Propylene Composition

Abstract

A polypropylene (PP) composition comprising a long-chain branched terpolymer of propylene, ethylene and 1-butene (LCB-TER), wherein the composition has an MFR2, determined in accordance with ISO 1133, in the range of 5 to 30 g / 10 min, a melting point Tm in the range of 100 to 150°C, and a crystallization temperature Tc in the range of 90 to 120°C. A method for producing the PP composition, including reactor post-treatment. A polymer film comprising the PP composition and a method for producing the same.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION The present invention relates to polypropylene compositions comprising long-chain branched terpolymers of propylene, ethylene and 1-butene, to a method for their preparation, to polymeric films comprising said compositions, and to their preparation and use, particularly in packaging applications. [Background technology]

[0002] background Propylene homopolymers and copolymers are suitable for many applications, including packaging, textiles, automotive, laboratory equipment, and pipes. In the packaging field, the polymers are particularly noteworthy for their suitability for film preparation, due to their combination of properties, including good stiffness and toughness, high transparency, good sealing properties, and good surface gloss. Furthermore, they are sterilizable. However, polypropylene materials are also known to exhibit a number of drawbacks during thermoplastic processing, including increased melt instability and the associated process output, reduced processing window related to bubble stability, and downgauging. There is a need to improve the melt strength of polypropylene.

[0003] This goal can be achieved by subjecting polypropylene to a post-reactor modification process, such as the high melt strength (HMS) process. This process generates branches in the polypropylene material, resulting in long-chain branched propylene polymer (LCB-PP). Long-chain branching is generally associated with improved melt strength. Therefore, long-chain branched polypropylene is often used to produce films.

[0004] The long-chain branched polymer composition can be prepared directly in the polymerization reactor or can be obtained via a post-reactor modification process.

[0005] EP 1903070 B1, EP 1900764 B1 and EP 1903579 B1 describe in-reactor produced LCB polypropylene compositions produced in the presence of a single-site catalyst.

[0006] EP 1939230 B1 provides details regarding an in-reactor process for producing HMS polypropylene in the presence of a particular metallocene catalyst.

[0007] WO2014 / 001394A1 describes a high melt strength (HMS) post-reactor modification process that uses peroxide and butadiene to produce long-chain branched polypropylene (b-PP) materials. The long-chain branched polypropylene from WO2014 / 001394 is used to prepare films with reduced gel index.

[0008] EP 3018154 A1 describes a long-chain branched polypropylene composition and a method for producing the same via post-reactor modification. The polypropylene composition may contain propylene homo- and / or copolymers and is used in film formation. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] European Patent No. 1903070 [Patent Document 2] European Patent No. 1900764 [Patent Document 3] European Patent No. 1903579 [Patent Document 4] European Patent No. 1939230 [Patent Document 5] International Publication No. 2014 / 001394 [Patent Document 6] European Patent Application Publication No. 3018154 Summary of the Invention [Problem to be solved by the invention]

[0010] Films, especially multilayer films, are commonly used in packaging applications. Multilayer films can provide access to materials that exhibit beneficial combinations of properties. However, to achieve this, multilayer films often use a variety of different materials. For example, different types of polymers (PET combined with PE / PP) or one or more types of polymer combined with paper / cardboard are used in such multilayer films / packaging materials. A drawback of such multi-material solutions is their limited recyclability. Therefore, there is a need to provide single-material solutions for film / packaging applications that contain only one type of polymer and are therefore easily recyclable. One approach to meeting this demand is to modify the material properties of a given polymer type. [Means for solving the problem]

[0011] Summary of the Invention The present invention is based on the discovery that the above objectives can be achieved by subjecting polypropylene, which is a terpolymer of propylene, ethylene and 1-butene, to a post-reactor peroxide treatment in the presence of at least one unsaturated monomer.

[0012] The present invention provides a polypropylene composition comprising a long-chain branched (LCB) terpolymer of propylene, ethylene and 1-butene, having an MFR2 measured in accordance with ISO 1133 in the range of 5.0 to 30.0 g / 10 min, a melting point Tm in the range of 125 to 150°C, and a crystallization temperature Tc in the range of 90 to 120°C, measured in accordance with ISO 11357-3. The melting point Tm and crystallization temperature Tc are preferably determined in accordance with ISO 11357-3 in a heat / cool / heat cycle between +23°C and +210°C, with heating and cooling rates of 10°C / min.

[0013] The present invention further relates to a method for producing the polypropylene composition described herein, comprising the steps of: (a) providing a terpolymer of propylene, 1-butene, and ethylene (TER1) having an MFR2 in the range of 0.1 to 8.0 g / 10 min, as measured in accordance with ISO 1133; (b) melt-mixing the terpolymer in the presence of a peroxide and a difunctional unsaturated monomer; and (c) recovering the high melt strength polypropylene.

[0014] The present invention likewise relates to a polypropylene composition obtainable by the above process.

[0015] In another aspect, the present invention relates to a polymer film comprising the polymer composition described herein.

[0016] Additionally, the present invention relates to a method for producing a polymeric film comprising extrusion coating or extrusion laminating the polymeric composition described herein onto a polypropylene-based substrate or between two substrates.

[0017] In yet another aspect, the present invention relates to the use of a polymeric film as described herein, or obtainable via a process as described herein, in packaging applications. DETAILED DESCRIPTION OF THE INVENTION

[0018] Detailed Description of the Invention Polypropylene composition The present invention relates to a polypropylene (PP) composition comprising a long-chain branched terpolymer of propylene, ethylene and 1-butene (LCB-TER), having an MFR2 determined in accordance with ISO 1133 in the range of 5.0 to 30.0 g / 10 min, a melting point Tm in the range of 100 to 150°C, and a crystallization temperature Tc in the range of 90 to 120°C, both determined in accordance with ISO 11357-3. The determination of the melting point Tm and crystallization temperature Tc is preferably carried out in accordance with ISO 11357-3 in a heat / cool / heat cycle between +23°C and +210°C, with a heating and cooling rate of 10°C / min.

