Polybutadienes with a reduced solution viscosity/mooney...

Details Polybutadienes with a reduced solution viscosity/mooney... Polybutadienes with a reduced solution viscosity/mooney...

2001-07-23

2003-06-10

Lu, Caixia (Department: 1713)

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

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S279000, C526S172000

Reexamination Certificate

active

06576731

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to a process for the preparation of polybutadienes with a reduced solution viscosity/Mooney viscosity ratio using functional dienes, the polybutadienes which can be prepared in this process, the use of the polybutadienes according to the present invention for the preparation of rubber mixtures, the use of the rubber mixtures for the production of all types of shaped articles, and the compound dimethyldi-2,4-pentadienyl-(E,E)-silane as an intermediate product for the preparation of the polybutadienes according to the present invention.
BACKGROUND OF THE INVENTION
Polybutadiene with a high content of cis-1,4 units has been produced on a large industrial scale for a relatively long time and is employed for the production of tires and other rubber goods and for impact modification of polystyrene.
Catalysts based on compounds of the rare earths, as described in EP-A1-0 011 184 and EP-A1-0 007 027, are currently almost exclusively employed to achieve high contents of cis-1,4 units.
However, in addition to the many industrial advantages, the commercially available polybutadienes with high contents of cis-1,4 units, particularly polybutadienes prepared with catalysts based on the rare earths, have the disadvantage that they have a relatively high solution viscosity with respect to the Mooney viscosity. This is a disadvantage in the preparation and processing of the polybutadienes and for the use of these polybutadienes as impact modifiers for thermoplastics.
SUMMARY OF THE INVENTION
Thus, an object of the present invention is to provide polybutadienes with better processability. Another object was to provide polybutadienes which offer advantages when employed as impact modifiers for thermoplastics.
This object is achieved according to the present invention by a process for the polymerization of dienes, characterized in that polydienyl compounds are employed as comonomers.
DETAILED DESCRIPTION OF THE INVENTION
Polydienyl compounds in the context of the present invention are condensation products of dienes of the general formula
R
z-y
—X—(—CR
2
—CR═CR—CR═CR)
y
  (I)
wherein
R in each case independently of one another, represents a radical chosen from the group of H, C
1
-C
20
-alkyl, C
6
-C
20
-aryl and C
7
-C
20
-alkylaryl, which in its turn can be mono- or polyunsaturated or saturated,
X represents an element from the group consisting of C, Si, Ge, Sn, B, Al, N, P, O and S, preferably C or Si, or X
 represents a polysubstituted alkyl or aryl link, such as —(CR
2
)
n
—, —O—(CR
2
)
n
—O—, —C
6
R
4
— or —O-aryl-O—,
 wherein
z represents the number of substituents necessary to satisfy the valencies of X
R has the same meaning as above, and
y represents an integer greater than 2 and is not greater than z, and preferably y=2.
Preferred polydienyl compounds are dimethyldi-2,4-pentadienylsilane, methyltri-2,4-pentadienylsilane and tetra-2,4-pentadienylsilane.
Polydienyl compounds can be prepared by techniques known to one of ordinary skill in the art.
A preferred polydienyl compound, dimethyldi-2,4-pentadienyl-(E,E)-silane, can advantageously be prepared from a technical-grade mixture comprising 1,3-pentadiene by reaction with butyllithium/potassium tert-butylate, coupling with dimethyl-dichlorosilane and subsequent distillation (cf. example 1). The invention also provides dimethyldi-2,4-pentadienyl-(E,E)-silane as an intermediate product.
It is common that various polydienyl compounds can also be employed as a mixture.
The molar ratio of the polydienyl compounds to the conventional dienes is as a rule in the range from 1:10 to 1:20,000, preferably 1:50 to 1:10,000, and most preferably, 1:100 to 1:5,000.
