High-melt-strength polypropylene

Abstract

The present invention relates to a process for high melt strength polypropylene (HMS-PP), comprising at least two electron beam irradiation periods, high melt strength polypropylene (HMS-PP) obtained by the process of the present invention, and articles comprising this high melt strength polypropylene (HMS-PP).

Description

Technical Field

[0001] The present invention relates to a process for producing high melt strength polypropylene (HMS-PP), high melt strength polypropylene (HMS-PP) obtained by this process, and articles containing this high melt strength polypropylene (HMS-PP).

Background Art

[0002] Propylene-based polymer compositions are versatile base materials that find applications in various fields such as food packaging or automotive parts.

[0003] When a propylene-based polymer composition is used to form a shaped article, it is necessary for the composition to have a melt strength that is high enough so that the composition can be shaped into the desired shape. This is the case, for example, when a propylene-based polymer composition is shaped into an object via a process in which the propylene-based polymer composition is heated until it exceeds its melting temperature and subsequently shaped into the desired object. In such a process, high shape stability is required for the propylene-based polymer composition at the temperature at which the object is formed. The propylene-based polymer composition needs to be able to maintain its shape in a molten state under such temperature conditions before solidification by cooling occurs.

[0004] Melt strength represents an index of the degree to which individual polymer molecules attempt to maintain their positions relative to each other (entanglement of molecules) under conditions where the polymer composition is in a molten state. In particular, melt strength can be described as the resistance of a polymer melt to stretching and disentanglement (dissolution of entanglement) under strain.

[0005] Linear polypropylene having a backbone that has no side chains or only a small number of side chains is relatively easily disentangled because there are few or no options for the polymer chains to entangle with each other. On the other hand, branched polypropylene exhibits remarkably high melt strength because its main polymer chains and side chains are intertwined with each other, which is why it is called high melt strength polypropylene (HMS-PP).

[0006] In particular, long-chain branching substantially alters the rheological behavior of polypropylene, such as its extensional viscosity and shear viscosity.

[0007] High melt strength provides products with beneficial properties such as improved elasticity and good mechanical properties, resulting in better processing capabilities in processes such as extrusion, blow molding, foaming, and thermoforming. Combined with the mechanical properties and chemical resistance of standard polypropylene, this also opens up possibilities for non-traditional polypropylene applications.

[0008] Although the applications of high melt strength polypropylene are widespread, several drawbacks still exist in the known preparation processes.

[0009] Several routes are being explored to obtain branched polypropylene. The three main known routes for producing branched polypropylene are as follows: A. Irradiation of polypropylene with or without a coupling agent. B. Reaction extrusion of polypropylene using low-temperature peroxides / peroxycarbonates alone or in combination with coupling agents. C. Polymerization of propylene and oligomers using a special catalyst.

[0010] Pathways A and B depend on the formation of radicals generated by either a high-energy beam or a peroxide reagent, respectively, for branching reactions. The use of peroxides on an industrial scale requires a higher level of security measures because peroxides are highly reactive and, if handled improperly, can lead to highly exothermic, explosive reactions. The drawbacks of route C stem from the need for special catalysts and polymerization conditions, as well as the small production volume compared to the typical size of commercially available polymerization reactors.

[0011] Pathway A is the most preferred path in terms of product purity, but ensuring product quality during the irradiation process is difficult because active macroradicals tend to initiate visbreaking reactions.

[0012] The production of high melt-strength polypropylene by irradiating linear polypropylene with an electron beam to form macroradicals that cause long-chain branching of linear polypropylene is known in the art.

[0013] This process applies (irradiates) the polypropylene with an electron beam having a specific energy corresponding to the acceleration voltage of the electron accelerator used. The amount of energy transferred to (i.e., absorbed by) the polypropylene determines the amount of radicals formed, which is typically described in units of gray, which corresponds to the absorption of 1 joule of radiation energy per kilogram of material.

[0014] European Patent Application Publication No. 0190889 discloses a process for producing branched polypropylene by irradiating polypropylene flakes under low-oxygen conditions without a coupling agent and in the presence of low levels of antioxidants. The radiation dose range is disclosed as 0.1 to 1000 kGy / min, and the ionizing radiation should have sufficient energy to penetrate to the desired extent in the mass of linear propylene polymer material being irradiated. The use of an accelerating potential (for electron generators) of 500 to 4000 kV and a radiation dose of 10 to 90 kGy is also disclosed. Following the irradiation step, the irradiated material is heated in an extruder to deactivate macroradicals.

