Modified Natural Rubber for Low Rolling Resistance Tires

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Solution Overview

Problem

Natural rubber products, such as tires, experience heat build-up and reduced durability due to high loss tangent (tan δ) values, which increase rolling resistance and decrease fuel economy, and existing methods fail to sufficiently reduce tan δ and achieve both good fuel economy and abrasion resistance simultaneously.

Innovation Solution

Saponification of natural rubber latex with an alkali, followed by washing to reduce protein, gel, and phospholipid contents, and further treatment with alkali metal carbonate to minimize nitrogen content, resulting in a modified natural rubber with reduced tan δ, sodium, and potassium levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If tan δ is reduced to improve fuel economy, then rolling resistance decreases, but abrasion resistance may be compromised

Engineering Contradiction:
Improverolling resistanceVSAvoidabrasion resistance
Core Design Contradiction:
Loss of energyVSReliability

Solution Approach 1:

The patent extracts and removes the harmful components (protein, phospholipid, and gel fraction) from natural rubber that cause high tan δ and heat build-up. By removing these specific components through alkali treatment and washing, the patent achieves low tan δ values for improved fuel economy while preserving the beneficial properties of natural rubber for abrasion resistance.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent creates a modified natural rubber composition with controlled content of various components (protein ≤0.3%, phospholipid ≤200 ppm, gel ≤20%). This composite approach allows optimization of both fuel economy (through low tan δ) and durability (through controlled composition) by precisely managing the proportions of different rubber components.

Inventive Principle:
Principle #40Composite materials

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 modified natural rubber composition exhibits lower tan δ values, reducing heat build-up and rolling resistance, while maintaining abrasion resistance and improving fuel economy, thus enhancing the performance and longevity of rubber products like tires.

Implementation Method 1

saponification of natural rubber latex with an alkali (e.g. sodium hydroxide, potassium hydroxide) followed by washing can reduce not only the protein content but also the gel and phospholipid contents

Methodology Applied
Scientific EffectSaponification: Hydrolysis

Data Source

PatentUS9181355B2Modified natural rubber, method for producing same, rubber composition, and pneumatic tire
Publication Date: 2015.11.10 SUMITOMO RUBBER INDUSTRIES LTD

AI summary

The present invention provides a modified natural rubber having a reduced tan δ, a method for producing the modified natural rubber, a rubber composition produced using the modified natural rubber, and a pneumatic tire produced using the rubber composition. The present invention also provides a modified natural rubber having a reduced tan δ, a method for producing the modified natural rubber, a rubber composition produced using the modified natural rubber and achieving good fuel economy and abrasion resistance at the same time, and a pneumatic tire produced using the rubber composition. The present invention relates to a modified natural rubber having a phosphorus content of 200 ppm or less and a total content of sodium and potassium of 350 ppm or less. The invention also relates to a modified natural rubber having a phosphorus content of 200 ppm or less and a nitrogen content of 0.2% by mass or less.