Polymers of propene

Details Polymers of propene Polymers of propene

1999-03-17

2001-06-19

Nutter, Nathan M. (Department: 1711)

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

Synthetic resins

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

C525S197000, C525S240000

Reexamination Certificate

active

06248829

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to polymers of propene consisting of from 50 to 99.9% by weight of an isotactic propene copolymer (A′) and from 0.1 to 50% by weight of a propene homopolymer or a propene copolymer (B′), wherein
a) the propene copolymer (A′) consists of from 80 to 99.9 mol % of propene and from 0.1 to 20 mol % of ethene and/or a C
4
-C
12
-1-olefin, at least 80% of all propene diads are isotactic meso diads, the propene copolymer (A′) has a proportion (X
S
) of material soluble in xylene at 20° C. which satisfies the inequality (1)
(
X
S
)<542 400 exp (−0.1
T
M
)+0.5  (1),
 the tensile modulus of elasticity (E) of the propene copolymer (A′) in MPa, determined in accordance with ISO 527, obeys the inequality (2)
(
E
)>1.9×10
−11
(
T
M
)
6.34
+180MPa  (2),
 where in both inequalities (1) and (2) T
M
is the melting point in ° C., and
b) the propene homopolymer or the propene copolymer (B′) consists of from 80 to 100 mol % of propene and from 0 to 20 mol % of ethene and/or a C
4
-C
12
-1-olefin, at least 55% of all regioregular propene diads are isotactic meso diads, an enthalpy of fusion &Dgr;H
m
of less than 50 J/g is observed in the DSC measurement of (B′) and no crystalline ex sequences are detectable.
The present invention further relates to a process for preparing polymers of propene, their use for producing films, fibers and moldings and also the films, fibers and moldings obtainable in this way.
Random propene copolymers with ethene or with a higher 1-olefin as comonomer prepared using metallocene catalyst systems are well suited to numerous applications in plastics technology (EP-A 668 157, DE-A 19 533 337). This is also true of multiphase propene copolymers, as described in EP-A 643 084, which can also consist of a plurality of different propene copolymers and are used, for example, for producing films, fibers or moldings.
Such random propene copolymers are used, inter alia, in injection molding, particularly in thin-wall injection molding, for example in the production of transparent packaging containers. Here, importance is attached both to high stiffness and transparency of the material and also to a minimum degree of impact toughness and thus resistance to breakage of the moldings produced. In the packaging sector, particularly when foods are to be packed, or in medical applications such as disposable syringes, low proportions of extractable material are often also required.
Compared to propene copolymers prepared using Ziegler-Natta catalysts, random propene copolymers prepared using metallocene catalysts have, at comparable melting points, higher stiffness, better transparency and very low proportions of extractable material [M. -J. Brekner: “Metallocene Based Isotactic Polypropylene For Selected Applications”, Proc. Metallocens '96, p. 155 ff., Düsseldorf, Mar. 6-7, 1996; J. J. McAlpin: “Enhanced Performance for Exxpol™ Propylene Polymers in Target Applications”, Proc. SPO '95, p. 125 ff., Houston, Sep. 20-22, 1995]. However, they have a significantly lower impact toughness which breaks down virtually completely at temperatures as high as 0° C. For this reason, it is precisely in this area of transparent food packaging where a high resistance to breakage is required even at refrigerator temperatures that random propene copolymers produced using metallocene catalysts are inferior to their conventional predecessors.
BRIEF SUMMARY OF THE INVENTION
It is an object of the present invention to remedy the abovementioned disadvantages and to provide polymers of propene which, compared to the previously known random propene copolymers which are obtained by means of metallocene catalyst systems, have an improved stiffness/impact toughness ratio, particularly at low temperatures too, and also have a high transparency and only a low extractables content.
We have found that this object is achieved by the polymers of propene defined at the outset.
We have also found a process for preparing the novel polymers of propene and their use for producing films, fibers and moldings. The present invention also extends to films, fibers and moldings comprising the novel polymers of propene.
DETAILED DESCRIPTION OF THE INVENTION
The novel polymers of propene consist of from 50 to 99.9% by weight, preferably from 70 to 99.5% by weight and in particular from 85 to 99% by weight, of an isotactic propene copolymer (A′) and from 0.1 to 50% by weight, preferably from 0.5 to 30% by weight and in particular from 1 to 15% by weight, of a propene homopolymer or a propene copolymer (B′). The sum of the percentages by weight is always 100. The propene homopolymer and the propene copolymer are hereinafter also referred to, either jointly or separately, as component (B′).
The propene copolymer (A′) contains from 80 to 99.9 mol %, preferably from 85 to 99.5 mol % and in particular from 90 to 99.5 mol %, of propene and from 0.1 to 20 mol %, preferably from 0.5 to 15 mol % and in particular from 0.5 to 10 mol %, of ethene and/or a C
4
-C
12
-1-olefin. The sum of the mol % is always 100.
For the purposes of the present invention, C
4
-C
12
-1-olefins are, in particular, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene and 1-octene, with particular preference being given to using 1-butene, 1-pentene and 1-hexene.
Furthermore, at least 80%, in particular at least 90%, of all propene diads, i.e. the sequences of two adjacent propene units, in the propene copolymers (A′) present in the novel polymers of propene are isotactic meso diads. Isotactic meso diads are two adjacent propene units having the same configuration of the methine carbon (H. L. Frisch et al., J.Chem. Physics., 1966, 45, p. 1565).
In addition, the propene copolymer (A′) has a proportion (X
S
) of materials soluble in xylene at 20° C. which satisfies the inequality (1)
(
X
S
)<542 400 exp (−0.1
T
M
)+0.5  (1),
where T
M
is the melting point in ° C. determined by DSC.
The propene copolymer (A′) also has a tensile modulus of elasticity (E) in MPa, determined in accordance with ISO 527, which obeys the inequality (2)
(
E
)>1.9×10
−11
(
TM
)
6.34
+180MPa  (2),
where T
M
is likewise the melting point determined by DSC.
The component (B′), i.e. the propene homopolymer or the propene copolymer (B′), contains from 80 to 100 mol %, in particular from 85 to 100 mol %, of propene and from 0 to 20 mol %, in particular from 0 to 15 mol %, of ethene and/or a C
4
-C
12
-1-olefin, where the sum of the mol % is always 100.
Here, the term C
4
-C
12
-1-olefin refers to the same comonomers used in the propene copolymers (A′).
Thus, the component (B′) can be either a propylene homopolymer or a propene copolymer which then consists of from 80 to 99.99 mol %, in particular from 85 to 99.5 mol %, of propene and from 0.01 to 20 mol %, in particular from 0.5 to 15 mol %, of ethene and/or a C
4-C
12
-1-olefin. The sum of the mol % is again always 100.
Furthermore, at least 55%, in particular at least 60% and preferably at least 80%, of all regioregular propene diads, i.e. the sequences of two adjacent propene units linked head-to-tail, in the component (B′) are present as isotactic meso diads.
In addition, the propene homopolymers or propene copolymers used as component (B′) have an enthalpy of fusion &Dgr;H
m
determined by means of DSC of less than 50 J/g, in particular less than 40 J/g. They also have no crystalline ex sequences, by which are meant crystallizable sequences of a plurality of directly successive ethene units.
Preferred propene homopolymers or propene copolymers (B′) have a proportion of regioirregular ′1-3′-inserted propene units of at least 4%, in particular at least 6%, based on all propene units. The ′1-3′ insertion of propene units is the linear incorporation of propene into the main polymer chain as a trime

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