Thermosensitive Adhesive for Flat Panel Display Substrate Handling
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Solution Overview
Problem
Conventional thermosensitive adhesives used for securing plastic substrates in flat panel displays face challenges with handling performance, chemical resistance, heat resistance, and easy peeling, particularly when exposed to high-temperature atmospheres and large substrate sizes.
Innovation Solution
A thermosensitive adhesive comprising a side chain crystal polymer with a melting point of 20-30°C and a tackifier, where the side chain crystal polymer is obtained by adding a metal chelate compound to a specific copolymer composition, allowing for reversible adhesive strength adjustment based on temperature, enhancing handling, chemical, and heat resistance while ensuring easy peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional thermosensitive adhesive is used to temporarily secure plastic substrate, then adhesive strength is controllable by heat, but handling performance is insufficient causing handling defectiveness
Solution Approach 1:
The patent applies parameter changes by utilizing the melting point transition of the side chain crystal polymer (20-30°C) to reversibly control adhesive strength. Below the melting point, the crystalline side chains provide strong adhesion; above the melting point, the polymer becomes soft and adhesive strength decreases, enabling easy peeling. This temperature-dependent parameter change resolves the contradiction between maintaining strong bonding during handling and enabling easy removal afterward.
Solution Approach 2:
The patent employs composite materials by combining the side chain crystal polymer (providing thermosensitive adhesive strength control) with a tackifier (providing initial tack and bonding capability). This composite adhesive formulation achieves both strong initial adhesion for secure handling and controlled peeling at high temperatures, resolving the handling performance issue while maintaining adhesive strength control.
2Adaptability or versatility
If thermosensitive adhesive is used for plastic substrate, then flexibility is enabled, but chemical resistance in photolithography and washing process is insufficient
Solution Approach 1:
The composite adhesive system combines the side chain crystal polymer with a tackifier to achieve both flexibility and chemical resistance. The tackifier component provides robust chemical resistance against photolithography solutions and washing processes, while the side chain crystal polymer maintains the thermosensitive flexibility and adhesive strength control, allowing the adhesive to withstand chemical processes while retaining its reversible bonding capability.
3Strength
If thermosensitive adhesive is used to secure substrate, then temporary bonding is achieved, but heat resistance is insufficient causing substrate floating and dimensional change at high temperatures
Solution Approach 1:
The patent utilizes phase transitions of the side chain crystal polymer to achieve temperature-dependent adhesive behavior. The side chains undergo a phase transition from crystalline (ordered) state below 20-30°C to molten (disordered) state above this temperature range. This phase transition causes the adhesive to maintain strong bonding strength at room temperature while becoming soft and easily peelable at high temperatures (100°C or higher), thereby achieving both strong temporary bonding and heat resistance without substrate floating or dimensional change.
4Strength
If adhesive strength is increased for large substrate, then bonding strength is improved, but easy peeling property deteriorates due to increased peeling stress
Solution Approach 1:
The patent applies parameter changes by exploiting the melting point transition of the side chain crystal polymer to decouple bonding strength from peeling difficulty. The adhesive maintains high bonding strength at room temperature through crystalline side chains, but at elevated temperatures (above 20-30°C), the side chains melt and the adhesive becomes soft, dramatically reducing peeling stress. This allows large substrates to be strongly bonded during handling while enabling easy peeling afterward, regardless of substrate size.
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 exhibits excellent handling performance, chemical resistance, heat resistance, and easy peeling properties, with adjustable adhesive strength and improved heat resistance, enabling secure bonding and easy removal of plastic substrates from glass bases without deformation or floating, even at high temperatures.
Implementation Method 1
a side chain crystal polymer having a melting point of 20-30° C.... Adhesive strength is to be deteriorated at a temperature below the melting point
Implementation Method 2
the side chain crystal polymer having a melting point of 20-30° C.... temperature is lowered to reduce the adhesive strength
Data Source
AI summary
A thermosensitive adhesive contains a side chain crystal polymer having a melting point of 20-30° C., and a tackifier. The side chain crystal polymer is obtainable by adding a metal chelate compound in the following amount of addition (A) into the following copolymer, followed by a crosslinking reaction. Adhesive strength is to be deteriorated at a temperature below the melting point. The copolymer is obtainable by polymerizing 25-30 parts by weight of (meth)acrylate having a straight-chain alkyl group having 16 to 22 carbon atoms, 60-65 parts by weight of (meth)acrylate having an alkyl group having 1 to 6 carbon atoms, 1-10 parts by weight of a polar monomer, and 1-10 parts by weight of a reactive fluorine compound. The amount of addition (A) is 3-10 parts by weight with respect to 100 parts by weight of a copolymer.