Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1998-05-21
2001-04-24
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...
C526S129000, C526S130000, C526S348600, C526S916000, C502S104000, C502S117000
Reexamination Certificate
active
06221984
ABSTRACT:
The present invention relates to random copolymers of propylene with ethylene and at least one C
4
-C
10
-alk-1-ene, which have a melting point, determined by the DSC method, of less than or equal to 135° C. and are obtainable by polymerization of propylene, ethylene and at least one C
4
-C
10
-alk-1-ene in the absence of a liquid reaction medium from the gas phase at from 50 to 100° C. and a pressure of from 15 to 40 bar in the presence of a Ziegler-Natta catalyst system comprising
a) a titanium-containing solid component comprising at least one halogen-containing magnesium compound, an electron donor and an inorganic oxide as support,
b) an aluminum compound and
c) a further electron donor compound,
wherein the ratio of the partial pressures of propylene and ethylene is set to from 20:1 to 100:1 and the ratio of the partial pressures of the C
4
-C
10
-alk-1-ene(s) and ethylene is set to from 2.5:1 to 20:1.
The present invention further relates to a process for preparing such random copolymers and to their use in films, fibers or moldings.
Ziegler-Natta catalyst systems are known, inter alia, from EP-B 014 523, EP-A 023 425, EP-A 045 975 and EP-A 195 497. These systems are used particularly for the polymerization of C
2
-C
10
-alk-1-enes and comprise, inter alia, compounds of polyvalent titanium, aluminum halides and/or aluminum alkyls, plus electron donor compounds, in particular silicon compounds, ethers, carboxylic esters, ketones and lactones which are used both in the titanium component and as cocatalyst.
The preparation of Ziegler-Natta catalysts is usually carried out in two steps. Firstly, the titanium-containing solid component is prepared, and this is subsequently reacted with the cocatalyst. The polymerization is then carried out using the catalysts obtained in this way.
U.S. Pat. No. 4,857,613 and U.S. Pat. No. 5,288,824 describe catalyst systems of the Ziegler-Natta type which comprise not only a titanium-containing solid component and an aluminum compound but also organic silane compounds as external electron donor compounds. The catalyst systems obtained in this way display, inter alia, a good productivity and give polymers of propylene having a high stereospecificity, ie. a high isotacticity, a low chlorine content and a good morphology, ie. a low proportion of fines. Copolymers of propylene with other alk-1-enes which are obtainable using such catalyst systems are described in EP-A 450 456.
Some fields of application for polymers of propylene require the polymers to have, inter alia, a high stiffness and only low proportions of xylene-soluble polymer particles. This applies, for example, to food packaging films which are produced from such propylene polymers. The copolymers of propylene known from EP-A 450 456 do not meet these requirements to a sufficient extent.
EP-A 778 295 describes propylene copolymers with copolymerized C
2
-C
10
-alk-1-enes, where, for the case of the copolymers of propylene, ethylene and 1-butene, the ratio of the partial pressures of 1-butene and ethylene is held in the range from 0.02:1 to 2:1.
Furthermore, U.S. Pat. No. 4,483,917 discloses a process for preparing terpolymers of propylene, ethylene and other &agr;-olefins. The terpolymers obtained by this process do have a low content of soluble material, but their sealability is still in need of improvement. In addition, the terpolymers obtained have a relatively high chlorine content.
It is an object of the present invention to develop, starting from the copolymers of propylene described in EP-A 450 456, improved copolymers which do not have the abovementioned disadvantages.
We have found that this object is achieved by the random copolymers of propylene with ethylene and at least one further C
4
-C
10
-alk-1-ene defined in the introduction.
For the purposes of the present invention, C
4
-C
10
-alk-1-enes are linear or branched alk-1-enes, in particular 1-butene, 1-pentene, 1-hexene, 1-heptene or 1-octene or a mixture of these comonomers; preference is given to using 1-butene.
The copolymers of the present invention have a melting point which is less than or equal to 135° C. However, in general, the melting point is not below 80° C. For the purposes of the present invention, the melting point is the melting point determined in accordance with ISO 3146 by means of differential scanning calorimetry (DSC) using a heating rate of 10° C. per minute.
According to the invention, the random copolymers are obtained in the presence of a Ziegler-Natta catalyst system which consists essentially of a titanium-containing solid component a) and, as cocatalysts, an aluminum compound b) and a further electron donor compound c).
