Tire with carbon black reinforced polyurethane

Abstract

This invention relates to a vehicular tire containing at least one carbon black reinforced polyurethane component.

Claims

1. A toroidal tire is provided containing at least one component comprised of a carbon black reinforced polyurethane containing a dispersion consisting of molecular sieve desiccant and from about 1 to about 5 weight percent of granules of pulverized pellets of compacted rubber reinforcing carbon black where said granules have an average aggregate particle size in a range of from about 1 to about 15 microns, wherein the polyurethane is the product of a reaction mixture of at least one polymeric polyol and organic polyisocyanate having a ratio of isocyanate groups to hydroxyl groups of said polymeric polyol in a range of from about 1.1/1 to about 2/1, wherein said polymeric polyol is comprised of at least one of polyester polyol and polyether polyol, wherein the carbon black reinforcement of said polyurethane is the product of said polyisocyanate and isocyanate reactive groups on said pulverized rubber reinforcing carbon black granules where said isocyanate reactive groups are comprised of at least one of hydroxyl groups, carboxylic acid groups, and quinone groups.

2. The tire of claim 1 wherein said component is selected from a circumferential tread, tire sidewalls and tire carcass.

3. The tire of claim 1 wherein said component is a tire carcass wherein the tire tread is a diene-based rubber composition.

4. The tire of claim 1 wherein said rubber reinforcing carbon black for said compacted carbon black pellets is characterized by having an iodine adsorption value (ASTM D1510) in a range of from about 100 to about 145 g/kg together with a dibutylphthalate (DBP) value (ASTM D2414) in a range of from about 40 to about 125 cc/100 g.

5. The tire of claim 1 wherein the polymeric polyol is a saturated hydrocarbon polymeric polyol having a hydroxyl functionality of from about 2 to about 3.

6. The tire of claim 1 wherein the polymeric polyol is a polymeric polyester polyol.

7. The tire of claim 1 wherein the polymeric polyol is a polymeric polyester polyol as a product of dicarboxylic acid having from about 4 to about 10 carbon atoms and hydroxyl terminated hydrocarbon diol having from 2 to 8 carbon atoms.

8. The tire of claim 7 wherein the polyester polyol is a condensation product of glycols and organic polycarboxylic acid or anhydride of polycarboxylic acid.

9. The tire of claim 8 wherein said glycols are comprised of at least one of ethylene glycol, propylene glycol, butylene glycol, pentylene glycol and decamethylene glycol.

10. The tire of claim 9 wherein said organic dicarboxylic acids are comprised of at least one of succinic acid, glutaric acid, adipic acid, phthalic acid, terephthalic acid, isophthalic acid, suberic acid, sebacic acid, pimelic acid, and azelaic acid.

11. The tire of claim 9 wherein said anhydrides are comprised of from about one to 20 percent by weight of organic polycarboxylic acid and at least one of a hydrocarbon triol or higher polyfunctional polyol can be present to promote branching in the polyurethane polymer.

12. The tire of claim 1 wherein the polymeric polyol is a polyether polyol.

13. The tire of claim 12 wherein the polyether polyol is a product of at least one of alkylene oxides and alkylene glycols.

14. The tire of claim 1 said polymeric polyols have a molecular weight in a range of form about 1,200 to about 1,400 Daltons.

15. The tire of claim 1 wherein said organic polyisocyanate is comprised of at least one of aromatic, aliphatic and cycloaliphatic polyisocyanate.

16. The tire of claim 1 wherein the ratio of isocyanate groups of said polyisocyanate to hydroxyl groups of said polymeric polyol is in a range of from about 0.8/1 to about 2/1.

17. The tire of claim 1 wherein polyurethane contains the dispersion of granules of pulverized pellets of compacted rubber reinforcing carbon black in an amount of from about 1 to about 54 weight percent.

18. The tire of claim 1 wherein the carbon black granules of pulverized compacted carbon black pellets have an average aggregate particle size in a range of from about 5 to about 10 microns.

