Provided are a film having an excellent balance between heat seal strength and opening strength, a method of producing the film, and a bag obtained by heat-sealing the film. According to the present invention, there is provided a film containing a resin, wherein a resin density of the film is 860 kg/m.sup.3 or more and less than 900 kg/m.sup.3, and on at least one surface of the film, an arithmetic mean height Sa satisfies the following Expression [1]:
0.10 μm≤Sa≤0.50 μm  [1], and a minimum autocorrelation length Sal satisfies the following Expression [2]:
0.2 μm≤Sal≤10.4 μm  [2].

A complex of formula (I): (I′) M is Hf; each X is a sigma ligand; L is a bridge of formula -(ER.sup.8.sub.2).sub.y—; y is 1 or 2; E is C or Si; each R.sup.8 is independently a C.sub.1-C.sub.20-hydrocarbyl, tri(C.sub.1-C.sub.20-alkyl)silyl, C.sub.6-C.sub.20-aryl, C.sub.7-C.sub.20-arylalkyl or C.sub.7-C.sub.20-alkylaryl or L is an alkylene group such as methylene or ethylene; Ar and Ar′ are each independently an aryl or heteroaryl group optionally substituted by 1 to 3 groups R.sup.1 or R.sup.1′ respectively; R.sup.1 and R.sup.1′ are each independently the same or can be different and are a linear or branched C.sub.1-C.sub.6-alkyl group, C.sub.7-20 arylalkyl, C.sub.7-20 alkylaryl group or C.sub.6-20 aryl group with the proviso that if there are four or more R.sup.1 and R.sup.1′ groups present in total, one or more of R.sup.1 and R.sup.1′ is other than tert butyl; R.sup.2 and R.sup.2′ are the same or are different and are a CH.sub.2—R.sup.9 group, with R.sup.9 being H or linear or branched C.sub.1-C.sub.6-alkyl group, C.sub.3-8 cycloalkyl group, C.sub.6-10 aryl group; each R is a —CH.sub.2—, —CHRx- or C(Rx).sub.2- group wherein Rx is C.sub.1-4 alkyl and where m is 2-6; R.sup.5 is a linear or branched C.sub.1-C.sub.6-alkyl group, C.sub.7-20 arylalkyl, C.sub.7-20 alkylaryl group or C.sub.6-C.sub.20-aryl group; R.sup.6 is a C(R.sup.10).sub.3 group, with R.sup.10 being a linear or branched C.sub.1-C.sub.6 alkyl group; and R.sup.6 and R.sup.7′ are the same or are different and are H or a linear or branched C.sub.1-C.sub.6-alkyl group. Invention relates also to a catalyst in solid form comprising (i) a complex of formula (I) and (ii) a cocatalyst of an aluminium compound and (iii) a cocatalyst of a boron compound. ##STR00001##

A complex of formula (I): (I′) M is Hf; each X is a sigma ligand; L is a bridge of formula -(ER.sup.8.sub.2).sub.y—; y is 1 or 2; E is C or Si; each R.sup.8 is independently a C.sub.1-C.sub.20-hydrocarbyl, tri(C.sub.1-C.sub.20-alkyl)silyl, C.sub.6-C.sub.20-aryl, C.sub.7-C.sub.20-arylalkyl or C.sub.7-C.sub.20-alkylaryl or L is an alkylene group such as methylene or ethylene; Ar and Ar′ are each independently an aryl or heteroaryl group optionally substituted by 1 to 3 groups R.sup.1 or R.sup.1′ respectively; R.sup.1 and R.sup.1′ are each independently the same or can be different and are a linear or branched C.sub.1-C.sub.6-alkyl group, C.sub.7-20 arylalkyl, C.sub.7-20 alkylaryl group or C.sub.6-20 aryl group with the proviso that if there are four or more R.sup.1 and R.sup.1′ groups present in total, one or more of R.sup.1 and R.sup.1′ is other than tert butyl; R.sup.2 and R.sup.2′ are the same or are different and are a CH.sub.2—R.sup.9 group, with R.sup.9 being H or linear or branched C.sub.1-C.sub.6-alkyl group, C.sub.3-8 cycloalkyl group, C.sub.6-10 aryl group; each R is a —CH.sub.2—, —CHRx- or C(Rx).sub.2- group wherein Rx is C.sub.1-4 alkyl and where m is 2-6; R.sup.5 is a linear or branched C.sub.1-C.sub.6-alkyl group, C.sub.7-20 arylalkyl, C.sub.7-20 alkylaryl group or C.sub.6-C.sub.20-aryl group; R.sup.6 is a C(R.sup.10).sub.3 group, with R.sup.10 being a linear or branched C.sub.1-C.sub.6 alkyl group; and R.sup.6 and R.sup.7′ are the same or are different and are H or a linear or branched C.sub.1-C.sub.6-alkyl group. Invention relates also to a catalyst in solid form comprising (i) a complex of formula (I) and (ii) a cocatalyst of an aluminium compound and (iii) a cocatalyst of a boron compound. ##STR00001##