[0015] Methods using additional crosslinking or branching agents are also known. International Publication No. 01 / 88001 discloses a process for preparing branched polypropylene by irradiation in the presence of crosslinking-promoting gases such as butadiene and acetylene. European Patent Application Publication No. 1187860 discloses a process for preparing high melt-strength polypropylene by irradiating polypropylene with a radiation dose of 5 to 100 kGy using an electron beam with an acceleration voltage greater than 5 MeV in the presence of branching agents such as acrylate, diacrylate, butadiene, and tetravinylsilane.

[0016] European Patent Application Publication No. 1170306 discloses a process for irradiating polypropylene polymerized using a Ziegler-Natta catalyst with an electron beam having an energy of at least 5 MeV and a radiation dose of at least 10 kGy, and for mechanically processing the irradiated molten polypropylene to form long-chain branches on polypropylene molecules.

[0017] International Publication No. 2018 / 028922 discloses a process for producing polypropylene with high melt strength by irradiation of polypropylene pellets containing only vitamin E.

[0018] European Patent Application Publication No. 0678527 discloses a process for producing modified polypropylene, wherein a mixture of polypropylene and a crosslinking agent is irradiated with ionizing radiation that gives an absorbed dose of 1 to 20 kGy, and the resulting material is subsequently heat-treated.

[0019] It is also known that when isotactic polypropylene produced using conventional Ziegler-Natta catalysts is irradiated with electron beams, the irradiation of polypropylene generates free macroradicals, and there is competition between chain severance and branching depending on the absorbed radiation dose and temperature.

[0020] Several unsaturated branching agents are disclosed for polypropylene to reach the required branching level at low doses without forming a gel. These substances are used to stabilize macroradicals formed by the extraction of hydrogen from polypropylene chains under high-energy irradiation, and to combine to form branched structures. Typical branching agents are highly reactive unsaturated chemical compounds, such as acrylates, diacrylates and triacrylates; conjugated dienes, such as butadiene and acetylene; or vinyl compounds, such as tetravinylsilane or divinylbenzene. The use of branching (or grafting or sensitizing) agents typically results in disadvantages such as unpleasant odors, increased costs, and increased environmental problems, particularly potential toxicity, due to unreacted branching or grafting agents in modified polypropylene. Another common problem with all these proposed substances is the potential for unreacted branching agents to migrate from the polymer into the environment.

[0021] Preferably, all substances used in the polypropylene composition (branching agents and antioxidants) should be derived from renewable sources and, since food packaging is one of the main uses of branched polypropylene, should be generally recognized as safe (GRAS) or food approved for use in polypropylene compositions. [Prior art documents] [Patent Documents]

[0022] [Patent Document 1] European Patent Application Publication No. 0190889 [Patent Document 2] International Publication No. 01 / 88001 Pamphlet [Patent Document 3] European Patent Application Publication No. 1187860 [Patent Document 4] European Patent Application Publication No. 1170306 [Patent Document 5] International Publication No. 2018 / 028922 Brochure [Patent Document 6] European Patent Application Publication No. 0678527 [Overview of the project] [Problems that the invention aims to solve]

[0023] The present invention aims to provide a process for obtaining a polypropylene resin having improved properties, particularly improved melt strength, and a method for producing such a polypropylene resin with a high production rate using optionally selected branching agents. [Means for solving the problem]

[0024] During extensive research in this field, it was surprisingly discovered that a process involving at least two irradiation periods instead of the single irradiation period known in the art leads to improved properties, such as higher melt strength and increased branching of the resulting high-melt-strength polypropylene, while adding the same total amount of radiation as in the known one-step method, without interrupting the ionization energy.

[0025] Therefore, the present invention relates to a process (method) for preparing high melt strength polypropylene (HMS-PP), a) A step of preparing a linear propylene polymer (L-PP), preferably a linear propylene homopolymer (H-PP), a1) Optionally, a step of blending the above propylene polymer (L-PP) with a coupling agent (CA) containing a polyunsaturated organic compound, preferably a polyunsaturated fatty acid, b) A step of irradiating the linear propylene polymer (L-PP) prepared in step a) or the blend obtained in step a1) with electron beam irradiation. It includes the above in the order, Step b) includes at least two irradiation periods, Between each irradiation period is a non-irradiation period. Each non-irradiation period is directed to a process (method) in the range of 0.01 minutes to 20 minutes, preferably 1.0 minutes to 20 minutes, and more preferably 2.0 minutes to 20 minutes.

[0026] Furthermore, the present invention is directed toward high melt strength polypropylene (HMS-PP) that can be obtained from the above process.

[0027] Finally, the present invention is directed toward articles containing the above-mentioned high-melt-strength polypropylene (HMS-PP). [Modes for carrying out the invention]

[0028] Preferred embodiments of the present invention are described in the dependent claims. The present invention will be described in detail below.

[0029] Linear propylene polymer (L-PP) The linear propylene polymer (L-PP) used in the present invention can be a homopolymer or copolymer of propylene.