To prepare the titanium-containing solid component a), the titanium compounds used are generally the halides or alkoxides of trivalent or tetravalent titanium; it is here also possible to use titanium alkoxy halogen compounds or mixtures of various titanium compounds. Examples of suitable titanium compounds are TiBr
3
, TiBr
4
, TiCl
3
, TiCl
4
, Ti(OCH
3
)Cl
3
, Ti(OC
2
H
5
)Cl
3
, Ti(O-iso-C
3
H
7
)Cl
3
, Ti(O-n-C
4
H
9
)Cl
3
, Ti(OC
2
H
5
)Br
3
, Ti(O-n-C
4
H
9
) Br
3
, Ti(OCH
3
)
2
Cl
2
, Ti(OC
2
H
5
)
2
Cl
2
, Ti(O-n-C
4
H
9
)
2
Cl
2
, Ti(OC
2
H
5
)
2
Br
2
, Ti(OCH
3
)
3
Cl, Ti(OC
2
H
5
)
3
Cl, Ti(O-n-C
4
H
9
)
3
Cl Ti(OC
2
H
5
)
3
Br, Ti(OCH
3
)
4
, Ti(OC
2
H
5
)
4
or Ti(O-n-C
4
H
9
)
4
. Preference is given to using titanium compounds which contain chlorine as halogen. Likewise preferred are the titanium halides which consist of only titanium and halogen, especially the titanium chlorides and in particular titanium tetrachloride.
The titanium-containing solid component a) comprises at least one or a mixture of various halogen-containing magnesium compounds. For the purposes of the present invention, halogens are chlorine, bromine, iodine or fluorine or mixtures of two or more halogens, with chlorine or bromine and in particular chlorine being preferred. The halogen-containing magnesium compounds are either added directly in the preparation of the titanium-containing solid component a) or formed in the preparation thereof. Magnesium compounds which are suitable for preparing the titanium-containing solid component a) are especially the magnesium halides, in particular the chlorides or bromides, or magnesium compounds from which the halides can be obtained in a customary manner, eg. by reaction with halogenating agents. Examples of such compounds are magnesium alkyls, magnesium aryls, magnesium alkoxy compounds or magnesium aryloxy compounds or Grignard compounds. Suitable halogenating agents are, for example, halogens, hydrogen halides, SiCl
4
or CCl
4
and preferably chlorine or hydrogen chloride.
Examples of halogen-free compounds of magnesium which are suitable for preparing the titanium-containing solid component a) are diethylmagnesium, di-n-propylmagnesium, diisopropylmagnesium, di-n-butylmagnesium, di-sec-butylmagnesium, di-tert-butylmagnesium, diamylmagnesium, n-butylethylmagnesium, n-butyl-sec-butylmagnesium, n-butyloctylmagnesium, diphenylmagnesium, diethoxymagnesium, di-n-propyloxymagnesium, diisopropyloxymagnesium, di-n-butyloxymagnesium, di-sec-butyloxymagnesium, di-tert-butyloxymagnesium, diamyloxymagnesium, n-butyloxyethoxymagnesium, n-butyloxy-sec-butyloxymagnesium, n-butyloxyoctyloxymagnesium or diphenoxymagnesium. Among these, particular preference is given to n-butylethylmagnesium or n-butyloctylmagnesium.
Examples of Grignard compounds are methylmagnesium chloride, ethylmagnesium chloride, ethylmagnesium bromide, ethylmagnesium iodide, n-propylmagnesium chloride, n-propylmagnesium bromide, n-butylmagnesium chloride, n-butylmagnesium bromide, sec-butylmagnesium chloride, sec-butylmagnesium bromide, tert-butylmagnesium chloride, tert-butylmagnesium bromide, hexylmagnesium chloride, octylmagnesium chloride, amylmagnesium chloride, isoamylmagnesium chloride, phenylmagnesium chloride and phenylmagnesium bromide.
Apart from magnesium dichloride or magnesium dibromide, particular preference is given to using the di(C
1
-C
10
-alkyl)magnesium compounds
Kersting Meinolf
Langhauser Franz
Schone Werner
BASF - Aktiengesellschaft
Harlan R.
Keil & Weinkauf
Wu David W.
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