High modulus low hysteresis rubber compound for pneumatic tires

• US 5,494,091 A
• Filed: 06/06/1995
• Issued: 02/27/1996
• Est. Priority Date: 12/30/1992
• Status: Expired due to Term

• Current Assignee: Bridgestone Corporation
• Original Assignee: Bridgestone Corporation
• Inventors: Hergenrother, William L., Ravagnani, Frederick J., Freeman, Roy M.
• Primary Examiner(s): Michl, Paul R.
• Assistant Examiner(s): Warzel, Mark L.
• Application Number:
  US08/470,606
• Time in Patent Office: 266 Days
• Field of Search: 152/517, 152/547, 152/520, 524/504, 525/71, 525/78
• US Class Current: 152/517
• CPC Class Codes: B60C 1/0025 Compositions of the sidewalls
• CPC Class Codes: B60C 13/00 Tyre sidewalls; Protecting, decorating, marking, or the like, thereof B60C17/08 takes precedence; tyre shoulders B60C11/01; removable tyre sidewall trim rings B60B7/01
• CPC Class Codes: B60C 17/0009 comprising sidewall rubber inserts, e.g. crescent shaped inserts
• CPC Class Codes: C08K 3/06 Sulfur
• CPC Class Codes: C08K 5/098 Metal salts of carboxylic acids
• CPC Class Codes: C08L 23/16 Elastomeric ethene-propene or ethene-propene-diene copolymers, e.g. EPR and EPDM rubbers
• CPC Class Codes: C08L 2666/04 Macromolecular compounds according to groups C08L7/00 - C08L49/00, or C08L55/00 - C08L57/00; Derivatives thereof
• CPC Class Codes: C08L 2666/08 Homopolymers or copolymers according to C08L7/00 - C08L21/00; Derivatives thereof
• CPC Class Codes: C08L 2666/24 Graft or block copolymers according to groups C08L51/00, C08L53/00 or C08L55/02; Derivatives thereof
• CPC Class Codes: C08L 51/04 grafted on to rubbers
• CPC Class Codes: C08L 7/00 Compositions of natural rubber
• CPC Class Codes: C08L 9/00 Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
• CPC Class Codes: C08L 9/06 Copolymers with styrene
• CPC Class Codes: Y10T 152/10846 Bead characterized by the chemical composition and or physical properties of elastomers or the like

Abstract

A sulfur-vulcanizable rubber compound, being devoid of peroxide components, having high modulus and low hysteresis properties subsequent to vulcanization. Such compounds comprise from about 25 to 55 parts by weight of polyisoprene; and from about 75 to 45 parts by weight of a diene polymer selected from the group consisting of homopolymers of conjugated diene monomers and copolymers thereof with monoolefin monomers and EPDM terpolymers to total 100 parts by weight of rubber polymer; from about 50 to 70 parts by weight of a reinforcing filler, per 100 parts by weight wherein at least a portion of at least one of the rubber polymers is grafted with a polymeric metal salt of an α, β-ethylenically unsaturated carboxylic acid to form an uncured graft rubber copolymer and at least about 4 parts by weight of a curative selected from the group consisting of sulfur and sulfur donors, per 100 parts by weight of rubber. Pneumatic tires and structural components therefor are manufactured from rubber compounds having high module, low hysteresis and high compressive flex fatigue and provide run flat operation.

Claims

1. A pneumatic tire having run flat properties imparted by at least one structural component having high compressive flex fatigue, high modulus and low hysteresis sulfur-vulcanizable rubber compound, capable of being worked prior to vulcanization, and having high modulus, low hysteresis properties subsequent to vulcanization comprising:

100 parts by weight of an uncured grafted rubber copolymer containing,

from about 25 to 55 parts by weight of polyisoprene,

from about 75 to 45 parts by weight of a diene polymer selected from the group consisting of homopolymers of conjugated diene monomers and copolymers thereof with monoolefin monomers and EPDM terpolymers, to total 100 parts by weight of said grafted rubber copolymer,

wherein a portion of at least one of said polyisoprene and said diene polymers is grafted with a polymeric metal salt of an α

, β

-ethylenically unsaturated carboxylic acid to form said uncured grafted rubber copolymer;

about 50 to 70 parts by weight of a reinforcing filler, per 100 parts by weight of said grafted rubber copolymer; and

at least about 4 parts by weight of a curative selected from the group consisting of sulfur and sulfur donors, per 100 parts by weight of said grafted rubber copolymer;

wherein the sulfur-vulcanizable rubber compound is devoid of peroxide components.

2. A pneumatic tire, as set forth in claim 1, wherein the mechanical static modulus of the sulfur-vulcanizable rubber compound is in the range from about 1400 to 4000 psi at 15% strain subsequent to vulcanization.

3. A pneumatic tire, as set forth in claim 1, wherein the tan δ

of the sulfur-vulcanizable rubber compound is in the range of from about 0.03 to 0.20, measured at 100°

C., 7% deflection and 10 Hz subsequent to vulcanization.

4. A pneumatic tire, as set forth in claim 1, wherein the Shore A hardness of the sulfur-vulcanizable rubber compound is in the range of from about 72 to 97 subsequent to vulcanization.

5. A pneumatic tire, as set forth in claim 1, wherein said uncured grafted rubber copolymer comprises:

from about 60 to 80 percent by weight of at least one of said polyisoprene and said diene polymer, and

from about 20 to 40 percent by weight of said polymeric metal salt of said α

, β

-ethylenically unsaturated carboxylic acid.

6. A pneumatic tire as set forth in claim 1, wherein said polymeric metal salt of said α

, β

-ethylenically unsaturated carboxylic acid is poly zinc dimethacrylate.

7. A pneumatic tire, as set forth in claim 1, wherein said reinforcing filler comprises carbon black.

8. A pneumatic tire, as set forth in claim 1, wherein said structural component comprises a sidewall insert having a crescent-shaped cross section.

9. A pneumatic tire, as set forth in claim 1, wherein said structural component comprises a bead filler.