EP0876420A1

EP0876420A1 - Biaxially aligned polypropylene film made from metallocene polypropylene

Info

Publication number: EP0876420A1
Application number: EP96941044A
Authority: EP
Inventors: Peter John Vaughan Jones; Roland Hingmann; Franz Langhauser; Bernd Lothar Marczinke; Murray Horton; David Fischer; Günther SCHWEIER; Meinolf Kersting; Wolfgang Bidell; Heike Gregorius; Ulrich Moll
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 1995-11-30
Filing date: 1996-11-28
Publication date: 1998-11-11
Also published as: DE19544709A1; AU1032497A; WO1997019980A1

Abstract

The disclosure relates to the use of homopolymers of propylene or copolymers of propylene with C2-C10-alk-1-enes obtainable by polymerisation of appropriate monomers with metallocene catalysts to produce a biaxially aligned single- or multi-layered polypropylene film.

Description

Biaxially oriented polypropylene film made of metallocene polypropylene

description

The present invention relates to the use of homopolycarbonates merisaten of propylene or copolymers of propylene with C ₂ - to Cιo ^-A lk-l ^-enen 'the monomers with metallocene catalysts are obtainable by the polymerization of the corresponding ^¬ a biaxially oriented for producing single or multilayer polypropylene film.

Plastics, in particular olefin polymers or polyvinyl chloride (PVC), are widely processed into foils with a thickness of 0.1 to 200 μm. These films can consist of a single layer or can be constructed from several layers, which are usually formed from different polymers (laminate film, coextrusion film).

The main area of application for plastic films is currently the packaging industry and here mainly the packaging of foodstuffs and luxury foods. Films are also used for the production of adhesive tapes, labels and electrical insulation films.

Great demands are placed on the films with regard to optical properties such as gloss, transparency, with regard to their mechanical properties such as rigidity, tear resistance and extensibility and with regard to their barrier properties.

The favorable properties should, not least for ecological reasons, unite a film with the smallest possible, constant film thickness and good machinability (easy to process at high stretching speeds).

In order to produce such high-quality films, the orientation (stretching) of the films in the longitudinal and transverse directions, based on the extrusion direction, after the extrusion of the polymer has been used (biaxially oriented films, bo process).

However, the polymers previously used for this have disadvantages; be it that, in order to be suitable for the bo process, they have to be mixed with foreign polymers as additives (DE-A 43 37 251) or that they may only have a very low melt flow index (MFI), for example less than 1 g / 10 min (EP-A 333 824). Polymers conventionally used with a melt flow index (MFR) of more than 1 g / 10 mm, measured at 230 ° C and 2.16 kg support weight, often tear when the films are stretched during the bo process.

A disadvantage of the additive admixture mentioned is that the additives can settle on important parts of the processing machines, such as rollers and screws, which can lead to malfunctions in the processing machines.

Polymers that have a low melt flow index, for example less than 1 g / 10 mm, have the disadvantage of the poor flowability of the polymer melt and thus its poor processability into films etc., which means a limitation for the processor and the customer.

The properties of the films obtained according to the prior art also leave something to be desired; the gloss and waviness (uneven distribution of the film thickness over its surface) of the films were particularly worth mentioning here.

The present invention was therefore based on the object to remedy the described disadvantages and in particular to provide a thin film which contains little or no foreign polymers as processing additives and can also be prepared from polymers with a higher melt flow index than, for example, 1 g / 10 mm, in particular with the bo process, and has good mechanical and optical properties, for example gloss.

Accordingly, the use of homopolymers of propylene or copolymers of propylene with C ₂ to Cio alk-1-enes, which are obtainable by polymerizing the corresponding monomers with metal ocene catalysts, was found for the production of biaxially oriented em or multilayer polypropylene film.

The film can be made up of one or more layers.

It generally contains an essential component of a propylene homopolymer or a copolymer of propylene and an alk-1-ene or more alk-1-enes, selected from the group consisting of ethylene, 1-butene, 1-pentene, 1-hexene, 1 -Hepten, 1-octene, 1-nonen, 1-decene or 4-methyl-1-pentene, or it contains mixtures of these polymers, the mixing ratios not being critical. Statistical copolymers are generally used as copolymers. The homopolymers of propylene or the copolymers of propylene with C ₂ -C 1 -C 1 -alk-1-enes can be obtained by polymerizing the corresponding monomers with metallocene catalysts.

