Oxidized polyolefin waxes

Details Oxidized polyolefin waxes Oxidized polyolefin waxes

2002-12-16

2004-11-30

Rabago, Roberto (Department: 1713)

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

Synthetic resins

Mixing of two or more solid polymers; mixing of solid...

C525S388000, C526S161000, C526S172000

Reexamination Certificate

active

06825283

ABSTRACT:

The present invention relates to oxidized polyolefin waxes having a molecular weight M
w
in the range from 1000 to 40,000 g/mol, obtainable by oxidizing polyolefins prepared by catalysis using a single-site catalyst based on a complex of a transition metal from groups 5 to 8 of the Periodic Table of the Elements containing not more than one cyclopentadienyl system per metal atom.
The present invention also relates to a process for preparing oxidized polyolefin waxes by oxidizing polyolefins having a molecular weight M
w
in the range from 1000 to 40,000 g/mol with oxygen agents at a temperature in the range from 140 to 350° C., and to the use of oxidized waxes as or in coating, floorcare or leathercare compositions, and also to the use of oxidized polyolefin waxes as or in coating compositions for citrus fruits.
Oxidized polyolefin waxes are known as such. They are generally obtained by oxidizing usually low molecular mass Ziegler polyethylene, Phillips polyethylene (PE-HD) or else high pressure polyethylene (PE-LD) using air or pure oxygen; see, for example, Kunststoff-Handbuch, Vol. 4, p. 161 ff., Carl-Hanser-Verlag, 1969.
Such oxidized waxes are used as coating compositions for various fields: in the surface treatment of floors or citrus fruits, for example.
The oxidation of polyolefin waxes is accompanied by the formation, inter alia, of carboxyl groups in or on the polymer chains of the polyolefin starting material, the number of these groups being determinable by way of what is known as the acid number. A high acid number in the waxes is generally of advantage, since the waxes can be dispersed and employed more effectively.
During the oxidation of known Phillips polyethylene, Ziegler polyethylene or, in particular, high-pressure polyethylene waxes, a sharp reduction is observed in the melting points of the oxidized waxes relative to the polymer starting materials, and goes hand in hand with an unwanted reduction in the hardness of the oxidized waxes. For use as or in coating compositions, in floorcare compositions or in the preservation of citrus fruits, for example, however, high hardness and thus a high melting point of the oxidized waxes are advantageous.
DE-A 196 17 230 discloses oxidized polyethylene waxes obtained by oxidizing waxes prepared by metallocene catalysis.
Moreover, EP-A 0 890 583 discloses a process for oxidizing polyethylene waxes where organic or inorganic acids are added to the polyethylene melt.
However, relative to the starting materials, the melt viscosities of the waxes obtainable in accordance with DE-A 196 17 230 and EP-A 0 890 583 are greatly reduced. This is due to degradation of the polymer chains. Severe degradation of the polymer chains, however, is disadvantageous, since it results in a deterioration in the performance properties. In particular, there is still room for improvement in the hardness in applications of the prior art oxidized waxes in or as floorcare or coating compositions for citrus fruits, for example.
Additionally, the reaction times for the oxidation run to several hours and are therefore disadvantageously long, reducing the capacity of the plant.
It is an object of the present invention to remedy the above disadvantages and, in particular, to provide oxidized polyolefin waxes combining a relatively high molecular weight with a high acid number, high saponification number, comparatively high hardness, and high melting point.
A further object of the present invention is to provide an oxidation process for polyolefins allowing access to oxidized polyolefin waxes having the desired properties specified in the preceding paragraph.