[0019] The PP composition may contain ethylene in an amount of 0.1 to 3.0% by weight, preferably 0.1 to 2.5% by weight, and more preferably 0.5 to 2% by weight, based on the total weight of the PP composition.

[0020] The PP composition may contain 3 to 15 wt %, preferably 5 to 12 wt %, more preferably 7 to 11 wt % of 1-butene based on the total weight of the PP composition.

[0021] The PP composition has an MFR2 measured in accordance with ISO1133 in the range of 5.0 to 30.0 g / 10 min, preferably 7.5 to 25.0 g / 10 min, and more preferably 10.0 to 20.0 g / 10 min.

[0022] Preferably, the MFR2 of the PP composition comprising the long-chain branched terpolymer of propylene, 1-butene, and ethylene is different from the MFR2 of the terpolymer of propylene, 1-butene, and ethylene (TER1). More preferably, the MFR2 of the PP composition is higher than the MFR2 of TER1.

[0023] The PP composition has a melting point Tm in the range of 100 to 150°C, preferably 110 to 145°C, and more preferably 125 to 140°C.

[0024] According to a particularly preferred embodiment, the PP composition is polymorphic and has first and second melting temperatures Tm1 and Tm2, ​​respectively. In such an embodiment, Tm1 is in the range of 100 to 150°C, preferably 110 to 145°C, and more preferably 125 to 140°C, and Tm2 is in the range of 110 to 140°C, preferably 115 to 135°C, and more preferably 120 to 130°C.

[0025] The PP composition has a crystallization temperature Tc in the range of 90 to 120°C, preferably 95 to 115°C, and more preferably 100 to 110°C.

[0026] The PP composition may have a melting enthalpy Hm in the range of 20 to 90 J / g, preferably 25 to 85 J / g, and more preferably 30 to 80 J / g.

[0027] According to a particularly preferred embodiment, the PP composition is polymorphic and has first and second melting enthalpies Hm1 and Hm2, respectively. In such an embodiment, Hm1 is in the range of 5 to 50 J / g, preferably 10 to 45 J / g, and more preferably 15 to 35 J / g, and Hm2 is in the range of 20 to 70 J / g, preferably 30 to 65 J / g, and more preferably 40 to 60 J / g. Furthermore, it is preferable that the following requirements be met:

[0028] 30<(Hm2 / (Hm1+Hm2))×100<80

[0029] Preferably, the PP composition has a fraction XHU (xylene heat insolubles), determined according to DIN EN 579, of less than 1.0 wt. %, more preferably between 0.01 and 0.75 wt. %, even more preferably between 0.01 and 0.5 wt. %.

[0030] Preferably, the PP composition further has a melt strength F30 in the range of 4 to 60 cN, more preferably 5 to 50 cN, even more preferably 6 to 45 cN; and a melt extensibility v30 in the range of 180 to 400 mm / s, more preferably 200 to 350 mm / s, even more preferably 220 to 350 mm / s, wherein F30 and v30 are determined according to ISO 16790:2005.

[0031] The PP composition may have a seal initiation temperature (SIT) in the range of 70 to 120°C, preferably 80 to 115°C, more preferably 90 to 112°C, and even more preferably 95 to 112°C.

[0032] The long-chain branched terpolymer of propylene, ethylene and 1-butene (LCB-TER) contained in the polypropylene composition is preferably obtained by polymerization in the presence of a Ziegler-Natta catalyst or a single-site catalyst, more preferably in the presence of a Ziegler-Natta catalyst, followed by reactive modification.

[0033] In particular, the use of single-site catalysts can result in significantly lower amounts of xylene heat insolubles (XHU), but the use of single-site catalysts typically results in 2,1 position defects in the polymer chain.

[0034] The LCB-TERs described herein are as detailed herein below. 13Preferably, the 2,1-position defects are in the range of 0.00 to 1.00 mol%, more preferably 0.00 to 0.75 mol%, and even more preferably 0.00 to 0.4 mol%, as measured by C-NMR spectroscopy. More specifically, LCB-TER obtained by polymerization in the presence of a Ziegler-Natta catalyst and subsequent reactive modification preferably have no 2,1-position defects, i.e., 0.00 mol% 2,1-position defects. For LCB-TER obtained via polymerization in the presence of a single-site catalyst and subsequent reactive modification, the amount of 2,1-position defects is preferably in the range of 0.05 to 1.0 mol%, more preferably 0.10 to 0.75 mol%, and even more preferably 0.10 to 0.40 mol%. More preferably, the PP composition is obtained via the process described herein below.

[0035] In addition to the long-chain branched terpolymer of propylene, ethylene and 1-butene (LCB-TER), the PP composition may optionally contain additives.

[0036] Preferably, the PP composition comprises the LCB-TER in an amount of 98 to 100 wt % based on the total weight of the PP composition.

[0037] The additive (A) can be any additive useful in the technical field of high melt strength polypropylene (HMS-PP) and its applications. Thus, the additive (A) to be used in the polypropylene composition of the present invention includes, but is not limited to, stabilizers such as antioxidants (e.g., sterically hindered phenols, phosphites / phosphonites, sulfur-containing antioxidants, alkyl radical scavengers, aromatic amines, hindered amine stabilizers, or blends thereof), metal deactivators (e.g., Irganox MD 1024), or UV stabilizers (e.g., hindered amine light stabilizers). Other typical additives are modifiers such as antistatic or antifogging agents (e.g., ethoxylated amines and amides, or glycerol esters), acid scavengers (e.g., calcium stearate), foaming agents, tackifiers (e.g., polyisobutene), lubricants and resins (ionomer waxes, PE and ethylene copolymer waxes, Fischer-Tropsch waxes, montan-based waxes, fluoro-based compounds, or paraffin waxes), nucleating agents (e.g., talc, benzoates, phosphorus-based compounds, sorbitols, nonitol-based compounds, or amide-based compounds), and slip and antiblocking agents (e.g., erucamide, oleamide, talc, natural and synthetic silica, or zeolites).