Metallocene catalysts are to be understood here as substances which generally consist of a combination of a transition metal compound or a plurality of transition metal compounds, preferably of titanium, zirconium or hafnium, which contains at least one ligand which, in the broadest sense, is a derivative of cyclopentadienyl ligand, with one Activator, also called cocatalyst or metallocenium ion-forming compound, is formed and, in general, has a polymerization-active smd in relation to the monomers described. Such catalysts are for example m EP-A 0 545 303, EP-A 0 576 970 and

EP-A 0 582 194. The metallocene catalysts according to the invention generally contain as active constituents

A) one or more metallocene complexes of the general formula (I)

m where the substituents and indices have the following meaning:

M titanium, zirconium, hafnium, vanadium, niobium or

Tantalum,

X ^ X ² fluorine, chlorine, bromine, iodine, hydrogen, -C ~ to Cio-alkyl, C ₆ - to -C ₅ aryl, -OR ⁶ or -NR ⁶ R ⁷

where R ⁶ , R ⁷ -C ~ to Cio-alkyl, C _ß - to cis-aryl, alkylaryl, arylalkyl, fluoroalkyl or fluoroaryl, each with 1 to 10 carbon atoms in the alkyl radical and 6 to 20 carbon atoms in

Aryl residue means

R ¹ to R ⁵ hydrogen, Cι ~ to Cio-alkyl, 5- to 7-glιedrιgeε

Cycloalkyl, which in turn can carry a C ~ to C ~ ^A alkyl as a substituent, C ₆ - to Ci ₅ ~ aryl or

Arylalkyl, where appropriate also two adjacent ones Residues can together stand for 4 to 15 C-containing cyclic groups, or S ι (R ⁸ ) _{3 with}

R ⁸ Ci to Cio-alkyl, C ₆ - bis Cι ₅ aryl or C ₃ - to CiQ-cycloalkyl,

being the leftovers

R ⁹ to R ^{13 are} hydrogen, -C ~ to -Cι ₀ alkyl, 5- to 7-glιedrιges

Cycloalkyl, may carry in turn em Cι ~ to Cιo ~ alkyl as a substituent, _C - to C-aryl or arylalkyl and wherein optionally two adjacent radicals can stand on facing cyclic groups together are 4 to 15 carbon atoms, or

Si (R ¹⁴ ) ₃ with

R ¹⁴ C _x - to Cio-alkyl, C ₆ - to -C ₅ aryl or C ₃ - to

Cio-cycloalkyl,

or being the leftovers

R ⁴ and Z together form a grouping ~ [Y (R ¹⁵ ) (R ¹⁶ )] _n -E- in which

can be the same or different and stands for silicon, germanium, tin or carbon.

R ¹⁵ , R ¹⁶ for hydrogen, Cι ~ to C ₁₀ alkyl, C ₃ - to Cι ₀ cyclo alkyl or C _$ - to Cι ₅ aryl

n for the numbers 1, 2, 3 or 4 or A, where A - 0 -

NR ¹⁷ or PRi7 means

with R ¹⁷ Ci to Cio-alkyl, C ₆ - to Cis-aryl, C ₃ - to Cio-cycloalkyl, alkylaryl or Sι (R ^ιa ) _3rd

with R ¹⁸ Ci to Cio-alkyl, C _e - to -C ₅ aryl, C ₃ - to Cio-cycloalkyl or alkylaryl

and

B) A metallocenium ion-forming compound

In general, all metallocene catalysts with which propylene polymers with a melt flow rate (MFR) measured according to DIN 53735 at 230 ° C. and 2.16 kg support weight in the range from 0.001 to 10000 g / 10 mm are suitable are suitable for the purposes of the invention let preserved.

Suitable transition metal compounds (I) are

and

The term metallocenes does not only mean the bis (η-cyclopentadienyl) metal complexes.

The radicals X ¹ , X ² can be the same or different, preferably smd the same.

