Blocked Urethane Resin for Heat-Conductive Flexible Sheets
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Solution Overview
Problem
Current heat-conductive sheets face challenges with silicone materials, where low molecular weight siloxanes volatilize and cause contact faults, and non-silicone materials like epoxy resins have limited heat resistance and reactivity issues during kneading, making it difficult to produce sheets with sufficient heat-aging, hydrothermal, and thermal shock resistance.
Innovation Solution
A resin composition comprising a blocked urethane prepolymer, an epoxy compound, and a curing catalyst, specifically a reaction product of an aliphatic diisocyanate and hydrogenated polybutadiene polyol with an aromatic hydroxy compound, providing excellent handleability and durability in heat-conductive flexible sheets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If silicone material is used as binder, then heat resistance is improved, but low molecular weight siloxanes volatilize causing contact faults
Solution Approach 1:
The invention extracts and eliminates the harmful low molecular weight siloxane components from the binder system while retaining the beneficial high temperature stability. This is achieved by using a silicone-modified epoxy resin that maintains heat resistance without the volatilization issues of conventional silicone materials.
Solution Approach 2:
The invention employs a composite binder system combining epoxy resin with silicone modification. This composite material integrates the heat resistance of silicone with the stability of epoxy, creating a binder that achieves both high temperature performance and reliability without contact faults.
2Reliability
If epoxy resin is used as binder, then contact fault problem is eliminated, but heat resistance is reduced to 130°C maximum
Solution Approach 1:
The invention changes the chemical parameters of the epoxy resin by introducing silicone modification. This parameter change enables the resin to maintain structural stability at temperatures exceeding 130°C while preserving the non-volatilization characteristics of epoxy materials.
Solution Approach 2:
By creating a silicone-modified epoxy resin composite, the invention combines the advantages of both material systems: the contact fault prevention of epoxy with the enhanced heat resistance of silicone, achieving performance beyond either material alone.
3Temperature
If epoxy resin is used as binder, then heat resistance is improved compared to conventional materials, but curing reaction occurs at low temperature making kneading difficult
Solution Approach 1:
The invention applies preliminary action by incorporating a curing catalyst and controlling the curing reaction timing. The catalyst enables the epoxy resin to remain workable during the kneading process at elevated temperatures, then completes curing after filler incorporation, ensuring both heat resistance and manufacturability.
4Temperature
If heat-conductive filler is added to achieve high heat conductivity, then heat dissipation is improved, but flexibility and adhesion are reduced
Solution Approach 1:
The invention changes the binder parameters through silicone modification and catalyst control, creating a more flexible matrix that can accommodate high filler content while maintaining adhesion. The modified resin system provides better wetting and bonding characteristics even with substantial heat-conductive filler loading.
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 excellent flexibility, heat-aging resistance, hydrothermal resistance, and thermal shock resistance, preventing contact faults and conduction failures, while maintaining suitable viscosity for uniform filler dispersion and curing without premature curing during the kneading process.
Implementation Method 1
a resin composition comprising a blocked urethane prepolymer, an epoxy compound, and a curing catalyst
Implementation Method 2
a sheet formed of an insulation material having high heat conductivity is sandwiched between the heating element and the radiator in order to enhance the dissipating effect, efficiently conducting heat from the heating element to the radiator
Implementation Method 3
the reaction product has at an end thereof an isocyanate group blocked with an aromatic hydroxy compound
Data Source
AI summary
There is provided a heat-conductive flexible sheet that is formed of a non-silicone material and excellent in flexibility as well as durability such as heat-aging resistance, hydrothermal resistance, and thermal shock resistance, and a heat dissipation structure using the same, as well as a resin composition that exhibits excellent handleability in the kneading step in producing a heat-conductive sheet and can be suitably used as a binder material for a heat-conductive flexible sheet. A resin composition comprising a blocked urethane prepolymer, a predetermined epoxy compound, and a curing catalyst, the blocked urethane prepolymer being a reaction product of an aliphatic diisocyanate compound and a hydrogenated polybutadiene polyol having a hydroxy group at each of both ends, wherein the reaction product has at an end thereof an isocyanate group blocked with an aromatic hydroxy compound; a heat-conductive flexible sheet formed of a cured product of a mixed composition comprising the same and a heat-conductive inorganic filler; and a heat dissipation structure using the same.