[0030] The term "linear" in relation to propylene polymers means that the branching within the polymer is low. In particular, the amount of branching in linear propylene polymers (L-PP) is preferably in the range of 0 to 10 branches / 1000 carbon atoms, more preferably in the range of 0 to 5 branches / 1000 carbon atoms, and even more preferably in the range of 1 to 5 branches / 1000 carbon atoms.

[0031] Polypropylene compositions comprising linear propylene homopolymers or linear propylene copolymers are well known.

[0032] Linear propylene homopolymers are obtained by polymerizing propylene under appropriate polymerization conditions. Linear propylene copolymers are obtained by copolymerizing propylene with one or more other olefins, preferably ethylene, under appropriate polymerization conditions.

[0033] The preparation of propylene homopolymers and copolymers is described, for example, in Moore, EP(996) Polypropylene Handbook. Polymerization, Characterization, Properties, Processing, Applications, Hanser Publishers; New York.

[0034] As used herein, polypropylene means a propylene homopolymer or a copolymer of propylene and an α-olefin selected from the group of α-olefins, such as α-olefins having 2 or 4 to 10 carbon atoms, preferably ethylene, wherein the amount of α-olefin such as ethylene is preferably less than 10% by weight based on the total propylene copolymer.

[0035] Polypropylene and copolymers of propylene and α-olefins can be prepared by any known polymerization technique and any known polymerization catalyst system. Regarding this technique, slurry polymerization, solution polymerization, or gas-phase polymerization may be referred to, and regarding the catalyst system, Ziegler-Natta catalyst systems, metallocene catalyst systems, or single-site catalyst systems may be referred to.

[0036] Preferably, the linear propylene polymer (L-PP) has a melt flow rate MFR2 (230°C, 2.16 kg) determined according to ISO 1133, in the range of 0.1 to 100 g / 10 min, more preferably in the range of 0.2 to 50 g / 10 min, and even more preferably in the range of 0.5 to 10.0 g / 10 min.

[0037] The linear propylene polymer (L-PP) may be a copolymer or homopolymer of propylene, with the latter being preferred. Furthermore, the linear propylene polymer (L-PP) may contain one or more different linear propylene polymer (L-PP) components.

[0038] When the linear propylene polymer (L-PP) is a copolymer of propylene, it is preferable that the linear propylene polymer (L-PP) has a comonomer content, such as ethylene content, in the range of 0.2 to 25.0 mol%, more preferably in the range of 0.5 to 20.0 mol%, and even more preferably in the range of 2.0 to 15.0 mol%, for example, in the range of 6.0 to 12.0 mol%.

[0039] The comonomer is preferably selected from ethylene and / or C4-C8α-olefins. It is particularly preferred that the comonomer is ethylene. For linear propylene polymers (L-PP) containing multiple, for example two, different propylene polymer components that are copolymers of propylene, it is preferable that all propylene polymer components contain the same comonomer, for example, ethylene.

[0040] Preferably, the propylene polymer (PP), for example, propylene homopolymer (H-PP), is isotactic. Therefore, it is preferable that the propylene polymer (PP), for example, propylene homopolymer (H-PP), has a fairly high pentad concentration (mmmm%), i.e., greater than 94.1%, more preferably greater than 94.4%, for example greater than 94.4-98.5%, and even more preferably at least 94.7%, for example greater than 94.7-97.5%.

[0041] According to a preferred embodiment of the present invention, the linear propylene polymer (L-PP) is a linear propylene homopolymer (H-PP).

[0042] According to the present invention, the expression "propylene homopolymer" refers to polypropylene consisting substantially of propylene units, i.e., at least 99.0% by weight, more preferably at least 99.5% by weight, even more preferably at least 99.8% by weight, for example, at least 99.9% by weight of propylene units. In another embodiment, only propylene units are detectable, i.e., only propylene is polymerized.

[0043] Optional coupling agents (CAs) containing polyunsaturated organic compounds Optionally, the process of the present invention may include step a1), which comprises blending a linear propylene polymer (L-PP) with a coupling agent (CA) comprising a polyunsaturated organic compound.

[0044] As used herein, the term “polyunsaturated organic compound” refers to an organic compound having at least two carbon-carbon double bonds.

[0045] The following embodiments refer to embodiments of the process of the present invention that include step a1).

[0046] The mixture obtained in step a1) of the process of the present invention contains a coupling agent (CA) comprising a polyunsaturated organic compound, preferably in an amount of 0.01% to 5.0% by weight, more preferably 0.1% to 2.0% by weight, based on the total weight of the mixture obtained in step a1). Preferably, the amount of polyunsaturated organic compound in the coupling agent (CA) containing the polyunsaturated organic compound is in the range of 20% to 100% by weight, preferably 30% to 90% by weight, and more preferably 40% to 80% by weight.