[0038] Preferably, the additive (A) is selected from the group consisting of an antioxidant (e.g., a sterically hindered phenol, a phosphite / phosphonite, a sulfur-containing antioxidant, an alkyl radical scavenger, an aromatic amine, a hindered amine stabilizer, or a blend thereof), a metal deactivator (e.g., IrganoxMD), a hydroxybenzoate (HBD ... 1024), or UV stabilizers (e.g., hindered amine light stabilizers), antistatic or antifog agents (e.g., ethoxylated amines and amides, or glycerol esters), acid scavengers (e.g., calcium stearate), foaming agents, tackifiers (e.g., polyisobutene), lubricants and resins (ionomer waxes, PE and ethylene copolymer waxes, Fischer-Tropsch waxes, montan waxes, fluoro compounds, or paraffin waxes), nucleating agents (e.g., talc, benzoates, phosphorus-based compounds, sorbitols, nonitol-based compounds, or amide-based compounds), slip agents, antiblocking agents (e.g., erucamide, oleamide, talc natural and synthetic silica, or zeolites), and mixtures thereof.

[0039] More preferably, the additive comprises at least an antioxidant and an acid scavenger, and even more preferably, the acid scavenger is calcium stearate.

[0040] Typically, the total amount of additive (A) in the polypropylene composition of the present invention is in the range of 0 to 2 wt % based on the total weight of the polypropylene composition, and the total amount of additive (A) in the polypropylene composition is preferably in the range of 0.01 to 2.0 wt %, more preferably in the range of 0.1 to 1.0 wt %, and even more preferably in the range of 0.2 to 0.5 wt %, based on the total weight of the polypropylene composition.

[0041] PP composition manufacturing method The present invention provides a method for producing a polypropylene composition as described herein, comprising the steps of: (a) providing a terpolymer of propylene, 1-butene, and ethylene (TER1) having an MFR2 in the range of 0.1 to 8.0 g / 10 min, as measured in accordance with ISO 1133; (b) melt-mixing the terpolymer in the presence of a peroxide and a difunctional unsaturated monomer; and (c) recovering a polypropylene composition comprising a long-chain branched terpolymer of propylene, 1-butene, and ethylene (LCB-TER).

[0042] Preferably, the linear terpolymer of propylene, 1-butene and ethylene (herein designated as TER1) provided as a starting material in step (a) is produced in the presence of a Ziegler-Natta catalyst or a single-site catalyst, more preferably in the presence of a Ziegler-Natta catalyst.

[0043] Preferably, based on the total weight of the terpolymer produced in step (a), the amount of comonomer units derived from ethylene in TER1 is in the range of 0.1 to 3.0 wt %, and the amount of comonomer units derived from 1-butene in said terpolymer is in the range of 3 to 15 wt %.

[0044] Preferably, TER1 has an MFR2, determined according to ISO1133, in the range of 1.5 to 6.0 g / 10 min, more preferably 2.5 to 5 g / 10 min, even more preferably 3 to 4 g / 10 min. The MFR2 of the reclaimed polypropylene composition comprising a long-chain branched terpolymer of propylene, 1-butene, and ethylene is advantageously different from the MFR2 of TER1.

[0045] Preferably, the MFR2 of the recycled polypropylene composition comprising long-chain branched terpolymer in step c) is higher than the MFR2 of the TER1 provided in step a).

[0046] TER1 preferably contains 0.1 to 3.0% by weight of ethylene, more preferably 0.1 to 2.5% by weight of ethylene, and even more preferably 0.1 to 2.0% by weight of ethylene.

[0047] TER1 preferably contains 3 to 15% by weight, preferably 5 to 12% by weight, and more preferably 7 to 11% by weight of 1-butene.

[0048] Polymerization methods suitable for producing propylene polymers are known in the art and include at least one polymerization stage, where polymerization is typically carried out in solution, slurry, bulk, or gas phase. Typically, the polymerization process includes additional polymerization stages or reactors. In one particular embodiment, the process includes at least one bulk reactor zone and at least one gas-phase reactor zone, each zone containing at least one reactor, all of which are arranged in a cascade configuration. In a particularly preferred embodiment, the polymerization process includes at least one bulk reactor and at least one gas-phase reactor arranged in this order. In some preferred methods, the process includes one bulk reactor and at least two, e.g., two or three, gas-phase reactors. The process can further include a pre-reactor and a post-reactor. The pre-reactor typically includes a prepolymerization reactor. In this type of process, it is preferable to use higher polymerization temperatures to achieve specific polymer properties. Typical temperatures in these processes are 70°C or higher, preferably 80°C or higher, or even 85°C or higher. Such higher polymerization temperatures can be applied to some or all of the reactors of the reactor cascade.

[0049] A preferred multi-stage process is the "loop-gas phase" process as developed by Borealis (known as BORSTAR® technology), which is described in patent documents such as EP 0 887 379, WO 92 / 12182, WO 2004 / 000899, WO 2004 / 111095, WO 99 / 24478, WO 99 / 24479, WO 00 / 68315, or WO 2021 / 001176. A further suitable slurry gas phase process is the Spheripol® process from Basell.

[0050] In step (a), a linear terpolymer (TER1) as detailed above is provided. Long chain branches are introduced into propylene by reactive modification of a linear terpolymer (TER1). This reactive modification process is also part of the present invention. The reactive modification to produce a long chain branched propylene copolymer is carried out via step (b) of melt-mixing the terpolymer (TER1) in the presence of a peroxide and a difunctional unsaturated monomer.

