# US 9,518,158 B1 · Tire with stratified tread composite

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- Number: US 9,518,158 B1
- Document ID: US9518158B1
- Status: Granted
- Kind: B1
- Application number: 14/792,892
- Filed: 2015-07-07
- Granted: 2016-12-13
- Earliest claimed: 2015-07-07
- Assignees: The Goodyear Tire & Rubber Company
- Applicants: The Goodyear Tire & Rubber Company
- Inventors: Roberto Cerrato Meza; Junling Zhao; Leandro Forciniti; Warren James Busch
- Web page: https://patentgrep.com/patent/US9518158B1

## CPC

- C08J 5/00: Manufacture of articles or shaped materials containing macromolecular substances (manufacture of semi-permeable membranes B01D67/00 - B01D71/00)
- B60C 1/0016: {Compositions of the tread}
- B60C 11/005: {with cap and base layers}
- C08K 3/04: Carbon
- C08K 3/36: Silica
- C08K 5/548: containing sulfur {(C08K5/5477 takes precedence)}
- C08L 7/00: Compositions of natural rubber
- C08L 9/00: Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
- C08L 9/06: Copolymers with styrene
- B60C 2200/06: for heavy duty vehicles
- C08J 2309/00: Characterised by the use of homopolymers or copolymers of conjugated diene hydrocarbons
- C08J 2407/00: Characterised by the use of natural rubber
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- B60C: VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)

## 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.

## Claims

### Claim 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,
BR1=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,
BR1=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.

### Claim 2 (depends on 1)

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

### Claim 3 (depends on 1)

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.

### Claim 4 (depends on 1)

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,
BR1=25+((BR−25)/2)×Y
where Y=is a value in a range of from 0.2 to 1.6.

### Claim 5 (depends on 4)

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

### Claim 6 (depends on 5)

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

### Claim 7 (depends on 5)

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.

### Claim 8 (depends on 1)

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.

### Claim 9 (depends on 1)

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.

### Claim 10 (depends on 1)

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.

### Claim 11 (depends on 2)

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.

### Claim 12 (depends on 3)

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.

### Claim 13 (depends on 4)

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.

### Claim 14 (depends on 5)

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.

### Claim 15 (depends on 1)

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

### Claim 16 (depends on 2)

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

### Claim 17 (depends on 3)

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

### Claim 18 (depends on 4)

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

### Claim 19 (depends on 1)

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.

### Claim 20 (depends on 1)

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 reinforcing carbon black has:
(1) an Iodine value in a range of from about 128 to about 125 g/kg, and
(2) a DBP value;
(a) in a range of from about 118 to about 134 cc/100 g and at least about 5 units greater than the DBP value for the said second carbon black, or
(b) in a range of from about 112 to about 118 cc/100 g and least 5 units less than the DBP value for said second carbon black.