Of the compounds of the formula (Ia), those are particularly suitable

R ¹ and R ^{9 are the} same and stand for hydrogen or Cι ~ to Cιo ~ alkyl groups,

R ⁹ and R ¹³ are smd and for hydrogen, a methyl, ethyl, iso-propyl or tert. -Butyl group stand

R ² , R ³ , R ¹⁰ and R ^{11 have} the meaning

R ³ and R ¹¹ Ci to C ₄ alkyl

R ² and R ^{10 have} hydrogen or two adjacent radicals R ² and R ³ and R ¹⁰ and R ¹¹ together represent cyclic groups containing 4 to 12 carbon atoms,

R ^{! $} , R ⁱ⁶ for Ci to Cs alkyl,

M stands for titanium, zirconium or hafnium, Y for silicon, germanium, tin or carbon and χ ⁱ , x ² for chlorine or Ci to C ₄ alkyl.

Examples of particularly suitable complex compounds include Dimethylsilanediylbis (cyclopentadienyl) zirconium dichloride, dimethylsilanediylbis (indenyl) zirconium dichloride, dimethylsilanediylbis (tetrahydroindenyl) zirconium dichloride, ethylene bis (cyclopentadienyl) zirconiumdichkonyldichloride (ethylene bis) dirconium dichloride,

Tetramethylethylene-9-fluorenylcyclopentadienylzirconium dichloride, dimethylsilanediylbis (-3-tert.butyl-5-methylcyclopentadιenyl) - zirconium dichloride,

Dimethylsilanediylbis (-3-tert.butyl-5-ethylcyclopentadιenyl) zirconium dichloride,

Dimethylsilanediylbis (-3-tert.butyl-5-methylcyclopentadιenyl) dimethylzirconium,

Dimethylsilanediylbis (-2-methylmdenyl) zirconium dichloride, dimethylsilanediylbis (-2-isopropylmdenyl) zirconium dichloride, dimethylsilanediylbis (-2-tert.butylindenyl) zirconium dichloride, diethylsilanediylbis (-2-methyldiryldilyl) (-2-methylidilyl) 5-methyldimidilyl (5-methyldiimidyl) (2-methyldiimidilyl) (-2-methyldiimidilyl) (-2-methyldiimidyl) (2-methyldiimidyl) (5-methyldiimidyl) (5-methyldiimidilyl) (2-methyldiimidyl) (5-methyldimidyl) (5-methyldiimidyl) (2-methyldimidyl) (5-methyldimidyl) (5-methyldiimidyl) (methyl-3-dimethyldi-bis) -methylcyclopentadιenyl) - zirconium dichloride,

Dimethylsilanediylbis (-3-ethyl-5-isopropylcyclopentadienyl) zirconium dichloride, dimethylsilanediylbis (-2-methylindenyl) zirconium dimethyl, dimethylsilanediylbis [3, 3 '- (-2-methylbenzmdenyl)] zirconium dichloride,

Dimethylsilanediylbis (-2-methylindenyl) hafnium dichloride, dimethylsilanediylbis [3,3 '- (2-methylbenzmdenyl)] hafnium dichloride, dimethylsilanediylbis [3, 3' - (2-methylbenzmdenyl)] zirconiumdimethyl.

In the case of the compounds of the general formula (Ib), those which are particularly suitable should be mentioned

M for titanium or zirconium, χ ^! , X ^{2 represents} chlorine or Cι ~ to C ₁₀ alkyl, Y represents silicon or carbon if n = 1 or for carbon if n = 2

R ¹⁵ , R ¹⁶ for Ci to C ₈ alkyl, C ₅ and C ₅ cycloalkyl or

for 0- NR ^{1 "}

and

R ¹ to R ³ and R ⁵ for hydrogen, Cι ~ to Cio-alkyl, C ₃ - to

Cio-cycloalkyl, C ₆ to C ₅ aryl or S 5 (R ⁸ ) ₃ , or where two adjacent radicals stand for cyclic groups having 4 to 12 C atoms.

