Polybutadiene and process for producing the same

Details Polybutadiene and process for producing the same Polybutadiene and process for producing the same

2002-09-05

2003-12-16

Seidleck, James J. (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S090000, C526S093000, C526S108000, C526S116000, C526S117000, C526S125100, C526S340400, C502S117000

Reexamination Certificate

active

06664347

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to polybutadiene having a controlled microstructure and a controlled linearity and to a process of producing the same.
2. Description of the Related Art
Polybutadiene has such a microstructure in which a structural unit produced by polymerization at the 1- and 4-positions (1,4-structure) and a structural unit produced by polymerization at the 1- and 2-positions (1,2-structure) are co-present in the molecular chain. The 1,4-structure is divided into a cis-structure and a trans-structure. The 1,2-structure has a vinyl group as a side chain.
It is known that the microstructure of polybutadiene varies depending on the polymerization catalyst used, and polybutadiene species having different microstructures find their respective uses according to their characteristics.
In particular, polybutadiene having high molecular linearity is excellent in abrasion resistance, heat generation resistance and impact resilience. Molecular linearity of a polymer can be represented by Tcp/ML
1+4
, wherein Tcp is a 5% toluene solution viscosity at 25° C., and ML
1+4
is a Mooney viscosity at 100° C. Tcp represents the degree of molecular entanglement in a thick solution. The greater the Tcp/ML
1+4
ratio, the higher the linearity with a smaller degree of branching.
The present inventors previously discovered that a polybutadiene having a high cis-/low trans-structure with a moderate 1,2-structure content and a high molecular linearity can be produced by using a polymerization catalyst comprising a metallocene type complex of vanadium and an ionic compound composed of a non-coordinating anion and a cation and/or an aluminoxane as disclosed in JP-A-9-291108. Having excellent characteristics, this polybutadiene is expected for application to high impact polystyrene, tires, etc. but, because of its relatively high cold flow, improvement is required for storage or transportation in some applications.
On the other hand, JP-A-5-52406 discloses a process of producing a conjugated diene having a branched structure, which comprises polymerizing a conjugated diene in the presence of a composite catalyst composed of an organic compound of a rare earth element, an organoaluminum compound, and a halogen-containing Lewis acid and adding a coupling agent such as an ester of a carboxylic acid with an alcohol or a phenol.
JP-A-8-208751 teaches that treatment of diene rubber obtained by polymerization using a neodymium catalyst with a chlorinated sulfur compound brings about improvements on cold flow properties and smell of rubber.
SUMMARY OF THE INVENTION
An object of the present invention is to provide polybutadiene having a high-cis and low-trans structure with a moderate 1,2-structure content and exhibiting improved characteristics such as cold flow properties and a process for producing the same.
The present invention provides modified polybutadiene obtained by modifying starting polybutadiene in the presence of a transition metal catalyst, the starting polybutadiene having a Tcp/ML
1+4
ratio, wherein Tcp is a 5% toluene solution viscosity at 25° C., and ML
1+4
is a Mooney viscosity at 100° C., of 2.5 or more.
The present invention also provides the following processes for the production of the modified polybutadiene described above:
(1) A process comprising preparing starting polybutadiene having a Tcp/ML
1+4
ratio of 2.5 or more by using a catalyst system comprising (A) a metallocene type complex of a transition metal and (B) at least one of (B1) an ionic compound composed of a non-coordinating anion and a cation and (B2) an aluminoxane and modifying the starting polybutadiene by addition of a transition metal catalyst.
(2) A process comprising preparing starting polybutadiene having a Tcp/ML
1+4