A thermoformable film comprises a polyethylene composition. The polyethylene composition comprises a first polyethylene which is an ethylene copolymer having a weight average molecular weight of from 70,000 to 250,000 and a molecular weight distribution M.sub.w/M.sub.n of <2.3, a second polyethylene which is an ethylene copolymer or homopolymer having a weight average molecular weight of from 15,000 to 100,000 and a molecular weight distribution M.sub.w/M.sub.n of <2.3, and a third polyethylene which is an ethylene copolymer or homopolymer having a weight average molecular weight of from 70,000 to 250,000 and a molecular weight distribution M.sub.w/M.sub.n of >2.3, where the first polyethylene has more short chain branching than the second polyethylene or the third polyethylene. The polyethylene composition has a melt flow ratio (I.sub.21/I.sub.2) of ≤50 and an area Dimensional Thermoformability Index (aDTI) at 105° C. of less than 15.

A thermoformable film comprises a polyethylene composition. The polyethylene composition comprises a first polyethylene which is an ethylene copolymer having a weight average molecular weight of from 70,000 to 250,000 and a molecular weight distribution M.sub.w/M.sub.n of <2.3, a second polyethylene which is an ethylene copolymer or homopolymer having a weight average molecular weight of from 15,000 to 100,000 and a molecular weight distribution M.sub.w/M.sub.n of <2.3, and a third polyethylene which is an ethylene copolymer or homopolymer having a weight average molecular weight of from 70,000 to 250,000 and a molecular weight distribution M.sub.w/M.sub.n of >2.3, where the first polyethylene has more short chain branching than the second polyethylene or the third polyethylene. The polyethylene composition has a melt flow ratio (I.sub.21/I.sub.2) of ≤50 and an area Dimensional Thermoformability Index (aDTI) at 105° C. of less than 15.

Disclosed is a method using a metallocene catalyst system so as to control the polymer structure of a diene-modified polypropylene through process simplification, thereby being capable of preparing a hyperbranched polypropylene resin having a low gel content and improved melt strength. The present invention provides a method using a catalyst so as to polymerize propylene and a diene compound, thereby preparing a diene-modified polypropylene resin having a branching index of 0.95 or less, a gel content of 3 wt % or less and an advanced rheometric expansion system (ARES) melt strength of 5 g or more.

Disclosed is a method using a metallocene catalyst system so as to control the polymer structure of a diene-modified polypropylene through process simplification, thereby being capable of preparing a hyperbranched polypropylene resin having a low gel content and improved melt strength. The present invention provides a method using a catalyst so as to polymerize propylene and a diene compound, thereby preparing a diene-modified polypropylene resin having a branching index of 0.95 or less, a gel content of 3 wt % or less and an advanced rheometric expansion system (ARES) melt strength of 5 g or more.

The present invention provides a process for the preparation of a multimodal polyethylene comprising: (i) polymerising ethylene and optionally an α-olefin comonomer in a first polymerisation stage to produce a first ethylene polymer; and (ii) polymerising ethylene and optionally an α-olefin comonomer, in the presence of said first ethylene polymer, in a second polymerisation stage, wherein the first and second polymerisation stages are carried out in the presence of an unsupported metallocene catalyst and each polymerisation stage produces at least 5% wt of the multimodal polyethylene, and the multimodal polyethylene has a multimodal molecular weight distribution, a molecular weight of at least 50,000 g/mol and a bulk density of at least 250 g/dm.sup.3, and wherein a solution of the unsupported metallocene catalyst in a solvent is employed. The present invention also provides a multimodal polyethylene, a process for preparing a pipe comprising preparing a multimodal polyethylene and extruding the multimodal recycle polyethylene to produce a pipe, and a pipe obtained by such a process.

The present invention provides a process for the preparation of a multimodal polyethylene comprising: (i) polymerising ethylene and optionally an α-olefin comonomer in a first polymerisation stage to produce a first ethylene polymer; and (ii) polymerising ethylene and optionally an α-olefin comonomer, in the presence of said first ethylene polymer, in a second polymerisation stage, wherein the first and second polymerisation stages are carried out in the presence of an unsupported metallocene catalyst and each polymerisation stage produces at least 5% wt of the multimodal polyethylene, and the multimodal polyethylene has a multimodal molecular weight distribution, a molecular weight of at least 50,000 g/mol and a bulk density of at least 250 g/dm.sup.3, and wherein a solution of the unsupported metallocene catalyst in a solvent is employed. The present invention also provides a multimodal polyethylene, a process for preparing a pipe comprising preparing a multimodal polyethylene and extruding the multimodal recycle polyethylene to produce a pipe, and a pipe obtained by such a process.

The present invention relates to use of a polypropylene composition comprising a polypropylene having—a melt flow rate MFR2 (230° C./2.16 kg) measured according to ISO 1133 of 10 to 40 g/10 min, —a melting temperature T.sub.m as determined by DSC according to ISO 11357 of 149 to 160° C., and—a molecular weight distribution MWD of 2.4 to 4.5 as determined by GPC, for extrusion coating of an article, to a process for extrusion coating of an article and to an extrusion coated article.