[0047] Polyunsaturated organic compounds can be, for example, polyunsaturated terpenes, dienes, or polyunsaturated fatty acids.

[0048] Polyunsaturated terpenes include, for example, squalene, geraniol, nerol, and linalool.

[0049] Examples of dienes include butadiene, 1,7-octadiene, 1,9-decadien, 1,13-tetradecadien, 1,8-nonadien, 1,10-undecadien, 1,11-dodecadien, 1,15-hexadecadien, 1,17-octadecadien, and norbornadiene.

[0050] Polyunsaturated fatty acids include, for example, linoleic acid, eicosadienoic acid, docosadienoic acid, alpha-linolenic acid, gamma-linolenic acid, pinolenic acid, eleostearic acid, meadic acid, dihomo-gamma-linolenic acid, eicosatrienoic acid, stearidonic acid, arachidonic acid, eicosatetraenoic acid, adrenaline, boseopentaenoic acid, osbondic acid, sardine acid, tetracosanolpentaenoic acid, cervonic acid, and herring acid.

[0051] Preferably, the coupling agent (CA) containing a polyunsaturated organic compound includes a bifunctional polyunsaturated organic compound, i.e., an organic compound having further functional groups other than a carbon-carbon double bond, such as a polyunsaturated fatty acid.

[0052] Preferably, the polyunsaturated organic compound is a polyunsaturated fatty acid selected from the group consisting of linoleic acid, eicosadienoic acid, docosadienoic acid, α-linolenic acid, γ-linolenic acid, pinolenic acid, eleostearic acid, meadic acid, dihomo-γ-linolenic acid, eicosatrienoic acid, stearidonic acid, arachidonic acid, eicosatetraenoic acid, adrenaline, bosopentaenoic acid, osbondic acid, sardic acid, tetracosanolpentaenoic acid, cervonic acid, and herringic acid. The most preferred polyunsaturated fatty acid is linoleic acid and / or α-linolenic acid.

[0053] It is particularly preferable that the coupling agent (CA) containing a polyunsaturated organic compound contains linoleic acid and / or alpha-linolenic acid.

[0054] Preferably, the coupling agent (CA) is a naturally occurring polyunsaturated fatty acid. In particular, the coupling agent (CA) is preferably selected from the group consisting of linseed oil, walnut oil, tung oil, and sunflower oil. Preferably, the coupling agent (CA) is linseed oil, more preferably natural linseed oil.

[0055] Alpha-linolenic acid has a unique reaction with oxygen in the air and therefore acts as a stabilizer / radical scavenger for polypropylene. Linseed oil is unique in its unusually high alpha-linolenic acid content and offers the highest content of polyunsaturated fatty acids and the lowest levels of saturated fatty acids available in commercially available vegetable oils. The USFDA has recognized high-alpha-linolenic acid linseed oil as generally recognized as safe (GRAS). Therefore, the high-melt-strength polypropylene (HMS-PP) according to the present invention is suitable for the manufacture of food containers and food-related products.

[0056] L-PP and CA blend Blending techniques, such as melt blending, dry blending, and solution blending, are well known in the relevant field. Linear propylene polymer (L-PP) is preferably melt-blended with a coupling agent (CA), for example by extrusion, or dry-blended.

[0057] The MFR can be adjusted by adding peroxides to the molten blend and chemical bis-breaking during the extrusion process. The blend of L-PP and CA may further contain organometallic stearates selected from magnesium stearate, aluminum stearate, sodium stearate, and calcium stearate. The blend preferably contains calcium stearate. The amount of organometallic stearate, preferably calcium stearate, may be in the range of 100 ppm by weight to 1000 ppm by weight, more preferably 200 ppm by weight to 800 ppm by weight, and even more preferably 400 ppm by weight to 600 ppm by weight, based on the total weight of the blend.

[0058] The blend of L-PP and CA may further contain antioxidants and process stabilizers used in polypropylene industry in 2022.

[0059] Suitable antioxidants and process stabilizers are known to those skilled in the art. For example, commercially available antioxidants and process stabilizers are described in Hans Zweifel's "Plastic Additives Handbook," 6th edition, 2009 (pp. 1141-1190).

[0060] In one embodiment of the present invention, the blend of L-PP and CA does not contain antioxidants and / or process stabilizers.

[0061] In another embodiment of the present invention, the blend of L-PP and CA contains, based on the total weight of the blend, an amount of antioxidant in the range of 50 to 500 ppm, preferably 100 to 200 ppm, and / or a amount of process stabilizer in the range of 50 to 500 ppm, preferably 100 to 200 ppm.

