Photocurable Adhesive for Gap-Free Liquid Crystal Panel Bonding
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Solution Overview
Problem
Conventional methods for bonding liquid crystal panels with cover panels face issues such as air bubble trapping, resin runoff, and damage due to high curing temperatures, especially when using photocurable adhesives, which hinder high production efficiency and result in gaps or defects.
Innovation Solution
A photocurable adhesive composition comprising a urethane (meth)acrylate oligomer with a specific weight-average molecular weight range, phenoxy resin, and a photopolymerization initiator, optimized to have a loss tangent that allows melting at low temperatures without damaging the liquid crystal panel, ensuring gap-free bonding and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a photocurable adhesive composition is used for bonding liquid crystal panels, then bonding strength and production efficiency are improved, but high curing temperatures damage the liquid crystal panel
Solution Approach 1:
The patent changes the molecular weight parameter of the urethane (meth)acrylate oligomer to a specific range (2,000-10,000) and adjusts the loss tangent of the adhesive composition to 0.05-0.50, which enables the adhesive to cure at low temperatures (80°C or less) while maintaining high bonding efficiency and preventing thermal damage to the liquid crystal panel
Solution Approach 2:
The patent creates a composite adhesive system combining urethane (meth)acrylate oligomer, phenoxy resin, and photopolymerization initiator, where each component contributes specific properties that enable low-temperature curing while maintaining bonding strength and preventing damage to the liquid crystal panel
2Ease of operation
If a liquid resin is used for bonding, then the resin can fill the space between panels, but air bubbles are trapped and resin runs off from edges
Solution Approach 1:
The patent adjusts the loss tangent parameter of the adhesive composition to a specific range (0.05-0.50) and controls the molecular weight of the urethane (meth)acrylate oligomer, which provides optimal balance between flowability for filling gaps and resistance to prevent air bubble trapping and resin runoff, achieving high bonding quality
Solution Approach 2:
The patent uses a solid adhesive composition at ordinary temperature as an intermediary material that can be applied in sheet form, providing controlled flow characteristics that fill irregularities without the problems of liquid resins, thereby ensuring high bonding precision
3Ease of manufacture
If a two-sided adhesive tape is used, then bonding is simple, but the adhesive cannot fill bumps on the cover panel
Solution Approach 1:
The patent creates an adhesive composition with dynamic flow characteristics by controlling the loss tangent and molecular weight parameters, allowing the solid adhesive to flow and fill bumps on the cover panel surface while maintaining ease of application, thereby achieving both simplicity and precision in bonding
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 adhesive composition effectively bonds liquid crystal panels to cover panels without forming gaps, maintains panel integrity, and achieves high production efficiency by melting at 80°C or less, preventing damage and ensuring good appearance and flexibility.
Implementation Method 1
a photocurable adhesive composition comprising (A) 100 parts by mass of a urethane (meth)acrylate oligomer having a weight-average molecular weight of 2,000 to 10,000, (B) 5 parts by mass to 70 parts by mass of a phenoxy resin, and (C) 0.1 part by mass to 10 parts by mass of a photopolymerization initiator
Implementation Method 2
the temperature at which the loss tangent of the uncured composition reaches 1 or more is 80° C. or less
Data Source
AI summary
Provided is a method of manufacturing a liquid crystal panel employing a photocurable adhesive composition which causes no damage to adherends during bonding and which, when used in bonding rugged adherends, can bond the adherends without forming a gap therebetween. The photocurable adhesive composition of the inventive method comprises (A) 100 parts by mass of a urethane (meth)acrylate oligomer having a weight-average molecular weight of 20,000 to 100,000, (B) 5 parts to 70 parts by mass of a phenoxy resin, and (C) 0.1 parts to 10 parts by mass of a photopolymerization initiator. The uncured composition has a loss tangent (loss modulus/storage modulus) of less than 1 at 25° C. and the temperature at which the loss tangent of the uncured composition reaches 1 or more is 80° C. or less.