Addition-curable liquid silicone rubber composition for airbags, and airbag
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Solution Overview
Problem
Existing addition-curable liquid silicone rubber compositions for airbags face issues with flame retardancy and color unevenness when applied in reduced amounts, leading to insufficient airtightness and varied base fabric properties due to non-uniform dispersion of solid flame retardants.
Innovation Solution
A composition comprising organopolysiloxane, organohydrogenpolysiloxane, silica fine powder, a catalyst for hydrosilylation reaction, an organosilicon compound with adhesiveness-imparting functional groups, and a metal carboxylate salt, which ensures uniform dispersion and improved adhesiveness, resulting in excellent flame retardancy and no color unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If the applying amount of silicone rubber composition is decreased to reduce space and weight, then the space and weight are reduced, but the flame retardancy and airtightness become insufficient
Solution Approach 1:
The patent changes the physical state of the flame retardant from solid to dissolved/ dispersed state in the silicone rubber composition. This allows uniform distribution at lower applying amounts while maintaining flame retardancy. The composition includes specific components (silica fine powder with surface treatment, organometallic compound) that enable this parameter change and ensure sufficient flame retardancy even with reduced coating weight.
Solution Approach 2:
The patent creates a composite silicone rubber composition by combining multiple components: base silicone rubber, silica fine powder with specific surface treatment, organometallic flame retardant compounds, and catalysts. This composite structure ensures uniform dispersion and maintains flame retardancy at lower applying amounts, resolving the contradiction between weight reduction and flame retardancy.
2Reliability
If solid flame retardant is blended in the silicone rubber composition, then flame retardancy is improved, but the flame retardant precipitates due to density difference
Solution Approach 1:
The patent changes the physical state and dispersion method of the flame retardant. Instead of using solid flame retardant particles that precipitate, the patent uses organometallic compounds that dissolve or disperse uniformly in the silicone rubber composition. This parameter change from solid to dissolved state eliminates precipitation while maintaining flame retardancy.
Solution Approach 2:
The patent introduces surface-treated silica fine powder as an intermediary carrier for the organometallic flame retardant compounds. The silica surface treatment creates a compatible interface that prevents aggregation and precipitation, ensuring uniform distribution throughout the silicone rubber composition while maintaining flame retardant functionality.
3Reliability
If solid flame retardant with large particle diameter is used, then flame retardancy is improved, but the flame retardant exposes on the surface of the thin silicone rubber layer
Solution Approach 1:
The patent changes the particle size parameter of the flame retardant system by using organometallic compounds at molecular/ionic level rather than large solid particles. This eliminates surface exposure issues in thin coatings while maintaining flame retardancy. The dissolved state ensures the flame retardant remains within the silicone rubber layer.
Solution Approach 2:
The patent transitions from a particulate (3D particle) flame retardant system to a molecularly dispersed (0D/1D) system. This dimensional change allows uniform distribution throughout the thin silicone rubber layer without surface exposure, maintaining both flame retardancy and airtightness.
4Reliability
If solid flame retardant is used, then flame retardancy is improved, but the flame retardant is not dispersed uniformly in the silicone layer
Solution Approach 1:
The patent changes the physical state parameter of the flame retardant from solid particles to dissolved organometallic compounds. This parameter change enables molecular-level dispersion throughout the silicone rubber composition, eliminating aggregation and ensuring uniform distribution while maintaining flame retardancy.
Solution Approach 2:
The patent achieves homogeneity by using organometallic compounds that dissolve uniformly in the silicone rubber matrix. The surface-treated silica fine powder acts as a uniform carrier, ensuring consistent distribution of flame retardant functionality throughout the composition without the heterogeneity caused by solid particle aggregation.
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 enhanced flame retardancy and adhesiveness to the airbag base fabric without color unevenness, maintaining airtightness and consistent properties across the coating.
Implementation Method 1
an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to a silicon atom (hydrosilyl groups) in one molecule
Data Source
AI summary
The present invention provides an addition-curable liquid silicone rubber composition for an airbag, the composition including: (A) an organopolysiloxane having two or more alkenyl groups bonded to a silicon atom in one molecule and having a polymerization degree of 50 to 2,000; (B) an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to a silicon atom (hydrosilyl groups) in one molecule; (C) silica fine powder having a BET-method specific surface area of 50 m2/g or more; (D) a catalyst for a hydrosilylation reaction; (E) an organosilicon compound having an adhesiveness-imparting functional group; and (F) a metal carboxylate salt. This provides: an addition-curable liquid silicone rubber composition for an airbag that yields an excellent low combustion rate property and that causes no color unevenness when applied on a base fabric for an airbag and cured; and an airbag.