[0062] To prevent bis-breaking reactions, it is preferable to manufacture the blend in a twin-screw extruder under nitrogen.

[0063] Preferably, the blend of L-PP and CA consists of the above-mentioned L-PP and CA in a total amount ranging from 95.0% to 100% by weight, preferably 97.0% to 100% by weight, and more preferably 99.0% to 100% by weight, based on the total weight of the blend.

[0064] Electron beam irradiation To initiate radical formation and subsequent long-chain branching, the linear propylene polymer (L-PP) or the blend of CA and L-PP is irradiated with an electron beam in step b) of the process of the present invention.

[0065] Surprisingly, it was found that an improved high melt strength polypropylene (HMS-PP) can be obtained in a process in which irradiation step b) includes at least two irradiation periods, compared to HMS-PP obtained from a process including only one irradiation period.

[0066] Irradiation of polymers by electron beam is well known in the art. Typically, the amount of radiation applied to each sample material is expressed in units of gray (Gy), which represents the absorption of 1 joule of radiation energy per kilogram of material.

[0067] Since the absorbed energy of a material varies at different depths, the radiation dose given in this disclosure refers to the amount of energy applied to the surface of the material facing the electron beam per kilogram of material, and is therefore referred to as the "surface radiation dose."

[0068] According to the present invention, by dividing the total surface radiation dose applied to a linear propylene polymer (L-PP) or a blend of a linear propylene polymer and a coupling agent into at least two irradiation periods, improved properties, such as F 30 HMS-PP with increased melt strength can be obtained.

[0069] Therefore, the surface radiation dose applied during the first of at least two irradiation periods is preferably in the range of 10 to 150 kGy, preferably 50 to 130 kGy, and more preferably 60 to 110 kGy.

[0070] Furthermore, the surface radiation dose applied during the second of at least two irradiation periods is preferably in the range of 5 to 150 kGy, preferably 8 to 80 kGy, and more preferably 10 to 50 kGy.

[0071] Preferably, the surface radiation dose applied during the second of at least two irradiation periods is lower than the surface radiation dose applied during the first of at least two irradiation periods.

[0072] Therefore, the ratio of the surface radiation dose applied during the first irradiation period of at least two irradiation periods to the surface radiation dose applied during the second irradiation period of at least two irradiation periods is preferably in the range of greater than 1.1 to 30, preferably 1.2 to 15, and more preferably 1.5 to 8.0.

[0073] The process of the present invention may include more than two irradiation periods, such as three, four, or five, but it is preferable that the irradiation in step b) includes two irradiation periods and does not include any further irradiation periods. Therefore, step b) consists of two irradiation periods and a non-irradiation period in between, and the non-irradiation period is preferably in the range of 0.01 minutes to 20 minutes, preferably 1.0 minutes to 20 minutes, and more preferably 2.0 minutes to 20 minutes. For the sake of clarity only, the process of the present invention does not include any further irradiation period before or after step b).

[0074] The total radiation dose applied is the sum of the radiation doses applied during each irradiation period in step b). In a preferred embodiment of the present invention, the total surface radiation dose applied in the process is in the range of 30 kGy to 200 kGy, preferably 50 kGy to 180 kGy, and more preferably 60 kGy to 130 kGy.

[0075] There is an irradiation-free period between each of at least two irradiation periods, and each irradiation-free period is in the range of more than 0.01 minutes to 20 minutes, preferably 1.0 minutes to 20 minutes, more preferably 2.0 minutes to 20 minutes, and even more preferably 4.0 minutes to 12 minutes.

[0076] Process parameters Methods for generating electron beams and applying radiation doses are well known in the art. Furthermore, it is well known that the acceleration voltage and beam current of the electron beam generator used directly affect the penetration depth and mobile energy of the electron beam.

[0077] According to the process of the present invention, the electron beam is preferably generated at an acceleration voltage in the range of 5 MeV to 15 MeV, preferably 7 MeV to 13 MeV, and more preferably 8 MeV to 12 MeV.

[0078] In order for the energy of the electron beam (corresponding to the surface radiation dose) to be transferred to each substance, that substance must be exposed to the electron beam.

[0079] This can be done, for example, by using a moving belt that passes under an electron beam, thereby subjecting the L-PP prepared in step a) or the blend obtained in step a1) which is placed on the belt to the electron beam.

[0080] The parameters that need to be adjusted to apply a specific dose of radiation are known to those skilled in the art.

[0081] For example, the faster the moving belt speed, the shorter the contact time between the electron beam and the irradiated object, and as a result, the amount of surface radiation applied decreases.

[0082] Other parameters that affect the applied surface dose include the quality of the electron beam focus, the size of the electron beam, and the distance of the material to the horn of the electron beam generator.