Metallocene complexes of the general formula (I) in which at least one of the radicals R ¹ to R ^{5 is} different from hydrogen are particularly preferred. Compounds of the formula (Ia) are preferably used, such as dimethylsilanediylbis (-2-methyl-indenyl) zirconium dichloride and dimethylsilanediylbis (indenyl) zirconium conium dichloride, very particularly preferred is the dimethylsilane diyl-bis- [3,3'- (2-methylbenzmdenyl)] zirconium dichloride as the transition metal compound (I).

The synthesis of such transition metal compounds (I) can be carried out by methods known per se, the reaction of the appropriately substituted cycloalkenylamones with halides of the transition metals, for example titanium, zirconium, hafnium, vanadium, niobium or tantalum, being preferred. Examples of corresponding production processes are described, inter alia, in the Journal of Organometallic Chemistry, vol. 369 (1989), pages 359 to 370.

Compounds B) forming metallocenium ions are known to the person skilled in the art and are described, for example, in WO 95/14044.

Well suited are, for example, open-chain or cyclic aluminum moxane compounds of the general formula (II) or (III)

R ¹⁹ .

AI — fO Al-h - _R 19 (II)

R ¹⁹

wherein R ^{19 is} a -C ~ to C ₄ alkyl group, preferred

Methyl or ethyl group and m is an integer from 5 to 30, preferably 10 to 25.

These oligomeric alumoxane compounds are usually prepared by reacting a solution of trialkylaluminum with water and are, inter alia, m EP-A 284 708 and US A 4,794,096.

As a rule, the oligomeric alumoxane compounds obtained in this way are present as mixtures of both linear and cyclic chain molecules of different lengths, so that m is to be regarded as the mean. The alumoxane compounds can also be present in a mixture with other metal alkyls, preferably with aluminum alkyls. It has proven to be advantageous to use the metallocene complexes and the oligomeric alumoxane compound in amounts such that the atomic ratio between aluminum from the oligomeric alumoxane compound and the transition metal from the metallocene complexes is in the range from 10: 1 to 10 ⁶ : 1, in particular in the range Range from 10: 1 to 10 ⁴ : 1.

Coordination complex compounds selected from the group of strong, neutral Lewis acids, ionic compounds with Lewis acidic cations and ionic compounds with Bronsted acid can also be used as cations as the metallocenium ion-forming compound B).

As strong neutral Lewis acids smd compounds of the general formula IV

M ² X ³ X ⁴ X ⁵ (IV)

preferred, m the

M ² em element of III. Main group of the periodic table means, in particular B, Al or Ga, preferably B,

X ³ , X ⁴ and X ⁵ for hydrogen, C _x - to Cio-alkyl, C ₆ - to -C ₅ aryl, alkylaryl, arylalkyl, haloalkyl or haloaryl, each with 1 to 10 C atoms in the alkyl radical and 6 to 20 C. -Atoms in the aryl radical or fluorine, chlorine, bromine or iodine, in particular for haloaryls, such as fluoroaryls, preferably for pentafluorophenyl.

Particularly preferred are compounds of the general formula (IV) in which X ³ , X ⁴ and X ^{5 are} identical, preferably Tns (pentafluorophenyl) borane. These compounds and processes for their preparation are known per se and are described, for example, in WO 93/3067.

As ionic compounds with Lewis acid cations smd compounds of the general formula (V)

[(T ^{a +} ) QιQ ₂ ... Q _z ] ^{d +} (V)

suitable for those

T is an element of I. to VI. Main group or the I. to VIII. Subgroup of the periodic table means Q _l to Q _z for simply negatively charged residues such as Ci bis

C ₂₈ alkyl, C ₆ - to C ₅ aryl, alkylaryl, arylalkyl, haloalkyl, haloaryl, each with 6 to 20 C atoms in the aryl and 1 to 28 C atoms in the alkyl radical, Ci to Cio-cycloalkyl, which optionally can be substituted with Ci to Cio alkyl groups, halogen, Ci to C ₂₈ alkoxy, C ₆ - to C _i5 aryloxy, silyl or mercaptyl groups

a represents integers from 1 to 6,

z for integers from 0 to 5

d corresponds to the difference a z, but d is greater than or equal to 1.