Description

EXAMPLE

(1) Polyurethane reaction mixtures are prepared to evaluate an inclusion of a dispersion of granular aggregates of pulverized compacted pellets of rubber reinforcing carbon black in a polyurethane reaction mixture comprised of polymeric polyester polyol and polyisocyanate. The carbon black aggregates were a product of pulverization of pellets of compacted rubber reinforcing carbon black by ball milling until the carbon black aggregates were reduced to a size in a range of from about 10 to about 12 microns.

(2) The carbon black of the carbon black pellets was a rubber reinforcing carbon black as N110, an ASTM designation, with a reported Iodine absorption number of about 145 g/kg according to ASTM D1510, and a DBP (dibutylphthalate) adsorption value of about 113 cc/100 g according to ASTM D2414.

(3) The carbon black pellets were heated to about 104° C. to initially remove residual water of absorption and then cooled under nitrogen. The ball milling of the carbon black pellets was conducted under a moisture-free, dry nitrogen atmosphere to form carbon black aggregates.

(4) The polymeric polyester polyol was blended with the carbon black aggregates, molecular sieve desiccant as well as dioctyl adipate plasticizer to reduce viscosity to promote its processability and this mixture was degassed separately from the polyisocyanate under vacuum to remove any residual moisture. For convenience, a plasticizer (e.g. dioctyl adipate) could have been blended with the polymeric polyol to make it more fluid.

(5) The polymeric polyester polyol containing the carbon black aggregates and molecular sieve desiccant was blended with the polyisocyanate to form a polyurethane reaction mixture which was cast into a toroidally shaped tire mold pre-heated to a temperature of about 82° C. and the polyisocyanate allowed to react with both the polymeric polyol and isocyanate reactive groups on the surface of the pulverized carbon black granules to form a molded (shaped) carbon black reinforced polyurethane tire. The polyurethane tire was allowed to further cure at a temperature of about 104° C.

(6) For this evaluation, a Control Sample A was prepared comprised of reacting a liquid reaction mixture comprised of polymeric polyester polyol and polyisocyanate without carbon black, dioctyl adipate or molecular sieves to form a polyurethane product.

(7) Experimental rubber Sample B was prepared with the polymeric polyol and polyisocyanate of Control rubber Sample A wherein granules of ball milled pellets of compacted rubber reinforcing carbon black were blended with the polymeric polyol together with desiccant of molecular sieves and plasticizer as the dioctyl adipate prior to adding the polyisocyanate to form the polyurethane.

(8) For Experimental rubber Sample B, the rubber reinforcing carbon black was N231, an ASTM designation, reportedly characterized by an iodine value (ASTM D1510) of about 121 g/kg and a DBP (dibutylphthalate) value of about 92 cc/100 g.

(9) Experimental rubber Sample C was prepared with the polymeric polyol and polyisocyanate of Control rubber Sample A wherein granules of ball milled pellets of compacted rubber reinforcing carbon black were blended with the polymeric polyol together with desiccant of molecular sieves and plasticizer as the dioctyl adipate prior to adding the polyisocyanate to form the polyurethane. For Experimental rubber Sample C, the rubber reinforcing carbon black was N120, an ASTM designation, reportedly characterized by an iodine value (ASTM D1510) of about 122 g/kg and a DBP (dibutylphthalate) value (ASTM D2414) of about 114 cc/100 g.

(10) The components of the polyurethane reaction mixture are reported in the following Table 1 where the values are reported in terms of weight unless otherwise indicated.

(11) TABLE-US-00001 TABLE 1 Polyurethane Reaction Mixture Parts by Weight Control Exp'l Exp'l Material Sample A Sample B Sample C Polymeric polyester polyol and 100 100 100 polyisocyanate.sup.1 Carbon black granules (N231).sup.2 0 1.4 0 Carbon black granules (N120).sup.3 0 0 2.1 Molecular sieves.sup.4 0.34 0.34 0.34 Plasticizer, dioctyl adipate.sup.5 0 6.2 4.8 .sup.1Polyurethane reaction mixture comprised of (a) 100 parts of polymeric polyester polyol as Elastocast ™ as a viscous liquid product of BASF, and (b) 46.5 parts of polyisocyanate as MDI as Lupranate MP102 ™ from BASF .sup.2and .sup.3Carbon black granules from ball milled pellets of compacted rubber reinforcing carbon black as N231 and N120 (ASTM designations), respectively, having an average aggregate particle size in a range of about 10 to about 12 microns. .sup.4Dried molecular sieves in a form of a white powder as a product of the Alfa Assar Company .sup.5The dioctyl adipate plasticizer from Sigma Aldrich

(12) The reaction mixtures were allowed to react to form polyurethanes. Various physical properties of the polyurethanes are reported in the following Table 2.