[0051] Preferably, the peroxide is selected from the group consisting of acyl peroxides, alkyl peroxides, hydroperoxides, peresters and peroxycarbonates.

[0052] The following peroxides are particularly preferred: Acyl peroxides: benzoyl peroxide, 4-chlorobenzoyl peroxide, 3-methoxybenzoyl peroxide and / or methylbenzoyl peroxide.

[0053] Alkyl peroxides: allyl t-butyl peroxide, 2,2-bis(t-butylperoxybutane), 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, n-butyl-4,4-bis(t-butylperoxy)valerate, diisopropylaminomethyl-t-amyl peroxide, dimethylaminomethyl-t-amyl peroxide, diethylaminomethyl-t-butyl peroxide, dimethylaminomethyl-t-butyl peroxide, 1,1-di-(t-amylperoxy)cyclohexane, t-amyl peroxide, t-butylcumyl peroxide, t-butyl peroxide and / or 1-hydroxybutyl n-butyl peroxide.

[0054] Peresters and percarbonates: butyl peracetate, cumyl peracetate, cumyl perpropionate, cyclohexyl peracetate, di-t-butyl peradipate, di-t-butyl perazelate, di-t-butyl perglutarate, di-t-butyl perthalate, di-t-butyl persebacate, 4-nitrocumyl perpropionate, phenylethyl 1-perbenzoate, phenylethyl nitroperbenzoate, t-butylbicyclo-(2,2,1)heptane percarboxylate, t-butyl-4-carbomethoxy perbutyrate, t-butylcyclobutane percarboxylate, t-butylcyclohexylperoxycarboxylate, t-butylcyclopentyl percarboxylate, t-butylcyclopropane percarboxylate, t-butyldimethyl percinnamate, t-butyl-2-(2,2-diphenylvinyl)perbenzoate, t-butyl 4-Methoxyperbenzoate, t-butyl perbenzoate, t-butylcarboxycyclohexane, t-butyl pernaphthoate, t-butylperoxypropylcarbonate, t-butyl persulfate, t-butyl-1-phenylcyclopropylpercarboxylate, t-butyl-2-propylperpenten-2-oate, t-butyl-1-methylcyclopropylpercarboxylate, t-butyl-4-nitrophenylperacetate, t-butylnitrophenylpercarbamate, t-butyl-N-succinimidopercarboxylate, t-butyl percrotonate, t-butyl permaleate, t-butyl permethacrylate, t-butyl peroctoate, t-butylperoxyisopropylcarbonate, t-butyl perisobutyrate, t-butyl peracrylate and / or t-butyl perpropionate.

[0055] Mixtures of the above listed peroxides are also contemplated.

[0056] According to an even more preferred embodiment, the peroxide comprises or consists of tert-butylperoxyisopropyl carbonate (CAS No. 2372-21-6).

[0057] Preferably, the peroxide is added in step (b) in an amount of 500 to 10,000 ppm, more preferably 1,500 to 7,500 ppm, and even more preferably 3,000 to 5,000 ppm, based on the weight of the terpolymer, and the difunctional unsaturated monomer is added in an amount of 500 to 5,000 ppm, more preferably 750 to 4,000 ppm, and even more preferably 1,000 to 2,000 ppm, based on the weight of the terpolymer (TER1).

[0058] As used herein, the expression "difunctional unsaturated monomer" refers to a monomer that contains two non-aromatic double bonds.

[0059] The difunctional unsaturated monomer may be selected from conjugated or non-conjugated, linear or branched dienes, preferably containing 4 to 20 carbon atoms, more preferably 4 to 10 carbon atoms. Preferred difunctional unsaturated monomers include 1,3-butadiene, isoprene, dimethylbutadiene, and divinylbenzene. The most preferred difunctional unsaturated monomer is 1,3-butadiene.

[0060] Typically, no more than three different difunctional unsaturated monomers, preferably one difunctional unsaturated monomer, are used in the process of the present invention.

[0061] Preferably, the difunctional unsaturated monomer is added in step (b) in an amount of 500 to 5000 ppm, more preferably 750 to 4000 ppm, even more preferably 1000 to 2000 ppm, based on the weight of the terpolymer (TER1).

[0062] Typically, the peroxide is added to a linear terpolymer of propylene, ethylene, and 1-butene (TER1) along with the difunctional unsaturated monomer. However, it is also possible, but less preferred, to add the difunctional unsaturated monomer first to the linear terpolymer of propylene, ethylene, and 1-butene (TER1) and then to the peroxide.

[0063] It should further be understood that the addition of the difunctional unsaturated monomer and peroxide may be accomplished all at once in the premixing stage or may be split into two additions, i.e., a first addition in the premixing stage and a second addition in the melt-mixing stage. It is preferred to add the difunctional unsaturated monomer and peroxide completely in the melt-mixing stage.

[0064] Please refer to the information above for definitions and preferred embodiments of the polymer film, the polypropylene composition, the long-chain branched terpolymer of propylene, ethylene and 1-butene (LCB-TER), the linear terpolymer of propylene, ethylene and 1-butene (TER1), and the additive (A).

