Tire with stratified tread composite

Patent metadata

Field	Value
Publication number	US-9518158-B1
Application number	US-201514792892-A
Country	US
Kind code	B1
Filing date	Jul 7, 2015
Priority date	Jul 7, 2015
Publication date	Dec 13, 2016
Grant date	Dec 13, 2016

Abstract

The invention relates to a pneumatic rubber truck tire having a circumferential stratified dual cap rubber tread comprised of an outer tread cap and underlying tread sub cap. The underlying tread sub cap rubber layer is provided to support the outer tread cap rubber layer with similar physical properties. Both of the tread cap rubber compositions are comprised of a combination of natural cis 1,4-polyisoprene and dual cis 1,4-polybutadiene elastomers and contain reinforcing fillers comprised of precipitated silica and rubber reinforcing carbon black. The tread cap rubber compositions differ from each other by containing different levels of the individual cis 1,4-polybutadiene rubbers and by containing different rubber reinforcing carbon blacks and precipitated silica.

First claim

What is claimed is:

1. A pneumatic rubber truck tire having a circumferential stratified dual cap rubber tread comprised of an outer tread cap and an underlying tread sub cap wherein, based on parts by weight per 100 parts by weight rubber (phr),
(A) said tread cap rubber composition is comprised of:
(1) conjugated diene based elastomers comprised of about 20 to about 80 phr of natural cis 1,4-polyisoprene rubber (NR) and about 80 to about 20 phr of cis 1,4-polybutadiene rubber (BR),
wherein said polybutadiene rubber (BR) is comprised of a combination of designated (BR1) and specialized (BR2) cis 1,4-polybutadiene rubbers, wherein, in terms of phr:
(a) if BR is less than or equal to 40 phr, BR=BR1,
(b) if BR is greater than 40 phr,
BR 1=25+(( BR− 25)/2)× Y

where Y=is a value in a range of from 0.2 to 1.6, and
(2) about 40 to about 90 phr of reinforcing filler comprised of about 50 to about 90 weight percent of a first rubber reinforcing carbon black and from about 10 to about 50 weight percent precipitated silica together with silica coupler for said precipitated silica containing a moiety reactive with hydroxyl groups on said precipitated silica and another different moiety interactive with said diene-based elastomers,

(B) said tread sub-cap rubber composition is comprised of:
(1) conjugated diene based elastomers comprised of about 40 to about 60 phr of natural cis 1,4-polyisoprene rubber (NR) and about 60 to about 40 phr of cis 1,4-polybutadiene rubber (BR),
wherein said polybutadiene rubber (BR) is comprised of a combination of designated (BR1) and specialized (BR2) cis 1,4-polybutadiene rubbers, wherein, in terms of phr:
(a) if BR is less than or equal to 40 phr, BR=BR1,
(b) if BR is greater than 40 phr,
BR 1=16+(( BR− 16)/2)× Y

where Y=is a value in a range of from 0.2 to 1.6, and
(2) about 40 to about 90 phr of reinforcing filler comprised of about 50 to about 90 weight percent of a second rubber reinforcing carbon black and from about 10 to about 50 weight percent precipitated silica together with silica coupler for said precipitated silica containing a moiety reactive with hydroxyl groups on said precipitated silica and another different moiety interactive with said diene-based elastomers,
wherein for said tread cap and said tread sub-cap rubber compositions, said specialized cis 1,4-polybutadiene rubber has a microstructure comprised of about 90 to about 99 percent cis 1,4-isomeric units, a number average molecular weight (Mn) in a range of from about 90,000 to about 220,000 and a heterogeneity index (Mw/Mn) in a range of from about 2.5/1 to about 5/1, and
said designated cis 1,4-polybutadiene rubber has a microstructure comprised of about 96 to about 99 percent cis 1,4-isomeric units, a number average molecular weight (Mn) in a range of from about 150,000 to about 300,000 and a heterogeneity index (Mw/Mn) in a range of from about 1.5/1 to about 2/1,
wherein said first rubber reinforcing carbon black for said tread cap rubber composition has an iodine adsorption value (ASTM D1510) in a range of from about 100 to about 150 g/kg together with a dibutyphthalate (DBP) adsorption number (ASTM D2414) of from about 110 to about 150 cc/100 g, and
wherein said second rubber reinforcing carbon black for said tread sub cap rubber composition has an iodine adsorption value (ASTM D1510) in a range of from about 70 to about 130 g/kg together with a dibutyphthalate (DBP) adsorption number (ASTM D2414) of from about 80 to about 130 cc/100 g.