[0083] The focused electron beam has dimensions of approximately 100 × 10 mm at a distance close to the horn. The beam width on the object's surface and the resulting contact time depend on the distance to the horn and the quality of the electron beam focus.

[0084] Therefore, the contact time t per unit of irradiation time can be calculated by dividing the width of the electron beam on the surface (mm) by the belt speed (mm / s).

[0085] The belt speed depends on the required surface dose and the energy (kWh) emitted from the accelerator. A typical contact time for PP pellets placed on a moving belt irradiated at 200 kWh / h with an output of 190 kW is less than 2 seconds, assuming an electron beam with dimensions of 100 × 10 mm width.

[0086] Containment The irradiation in step b) can be carried out in an inert or non-inert environment. Preferably, step b) is carried out on a moving belt in an inert atmosphere. In particular, irradiation is preferably carried out under nitrogen.

[0087] To control the gaseous environment, the L-PP prepared in step a) or the blend obtained in step a1) can be placed in a sealable containment facility before irradiation in step b). The term "sealable" refers to the condition that one gaseous environment (e.g., inside a containment facility) can be separated from another gaseous environment (outside a containment facility) in order to avoid substantial gas exchange between the two gaseous environments.

[0088] The form of a sealable containment device is not limited to any particular form. A sealable containment device may be a container, an airtight chamber, or a mixer, such as a fluidized bed reactor or a stirred tank reactor. The container shape can be selected from, for example, a cube, a cube-like shape, or a cylindrical shape, and preferably, a sealable container has a cylindrical shape.

[0089] To avoid undesirable side reactions, such as uncontrolled peroxide formation due to oxygen in the air, a sealable containment facility containing the L-PP prepared in step a) or the blend obtained in step a1) can be flushed with nitrogen until an atmosphere with an oxygen concentration of 1 to 1000 ppm, preferably 50 to 400 ppm, and more preferably 100 to 300 ppm is reached inside the containment facility.

[0090] During irradiation and the resulting radical reaction, hydrogen gas is generated. Although hydrogen gas poses an explosion risk, it supports the formation of long-chain branching in PP.

[0091] Containment equipment or reaction vessels can be used to collect hydrogen for further use as energy generation and to create a reaction environment that supports the formation of long-chain branching by increasing the partial pressure of hydrogen during the irradiation process and subsequent steps until all radicals are deactivated.

[0092] In one embodiment of the present invention, it is preferable that the maximum (excess) pressure in the process does not exceed 0.2 bar. Therefore, the pressure during the process is preferably in the range of 0.0 to 0.2 bar.

[0093] To ensure that the maximum pressure inside the containment facility is less than 0.2 bar, a sealable containment facility can be used that includes a safety valve that releases excess gas when the internal pressure reaches a level exceeding a selected threshold.

[0094] In another embodiment of the present invention, the (excess) pressure during the process is preferably greater than 0.2 bar, and more preferably in the range of greater than 0.2 bar to 2 bar.

[0095] Further processing The irradiated L-PP or irradiated blend obtained after step b) contains reactive radicals. To complete the branching reaction and inactivate most of the radicals, the process of the present invention may include a further step c) after step b), which includes a tempering period during which the irradiated L-PP or irradiated blend obtained in step b) is tempered to a temperature in the range of 40 to 140°C, preferably 50 to 70°C.

[0096] Temperature control in this disclosure should be understood as heat treatment.

[0097] Furthermore, the temperature adjustment period in step c) is preferably in the range of 5 minutes to 120 minutes, more preferably 45 minutes to 90 minutes.

[0098] Due to the difference in absorbed energy depending on the depth of the irradiated object, a mixture of unmodified or less modified PP and modified PP is obtained after step b) or step c).

[0099] To homogenize the resulting PP mixture, the process of the present invention may include a further step d), which includes homogenizing the irradiated L-PP or irradiated blend obtained after step b) or step c). Techniques for homogenization are known to those skilled in the art. For example, the irradiated L-PP or irradiated blend obtained after step b) or step c) can be homogenized by extrusion.

[0100] Step d) can further be used to compound or blend the obtained HMS-PP with an additive (AD) in order to achieve beneficial properties.

[0101] It is preferable that the irradiation product from step b) or c) does not come into contact with oxygen before or during the addition of the additive in step d).

[0102] Suitable additives (ADs) include nucleating agents and clarifying agents, stabilizers, release agents, fillers, peroxides, plasticizers, antioxidants, lubricants, antistatic agents, scratch resistant agents, high-performance fillers, pigments and / or colorants, impact modifiers, flame retardants, foaming agents, acid scavengers, recycling additives, coupling agents, antimicrobial agents, anti-fogging additives, slip agents, anti-blocking additives, polymer processing aids, etc. Such additives are commercially available and are described, for example, in Hans Zweifel's "Plastic Additives Handbook," 6th edition, 2009 (pp. 1141-1190). Preferably, the additive (AD) is selected from the group consisting of antioxidants, process stabilizers, or mixtures thereof.