[0065] The linear terpolymer (TER1) can be premixed with the difunctional unsaturated compound and peroxide in a powder mixing device, such as a horizontal mixer equipped with a paddle stirrer. Premixing is typically performed at a temperature of 20 to 100°C, preferably at a polymer powder temperature of 30 to 90°C, and most preferably in the range of 40 to 80°C. The residence time of the propylene homopolymer and / or copolymer in the premixing step is typically at least 2 minutes, preferably 5 to 45 minutes, and more preferably 8 to 30 minutes. Following the premixing step, the premixed materials are melted and then melt-mixed in a continuous melt-mixing device, such as a single-screw extruder, co-kneader, or preferably a co-rotating twin-screw extruder. Preferably, the melt-mixing device includes a feed zone, melt zone, kneading zone, and die zone. More preferably, the temperature profile in the extruder is selected to be 20 to 80°C in the feed barrel and 170 to 280°C from the melt zone to the die plate in a pelletizing system. The screw speed of the melt-mixing device can be adjusted depending on the material properties. Those skilled in the art will recognize the effect of screw speed on the process and can therefore select an appropriate screw speed. Generally, the screw speed can be adjusted within the range of 100 to 750 revolutions per minute (rpm), preferably 150 to 650 revolutions per minute (rpm). Following the melt-mixing step, the resulting long-chain branched terpolymer (LCB-TER) melt can be pelletized, preferably in an underwater pelletizer, or in a strand pelletizer after solidifying one or more strands in a water bath. In step (c), a polypropylene composition containing the long-chain branched terpolymer (LCB-TER) of propylene, 1-butene, and ethylene is recovered. Preferably, step (c) includes recovering the pelletized product as defined above.

[0066] Preferably, the method further comprises adding one or more additives to the composition at a point where the long chain branching reaction is expected to be near completion, preferably in the melt mixing apparatus, preferably near the die zone, The screw design of the melt mixing apparatus is selected to allow adequate mixing of the additives with the melt prior to pelletization.

[0067] Preferably, step (b) comprises melt-mixing the terpolymer (TER1), peroxide, and a difunctional unsaturated monomer selected from the group consisting of 1,3-butadiene, isoprene, dimethylbutadiene, and divinylbenzene in an extruder at a barrel temperature in the range of 40 to 280°C.

[0068] Further suitable methods for obtaining long chain branched terpolymers (LCB-TER), i.e. high melt strength terpolymers (HMS-TER), are disclosed in EP 0 787 750, EP 0 879 830 A1 and EP 0 890 612 A2.

[0069] Preferably, the present invention relates to a polypropylene composition obtainable by the above process.

[0070] Polymer film and method for producing the same The present invention further relates to a polymer film comprising the polypropylene composition described herein above.

[0071] The polymer film may be selected from the group of coated films, blown films and cast films.

[0072] Preferably, the polymer film is a multilayer film.

[0073] Preferably, the film comprises at least 90% by weight, more preferably at least 95% by weight, of polypropylene, based on the total weight of the film. Even more preferably, the film consists of polypropylene.

[0074] In a particularly preferred embodiment, the polymer film is a multi-layer film made of polypropylene.

[0075] The present invention further provides a method for producing a polymer film comprising the step of extrusion coating or extrusion laminating a polymer composition as described herein above onto a polypropylene based substrate or between two substrates.

[0076] Film preparation is accomplished through techniques known in the art. For example, films can be produced by cast or blown film techniques. In the cast film technique, molten long-chain branched propylene homopolymer and / or copolymer (b-PP) and / or long-chain branched polypropylene composition (b-PP-C) are extruded through a slot extrusion die onto a chill roll, where the polymer is cooled to form a solid film. Typically, the long-chain branched propylene homopolymer and / or copolymer (b-PP) and / or long-chain branched polypropylene composition (b-PP-C) are first compressed and melted in an extruder. Any additives can be added to the polymer already or introduced at this stage via a masterbatch. The melt is then forced through a flat film die (slot die), and the extruded film is removed by one or more take-off rolls, during which it is cooled and solidified. It has been found particularly advantageous to maintain the one or more take-off rolls for cooling and solidifying the extruded film at a temperature of 10 to 50°C, preferably 10 to 40°C, and more preferably 12 to 35°C. The resulting product is an unstretched film, optionally stretched unidirectionally or bidirectionally.

[0077] In the extrusion coating or extrusion lamination process, the melt is forced through a flat die with internal and external restrictors and drawn into a thin layer in a nip consisting of a chill roll and a pressure roll, where the molten film is pressed against a substrate and cooled by the chill roll.

[0078] In the blown film process, long-chain branched propylene homopolymer and / or copolymer (b-PP) and / or long-chain branched polypropylene composition (b-PP-C) are extruded through an annular die and blown into a tubular film by forming bubbles that solidify and then collapse between nip rollers. This blown extrusion is preferably carried out at a temperature in the range of 160 to 240°C. Cooling can be carried out by water or, preferably, by blowing a gas (typically air) at a temperature of 10 to 50°C to provide a frost line height of 0.5 to 8 times the die diameter. The blow-up ratio should generally be in the range of 1.5 to 4, e.g., in the range of 2 to 4, preferably in the range of 2.5 to 3.5.

[0079] use The polymer films described above or obtainable via the methods described above can be used in packaging applications. The present invention will be described below with reference to examples. [Example]

[0080] Example Measurement method Unless otherwise stated in the specification or experimental section, the following methods were used for characterization of the polymers and / or any sample preparations thereof specified in the text or experimental section.

[0081] a) Melt flow rate The melt flow rate (MFR) is determined according to ISO 1133 and is expressed in g / 10 min. MFR is a measure of the flowability and therefore the processability of a polymer. The higher the melt flow rate, the lower the viscosity of the resin. The MFR2 of polypropylene is measured at a temperature of 230°C and under a load of 2.16 kg.

[0082] b)F 30 Melt strength and v 30 Melt extensibility The tests described here follow ISO 16790:2005. The stress (strain) hardening behavior is determined by the method described in M.H. Wagner, Polymer Engineering and Science, Vol. 36, pp. 925-935. The strain hardening behavior of polymers is analyzed using a Rheotens apparatus (product of Goettfert, Siemensstr. 2, 74711 Buchen, Germany), which stretches a molten strand by pulling it at a defined acceleration. Rheotens experiments simulate industrial spinning and extrusion processes. In principle, the melt is pressed or extruded through a circular die, and the resulting strand is conveyed away. The stress on the extrudate is recorded as a function of the melt properties and the measured parameters (in particular, the ratio of power to conveying speed, which is actually a measure of the drawing speed).

