Fluoroalkyl Organopolysiloxane Adhesive for High Dielectric Touch Panels
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Solution Overview
Problem
Current polysiloxane pressure-sensitive adhesive compositions lack high dielectric properties and transparency, particularly in addition curing systems, which are essential for electronic applications like touch panels and sensors, and they also face challenges with processability and curing conditions.
Innovation Solution
A curable organopolysiloxane composition containing a fluoroalkyl group, specifically a trifluoropropyl group, which can be cured via an addition reaction using organohydrogen polysiloxane, providing high specific permittivity, transparency, and favorable mold processability with minimal shrinking and easy curing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polysiloxane pressure-sensitive adhesive composition is used for electronic applications, then heat resistance and electrical insulating properties are improved, but dielectric properties and transparency are insufficient
Solution Approach 1:
The patent modifies the chemical structure of polysiloxane by introducing fluoroalkyl groups (specifically trifluoropropyl groups) as substitution groups on silicon atoms. This parameter change in molecular structure increases the dielectric constant from typical values of 2-4 to 5.7 or higher, while simultaneously improving transparency and maintaining heat resistance and electrical insulating properties.
Solution Approach 2:
The invention creates a composite pressure-sensitive adhesive composition by combining fluoroalkyl-containing organopolysiloxane with MQ resin and silane-modified polyether sulfone. This composite approach integrates the high dielectric constant of fluoroalkyl groups with the adhesive properties of MQ resin and the thermal stability of polyether sulfone, achieving multiple performance requirements simultaneously.
2Quantity of substance
If vinylidene fluoride copolymers are used to achieve high dielectric constant, then specific permittivity is improved, but processability for manufacturing molded products deteriorates
Solution Approach 1:
The patent changes the polymer chemistry from vinylidene fluoride copolymers to fluoroalkyl-containing polysiloxane. This parameter change maintains high specific permittivity (dielectric constant of 5.7 or higher) while dramatically improving processability, as the polysiloxane composition can be cured via addition reaction at room temperature or mild heating without the crystallinity issues that plague vinylidene fluoride polymers.
3Productivity
If addition reaction curing is used for polysiloxane pressure-sensitive adhesive, then curing speed and absence of byproducts are improved, but dielectric properties and transparency are insufficient
Solution Approach 1:
The patent modifies the base polysiloxane structure by incorporating fluoroalkyl groups, which fundamentally changes the dielectric properties of the cured product. This parameter change enables the addition reaction curing system to achieve both fast curing speed and high dielectric constant (5.7 or higher) with excellent transparency, resolving the previous insufficiency of dielectric properties in addition-cured polysiloxane systems.
4Ease of manufacture
If general-purpose polymeric materials with excellent transparency and processability are used, then transparency and processability are improved, but specific permittivity remains low
Solution Approach 1:
The patent introduces fluoroalkyl substitution groups on silicon atoms in the polysiloxane chain. This parameter change in molecular structure increases the dielectric constant from typical values of 2-4 to 5.7 or higher, while the addition reaction curing mechanism and low-viscosity composition maintain excellent transparency and processability for manufacturing electronic components.
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 composition achieves a high specific permittivity and transparency, making it suitable for electronic applications as a pressure-sensitive adhesive, particularly in touch panels and sensors, with improved processability and curing efficiency.
Implementation Method 1
The addition reaction curing type pressure-sensitive adhesive compositions are widely used, because curing is quickly performed at room temperature or by heating, and byproducts are not generated.
Implementation Method 2
In order to enhance the sensor sensitivity, a high electrostatic capacitance under a constant voltage must be achieved, and for this purpose, a high dielectric constant is required in the material that is used.
Data Source
AI summary
(A) A curable organopolysiloxane composition containing a fluoroalkyl group, containing: (R13SiO1/2)a(R22SiO)b(R3SiO3/2)c(SiO2)d {Where 10 mol% or more of substitution groups are fluoroalkyl groups, other substitution groups are alkyl groups or the like, and a, b, c, and d represent a number satisfying 0 ≤ a ≤ 0.5, 0 ≤ b ≤ 0.7, 0 ≤ c ≤ 1,0 ≤ d ≤ 0.7, 0.3 ≤ c + d ≤ 1, and a + b + c + d = 1}; (B) R43Si(OSiR42)eOSiR43 (II) {Where 5 mol% or more of substitution groups are fluoroalkyl groups, and of other R4s, at least two are alkenyl groups}; (C) is an organohydrogen polysiloxane; (D) is an effective amount of a hydrosilylation reaction catalyst; and (E) is a solvent. The present invention provides a curable composition with a high dielectric constant and favorable transparency, a pressure-sensitive adhesive as a cured product thereof, and a display device.