[0103] The term "additive (AD)" in this invention also includes carrier materials, particularly polymer carrier materials.

[0104] Instead of adding the additive (AD) in step d) to the irradiated L-PP or irradiated blend obtained after step b) or step c), or in addition to adding it, the additive (AD) may be applied to the surface of the homogenized irradiated L-PP or homogenized irradiated blend to achieve cost-effective and energy-efficient surface stabilization.

[0105] In a preferred embodiment of the present invention, the process of the present invention is as follows: a) A step of preparing a linear propylene polymer (L-PP), preferably a linear propylene homopolymer (H-PP), a1) A step of blending the above propylene polymer (L-PP) with a coupling agent (CA) containing polyunsaturated fatty acids, b) A step of irradiating the blend obtained in step a1) with electron beam irradiation, c) A step of adjusting the temperature of the irradiated blend obtained in step b) to a temperature in the range of 50°C to 70°C, d) A process to homogenize the irradiated blend obtained in step c) and Step b) includes two irradiation periods and one non-irradiation period between these two irradiation periods, preferably consisting of these. The surface radiation dose applied during the first irradiation period is in the range of 60 kGy to 110 kGy. The surface radiation dose applied during the second irradiation period is in the range of 10 kGy to 50 kGy. The period without irradiation between the two irradiation periods ranges from 2 to 20 minutes. The temperature adjustment period in step c) is in the range of 45 to 90 minutes.

[0106] HMS-PP The high melt strength polypropylene (HMS-PP) relating to this disclosure is linear polypropylene having the same melt flow rate MFR2, as determined according to ISO 16790:2005. 30 Compared to the melt strength (LMS), an additional F of 5 cN or more 30 It has melt strength (AMS).

[0107] This invention provides a process for producing such high melt-strength polypropylene (HMS-PP).

[0108] In particular, the process of the present invention can be used to produce high melt strength polypropylene (HMS-PP) having the following properties.

[0109] i) Propylene, and ii) At least one polyunsaturated fatty acid A high melt-strength polypropylene (HMS-PP) containing units that can be derived from, wherein this high melt-strength polypropylene (HMS-PP) has a crystallization temperature Tc determined according to DSC in the range of over 120°C, preferably in the range of 120°C to 132°C. F measured by Rheotens measurement according to ISO 16790:2005 at 200℃, 120 mm / sec acceleration, and standard shear (die pressure 30 bar). 30 The melt strength is greater than 26 cN, preferably in the range of greater than 26 cN to 50 cN. The melt flow rate MFR2 (230°C, 2.16 kg), determined according to ISO 1133, is in the range of 1.0 to 2.4 g / 10 min. Complex shear viscosity η at a frequency of 285 rad / s, determined by dynamic shear measurements in accordance with ISO standards 6721-1 and 6721-10. * The pressure is greater than 170 Pa·s, preferably in the range of greater than 170 Pa·s to 220 Pa·s.

[0110] Preferably, the units that can be derived from at least one polyunsaturated fatty acid are derived from linseed oil. Therefore, linseed oil is a coupling agent (CA) containing polyunsaturated organic compounds in the process of producing the high-melt-strength polypropylene (HMS-PP).

[0111] Finally, the present invention relates to a foam or article manufactured using high-melt-strength polypropylene (HMS-PP) according to the present invention.

[0112] The present invention is further directed to articles comprising the high melt-strength polypropylene (HMS-PP). Preferably, the article comprises at least 80% by weight, more preferably at least 90% by weight, even more preferably at least 95% by weight, for example at least 99% by weight, of the total weight of the article, of the high melt-strength polypropylene (HMS-PP). It is particularly preferable that the article is made of the high melt-strength polypropylene (HMS-PP). The article is preferably a foamed article, more preferably an extruded foamed article, a foamed injection molded article, a pearl foamed article, an injection blow molded article, or an inflation film.

[0113] Preferably, the article is a foamed article, an injection blow-molded article, or an inflation film. It is particularly preferable that the article is a foamed article such as an extruded foamed article, a foamed injection-molded article, or a granular foamed article.