Carbonium cations, oxomum cations and sulfonium cations as well as katiom transition metal complexes are particularly suitable. In particular, the triphenylmethyl cation, the silver cation and the 1, 1 '-dimethylferrocenyl cation should be mentioned.

They preferably have non-coordinating counterions, especially boron compounds, as they are also called in WO 91/09882, preferably tetrakis (pentafluorophenyl) borate.

Ionic compounds with Bronsted acids as cations and preferably also non-coordinating counterions mentioned in WO 93/3067, preferred cation is the N, N-dimethylanilinium.

It has proven particularly suitable if the molar ratio of boron from the compound forming the metallocenium ion to transition metal from the metallocene complex is in the range from 0.1: 1 to 10: 1, in particular in the range from 1: 1 to 5: 1.

The metallocenium-forming compounds B) are usually used alone, in a mixture with one another or in a mixture with organometallic compounds of the first to third main groups of the Periodic Table of the Elements, for example n-butyllithium, di-n-butylmagnesium, butyloctylmagnesium, trimethylaluminium, triethylaluminum, triisobutylaluminum, diisobutylumium dπd used, the mixing ratio of the components to one another being generally not critical. Methylaluminoxane or Trιs- (penta fluorophenyl) boron is preferably used as the compound B) forming metallocenium ions, and in particular methylaluminoxane.

The metallocene catalysts according to the invention can also be used on a support material.

The carrier materials used are preferably finely divided carriers which preferably have a particle diameter in the range from 1 to 300 μm, in particular from 30 to 70 μm. Suitable carrier materials are, for example, silica gels, preferably those of the formula Ξι0 ₂ ^• a A1 ₂ 0 ₃ , in which a is a number in the range from 0 to 2, preferably 0 to 0.5; this is alumo silicates or silicon dioxide. Such products are commercially available, for example Silica Gel 332 from Grace. Other carriers include, inter alia, polyolefins, such as polypropylene.

The propylene polymers can be prepared in the usual reactors used for the polymerization of olefins either discontinuously or preferably continuously.

Suitable reactors include continuously operated ones

Ruhr kettles, where it is also possible to use a series of several Ruhr kettles connected in series. The polymerization reactions can be carried out in the gas phase in suspension, in liquid and in supercritical monomers or in inert solvents.

The polymerization conditions are not critical per se. Pressures of 100 to 350,000 kPa, preferably 100 to 250,000 and ms, particularly 100 to 100,000 kPa, temperatures of 0 to 400 ° C, preferably 20 to 250 ° C and in particular 50 to 100 ° C have proven to be suitable.

Preferably, the homopolymerizations of propylene or the copolymeπsations of propylene with C ₂ - to Cιo-Alk-1-enes in emer stirred gas phase, such as the NOVOLEN ^® -Propylenpolymerιsatιonsverfahren from BASF durcn. Well suited process conditions for this are polymerization pressures in the range of 1000 to 4000 kPa and polymerization temperatures in the range of 50 to 100 ° C. There can also be several polymerization reactors, preferably two reactors, connected in series.

The average molecular weight of the polymers can be controlled using the methods customary in polymerization technology, for example by adding molecular weight regulators, such as Hydrogen, which leads to a reduction in the molecular weight of the polymer or by varying the polymerization temperature, high polymerization temperatures usually also leading to reduced molecular weights. 5

The homopolymers of propylene according to the invention or copolymers of propylene with C ₂ -C ₁ -C -alk-1-enes generally have a melt flow rate (MFR) measured at 230 ° C. and a coating weight of 2.16 kg according to DIN 53735 in the range from 0.1 10 to 10000 g / 10 mm, preferably in the range from 2 to 10000 and in particular in the range from 2 to 500.

The average molecular weight Mw of the homopolymers of propylene according to the invention or copolymers of propylene with C ₂ - 15 to Cιo-Alk-1-enes, measured by the method of gel permeation chromatography (GPC) at 140 ° C in 1, 2, 4-trichlorobenzene against polypropylene standard, is usually in the range from 4,000 to 850,000, preferably in the range from 50,000 to 450,000 and in particular in the range from 100,000 to 450,000.

20th

The molecular weight distribution of the propylene polymers Mw / Mn according to the invention, determined like the average molecular weight Mw by means of GPC, is generally in the range from 1.2 to 6.0 and preferably in the range from 1.5 to 3.0.