2. The tire of claim 1 wherein the tread cap and tread sub cap components are sulfur cured tire components.

3. The tire of claim 1 wherein the tread cap rubber composition contains levels of the said designated (BR1) and specialized (BR2) cis 1,4-polybutadiene rubbers different from the levels of said designated (BR1) and specialized (BR2) cis 1,4-polybutadiene rubbers contained in said tread sub cap rubber composition.

4. The tire of claim 1 wherein said tread cap rubber composition contains up to about 40 phr of at least one additional diene-based elastomer (R′), wherein
(A) NR=100−BR−R′
(B) BR is in a range of from about 20 to about 80 (phr)
(C) BR=BR1+BR2, wherein:
(1) if BR is less than or equal to 40 phr, BR=BR1,
(2) if BR is greater than 40 phr,
BR 1=25+(( BR− 25)/2)× Y

where Y=is a value in a range of from 0.2 to 1.6.

5. The tire of claim 4 wherein said additional diene-based elastomer (R′) is comprised of a styrene/butadiene rubber (SBR).

6. The tire of claim 5 wherein the tread cap rubber composition contains from about 10 to about 30 phr of said styrene/butadiene rubber.

7. The tire of claim 5 wherein said tread cap rubber composition contains levels of the said designated (BR1) and specialized (BR2) cis 1,4-polybutadiene rubbers different from the levels of said designated (BR1) and specialized (BR2) cis 1,4-polybutadiene rubbers contained in said tread sub cap rubber composition.

8. The tire of claim 1 wherein said specialized cis 1,4-polybutadiene rubber is the product of polymerization of 1,3-butadiene monomer in an organic solvent in the presence of a organonickel based catalyst and said designated cis 1,4-polybutadiene rubber is the product of polymerization of 1,3-butadiene monomer in an organic solvent in the presence of a neodymium based catalyst.

9. The tire of claim 1 wherein said silica coupler is comprised of bis (3-trialkoxysilylalkyl) polysulfide having an average of from 2 to 4 connecting sulfur atoms in its polysulfidic bridge or comprised of an alkoxyorganomercaptosilane.

10. The tire of claim 1 wherein said silica coupler is comprised of bis (3-triethoxysilylpropyl_ polysulfide having an average of from 2 to 4 connecting sulfur atoms in its polysulfidic bridge.

11. The tire of claim 2 wherein said silica coupler is comprised of bis (3-triethoxysilylpropyl) polysulfide having an average of from 2 to 4 connecting sulfur atoms in its polysulfidic bridge.

12. The tire of claim 3 wherein said silica coupler is comprised of bis (3-triethoxysilylpropyl) polysulfide having an average of from 2 to 4 connecting sulfur atoms in its polysulfidic bridge.

13. The tire of claim 4 wherein said silica coupler is comprised of bis (3-triethoxysilylpropyl) polysulfide having an average of from 2 to 4 connecting sulfur atoms in its polysulfidic bridge.

14. The tire of claim 5 wherein said silica coupler is comprised of bis (3-triethoxysilylpropyl) polysulfide having an average of from 2 to 4 connecting sulfur atoms in its polysulfidic bridge.

15. The tire of claim 1 wherein said silica coupler is comprised of an alkoxyorganomercaptosilane.

16. The tire of claim 2 wherein said silica coupler is comprised of an alkoxyorganomercaptosilane.

17. The tire of claim 3 wherein said silica coupler is comprised of an alkoxyorganomercaptosilane.

18. The tire of claim 4 wherein said silica coupler is comprised of an alkoxyorganomercaptosilane.

19. The tire of claim 1 wherein:
(A) said specialized cis 1,4-polybutadiene rubber has a number average molecular weight (Mn) in a range of from about 90,000 to 180,000, and
(B) said designated cis 1,4-polybutadiene rubber has a number average molecular weight (Mn) in a range of from about 200,000 to 300,000.

20. The tire of claim 1 wherein:
(A) the second rubber reinforcing carbon black has:
(1) an Iodine value in a range of from about 80 to about 125 g/kg, and
(2) a DBP value in a range of from about 120 to about 128 cc/100 g, and

(B) the first rubber reinforc

Assignees

• Goodyear Tire & Rubber

Inventors

• Meza Roberto Cerrato
• Zhao Junling
• Forciniti Leandro
• Busch Warren James

Classifications

• B60C11/005

  with cap and base layers · CPC title

• C08J2407/00

  Characterised by the use of natural rubber · CPC title

• B60C11/0041

  comprising different tread rubber layers · CPC title

• C08J5/00 Primary

  Manufacture of articles or shaped materials containing macromolecular substances (manufacture of semi-permeable membranes B01D67/00 - B01D71/00) · CPC title

• B60C1/00

  Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition · CPC title