ratio of 2.5 or more by using a catalyst system comprising (A) a metallocene type complex of a transition metal, (B1) an ionic compound composed of a non-coordinating anion and a cation, (C) an organometallic compound of an element of the group 1 to 3 of the Periodic Table, and (D) water and modifying the starting polybutadiene by addition of a transition metal catalyst.
DETAILED DESCRIPTION OF THE INVENTION
The starting polybutadiene which can be used in the present invention has a 1,2-structure content of 4 to 30%, preferably 5 to 25%, still preferably 7 to 15%; a cis-1,4-structure content of 65 to 95%, preferably 70 to 95%, still preferably 70 to 92%; and a trans-1,4-structure content of not more than 5%, preferably 4.5% or less, still preferably 0.5 to 4%.
If the microstructure of the starting polybutadiene is outside the above defined range, the modified polybutadiene derived therefrom leaves something to be desired in reactivity in grafting, crosslinking, etc. Further, it has insufficient rubbery properties for use a modifier additive, adversely affecting the balance of physical properties and external appearance of matrices.
The toluene solution viscosity (Tcp) to Mooney viscosity at 100° C. (ML
1+4
) ratio, Tcp/ML
1+4
, of the starting polybutadiene is 2.5 or more, preferably 3 to 5.
It is preferred for the starting polybutadiene to have a toluene solution viscosity (Tcp) ranging from 25 to 600, particularly 60 to 300, and a Mooney viscosity at 100° C. (ML
1+4
) ranging from 10 to 200, particularly 25 to 100.
The molecular weight of the starting polybutadiene is preferably such that the intrinsic viscosity [&eegr;] as measured in toluene at 30° C. is 0.1 to 10, particularly 1 to 3. On polystyrene conversion, the molecular weight corresponds to a number average molecular weight (Mn) of 0.2×10
5
to 10×10
5
, preferably 0.5×10
5
to 5×10
5
, and a weight average molecular weight (Mw) of 0.5×10
5
to 20×10
5
, preferably 1×10
5
to 10×10
5
. A preferred molecular weight distribution in terms of Mw/Mn is 1.5 or greater, particularly 1.6 to 10, especially 1.8 to 5.
The starting polybutadiene can be prepared by, for example, polymerizing butadiene in the presence of a catalyst system comprising (A) a metallocene type complex of a transition metal and (B) an ionic compound composed of a non-coordinating anion and a cation and/or an aluminoxane.
The starting polybutadiene can also be prepared by polymerizing butadiene in the presence of a catalyst system comprising (A) a metallocene type complex of a transition metal, (B1) an ionic compound composed of a non-coordinating anion and a cation, (C) an organometallic compound of an element of the group 1 to 3 of the Periodic Table, and (D) water.
The metallocene type complex of a transition metal as component (A) includes metallocene type complexes of transition metals of the groups 4 to 8 of the Periodic Table, such as the group 4 transition metals (e.g., titanium and zirconium), the group 5 transition metals (e.g., vanadium, niobium or tantalum), the group 6 transition metals (e.g., chromium), and the group 8 transition metals (e.g., cobalt or nickel). CpTiCl
3
(Cp: cyclopentadienyl) can be mentioned as an example of the group 4 transition metal metallocene type complex.
Inter alia, metallocene type complexes of the group 5 transition metals are suitable, including the compounds represented by formulae (1) to (6) shown below:
RM.L
a
  (1)
R
n
MX
2-n
.L
a
  (2)
R
n
MX
3-n
.L
a
  (3)
RMX
3
.L
a
  (4)
RM(O)X
2
.L
a
  (5)
R
n
MX
3-n
(NR′)  (6)
wherein n is 1 or 2; and a is 0, 1 or 2.
Preferred of these compounds are RM·L
a
, RMX
3
·L
a
, and RM(O)X
2
·L
a
.
In the formulae, M represents a transition metal of the group 5 of the Periodic Table, such as vanadium (V), niobium (Nb) or tantalum (Ta), with vanadium being preferred.
R represents a cyclopentadienyl group, a substituted cyclopentadienyl group, an indenyl group, a substituted indenyl group, a fluorenyl group or a substituted fluorenyl group.
The substituent in the substituted cyclopentadienyl group, the substituted indenyl group and the substituted fluorenyl gro

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