25

Both the molecular weight Mw, the molecular weight distribution Mw / Mn and, in particular, the MFR value can also be set using the method of peroxidically initiated degradation of a starting polymer, advantageously in an extruder. 30 This method is known to the person skilled in the art.

The homopolymers of propylene according to the invention generally have a melting point, determined by the method of differential scanning calorimetry (DSC) in the range from 80 ° C to 35 165 ° C, preferably in the range from 135 ° C to 165 ° C and in particular in particular Range from 140 ° C to 165 ° C.

The copolymers of propylene with C ₂ - to C ₁ -C 1 -en-enes according to the invention generally have a melting point, determined 40 using the differential scanning method (DSC).

(Heating rate 20 ° C / mm.), In the range from 60 ° C to 160 ° C, preferably in the range from 80 to 150 ° C and in particular in the range from 100 ° C to 150 ° C.

45 The pentad content mmmm of the homopolymer seed according to the invention, determined by the 13C-NMR spectroscopy method, is usually in the range from 60% to 99%, preferably in the range from 80% to 98%.

The chemically bound comonomer fraction of the copolymers of propylene according to the invention with C ₂ -C 1 -C 1 -alk-1-enes, measured using the 13C-NMR spectroscopy method, is generally in the range from 0.001 to 35 mol%, preferably in the range from 0.01 to 15 mol%, based on the copolymer.

Propylene homopoly mesates or copolymers of propylene with C ₂ - to C ₁ -C 1 -alkenes which are very suitable in the context of the invention are obtained if the corresponding monomers are polymerized in the presence of a catalyst system according to the invention, which dimethylsilanediyl-bis- [3, 3 '- (2-methylbenz-indenyl)] zirconium dichloride as a metallocene complex (I) contains.

The propylene homopolymers or copolymers obtainable in this way then generally have the polymer properties already mentioned, such as MFR, Mw, Mw / Mn, melting point, pentad content and comonomer.

Preferred copolymers of propylene obtainable with the dimethylsilanediylbis [3, 3 '- (2-methylbenzenedenyl)] zirconium dichloride catalyst with C ₂ - to C ₁ -C 1 -alkenes, and random copolymers of propylene and ethylene with 0.1% to 10 mol%, preferably 0.2 to 7 mol%, based on the polymer, of units derived from ethylene, random copolymers of propylene and 1-butene with 0.5 to 20 mol%, preferably 1 to 15 mol%, based on the polymer, of derivatives derived from 1-butene, statistical terpolymers of propylene, ethylene and 1-butene with 0.1 to 10 mol%, preferably 0.2 to 7 mol% %, based on the terpolymer, of units derived from ethylene and 0.5 to 20 mol%, preferably 1 to 15 mol%, based on the terpolymer, of units derived from 1-butene.

To produce the film according to the invention, propylene homo- or copolymer or mixtures of these polymers according to the invention are usually melted in one or more extruders and the melt is extruded or coextruded through a slot die. The film cooled below the melting point of the polymer is then biaxially stretched longitudinally and transversely to the extrusion direction, the stretching ratio in the longitudinal direction generally being in the range from 1 to 20, preferably in the range from 3.5 to 10, and the product the stretch Ratios in the longitudinal and transverse directions are generally in the range from 1 to 20, preferably in the range from 3.5 to 10.

The film can only be stretched in the same direction and then in the other direction (tenter process) or stretched in both directions can be carried out simultaneously (film blowing process, "bubble process").

The extrusion temperature of the polymer is usually in the range from 180 to 280 ° C., preferably in the range from 210 to

260 ° C. The person skilled in the art can determine the suitable temperature of the film which has cooled before stretching in a few experiments. It is usually in the range from 1 to 50 ° C., preferably in the range from 2 to 25 ° C. and in particular in the range from 2 to 10 ° C. below the value of the highest melting point, of the polymer or polymer mixture used for the extrusion the biaxial orientation per se is known to the person skilled in the art and, moreover, in the handbook of plastic extrusion technology, volume 2, ed. F. Hensen, Carl Hanser Verlag, Munich, Vienna (1986), chapter 8, in particular 8.3.1, pages 243 to 270 , described in detail.

