Polyolefin wax

Details Polyolefin wax Polyolefin wax

1995-12-22

2002-06-18

Wu, David W. (Department: 1713)

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

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S165000, C526S351000, C526S943000, C585S010000, C585S512000

Reexamination Certificate

active

06407189

ABSTRACT:

The present invention relates to a polyolefin wax having a high melting point, reduced isotacticity, reduced crystallinity and reduced hardness and also to a process for its preparation.
The preparation of polyolefin waxes having a broad molecular weight distribution M
w
/M
n
and an isotactic index of from 60 to 80% by means of supported catalyst, cocatalyst and stereoregulator at temperatures of above 95° C. is known (cf. DE-A 31 48 229). However, in addition to the high temperature, large amounts of hydrogen have to be used as molecular weight regulator. To achieve degrees of polymerization typical of waxes, the hydrogen partial pressure exceeds the partial pressure of the olefin. However, such polymerization conditions cause a significant olefin loss by hydrogenation to the alkane and decreased catalyst activities which result in high residual ash contents in the products. In particular, the high chlorine and titanium contents require complicated purification steps for the product.
The preparation of 1-olefin polymer waxes having a narrow molecular weight distribution and high isotacticity using metallocene catalysts (EP 321 852) is known. For many wax applications, the high isotacticity and hardness of these, products, which shows up in a high heat of fusion of more than 80 [J/g] for polypropylene waxes, is disadvantageous.
The preparation of a 1-olefin stereoblock polymer wax (EP 321 853) using metallocene catalysts which lower the isotacticity by means of a large number of misinsertions is known. Disadvantages are the low activity of these catalyst systems and the lack of controllability of the isotacticity.
The preparation of polyolefin waxes having different isotacticity by changing the polymerization temperature (EP 416 566 is known. However, disadvantages are that the activity of the catalyst decreases sharply with the polymerization temperature and that the achievable molecular weights are low and cannot be adjusted independently of the isotacticity.
Furthermore, it is known that the crystallinity can be reduced by copolymerization (EP 384 264). A disadvantage is the lowering of the melting point of the copolymers in comparison with the melting point of the homopolymer, which limits the range of applications.
It is therefore an object of the present invention to provide a polyolefin wax which avoids the disadvantages of the prior art and, in particular, has reduced isotacticity and hardness at the same time as high melting point.
The present invention accordingly provides a polyolefin wax having a melt viscosity of from 0.1 to 100,000 mPas, preferably from 1 to 60,000 mPas, particularly preferably from 50 to 60,000 mPas, at 170° C., a DSC heat of fusion less than 80 J/g, a DSC melting point of greater than 130° C. and a molecular weight distribution M
w
/M
n
of less than or equal to 3. Preference is given to polypropylene waxes.
The polyolefin waxes of the present invention can be extracted to an extent of at least 10% by weight with diethyl ether. A possible way of determining the isotacticity of crystalline polyolefin waxes is the extraction method using a solvent in a Soxhlet extractor, with the highly crystalline isotactic products remaining undissolved in the residue. The ether-extracted part corresponds to the atactic parts of the polyolefin wax.
The present invention also provides a process for preparing polyolefin waxes having a melt viscosity of from 50 to 100,000 mPas at 170° C., a DSC heat of fusion less than 80 J/g, a DSC melting point of greater than 130° C. and a molecular weight distribution M
w
/M
n
of less than or equal to 3, in the presence of a catalyst comprising a stereo-rigid metallocene compound A and a cocatalyst B. with the metallocene compound A being used as a mixture of racemic form and meso form in a rac/meso ratio of <0.5.
