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Cellulose Ester Additive for Increased Tear Strength In Natural Rubber Formulations

IP.com Disclosure Number: IPCOM000242986D
Publication Date: 2015-Sep-04

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The IP.com Prior Art Database

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EASTMAN CHEMICAL COMPANY: OWNER [+6]

Abstract

Abstract: This invention describes the use of Eastman plasticized cellulose esters as a performance additive in silica filled, natural rubber formulations. The testing conducted focuses on the performance of cellulose esters for the Off The Road (OTR) tire market. This type of tires is used in uniquely harsh conditions of high temperature, very large load, and very rough surfaces. Due to these harsh conditions, the common failure modes of these tires are cutting and chunking and tire blow out due to heat build-up in the tire. Current technology forces a tradeoff between the heat build-up and cut and chip strength of the tire tread formulation. In this study, plasticized cellulose esters were mixed into model OTR tread formulations and their performance was measured against control formulations. The cellulose ester containing compounds showed equivalent processing and mechanical properties, while almost doubling the cut and chip performance versus the control formulations. This increase in cut and chip resistance was accomplished with only minor increases in the heat build-up properties of the compound, showing the utility of the Eastman solution in this application.

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Cellulose Ester Additive for Increased Tear Strength In Natural Rubber Formulations

Authors: Christopher Thomas Scilla, Mark Thomas Arigo, Christopher

George Robertson, Soumendra Kumar Basu

Abstract: This invention describes the use of Eastman plasticized cellulose esters as a performance additive in silica filled, natural rubber formulations. The testing conducted focuses on the performance of cellulose esters for the Off The Road (OTR) tire market. This type of tires is used in uniquely harsh conditions of high temperature, very large load, and very rough surfaces. Due to these harsh conditions, the common failure modes of these tires are cutting and chunking and tire blow out due to heat build-up in the tire. Current technology forces a tradeoff between the heat build-up and cut and chip strength of the tire tread formulation. In this study, plasticized cellulose esters were mixed into model OTR tread formulations and their performance was measured against control formulations. The cellulose ester containing compounds showed equivalent processing and mechanical properties, while almost doubling the cut and chip performance versus the control formulations. This increase in cut and chip resistance was accomplished with only minor increases in the heat build-up properties of the compound, showing the utility of the Eastman solution in this application.

Large tires used on heavy earthmover equipment, of the types commonly used in the mining industry, present a unique niche of the global tire market. These tires, collectively known as "off the road" (OTR) tires, encounter uniquely harsh working conditions, and are evaluated on unique performance metrics. Tire failure leads to expensive, $5k - $25k /hr, equipment downtime. These failures can be caused by a variety of mechanisms, but are primarily due to either the physical cutting and chunking of the tire by debris or the rough surface of the mine floor, or by tire blow out due to internal heating and subsequent weakening of the rubber of the tire tread. Thus, two of the most important performance metrics for the OTR tire segment are the cut and chip resistance and heat build-up properties of the tread compound of the tire.

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While a wide range of solutions exists for altering the heat build-up and cut and chip properties of an OTR tire formulation, the two properties tend to be inversely related. Thus, any increase in the performance of the tread compound in one property is typically accompanied by a performance decrease in the other. This trade off arises from the fact that in order to resist the propagation of a cut, the rubber compound needs to have a mechanism for dissipating the cut energy. This same mechanism for energy dissipation converts some of the energy imparted by the deformation of the tire during normal operation into heat which causes the temperature of the rubber tread to rise, and can eventually lead to tire failure. Any additive that could break th...