The thickness of the monolayer films according to the invention that can be obtained in this way is generally in the range from 0.1 to 150 μm, preferably in the range from 0.2 to 100 μm and in particular in the range from 0.4 to 70 μm.

The thickness distribution or "waviness" of the film transverse to the direction of extrusion is very low; it is generally in the range from 0.05 to 5%, preferably in the range from 0.05 to 1.5%.

In the case of multilayer films, the number of layers and their sequence are generally not critical, but two-layer or three-layer films are preferred.

The films according to the invention are distinguished by good optical, thermal and mechanical properties; they are very easy to work with and can be oriented especially at high stretching speeds.

The scatter value of the films according to the invention, measured according to ASTM D1003 (1990), is generally in the range from 0.05 to 3.5%, preferably in the range from 0.05 to 2% and in particular in the range from 0.1 to 0 , 5%. The gloss of the films according to the invention, measured according to ASTM D2457 at 20 °, is generally in the range from 50 to 200 skt, preferably in the range from 100 to 200 skt.

The modulus of elasticity of the films according to the invention, measured according to ASTM D882, is generally in the range from 800 to 6000 N / mm ² , preferably in the range from 1000 to 5000 N / mm ² and in particular in the range from 2000 to 4500 N / mm ² .

The permeability of the films according to the invention to water vapor, measured according to DIN 53122, is generally in the range from 0.05 to 0.5 g / m ² / d, preferably in the range from 0.1 to 0.3 g / m ² / d .

The single-layer or multilayer films according to the invention can also contain the usual thermoplastic additives in the usual amounts. Suitable additives are antistatic agents, lubricants, such as fatty acid amides, for example erucasaureamide, stabilizers, neutralizing agents, such as calcium stearate, pigments and also inorganic fillers, such as talc, aluminum oxide, aluminum sulfate, barium sulfate, calcium magnesium carbonate,

Silicon dioxide, titanium dioxide and organic fillers such as polyester, polystyrene, polyamide and halogenated organic polymers.

The films according to the invention are distinguished, inter alia, by the fact that they can be produced from propylene polymers with a relatively high MFR value in the biaxial orientation process, and in that they have very good mechanical and optical properties (for example gloss), inter alia are thin and tearproof. Furthermore, the films according to the invention generally have good heat-sealing properties (low heat-sealing temperature), which predestines them, inter alia, for use in packaging. In multilayer films, a thin cover layer made of the inventive polypropylene film is usually sufficient, for example for favorable heat sealing properties. Furthermore, the foils according to the invention are very well suited, inter alia for reasons of the small thickness of the dielectric (foil), as an electrical insulating foil and in particular as a capacitor foil. Examples

Examples 1 to 6

5 Production of bo-homopolypropylene film according to the invention

Homopolypropylene, which by means of N0V0LEN ^® gas phase polymerization of propylene at a temperature of 60 ° C and a pressure of 2400 kPa, without hydrogen regulation of the molecular

10 weight was produced in the presence of a dimethylsilanediylbis [3,3 '- (2 methylbenzmdenyl)] zirconium dichloride / methylaluminoxane catalyst fixed on silica gel, had an MFR of 4.0 g / 10 mm and a DSC melting point of 145 ° C. Part was broken down to an MFR of 8 or by means of peroxide degradation in the extruder

15 20 g / 10 mm mined.

The polymers were extruded and stretched bidirectionally at a temperature of 140 ° C. on a so-called tenter unit (bo process). This gave the o-PP films listed in Ta 20 belle 1 smd.

Table 1

25

30

35

40

45

Examples 7 to 13

Production of bo-propylene copolymer films according to the invention

Using NOVOLEN ^® gas phase polymerization, propylene was copolymerized with various comonomers (see Table 2) at 60 ° C and 2400 kPa in the presence of a dimethylsilanediyl bis [3,3 '(2-methylbenzmdenyl)] zirconium dichloride / methylaluminoxane catalyst fixed on silica gel.

The polymers were then further processed to bo foils ("bubble process").

The great strength, elongation and tear strength were determined on the films in the tear resistance test according to ISO 527.

