{
  "$type": "site.standard.document",
  "description": "A pneumatic tire having a circumferential tread (2) comprising an outer tread cap layer (3) and an underlying sub tread cap layer (4) is disclosed. The outer tread cap layer (3) is of a rubber composition comprising conjugated diene based elastomers comprising 20 to 80 phr of natural cis…",
  "path": "/patents/932283",
  "publishedAt": "2017-01-11T00:00:00.000Z",
  "site": "at://did:plc:oql6ds5vnff4ugar6rruliwd/site.standard.publication/3mn3ohu7oxx5w",
  "tags": [
    "B60C1/0016",
    "GOODYEAR TIRE & RUBBER [US]"
  ],
  "textContent": "A pneumatic tire having a circumferential tread (2) comprising an outer tread cap layer (3) and an underlying sub tread cap layer (4) is disclosed. The outer tread cap layer (3) is of a rubber composition comprising conjugated diene based elastomers comprising 20 to 80 phr of natural cis 1,4-polyisoprene rubber (NR) and 80 to 20 phr of cis 1,4-polybutadiene rubber (BR), wherein the polybutadiene rubber (BR) comprises a combination of a designated (BR1) and a specialized (BR2) cis 1,4-polybutadiene rubber. The underlying sub tread layer (4) is of a rubber composition comprising conjugated diene based elastomers comprising 40 to 60 phr of natural cis 1,4-polyisoprene rubber (NR) and 60 to 40 phr of cis 1,4-polybutadiene rubber (BR), wherein the polybutadiene rubber (BR) comprises a combination of the designated (BR1) and the specialized (BR2) cis 1,4-polybutadiene rubber. The specialized cis 1,4-polyisoprene rubber has a microstructure comprising 90 to 99 percent cis 1,4-isomeric units, a number average molecular weight (Mn) in a range of from 90,000 to 220,000 and a heterogeneity index (Mw/Mn) in a range of from 2.5/1 to 5/1. The designated cis 1,4-polybutadiene rubber has a microstructure comprising 96 to 99 percent cis 1,4-isomeric units, a number average molecular weight (Mn) in a range of from 150,000 to 300,000 and a heterogeneity index (Mw/Mn) in a range of from 1.5/1 to 2/1.",
  "title": "TIRE WITH STRATIFIED TREAD COMPOSITION"
}