Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
1998-10-27
2002-02-19
Lipman, Bernard (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
Reexamination Certificate
active
06348547
ABSTRACT:
The present invention relates to oxidized waxes obtainable by oxidation of polyolefins obtainable by means of metallocene catalysis and having a molecular weight Mw in the range from 1000 to 40,000 g/mol. The polyolefins obtainable by means of metallocene catalysis are, in the interest of simplicity, hereinafter referred to as metallocene polyolefins.
In addition, the present invention relates to a process for preparing oxidized polyolefin waxes by oxidation of polyolefins having a molecular weight M
w
in the range from 1000 to 40,000 g/mol using oxygen-containing agents at from 140 to 350° C., and also to the use of oxidized waxes as or in coating compositions, as or in floor polishes and to the use of oxidized polyolefin waxes as or in coating compositions for citrus fruits.
Oxidized polyolefin waxes are already known. They are generally obtained by oxidation of, in general low molecular weight, Ziegler polyethylene, Phillips polyethylene (HDPE) or high-pressure polyethylene (LDPE) using air or pure oxygen, Kunststoff-Handbuch, volume 4, p. 161 ff. Carl-Hanser-Verlag, 1969.
Such oxidized waxes are already used as coating compositions for various applications, for example in the surface treatment of floors or citrus fruits.
The polyolefin wax oxidation forms, inter alia, carboxyl groups in or on the polymer chains of the starting polyolefin, the number of which can be determined by means of the acid number. A high acid number of the waxes is generally advantageous since the waxes can be dispersed and applied better.
In the oxidation of known Phillips polyethylene waxes, Ziegler polyethylene waxes or, in particular, high-pressure polyethylene waxes, a great reduction in the melting point of the oxidized waxes compared to the starting polymer is observed and this is associated with an undesired reduction in the hardness of the oxidized waxes. However, a high hardness and thus a high melting point of the oxidized waxes is advantageous for use as or in coating compositions, for example in floor polishes or for preserving citrus fruits.
Furthermore, the oxidation of the known polyolefin waxes results in an unfavorable ratio of acid number to saponification number of <1:1 and this generally has an adverse effect on the dispersibility of the waxes in aqueous media. The dispersibility can generally be improved by increasing acid number and saponification number.
It is an object of the present invention to find a remedy to the disadvantages mentioned and to provide, in particular, oxidized polyolefin waxes having a relatively high molecular weight and at the same time a high acid number, high saponification number and comparatively high hardness, and also a high melting point. Furthermore, it is an objective of the present invention to provide an oxidation process for polyolefins which makes it possible to obtain oxidized polyolefin waxes having the abovementioned desired properties.
We have found that these objects are achieved by oxidized waxes obtainable by oxidation of polyolefins obtainable by means of metallocene catalysis and having a molecular weight M
w
in the range from 1000 to 40,000 g/mol and a process for preparing oxidized polyolefin waxes by oxidation of polyolefins having a molecular weight Mw in the range from 1000 to 40,000 g/mol using oxygen-containing agents at from 140 to 350° C., wherein the polyolefins used are ones which are obtainable by means of metallocene catalysis.
The present invention also provides for the use of oxidized waxes as or in coating compositions, the use of oxidized waxes as or in floor polishes 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 gel permeation chromatography (GPC) in 1,2,4-trichlorobenzene at 135° C. using a polyethylene or polypropylene standard, 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 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 can be obtained by polymerization of the corresponding monomers in the presence of metallocene catalysts (metallocene catalysis).
Well suited monomers are ethylene and C
3
-C
10
-alk-1-enes, i.e. propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene. Preference is given to using ethylene and/or propylene as monomers.
The monomers can be homopolymerized or copolymerized with one another in any ratio. Preferred polyolefins on which the oxidized waxes are based are ethylene homopolymers having a density in the range from 0.90 to 0.98 g/cm
3
, preferably in the range from 0.94 to 0.97 g/cm
3
, and an M
w
, determined by GPC as described above, in the range from 1000 to 40,000 g/mol, preferably in the range from 2000 to 20,000 g/mol.
Other suitable starting polyolefins are ethylene-C
3
-C
10
-alk-l-ene copolymers containing a total of from 0.1 to 15 mol %, preferably from 1 to 10 mol %, mol %, based on the copolymer, of structural units derived from the alk-1-ene or alk-1-enes. Preferred ethylene-alk-1-ene copolymers are ethylene-propylene copolymers containing from 0.1 to 10 mol %, preferably from 1 to 5 mol %, based on the copolymer, of structural units derived from the propylene. The copolymers generally have an M
w
, determined by GPC as described above, in the range from 1000 to 40,000 g/mol, preferably in the range from 2000 to 20,000 g/mol.
Further preferred polyolefins on which the oxidized waxes are based are isotactic propylene homopolymers having an isotactic pentad mnmnmm content, determined by
13
C-NMR spectroscopy, in the range from 90 to 98% and an Mw, determined by GPC as described above, in the range from 1000 to 40,000 g/mol, preferably in the range from 2000 to 20,000 g/mol.
Other suitable base polyolefins are copolymers of propylene with ethylene and/or C
4
-C
10
-alk-1-enes. These propylene copolymers usually contain a total of from 0.1 to 15 mol %, preferably from 1 to 10 mol %, based on the copolymer, of structural units derived from the ethylene and/or the C
4
-C
10
-alk-1-enes. Preferred propylene copolymers are propylene-ethylene copolymers containing from 0.1 to 10 mol %, preferably from 1 to 5 mol %, based on the copolymer, of structural units derived from the ethylene. The propylene copolymers generally have an M
w
, determined by GPC as described above, in the range from 1000 to 40,000 g/mol, preferably in the range from 2000 to 20,000 g/mol.
The monomers are homopolymerized or copolymerized in the presence of metallocene catalysts (metallocene catalysis).
For the purposes of the present invention, metallocene catalysts are substances which are generally formed by combining a transition metal compound or a plurality of transition metal compounds, preferably of titanium, zirconium or hafnium, which contain at least one ligand which is in the widest sense a derivative of cyclopentadienyl ligands with an activator, also known as cocatalyst or compound capable of forming metallocenium ions, and are generally polymerization-active toward the monomers described. Such catalysts are described, for example, in EP-A 0 545 303, EP-A 0 576 970 and EP-A 0 582 194. The catalyst systems according to the present invention generally comprise as active constituents
A) a metallocene complex or a plurality of metallocene complexes of the formula (I)
where the substituents and indices have the following meanings:
M is titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum or tungsten,
X
1
, X
2
are fluorine, chlorine, bromine, iodine, hydrogen, C
1
-C
10
-alkyl, C
6
-C
15
-aryl, —OR
6
or —NR
6
R
7
,
where R
6
, R
7
are C
1
-C
10
-alkyl, C
6
-C
15
-aryl, alkylaryl, arylalkyl, fluoroalkyl or fluoroaryl each having from 1 to 10 carbon atoms in the alkyl radical and from 6 to 20 carbon atoms in the aryl radical,
R
1
to R
5
are h
Deckers Andreas
Kingma Arend Jouke
Moll Ulrich
Weber Wilhelm
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