The data are compiled in Table 2.

Q)

0) A <fl

Claims

claims

1. Use of homopolymers of propylene or copolymers of propylene with C ₂ -C ₁ -C -alk-1-enes, which can be obtained by polymerizing the corresponding monomers with metal ocene catalysts, for the production of a biaxially oriented em- or multilayer polypropylene ¬ foil.

2. Use of homopolymers of propylene or copolymers of propylene with C ₂ -C ₁₀ -alk-1-enes according to Claim 1, the homopolymers of propylene or the copolymers of propylene having a melt flow index in the range of 2 up to 10,000 g / 10 mm.

3. Use of homopolymers of propylene or copolymers of propylene with C ₂ - to Cχo-alk-1-enes according to claims 1 to 2, wherein the homopolymers of propylene or the copolymers of propylene have a melting point in the range from 80 to 150 ° C.

4. Use of homopolymers of propylene or copoly merisaten of propylene with C ₂ - to Cio-Alk 1-enes according to claims 1 to 3, wherein as metallocene catalysts, those containing active ingredients

A) one or more metallocene complexes of the general formula (I)

MX ^X X ²

in which the substituents and indices have the following meaning: M titanium, zirconium, hafnium, vanadium, niobium or

Tantalum,

X ^ X ² fluorine, chlorine, bromine, iodine, hydrogen, Ci- to Cio-alkyl, C ₆ - to -C ₅ aryl, -OR ⁶ or

-NR ⁶ R ⁷

where R ⁶ , R ⁷ Ci- to Cio-alkyl, C ₆ - to -CC ₅ aryl, AlKylaryl,

Arylalkyl, fluoroalkyl or fluoroaryl, each with 1 to 10 carbon atoms in the alkyl radical and 6 to 20 carbon atoms

Atoms in the aryl radical means

R ¹ to R ^{5 are} hydrogen, C ¹ -C ¹ -alkyl, 5- to 7-glιedπ ges cycloalkyl, which in turn may carry C 1 -C 1 -C 6 alkyl as a substituent, Cg bis

Cis-aryl or arylalkyl, where optionally also two adjacent radicals together can represent cyclic groups having 4 to 15 carbon atoms, or Si (R ⁸ ) ₃ with

Ci- to Cio-alkyl, Cg- to Cι ₅ aryl or C ₃ - to Cio-cycloalkyl,

being the leftovers

R ⁹ to R ^{13 are} hydrogen, C ¹ -C 7 -alkyl, 5- to 7-glιedrι ges cycloalkyl, which in turn can carry C _± - C 1 -C 8 -alkyl as a substituent, are Cg to Cis-aryl or arylalkyl and are countered optionally also two adjacent radicals together can stand for cyclic groups having 4 to 15 carbon atoms, or S (R ¹⁴ ) ₃ with

R ¹⁴ Ci to Cio alkyl, Cg to Cι ₅ aryl or C ₃ - to

Cio-cycloalkyl,

or being the leftovers

R ⁴ and Z together form a grouping ~ [Y (R ¹⁵ ) (R ¹⁶ )] _n -E- in which Y can be the same or different and stands for silicon, germanium, tin or carbon,

R ¹⁵ , R ¹⁶ for hydrogen, Cι ~ to Cι ₀ alkyl, C ₃ - to Cio-cycloalkyl or Cg- to Cι ₅ aryl

n for the numbers 1, 2, 3 or 4

NR ¹⁷ or PR ¹⁷ means

with R ¹⁷ Ci to Cio-alkyl, C ₅ - to -C ₅ aryl, C ₃ - to

Cio-cycloalkyl, alkylaryl or Sι (R ¹⁸ ) ₃

with R ¹⁸ Ci to Cio alkyl, Cg to Cis aryl, C ₃ to

Cio-cycloalkyl or alkylaryl

and

B) a metallocenium ion-forming compound is used.

5. Use of homopolymers of propylene or copolymers of propylene with C ₂ - to Cio-alk-1-enes according to claim 4, the metallocene complex (I) dimethylsilanediyl bis- [3,3 '- (2) -methylbenzmdenyl )] is zirconium dichloride.