(13) TABLE-US-00002 TABLE 2 Polyurethane Properties Control Experimental Polyurethane Property Sample A Sample B Sample C Shore A hardness (23° C.) 77 74 74 Percent dispersion of granules in the n/a 88 82 polyurethane Modulus (300%), MPa 8 6.5 7 Tensile strength, MPa 8.8 28 32 Elongation at break (percent) 319 544 547 Grosch abrasion rate (high severity 539 697 498 test) (mg/km) Ross flex test, number of cycles, 17,000 71,000 54,000 (higher is better) Tear strength, N/mm 106 90 123 .sup.1The percent dispersion relates to the degree of dispersion of the carbon black granules in the polyurethane. .sup.2The Grosch abrasion rate can be run on a LAT-100 Abrader and is measured in terms of mg/km of rubber abraded away. The test rubber sample is placed at a slip angle under constant load (Newtons) as it traverses a given distance on a rotating abrasive disk (disk from HB Schleifmittel GmbH). In practice, a low abrasion severity test may be run, for example, at a load of 20 Newtons, 2° slip angle, disk speed of 40 km/hr for a distance of 7,500 meters; a medium abrasion severity test may be run, for example, at a load of 40 Newtons, 6° slip angle, disk speed of 20 km/hr and distance of 1,000 meters; a high abrasion severity test may be run, for example, at a load of 70 Newtons, 12° slip angle, disk speed of 20 km/hr and distance of 250 meters; and an ultra-high abrasion severity test may be run, for example, at a load of 70 Newtons, 16° slip angle, disk speed of 20 km/hr and distance of 500 meters. .sup.3ASTM Test D1052 - The Ross Flex Test is a measure of 500 percent growth of an initial crack length in terms of cycles to achieve such growth, where a higher number of cycles is better. .sup.4Data obtained according to a tear strength (peal adhesion), or tear resistance test as ASTM D624 Test

(14) From Table 2 it can be seen that the polyurethane was dynamically reinforced by the granules of pulverized compacted carbon black (including use of the molecular sieves for the polymeric polyol component of the polyurethane) as shown by the Ross flex values (number of cycles for 500 percent crack growth). In particular, the Ross flex values (cycles) for the polyurethane of Experimental Samples B and C containing the granular pulverized carbon black pellets were significantly and beneficially higher than the ross flex value for the Control polyurethane Sample A which did not contain the granular pulverized carbon black pellets.

(15) From Table 2 it can also be seen that the tensile strength, elongation at break and tear resistance properties of the polyurethanes of Samples B and C with the inclusion of the addition of the granular pulverized pellets of compacted rubber reinforcing carbon black.

(16) It can additionally be seen from Table 2 that the polyurethane of Sample B containing the granules of pulverized pellets of compacted rubber reinforcing carbon black N231 presented increased tensile strength and elongation values as compared to polyurethane Sample C containing the granules of pulverized pellets of compacted rubber reinforcing carbon black N120.

(17) From Table 2 it can further be seen that the Shore A hardness values remained in a range of from about 74 to about 77. This consistency is considered to be beneficial in a sense that the Shore A hardness of the polyurethane is understood to be determinative of the vertical spring rate of a tire composed of the polyurethane and thereby a handling component of the tire. In other words, the inclusion of the small amount of granules of disintegrated carbon black pellets significantly beneficially affected the physical properties of the polyurethanes with little effect on their Shore A hardness values.

(18) Therefore, it is concluded that the inclusion of the granular pulverized pellets of compacted rubber reinforcing carbon black in the polyurethane, together the use of molecular sieve desiccant for its preparation, enabled a successful preparation of a carbon black reinforced polyurethane as being useful for dynamic polyurethane application as indicated by the Ross flex values.

(19) While in accordance with the patent statutes the best mode and preferred embodiment has been set forth, the scope of the invention is not limited thereto, but rather by the scope of the attached claims.