[0083] For the results shown below, materials were extruded using a laboratory extruder, a HAAKE Polylab system, and a gear pump with a cylindrical die (L / D = 6.0 / 2.0 mm). The gear pump was pre-adjusted to a strand extrusion rate of 5 mm / s, and the melt temperature was set to 200 °C. The spin line length between the die and the Rheotens wheel was 80 mm. At the start of the experiment, the winding speed of the Rheotens wheel was adjusted to the speed of the extruded polymer strand (zero tensile force). The experiment was then initiated by slowly increasing the winding speed of the Rheotens wheel until the polymer filament broke. The wheel acceleration was small enough that the tensile force was measured under quasi-steady conditions. The acceleration of the molten strand drawn downward was 120 mm / s. 2 The Rheotens was operated in conjunction with the PC program EXTENS, a real-time data acquisition program that displays and stores the measured data of the pull force and drawdown speed. The end points of the Rheotens curve (force vs. pulley speed) were measured as F. 30 The melt strength and stretchability values ​​were recorded.

[0084] c) Melting point, crystallization temperature and enthalpy of fusion Melting temperature Tm is determined by differential scanning calorimetry (DSC) according to ISO 11357-3 using a TA-Instruments 2920 Dual Cell equipped with an RSC refrigeration unit and data station. Heating and cooling rates of 10 °C / min are applied in heat / cool / heat cycles between +23 °C and +210 °C. The cooling step determines the crystallization temperature (Tc), and the second heating step determines the melting temperature (T m ) and enthalpy of fusion (Hm).

[0085] For polymorphic samples, the measurement principle is the same as above, but the first and second melting temperatures Tm1 and Tm2, ​​as well as the first and second melting enthalpies Hm1 and Hm2, can be observed.

[0086] d) Xylene heat insolubles (XHU) The xylene heat insoluble (XHU) fraction is determined according to EN 579. Approximately 2.0 g of polymer (m p ) was weighed and placed in a weighed metal mesh, and the total weight was calculated as (m p+m The polymer in the mesh is extracted in a Soxhlet apparatus with boiling xylene for 5 hours. The eluent is then replaced with fresh xylene and boiling is continued for another hour. The mesh is then dried and weighed again (m XHU+m ). formula m XHU+m -m m =m XHU The mass of the xylene heat insolubles (mXHU) obtained by p ) and xylene insoluble matter m XHU / m p Get the percentage of

[0087] e) Quantification of microstructure by NMR spectroscopy Quantitative nuclear magnetic resonance (NMR) spectroscopy was used to quantify the comonomer content of the polymers. 500.13MHz and 125.76MHz respectively 1 H and 13 Quantitative data recorded in the melt using a Bruker Avance II 500 NMR spectrometer operating at C13 C{ 1 H} NMR spectra. All spectra are 13 Recorded at 180 °C using a 7 mm magic angle spinning (MAS) probe head optimized for C, using nitrogen gas for all air pressures.

[0088] Approximately 200 mg of material was loaded into a 7 mm outer diameter zirconia MAS rotor and spun at 4 kHz. This setup was chosen primarily for the high sensitivity necessary for rapid identification and accurate quantification {klimke08, parkinsonQ7, castignolles09}. Standard single-pulse excitation was used, utilizing NOE {pollard04, klimke08} and RSHEPT decoupling schemes {fillip05, griffin07} with a short recycle delay of 3 seconds. A total of 1024 (1k) transients were acquired per spectrum.

[0089] quantitative 13 C{ 1 H} NMR spectra were processed and integrated, and relevant quantitative properties were determined from the integration. All chemical shifts are internally referenced to the methyl isotactic pentad (mmmm) at 21.85 ppm.

[0090] A characteristic signal corresponding to the incorporation of 1-butene was observed {brandolini01}, allowing the quantification of the comonomer content.

[0091] The amount of isolated 1-butene incorporated into the PBP sequence was quantified using the integral of the αB2 site at 43.6 ppm, taking into account the number of reporting sites per comonomer. B=I αB2 / 2

[0092] The amount of 1-butene successively incorporated into the PBBP sequence was quantified using the integral of the ααB2B2 sites at 40.5 ppm, taking into account the number of reporting sites per comonomer. BB=2*l ααB2B2

[0093] If BB is present, the value of B must be corrected for the influence of the αB2 site resulting from BB. B=(l αB2 / 2)-BB / 2

[0094] The total 1-butene content was calculated based on the sum of isolated 1-butene and continuously incorporated 1-butene. B total =B+BB

[0095] A characteristic signal corresponding to ethylene incorporation was observed {brandolini01} and the comonomer content was quantified.

[0096] The amount of isolated ethylene incorporated into the PEP sequence was quantified using the integral of the Sββ site at 24.3 ppm, taking into account the number of reported sites per comonomer. E=I Sββ

[0097] When a characteristic signal corresponding to the sequential incorporation of ethylene in the PEE sequence was observed, the Sβδ site at 27.0 ppm was used for quantification. EE=l Sβδ

[0098] Characteristic signals corresponding to position defects were observed {resconi00}. The presence of an isolated 2,1-erythro region defect was indicated by the presence of two methyl moieties at 17.7 and 17.2 ppm, a methylene moiety at 42.4 ppm, and other characteristic moieties. The presence of a 2,1 region defect adjacent to an ethylene unit was indicated by two unequal Sαβ signals at 34.8 and 34.4 ppm and a Tγγ signal at 33.7 ppm.

