Patent Application
20080066839
Rubber compositions were prepared for evaluating an effect of an inclusion in a rubber composition of scrap rubber or coal dust for a transition, intermediate layer for a tire tread.
Sample A is a Control rubber sample. Experimental rubber Samples B through G contained various amounts of scrap rubber or coal dust.
The scrap rubber was scrap rubber in the sense of partially depolymerized cured rubber or particulate (ground) pre-vulcanized rubber.
The rubber compositions were prepared by mixing the ingredients in sequential non-productive (NP) and productive (PR) mixing steps in one or more internal rubber mixers.
The basic recipe for the rubber Samples is presented in the following Table 1 and recited in parts by weight unless otherwise indicated.
1emulsion polymerization prepared styrene/butadiene rubber as PLF1712 ™ from The Goodyear Tire & Rubber Company having a bound styrene content of about 23.5 percent
2Rubber reinforcing carbon black as N299, an ASTM designation
3Rubber processing oil and microcrystalline wax
4Fatty acid comprised (composed) of at least 90 weight percent stearic acid and a minor amount of other fatty acid comprised (composed of) primarily of palmitic and oleic acids.
5Antidegradant of the phenylene diamine type
6Recycle rubber as partially depolymerized cured rubber as RNR 50B11 ™ from Rubber Resources; reclaim rubber as ground cured rubber particles as TR-30 ™ from Edge Rubber; and coal dust as Austin Black 325 ™ from Coal Fillers.
The following Table 2 illustrates cure behavior and various physical properties of rubber compositions based-upon the basic recipe of Table 1.
1Data according to Rubber Process Analyzer as RPA 2000 ™ instrument by Alpha Technologies, formerly the Flexsys Company and formerly the Monsanto Company.
2Data according to Automated Testing System instrument by the Instron Corporation which incorporates six tests in one system. Such instrument may determine ultimate tensile, ultimate elongation, modulii, etc. Data reported in the Table is generated by running the ring tensile test station which is an Instron 4201 load frame.
3Data according to Rubber Process Analyzer as RPA 2000 ™ instrument by Alpha Technologies, formerly the Flexsys Company and formerly the Monsanto Company. References to an RPA-2000 instrument may be found in the following publications: H. A. Palowski, et al, Rubber World, June 1992 and January 1997, as well as Rubber & Plastics News, April 26 and May 10, 1993.
4Data obtained according to a tear strength (peal adhesion) test to determine interfacial adhesion between two samples of a rubber composition. In particular, such interfacial adhesion is determined by pulling one rubber composition away from the other at a right angle to the untorn test specimen with the two ends of the rubber compositions being pulled apart at a 180° angle to each other using an Instron instrument at 95° C. and reported as Newtons force.
It can be seen from Table 2 that the most of the overall cured physical properties for the lower cost rubber compounds Samples B through G (lower cost in the sense of containing said scrap rubber and/or coal dust) are comparable to the Control Sample A. However, it is expected that rubber Samples B through G would exhibit a reduced abrasion resistance property in a sense of providing increased DIN abrasion values (e.g. increased abrasion loss values).
Rubber compositions were prepared and evaluated as in Example I for an effect of an inclusion in a rubber composition of scrap rubber and coal dust for a transition, intermediate layer for a tire tread, particularly including an evaluation of abrasion resistance of the cured rubber composition.
Sample H is a Control rubber sample. And Experimental rubber Sample I contained both scrap rubber and coal dust.
The scrap rubber was scrap rubber in the sense of partially depolymerized cured rubber and/or particulate (ground) pre-vulcanized rubber.
Various physical properties for the Samples are reported in the following Table 3.
5Data according to DIN 53516 abrasion resistance test procedure using a Zwick drum abrasion unit, model 6102 with 2.5 Newtons force. DIN standards are German test standards. The DIN abrasion results are reported as relative values to a control rubber composition used by the laboratory.
From Table 3 it can be seen that most of the reported physical properties for the lower cost rubber compound Sample I (lower cost in the sense of containing said scrap rubber and coal dust) are comparable to the Control Sample H.
However, cured rubber Sample I exhibited a significantly reduced abrasion resistance property in a sense of providing a significantly increased DIN abrasion value, namely a significantly increased abrasion loss value, as compared to the Control rubber Sample H.
While certain representative embodiments and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in this art that various changes and modifications can be made therein without departing from the scope of the subject invention.
