Curable Silicone Rubber Composition for Coatings
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Solution Overview
Problem
Silicone rubber compositions used in coatings for electrical and electronic components face issues with surface tackiness and dust adhesion, leading to reliability problems and cracking, while attempts to improve strength with resin-like organopolysiloxane additions do not fully address these issues and often result in brittle materials.
Innovation Solution
A curable silicone rubber composition comprising an organopolysiloxane with aliphatic unsaturated bonds, an organopolysiloxane with a three-dimensional network structure, an organohydrogenpolysiloxane, and a platinum group metal-based catalyst, where the component with the three-dimensional network structure constitutes 20-80% by mass, to produce a cured product with improved hardness, refractive index, and no surface tackiness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silicone rubber composition is used for coating electrical and electronic components, then excellent rubber-like properties and weather resistance are achieved, but surface tackiness causes dust adhesion problems
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating specific resin-like organopolysiloxane components (containing phenyl or cyclohexyl groups) in controlled amounts (5-50 mass%) to modify the surface properties of the cured silicone rubber, eliminating surface tackiness while preserving bulk rubber-like properties
Solution Approach 2:
The patent creates a composite material system combining conventional silicone rubber base components with resin-like organopolysiloxane modifiers, achieving a synergistic effect where the composite formulation eliminates surface tackiness while maintaining excellent elasticity and mechanical properties
2Strength
If resin-like organopolysiloxane is added to improve strength, then tensile strength increases, but surface tackiness and dust adhesion remain problems
Solution Approach 1:
The patent optimizes the molecular structure parameters of the organopolysiloxane component by selecting compounds with specific characteristics (phenyl or cyclohexyl groups, controlled viscosity ranges) to achieve both strength enhancement and surface tackiness elimination simultaneously
3Object-generated harmful factors
If silicone varnish is used to eliminate surface tackiness, then dust adhesion is reduced, but cracking occurs in the cured product
Solution Approach 1:
The patent modifies the crosslinking density and network structure parameters by using addition-curable organopolysiloxane systems with controlled resin content, achieving surface tackiness elimination while maintaining flexible crack resistance through optimized molecular architecture
Solution Approach 2:
The patent develops a composite formulation that integrates the benefits of both silicone rubber (crack resistance) and resin-like modifiers (surface properties), creating a synergistic material that avoids the cracking problem of pure silicone varnishes while eliminating surface tackiness
4Object-generated harmful factors
If reduced hardness resins are produced by adding silicone oil to silicone varnish, then surface tackiness is reduced, but the material becomes extremely brittle
Solution Approach 1:
The patent changes the molecular architecture parameters by using addition-curable crosslinking systems with controlled resin content (5-50 mass%), achieving surface property improvement while preventing brittleness through optimized network structure formation
Solution Approach 2:
The patent creates a composite material system that combines the flexibility of silicone rubber with the surface properties of resin-like organopolysiloxane, avoiding the extreme brittleness of reduced hardness resins while eliminating surface tackiness
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 cured product with high refractive index, excellent impact resistance, and no dust adhesion, effectively addressing the drawbacks of surface tackiness and brittleness in silicone elastomers.
Implementation Method 1
a platinum group metal-based catalyst
Data Source
AI summary
Provided is a curable silicone rubber composition, comprising (A) an organopolysiloxane containing two or more aliphatic unsaturated bonds within each molecule, having a viscosity at 25° C. within a range from 10 to 100,000 mm2/s, and containing a phenyl group and/or cyclohexyl group, (B) an organopolysiloxane with a resin structure comprising SiO2 units and (R1)3SiO0.5 units (wherein, each R1 represents, independently, a vinyl group, an allyl group, or a monovalent hydrocarbon group that contains no aliphatic unsaturated bonds, provided one or more of all the R1 groups within this component (B) represent, independently, a phenyl group or a cyclohexyl group), (C) an organohydrogenpolysiloxane, and (D) a platinum group metal-based catalyst, wherein the component (B) exists in a quantity that represents from 20 to 80% by mass of the combination of the component (A) and the component (B). The composition is capable of forming a cured product with improved hardness, no surface tackiness, and a high refractive index, without any loss in rubber-like properties such as elongation. A substrate such as an electrical or electronic component or an optoelectronic component can be coated with the cured product by applying the composition to the substrate and curing the composition to form the cured product on top of the substrate.