[0099] Isolated 2,1-erythro-deleted (P 21e isolated The amount of ) was quantified using the integral of the methylene moiety at 42.4 ppm (19). P 21eisolated =l e9

[0100] If present, ethylene (P E21 The amount of defects in the 2,1 region adjacent to the Tγγ ) was used for quantification. P E21 =I Tγγ

[0101] The total ethylene content was then calculated based on the sum of the ethylene isolated, successively incorporated, and adjacent to the 2,1 domain defect. E total =E+EE+P E21

[0102] The amount of propene was quantified based on 46.7 ppm of Sαα methylene sites, including all additional propene units not covered by Sαα. For example, the factor 3*P 21e isolated describes the three missing propene units from the isolated 2,1-erythro region deletion. P total =I Sαα +3*P 21e isolated +B+0.5*BB+E+0.5*EE+2*P E21

[0103] The total mole fraction of 1-butene and ethylene in the polymer was then calculated as follows: fB=B total / (E total +P total +B total ) fE=E total / (E total +P total +B total )

[0104] The mole percent comonomer incorporation was calculated from the mole fraction. B[mol%]=100*fB E[mol%]=100*fE

[0105] The wt% incorporation of the comonomer was calculated from the mole fraction. B[wt.%]=100*(fB*56.11) / ((fE*28.05)+(fB*56.11)+((1-(fE+fB))*42.08)) E[wt.%]=100*(fE*28.05) / ((fE*28.05)+(fB*56.11)+((1-(fE+fB))*42.08))

[0106] The mole percent of isolated 2,1-erythro region defects was quantified for all propenes. [21e]mol%=100*P 21e isolated / P total

[0107] The mole percentage of 2,1 domain defects adjacent to ethylene was quantified for all propenes. [E21]mol%=100*P E21 / P total

[0108] 2.1 The total amount of defects was quantified as follows:

[21] mol%=[21e]+[E21]

[0109] No characteristic signals corresponding to other types of positional defects (2,1-threo, 3,1-intercalation) were observed {resconi00}.

[0110] References (see above): Klimke06:Klimke, K., Parkinson, M., Piel, C., Kaminsky, W., Spiess, HW, Wilhelm, M., Macromol.Chem.Phys.2006;207:382. parkinson07:Parkinson, M., Klimke, K., Spiess, HW, Wilhelm, M., Macromol.Chem.Phys.2007;208:2128. pollard04: Pollard, M., Klimke, K., Graf, R., Spiess, H.W., Wilhelm, M., Sperber, O., Piel, C., Kaminsky, W., Macromolecules 2004; 37: 813. Filip05: Filip, X., Tripon, C., Filip, C., J.Mag.Resn.2005, 176, 239. griffin07: Griffin, J.M., Tripon, C., Samoson, A., Filip, C., and Brown, S.P., Mag.Res.in Chem.2007 45, S1, S198. castignolles09: Castignolles, P., Graf, R., Parkinson, M., Wilhelm, M., Gaborieau, M., Polymer 50 (2009) 2373. resconi00: Resconi, L., Cavallo, L., Fait, A., Piemontesi, F., Chem.Rev.2000, 100, 1253. brandolini01: A.J.Brandolini, D.D.Hills, “NMR spectra of polymers and polymer additives”, Marcel Deker Inc., 2000

[0111] f) Seal start temperature (SIT) This method is used to determine the sealing window (sealing temperature range) of a film. The lower limit (seal initiation temperature - SIT) is the sealing temperature at which a sealing force of 5 N is achieved. This test is based on ASTM F1921-12, with some deviations. The force / temperature curve is determined until thermal failure of the film. In addition to the failure mode assessment described in the standard, additional failure modes are used. The temperature interval is set to 5°C by default, but if the force value increases or decreases rapidly between two temperature steps, the temperature interval can be reduced to 1°C to better represent the curve profile. In this case, a cast film with a thickness of 50 μm is used (see the Film Formation section).

[0112] Standard conditions: Conditioning time: Over 96 hours at 23°C and 50% RH Sealing jaw dimensions: 50 x 5 mm Sealing jaw shape: Flat Sealing jaw coating: Niptef Sealing temperature: ambient temperature to 240°C Sealing temperature interval: 5℃ Sealing time: 1 second Delay time: 30 seconds Sealing pressure: 0.4N / mm 2 (PE), 0.67N / mm 2 (PP) Grip separation speed: 42 mm / sec Sealing start force: 5N Sample width: 25mm

[0113] result: The output of this method is a ceiling curve. Sealing start temperature [℃] Sealing end temperature [℃] Temperature at maximum load [℃] ·Maximum load [N] Maximum relative force [N / cm] Energy up to maximum load [mJ] Total energy [mJ] Total strain [%] Thickness [mm] Destruction mode (destruction + type of destruction)

[0114] material PP-1 / TER1: A terpolymer of propylene, ethylene and 1-butene having an MFR2 of 3.5 g / 10 min, an ethylene content of 1 wt%, a 1-butene content of 9 wt%, and a total 2,1-positional defects of 21.0 mol%; further details are shown in Table 1.

[0115] PP-2: PP-2, a structurally isomeric modified propylene homopolymer with a MFR2 of 3 g / 10 min, a melt strength (F30) of 7 cN, and a melt extensibility (v30) of 250 mm / sec, is commercially available from Borealis AG.

[0116] Irganox B 215 FF: Antioxidant, commercially available from BASF.

[0117] Peroxan BIC-75: tert-Butyl peroxyisopropyl carbonate (CAS No. 2372-21-6), commercially available from Nouryon.

[0118] Calcium stearate: Ceasit AV-FI VEG, manufactured by Baerlocher

[0119] 1,3-Butadiene: purchased from OMV

[0120] Preparation of terpolymer PP1 / TER1 The terpolymer was prepared in a Bolster pilot plant in a prepolymerization and loop configuration. A fourth-generation Ziegler-Natta catalyst was used (catalyst preparation details are described, for example, in EP 491566, EP 591224, and EP 586390). Donor D (dicyclopentyldimethoxysilane) was used as an external donor. The concentrations of H2, C2, and C4 in the reactor were adjusted by a skilled artisan according to the product characteristics (C2, C4, MFR). Typical conditions are listed in Table 1.

