Patent Application
20080066838
Rubber compositions were prepared for evaluating an effect of an inclusion of a dispersion of small amount of cross-linked, water absorbing polymer granules (SAP) in a carbon black-reinforced, conjugated diene-based elastomer-containing rubber composition.
Samples CE1, CE2 and CE3 are comparative rubber samples which contained various amounts of rubber reinforcing carbon black without silica reinforcing filler and without an inclusion of the SAP.
Samples E1, E2 and E3 are experimental samples which contained rubber reinforcing carbon black without silica reinforcing filler and contained various amounts of an SAP dispersion.
Comparative rubber Sample CE2 and Experimental rubber Samples E1, E2 and E3 (containing the water absorbing granule dispersion) were comparatively similar in a sense that each contained 50 phr of rubber reinforcing carbon black.
The rubber compositions were prepared by mixing the ingredients in sequential 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.
1As Budene 1207 ™ from The Goodyear Tire & Rubber Company
2Solution polymerization prepared styrene/butadiene rubber as SLF16Sn42 ™ from The Goodyear Tire & Rubber Company having a bound styrene content of about 16 percent
3Rubber reinforcing carbon black as N299, an ASTM designation
4Water absorbing resin granules as Liquasorb 1010 ™ from the BASF company, a cross-linked sodium polyacrylate resin reportedly having an ability to absorb up to 240 g/g distilled water at a temperature of about 23° C. and having an average particle size smaller than 100 microns
5Rubber processing oil
6Fatty acid comprised (composed) of at least 90 weight percent stearic acid and a minor amount of other fatty acid comprised (composed) primarily of palmitic and oleic acids.
7Antidegradant of the diamine type
The following Table 2 illustrates cure behavior and various physical properties of rubber compositions based upon the basic recipe of Table 1.
1Data obtained from the measurement of weight percentage gain of a very thin cured rubber sheet (1 inch wide by 1 inch long by 1/8 inch thick, or 2.54 cm wide by 2.54 cm long by 0.32 cm thick) immersed in de-ionized water at 23° C. for 60 seconds.
2Measurement not determined (ND)
3Data 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.
4Data 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.
5Data according to ASTM E303 using a British Portable Skid Tester (BPST). Reference to the BPST may be found in G. B. Ouyang et al, paper presented at a meeting of the Rubber Division of the American Chemical Society, Denver, Colorado, May 1 through 20, 1993; and Guistino et al paper presented at a meeting of the Rubber Divisionof the American Chemical Society, Toronto, Ontario, May 10 through 12, 1983. The surface of the BPST test block was in contact with a wet towel for about one minute at about 23° C. prior to the test to ensure that the sample testing surface was wet. The wet skid resistance of the rubber composition is reported as relative values (%) toComparative rubber Sample CE2 normalized to a value of 100.
It can be seen from Table 2 that the addition of 5, 10 and 20 phr of the superabsorbent polymer resulted in some increase in the Experimental rubber Samples E1, E2 and E3 Shore A hardnesses relative to Comparative rubber Sample CE2, all of which contained 50 phr of rubber reinforcing carbon black.
This is considered herein to be significant in the sense of indicating a potential enhancement of dry handling of a tire having a tread of such rubber composition.
It can further be seen from Table 2 that the addition of 5, 10 and 20 phr of the superabsorbent polymer led to an increased wet skid resistance of Experimental rubber Samples E1, E2 and E3 relative to Comparative rubber Sample CE2.
This is considered herein to be significant in the sense of indicating a potential enhancement of wet traction of a tire tread of such rubber composition.
While certain representative embodiments and details have been shown for the purpose of illustrating the invention, it will be apparent to those skilled in this art that various changes and modifications may be made therein without departing from the spirit or scope of the invention.
