Silica-Free Rubber Composition for Transparency and Toughness
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Solution Overview
Problem
Conventional transparent rubber compositions fail to achieve a balance between transparency and strength, often compromising on either property due to the use of silica, which impairs transparency, or relying on complex processes and insufficient transparency when using silicon-based materials.
Innovation Solution
A transparent, crosslinked rubber composition comprising low-cis isoprene rubber and a rubber polymer component, such as butadiene rubber, crosslinked with radical crosslinking agents or peroxides, without silica, achieving a haze of 20% or less and total light transmittance of 88% or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If silica is added to improve strength, then strength is improved, but transparency deteriorates (material becomes clouded or yellowed)
Solution Approach 1:
The patent removes silica from the composition entirely, replacing it with a silica-free rubber polymer system. This extraction of the problematic ingredient (silica) eliminates the clouding and yellowing effects while maintaining strength through alternative crosslinking mechanisms using peroxides and radical crosslinking agents.
Solution Approach 2:
The patent changes the chemical composition parameters by using specific rubber polymers (polyisoprene with 92-98% cis content, polybutadiene, SBR, NBR, HNBR, U, EPM, EPDM, or NR) and controlling crosslinking density through peroxide and radical crosslinking agents. This parameter change achieves both high transparency (88% or more total light transmittance) and adequate strength without silica.
2Ease of operation
If oil is added to silicon-based material to improve flexibility, then flexibility is improved, but transparency deteriorates (oil bleeding occurs over time)
Solution Approach 1:
The patent removes oil from the composition by designing a silica-free rubber polymer system that does not require oil as a softener. The flexibility is achieved through the inherent properties of the rubber polymers and crosslinking structure rather than through oil addition, thereby preventing oil bleeding and maintaining long-term transparency.
Solution Approach 2:
The patent replaces the temporary flexibility provided by oil (which bleeds over time) with a permanent flexibility inherent to the crosslinked rubber polymer network. This substitution eliminates the need for short-lived oil softeners and provides lasting flexibility without transparency degradation.
3Illumination intensity
If conventional transparent materials are used, then transparency is achieved, but strength and toughness are insufficient for practical applications
Solution Approach 1:
The patent creates a composite rubber polymer system combining multiple polymer types (polyisoprene, polybutadiene, SBR, NBR, HNBR, U, EPM, EPDM, or NR) with crosslinking agents. This composite structure achieves both high transparency (88% or more total light transmittance) and practical strength/toughness for applications like shoes and tires, overcoming the limitations of conventional transparent materials.
Solution Approach 2:
The patent optimizes the chemical composition parameters by selecting specific rubber polymers with controlled cis content (92-98% for polyisoprene) and controlling crosslinking density through peroxide and radical crosslinking agents. This parameter optimization achieves the rare combination of high transparency and adequate strength/toughness for practical rubber applications.
4Illumination intensity
If silica is used to improve transparency, then transparency is improved, but manufacturing complexity increases (complicated process required to disperse silica)
Solution Approach 1:
The patent removes silica from the composition entirely, eliminating the need for complicated silica dispersion processes. The transparency is achieved through the inherent optical properties of the silica-free rubber polymer system and controlled crosslinking, greatly simplifying the manufacturing process while maintaining high transparency (88% or more total light transmittance).
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 provides excellent transparency and strength, overcoming the limitations of previous materials by maintaining high transmittance and hardness while avoiding the issues of silica-induced clouding and oil bleeding.
Implementation Method 1
the low-cis isoprene rubber and the rubber polymer component are crosslinked with one or more of the crosslinkers selected from radical crosslinking agents, and peroxides
Data Source
AI summary
In order to provide a rubber composition having high transparency and toughness, the present invention can provide a crosslinked rubber composition, being substantially free of silica, comprising a first olefin polymer having refractive index of between 1.500 to 1.525 at 23 degree C; and a second olefin polymer which is different from the first olefin polymer, wherein the composition has haze of 20 % or less on 2 mm thick sheet, measured according to JIS K7136, and wherein the composition has Type A Durometer hardness (0 sec) of 35 or more, measured according to JIS K6253.