We have found that these objects are achieved by oxidized waxes which were prepared by oxidizing polyolefin waxes obtained by catalysis using selected complexes of transition metals from groups 5 to 8 of the Periodic Table of the Elements. The oxidized waxes of the invention have a molecular weight M
w
in the range from 1000 to 40,000 g/mol. We have also found a process for preparing the oxidized polyolefin waxes of the invention by oxidizing polyolefins having a molecular weight M
w
in the range from 1000 to 40,000 g/mol with oxygen agents at a temperature in the range from 140 to 350° C.
We have additionally found the use of oxidized waxes as or in coating compositions, the use of oxidized waxes as or in floorcare compositions, and the use of oxidized waxes as or in coating compositions for citrus fruits.
The polyolefins on which the oxidized waxes are based have a weight average molecular weight M
w
, determined by the method of gel permeation chromatography (GPC) in 1,2,4-trichlorobenzene at 135° C. using polyethylene or polypropylene standards, in the range from 1000 to 40,000 g/mol, preferably in the range from 2000 to 20,000 g/mol. The polydispersity M
w
/M
n
of the polyolefins on which the oxidized waxes are based, measured by the method of GPC as described, is generally in the range from 1.5 to 3.0, preferably in the range from 1.8 to 2.5.
The polyolefins on which the oxidized waxes are based may be obtained by polymerizing the corresponding monomers in the presence of complexes of the formulae I a to c.
Waxes preparable using such single-site catalysts of a transition metal from groups 5 to 8 of the Periodic Table, containing not more than one cyclopentadienyl system per transition metal atom, are known per se. In one embodiment the single-site catalysts comprise as catalytically active component a tri-pnicogen-cyclohexane complex of a transition metal from groups 5 to 8 of the Periodic Table. Such tri-pnicogen-cyclohexane complexes are, for example, a 1,3,5-triazacyclohexane complex, a 1,3-dia-za-5-phosphacyclohexane complex or a 1,3,5-triphosphacyclohexane complex of a transition metal from groups 5 to 8 of the Periodic Table. The chromium complexes required for this preparation comprise compounds of the formula I a to c.
In formula I a
M is an element from the group consisting of V, Nb, Ta, Cr, Mo, W, Mn, and Fe in the +3 oxidation state; preferably V, Cr or Mo, and with particular preference Cr;
X
1
and X
2
are selected from
halogen such as fluorine, chlorine, bromine or iodine, chlorine and bromine being particularly preferred;
trifluoroacetate,
BF
4
<
, PF
6
−
or SbF
6
−
,
C
1
-C
18
alkyl such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl, neopentyl, 1,2-dimethylpropyl, isoamyl, n-hexyl, isohexyl, sec-hexyl, n-heptyl, isoheptyl, n-octyl, n-nonyl, n-decyl, and n-dodecyl; preferably C
1
-C
6
alkyl such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl, neopentyl, 1,2-dimethylpropyl, isoamyl, n-hexyl, isohexyl, sec-hexyl, with particular preference C
1
-C
4
alkyl such as methyl, ethyl, n-propyl and n-butyl;
C
3
-C
12
cycloalkyl such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cycloundecyl and cyclododecyl; cyclopentyl, cyclohexyl and cycloheptyl are preferred,
C
7
to C
20
aralkyl, preferably C
7
to C
12
phenylalkyl such as benzyl, 1-phenethyl, 2-phenethyl, 1-phenylpropyl, 2-phenylpropyl, 3-phenylpropyl, 1-phenylbutyl, 2-phenylbutyl, 3-phenylbutyl and 4-phenylbutyl, with particular preference benzyl,
C
6
-C
14
aryl such asphenyl, 1-naphthyl, 2-naphthyl, 1-anthryl, 2-anthryl, 9-anthryl, 1-phenanthryl, 2-phenanthryl, 3-phenanthryl, 4-phenanthryl and 9-phenanthryl, preferably phenyl, 1-naphthyl and 2-naphthyl, with particular preference phenyl;
C
1
-C
12
alkoxy, preferably C
1
-C
6
alkoxy such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, n-pentoxy, isopentoxy, n-hexoxy and isohexoxy, with particular preference methoxy, ethoxy, n-propoxy and n-butoxy; or
NR
8
R
9
, where R
8
and R
9
independently of one another are selected from hydrogen, C
1
-C
12
alkyl, C
2
-C
12
alkenyl and C
6
-C
14
aryl, which may form a saturated or unsaturated 5- to 10-membered ring; preference is given to the dimethylamino, the diethylamino, the

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