Isoprene copolymer and method of producing the same

Patent metadata

Field	Value
Publication number	US-9777101-B2
Application number	US-201314408812-A
Country	US
Kind code	B2
Filing date	Jul 11, 2013
Priority date	Jul 12, 2012
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

A copolymer having properties (durability (fracture resistance, abrasion resistance, and crack-growth resistance)) similar to those of natural rubber and a method of producing the copolymer are provided. An isoprene copolymer has a styrene block or a butadiene block at a terminal thereof, wherein styrene monomers account for less than 5 mol % of all monomers forming the isoprene copolymer having the styrene block; butadiene monomers account for 10 mol % or less of all monomers forming the isoprene copolymer having the butadiene block; and cis-1,4 bond content of a portion derived from isoprene accounts for at least 95% in total.

First claim

The invention claimed is:

1. A method for producing a styrene-isoprene copolymer having a styrene block at a terminal thereof, the method comprising:
polymerizing monomers in the presence of catalyst through at least two polymerization processes, wherein
monomers forming the styrene-isoprene copolymer are styrene monomers and isoprene monomers;
styrene monomers account for less than 5 mol % of all monomers forming the styrene-isoprene copolymer;
cis-1,4 bond content of a portion derived from isoprene accounts for at least 97% in total; and
in a first polymerization process, styrene monomers are polymerized without isoprene monomers.

2. The method according to claim 1 , wherein the number of styrene monomer units per styrene block is no more than 10.

3. The method according to claim l, wherein molecular weight per styrene block is no more than 1000.

4. The method according to claim 1 , wherein the catalyst contains a rare earth element compound expressed by the following formula (i):
M-(NQ) 1 (NQ) 2 (NQ) 3   (i)

(provided that M represents at least one of a lanthanoid element, scandium, and yttrium, and “(NQ) 1 , (NQ) 2 and (NQ) 3 ” represent amide groups that are identical to or different from one another having M-N bond).

5. The method according to claim 4 , wherein an anionic ligand is further added.

Assignees

• Bridgestone Corp

Inventors

• Tamaki Satoru
• Matsushita Junko
• Kaita Shojiro

Classifications

• C08F297/046 Primary

  polymerising vinyl aromatic monomers and isoprene, optionally with other conjugated dienes · CPC title

• B60C1/00 Primary

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

• C08F297/06

  using a catalyst of the coordination type · CPC title

• B60C1/0016

  Compositions of the tread · CPC title

• C08L53/02

  of vinyl-aromatic monomers and conjugated dienes · CPC title