Conventional dienes in the context of the present invention are all the dienes which are known to one of ordinary skill in the art and have been employed with respect to polybutadiene, in particular 1,3-butadiene, 1,2-butadiene, isoprene, pentadiene and 2,3-dimethylbutadiene.
Suitable catalysts for the polymerization of the dienes and polydienyl compounds are preferably the catalyst systems which are known to one of ordinary skill in the art and are based on the rare earths, comprising
A) an alcoholate of the rare earths (II),
a carboxylate of the rare earths (III),
a complex compound of the rare earths with diketones (IV) and/or an addition compound of the halides of the rare earths with an oxygen or nitrogen donor compound (V), of the following formulae:
 and MX
3
m donor (V),
B) an aluminum-trialkyl, a dialkylaluminum hydride and/or an alumoxane of the formulae (VI) to (IX):
AlR
3
  (VI)
HAlR
2
  (VII),
 wherein, in the formulae
 (Al—O)
n+1
  (IX)
and
M denotes a trivalent element of the rare earths with atomic numbers 57 to 71,
R is identical or different and denotes alkyl radicals having 1 to 10 carbon atoms,
X represents chlorine, bromine or iodine,
m denotes 1 to 6 and
n denotes 1 to 50,
C) and at least one further Lewis acid.
Preferred compounds A) are those in which M denotes lanthanum, cerium, praseodymium or neodymium or a mixture of elements of the rare earths which comprises at least one of the elements lanthanum, cerium, praseodymium or neodymium to the extent of at least 10 wt. %.
Compounds A) in which M denotes lanthanum or neodymium or a mixture of rare earths which comprises lanthanum or neodymium to the extent of at least 30 wt. % are most preferred.
Examples of suitable carboxylates of the rare earths are: lanthanum tris-(2,2-diethyl-hexanoate), praseodymium tris(2,2-diethyl-hexanoate), neodymium tris(2,2-diethyl-hexanoate), lanthanum tris(2,2-diethyl-heptanoate), praseodymium tris(2,2-diethyl-heptanoate), neodymium tris(2,2-diethyl-heptanoate), lanthanum versaticate (lanthanum salt of Versatic Acid, commercial product of Shell Chemie), praseodymium versaticate and neodymium versaticate, lanthanum naphthenate, praseodymium naphthenate and neodymium naphthenate.
Examples of suitable aluminumalkyls B) are: trimethylaluminum, triethylaluminum, tri-n-propylaluminum, triisopropylaluminum, tri-n-butylaluminum, triisobutylaluminum, tripentylaluminum, trihexylaluminum, tricyclohexylaluminum, trioctylaluminum, diethylaluminum hydride, di-n-butylaluminum hydride and di-iso-butylaluminum hydride. Triethylaluminum, triisobutylaluminum and diisobutylaluminum hydride are preferred.
Lewis acids are employed as component C. Examples, which may be mentioned, are the organometallic halides in which the metal atom belongs to group 2 or 13, 14 or 15 of the periodic table according to IUPAC 1985 and halides of elements of group 15 of the period table according to IUPAC 1985, such as methylaluminum dibromide, methylaluminum dichloride, ethylaluminum dibromide, ethylaluminum dichloride, butylaluminum dibromide, butylaluminum dichloride, dimethylaluminum bromide, dimethylaluminum chloride, diethylaluminum bromide, diethylaluminum chloride, dibutylaluminum bromide, dibutylaluminum chloride, 1-methylaluminum sesquibromide, methylaluminum sesquichloride, ethylaluminum sesquibromide, ethylaluminum sesquichloride, dibutyltin dichloride, aluminum tribromide, antimony trichloride, antimony pentachloride, phosphorus trichloride, phosphorus pentachloride and tin tetrachloride.
Diethylaluminum chloride, ethylaluminum sesquichloride, ethylaluminum dichloride, diethylaluminum bromide, ethylaluminum sesquibromide and ethylaluminum dibromide are preferred.
The reaction products of alkylaluminum compounds with halogens, e.g., triethylaluminum and bromine, as well as alkyl halides, aryl halides, arylalkyl halides and chlorosilanes, can also be employed as component C.
The molar ratio in which the catalyst components are used can be varied within wide limits.
The molar ratio of component A to component B is 1:1 to 1:100, preferably 1:3 to 1:80, and most preferably 1:3 to 1:50. The molar ratio of component A to component C is 1:0.4 to 1:15, preferably 1:0.5 to 1:8.
The polymerization is carried out in organic solvents. These solvents must be inert towards the catalyst system used.

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