Improved natural rubber compositions

Abstract

There is herein described improved natural rubber compositions having nanocarbon and carbon black as reinforcing agents wherein the nanocarbon is uniformly pre-dispersed within the rubber component. In particular there is described rubber compositions comprising a mixture of natural rubber, nanocarbon and carbon black wherein the relative amount in parts per hundred rubber (pphr) of nanocarbon to carbon black is in the range of about 1:40 to about 1:2 and the relative amount in parts per hundred rubber (pphr) of nanocarbon to natural rubber is in the range of about 1:100 to about 10:100 and wherein the nanocarbon component is pre-dispersed within the natural rubber component.

Description

FIELD OF THE INVENTION[0001]The present invention relates to improved natural rubber compositions. More particularly, the present invention relates to improved natural rubber compositions having nanocarbon and carbon black as reinforcing agents wherein the nanocarbon is uniformly pre-dispersed within the rubber component.BACKGROUND OF THE INVENTION[0002]The rubber industry is the second largest industry in the world after iron and steel, with 92% of global supplies of natural rubber from Asia, and its major use in commercial terms relating to the manufacture of tires with a recent projection of global demand to reach 3.3 billion units creating a market of $220 billion by 2012. As such, the drive to provide products for all sectors within this market, high-performance, heavy duty, automobile, truck, bus and such like is extremely high.[0003]Following the discovery of nanosized carbon structures, also referred to as nanocarbon / nanotubes, and their unique combination of extraordinary s...

AI Technical Summary

Benefits of technology

[0013]The Applicant has now developed a novel rubber composition suitable for use in tires with nanocarbon and carbon black as reinforcing agents and which includes a unique ratio of rubber:nanocarbon:carbon black wherein the nanocarbon is uniformly predispersed within the rubber component. The novel and inventive formulations developed by the Applicant provide both processing advantages such as longer cure time and performance advantages such as longer blow out time and low heat build-up in addition to demonstrating desirable physical properties such as tensile strength, hardness, elasticity, resilience and the like.

[0015]The Applicant has found that it is possible to provide rubber compositions, suitable for use in tires, having improvements in wear abrasion and rolling resistance, reduced heat build-up—(HBU) and longer blowout times, as well as providing desirable strength, hardness and resistance, when compared to conventional rubber compositions, by utilizing particular mixtures of nanocarbon, uniformly pre-dispersed within natural rubber, and carbon black as reinforcing agents.

[0017]The present invention therefore provides rubber compositions having improved thermal and heat resistance properties and desirable strength, hardness and reduced rolling resistance as provided by utilizing particular mixtures of nanocarbon, which has been uniformly pre-dispersed within natural rubber, and carbon black as reinforcing agents.

[0043]Carbon black may be included at a level of from about 10 pphr to 50 pphr; 20 pphr to 40 pphr, preferably from 25 pphr to 35 pphr and preferably from 30 pphr to 35 pphr in compositions according to the invention. ISAF N220 is a preferred form of carbon black for use in compositions according to the invention. The Applicant has found that the compositions of the invention, which use it are possible to significantly reduce levels of carbon black, versus standard rubber compositions, as demonstrated in the Examples hereinafter, are capable of delivering both improvements in key processing attributes, such as for example cure time, as well as improvements in highly desirable performance attributes, such as for example increased blowout time, increased resilience. In particular the compositions of the invention include carbon black at from about 20% to less than about 40%, and preferably from about 25% to about 35% and more preferably from about 30% to about 35% of carbon black to 100% of rubber.

[0048]Examples of suitable vulcanization activating agents for inclusion to the rubber compositions of the invention include zinc oxide (ZnO), stearic acid (octadecanoic acid), stearic acid / palmitic acid mixture, or other suitable alternatives. It is thought that vulcanization activating agents essentially accelerate the vulcanization process by promoting the effectiveness of the curing agent. Vulcanization activating agents can be included at a total level of from about 2 pphr to about 10 pphr, preferably from about 3 pphr to about 7 pphr and preferably from about 4 pphr to about 6 pphr. Zinc oxide and stearic acid are preferred vulcanization activating agents for incorporation into the compositions according to the invention at individual levels of zinc oxide at a level of from about 1.5 pphr to about 6 pphr, preferably from about 2 pphr to about 4 pphr and preferably about 3 pphr and stearic acid at from about 0.5 pphr to about 4 pphr, preferably from about 1 pphr to about 3 pphr and preferably about 2 pphr.

Problems solved by technology

Until recently it has not yet been possible to fully explore and exploit the potential of nanocarbon as a rubber reinforcing agent due to dispersion associated difficulties in processing.