating flexibility) and 10⁴ to 10⁵ Pa at 4000 mJ/cm² (for bonding strength), resolving the contradiction between elastic modulus and bonding reliability through controlled physical parameter transformation during the curing process
Solution Approach 2:
The patent implements preliminary action by performing partial UV curing at 200 mJ/cm² before final bonding. This preliminary curing step establishes the appropriate storage modulus range (10³ to 10⁴ Pa) that enables suitable coating properties and prevents bonding failures, while the remaining uncured portions allow for subsequent final curing to achieve adequate elastic modulus and bonding strength
2Reliability
If the adhesive resin is made more rigid to improve bonding strength, then bonding reliability improves, but the adhesive resin cannot accommodate folding or bending operations
Solution Approach 1:
The patent applies dynamics by creating a time-dependent mechanical property profile in the adhesive resin. The storage modulus dynamically evolves from a lower range (10³ to 10⁴ Pa) during initial coating and folding operations to a higher range (10⁴ to 10⁵ Pa) after complete UV curing. This dynamic property change allows the adhesive to accommodate folding operations when needed while providing bonding strength when required
Solution Approach 2:
The patent implements periodic action through multi-stage UV irradiation processing. The adhesive resin undergoes periodic curing cycles: first irradiation at 200 mJ/cm² to achieve initial gelation with suitable flexibility for folding, followed by additional irradiation to reach 4000 mJ/cm² total dose for final bonding strength. This periodic action sequence resolves the contradiction between operational flexibility and bonding rigidity
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 resin composition ensures reliable adhesion and flexibility, enhancing the operational reliability of foldable or bendable display devices by maintaining adhesive strength and shape integrity during folding or bending.
Implementation Method 1
the resin composition may be photo-cured
Data Source
AI summary
A resin composition comprises a urethane (meth)acrylate oligomer. The resin composition has a storage modulus of about 2×103 Pa to about 2×104 Pa when irradiated with 200 mJ/cm2 of an ultraviolet light.