[0121] [Table 1]

[0122] Reactive Modification For the preparation of the high melt strength polypropylene composition of inventive Example IE1, a propylene terpolymer (TER1) was subjected to reactive modification using Peroxan BIC-75 (tert-butyl peroxyisopropyl carbonate, commercially available from Nouryon) as the peroxide.

[0123] Both butadiene and peroxide were premixed with the polymer powder in a horizontal mixer equipped with a paddle-type agitator at 65 °C, maintaining an average residence time of 15 min, prior to the melt-mixing step. The amounts of butadiene and peroxide are based on the total amount of linear terpolymer (TER1). This premix was transferred to a Theyson TSK60 co-rotating twin-screw extruder with a barrel diameter of 60 mm and an L / D ratio of 48, equipped with a high-intensity mixing screw and a two-stage degasser. The melt temperature profile was selected: initial temperature T1 = 20–80 °C in the feed zone, T2 = 240 °C in the melt zone, T3 = 240 °C in the kneading zone, and final temperature T4 = 220–230 °C in the die zone. All temperatures were defined as barrel temperatures. The screw speed was set at 320 rpm.

[0124] Following the melt mixing step, the resulting polymer melt was pelletized in an underwater pelletizer at a process water temperature of 40° C. The reaction conditions and properties of the resulting compositions are summarized in Table 2.

[0125] An additive package of antioxidant Irganox B 215 (commercially available from BASF SE) and calcium stearate was added during the melt mixing process near the die zone of the extruder.

[0126] For Comparative Example 1, PP-2, a commercially available HMS polypropylene (see above), was used.

[0127] Film formation Films were prepared using the IE1 LCB-PP composition by the cast film method. Production was carried out on a laboratory-scale Collin 30 cast film line with a film thickness of 50 μm, a throughput of 10 kg / h, and a melt temperature of 250 °C. The chill rolls were operated at 20 °C.

[0128] [Table 2]

[0129] It has been found that the reactive modification process results in high melt strength polypropylene compositions comprising long-chain branched terpolymers of propylene, ethylene and 1-butene (LCB-TER), which exhibit an improved balance of properties in terms of low melting and crystallization temperatures and high melt strength. In addition, the PP compositions according to the present invention exhibit low SIT, which is beneficial for packaging applications.

Claims

1. A polypropylene composition comprising a long-chain branched terpolymer of propylene, ethylene and 1-butene (LCB-TER), having an MFR determined in accordance with ISO 1133 ２ in the range of 5 to 30 g / 10 min, a melting point Tm determined in accordance with ISO 11357-3 in the range of 100 to 150°C, and a crystallization temperature Tc in the range of 90 to 120°C.

2. 2. The polypropylene composition of claim 1, wherein the terpolymer of propylene, ethylene and 1-butene comprises 0.1 to 3.0 wt% ethylene based on the total weight of the polypropylene composition.

3. 3. The polypropylene composition according to claim 1, wherein the terpolymer of propylene, ethylene and 1-butene comprises 3 to 15% by weight of 1-butene based on the total weight of the polypropylene composition.

4. 4. The polypropylene composition according to any of claims 1 to 3, having a melt strength F30 in the range of 4 to 60 cN and a melt extensibility v30 in the range of 180 to 400 mm / s, wherein F30 and v30 are determined according to ISO 16790:2005.

5. The polypropylene composition according to any one of claims 1 to 4, having a melting point Tm in the range of 125 to 150°C.

6. A method for producing the polypropylene composition according to claim 1, comprising: (a) MFR measured according to ISO 1133 ２ providing a terpolymer of propylene, 1-butene and ethylene (TER1) having a viscosity in the range of 0.1 to 8.0 g / 10 min; (b) melt-mixing the terpolymer in the presence of a peroxide and a difunctional unsaturated monomer; and (c) recovering a polypropylene composition comprising a long-chain branched terpolymer of propylene, 1-butene and ethylene (LCB-TER). A method comprising:

7. 7. The process according to claim 6, wherein the terpolymer (TER1) provided in step (a) is prepared in the presence of a Ziegler-Natta catalyst or a single-site catalyst, preferably in the presence of a Ziegler-Natta catalyst.

8. 8. The method according to any of claims 6 to 7, wherein step (b) comprises melt-mixing the terpolymer (TER1), peroxide, and a difunctional unsaturated monomer selected from the group consisting of 1,3-butadiene, isoprene, dimethylbutadiene, and divinylbenzene, preferably 1,3-butadiene, in an extruder having a barrel temperature profile in the range of 20 to 280°C.

9. 9. The method according to any one of claims 6 to 8, wherein the amount of comonomer units derived from ethylene in the terpolymer (TER1) provided in step (a) is in the range of 0.1 to 3.0 wt. % and the amount of comonomer units derived from 1-butene in said terpolymer is in the range of 3 to 15 wt. %, based on the total weight of the terpolymer.

10. 10. The method according to claim 6, wherein in step (b), the peroxide is added in an amount of 500 to 10,000 ppm based on the weight of the terpolymer, and the difunctional unsaturated monomer is added in an amount of 500 to 5,000 ppm based on the weight of the terpolymer (TER1).

11. A polymer film comprising the polypropylene composition according to any one of claims 1 to 5.

12. The polymer film of claim 11 , wherein the film is a multilayer film.

13. 13. The polymer film according to any one of claims 11 to 12, comprising at least 90% by weight of polypropylene, based on the total weight of the film.

14. A method for producing a polymer film, comprising a step of extrusion coating or extrusion laminating the polypropylene composition according to any one of claims 1 to 5 onto a polypropylene-based substrate or between two substrates.

15. Use of a polymer film according to any one of claims 11 to 13 or obtainable by the method according to claim 14 in packaging applications.

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