In the racemic form (rac form) of the stereorigid metallocene compound A, the two enantiomers can be converted into one another only by the mirroring operation. In the case of the meso form, the structure and its mirror image can be converted into one another by rotation. The term meso form also includes the case where, when the ligands of the metallocene are different such as in dimethylsilyl(2-methylindenyl)(indenyl)ZrCl
2
, a second pair of enantiomers arises in which the more voluminous parts of the two ligand systems each lie above one another.
The compounds (b) and (c) below are accordingly the rac form and the compounds (a) and (d) below are the meso form.
X=R
7
, ML
2
=M
1
R
10
R
11
as defined for formula I
The stereorigid metallocene compound A is preferably a metallocene of the formula I
where
M
1
is titanium, zirconium, hafnium, vanadium, niobium or tantalum,
R
1
, R
2
, R
3
1
, R
4
and R
5
are identical or different and are each hydrogen, (C
1
-C
20
)alkyl, (C
6
-C
14
)aryl, (C
1
-C
10
)alkoxy, (C
2
-C
10
)alkenyl, (C
7
-C
20
)arylalkyl, (C
7
-C
20
)alkylaryl, (C
6
-C
10
)aryloxy, (C
1
-C
10
)fluoroalkyl, (C
6
-C
10
)haloaryl, (C
2
-C
10
)alkynyl, a radical —SiR
6
3
, where R
6
is (C
1
-C
10
)-alkyl, a halogen atom or a heteroaromatic radical having 5 or 6 ring atoms and able to contain one or more hetero atoms, or adjacent radicals R
1
to R
4
together with the atoms connecting them form one or more rings,
R
7
is a radical
where
M
2
is carbon, silicon, germanium or tin,
R
8
and R
8
are identical or different and are each hydrogen, (C
1
-C
20
)alkyl, (C
6
-C
14
)aryl, (C
1
-C
10
)alkoxy, (C
2
-C
10
)alkenyl, (C
7
-C
20
)arylalkyl, (C
7
-C
20
)alkylaryl, (C
6
-C
10
)aryloxy, (C
1
-C
10
)fluoroalkyl, (C
6
-C
10
)haloaryl, (C
2
-C
10
)alkynyl or halogen, or R
8
and R
9
together with the atom connecting them form a ring, p is 0, 1, 2 or 3 and R
10
and R
11
are identical or different and are each hydrogen, (C
1
-C
10
)alkyl, (C
1
-C
10
)alkoxy, (C
6
-C
10
)aryl, (C
6
-C
10
)aryloxy, (C
2
-C
10
)alkenyl, (C
7
-C
40
)arylalkyl, (C
7
-C
40
) alkylaryl, (C
8
-C
40
) arylalkenyl, hydroxy or a halogen atom.
The compound of the formula I is preferably one in which M
1
is zirconium or hafnium, in particular zirconium, R
1
, R
2
, R
3
1
, R
4
are identical or different and are each hydrogen, (C
1
-C
10
)alkyl, (C
6
-C
14
)aryl, (C
1
-C
4
)alkoxy, (C
2
-C
6
)alkenyl, (C
1
-C
6
)fluoroalkyl, a halogen atom or a heterocyclic aromatic radical having 5 or 6 ring atoms and able to contain one or more hetero atoms, or adjacent radicals R
1
to R
4
together with the atoms connecting them form a ring, and R
5
is (C
1
-C
10
)alkyl,
M
2
is carbon or silicon, in particular silicon, R
8
and R
9
are identical or different and are each hydrogen, (C
1
-C
6
)alkyl, (C
6
-C
10
)aryl, (C
1
-C
6
)alkoxy, (C
2
-C
4
)alkenyl, (C
7
-C
10
) arylalkyl, (C
7
-C
10
) alkylaryl, or R
8
and R
9
together with the atom connecting them form a ring, p is 1 or 2, preferably 1, and R
10
and R
11
are identical or different and are each hydrogen, (C
1
-C
3
)alkyl, in particular methyl, (C
1
-C
3
)alkoxy, (C
6
-C
8
)aryl, (C
6
-C
8
)aryloxy, (C
2
-C
4
)alkenyl, (C
7
-C
10
) arylalkyl, (C
7
-C
10
) alkylaryl, (C
8
-C
12
)arylalkenyl or a halogen atom, preferably chlorine.
Examples of the metallocene component of the catalyst system of the present invention are the rac and meso forms of the following metallocene compounds:
dimethylsilanediylbis(indenyl)zirconium dichloride dimethylsilanediylbis(tetrahydroindenyl)zirconium dichloride
dimethylsilanediylbis(4-naphthylindenyl)zirconium dichloride
dimethylsilanediylbis(2-methylbenzoindenyl)zirconium dichloride
dimethylsilanediylbis(2-methylindenyl)zirconium dichloride
dimethylsilanediylbis(2-methyltetrahydroindenyl)zirconium dichloride
dimethylsilanediylbis(2-methyl-4-(1-naphthyl)indenyl)zirconium dichloride
dimethylsilanediylbis(2-methyl-4-(2-naphthyl)indenyl)zirconium dichloride
dimethylsilanediylbis(2-methyl-4-phenylindenyl)zirconium dichloride
dimethylsilanediylbis (2-methyl-4-t-butylindenyl)zirconium dichloride
dimethylsilanediylbis(2-methyl-4-isopropylindenyl)zirconium dichloride
dimethylsilanediylbis(2-methyl-4-ethylindenyl)zirconium dichloride
dime

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