[0114] The high melt strength polypropylene (HMS-PP) according to the present invention may be formed into a foamed structure by a melting process. Such a melting process may be carried out in a melt extruder. A blowing agent may be added to the melting process to induce the formation of foam cells. Such a blowing agent may be a chemical blowing agent or a physical blowing agent. Chemical blowing agents may be selected from, for example, sodium bicarbonate, citric acid derivatives, azodicarbonamide, hydrazodicarbonamide, 4,4'-oxybis(benzenesulfonyl hydrazide), N,N-dinitrosopentamethylenetetramine, 5-phenyltetrazole, p-toluenesulfonyl hydrazide, and / or p-toluenesulfonyl semicarbazide. Physical blowing agents may be selected from, for example, nitrogen, carbon dioxide, isobutane, pentane, and cyclopentane. Preferably, the blowing agent is isobutane.

[0115] The blowing agent may be introduced into the extruder at the point where the high-melt-strength polypropylene (HMS-PP) according to the present invention is in a molten state. For example, the blowing agent is preferably introduced in an amount in the range of 1.0 to 20.0% by weight, more preferably in the range of 1.5 to less than 10.0% by weight, and even more preferably in the range of 2.0 to 5.0% by weight, based on the total weight of the high-melt-strength polypropylene (HMS-PP). The introduction of such an amount of blowing agent may contribute to the formation of a foamed structure having a desired low density combined with a desired high closed-cell ratio. It is preferable that isobutene is used as the blowing agent in an amount of 2.0 to less than 10.0% by weight, more preferably greater than 2.0 to 5.0% by weight, based on the total weight of the high-melt-strength polypropylene (HMS-PP).

[0116] In addition, further generally known additives suitable for the production of foamed structures from propylene polymer compositions may be used. For example, a certain amount of a nucleating agent such as talc and / or fatty acid (bis)amide may be added. Preferably, talc is used as the nucleating agent. For example, the nucleating agent is preferably added in an amount of 0.1 to 2.0% by weight, more preferably 0.5 to 1.5% by weight, based on the total weight of high melt strength polypropylene (HMS-PP).

[0117] In addition, a certain amount of cell stabilizer, such as glycerol monostearate (GMS), glycerol monopalmitate (GMP), glycol distearate (GDS), palmitide and / or amide, such as stearyl stearamide, palmitoamide and / or stearamide, may be added. Preferably, glycerol monostearate is used as the cell stabilizer. For example, the cell stabilizer is preferably added in an amount of 0.1 to 2.0% by weight, more preferably 0.5 to 1.5% by weight, based on the total weight of high melt strength polypropylene (HMS-PP).

[0118] The high melt-strength polypropylene (HMS-PP) may then be extruded from the die outlet of a melt extruder. This may form a foamed structure. The present invention also relates to foams produced using high-melt-strength polypropylene (HMS-PP) obtained by the irradiation process according to the present invention.

[0119] The density of the foamed structure is 20-800 kg / m³. 3 The density of the foamed structure was determined as the apparent total density according to ISO 845 (2006). The closed-cell ratio is preferably 90% or more, more preferably 98% or more, and even more preferably greater than 98%. The closed-cell ratio was determined by placing samples of foam with a known mass and a known density, determined as the apparent total density according to ISO 845 (2008), in a desiccator. Each sample was 5 cm long and 3 cm wide. The desiccator was filled with water and polyethylene glycol as a surfactant. The pressure inside the desiccator was reduced to 500 mbar. The samples were held under these conditions for 0 minutes, after which the material was measured by a melt extrusion foaming method using a propylene-based composition produced according to the process of the present invention, with a foaming window of 5°C or higher, and the foaming window was 175 kg / m³ as determined according to ISO 845 (2006) when using 2.3 wt% isobutane as the foaming agent. 3 This is defined as the temperature range in which foams having the following apparent overall density and a closed-cell content of 90% or more may be produced.

[0120] Furthermore, the present invention relates to the following numbered embodiments.

[0121] 1. A process for producing high melt strength polypropylene (HMS-PP), the following: a) A step of preparing a linear propylene polymer (L-PP), b) A step of irradiating the linear propylene polymer (L-PP) prepared in step a) with electron beam irradiation. Step b) includes at least two irradiation periods, There is a period without irradiation between each irradiation period. Each non-irradiation period is in the range of more than 0.01 minutes to 20 minutes, preferably 1.0 minutes to 20 minutes, more preferably 2.0 minutes to 20 minutes, process.

[0122] 2. The high melt strength polypropylene (HMS-PP) has an F of linear polypropylene having the same melt flow rate MFR2 (ISO 1133, 2.16 kg, 230 °C) as the high melt strength polypropylene (HMS-PP) calculated according to formula (II). 30 Additional F of 5 cN or more compared to the melt strength (LMS). 30 Has a melt strength (AMS). AMS = MS(HMS-PP) - LMS (II) In the formula, AMS is the F of linear polypropylene having the same melt flow rate MFR2 (230 °C, 2.16 kg) as the high melt strength polypropylene (HMS-PP) determined according to ISO 1133. 30 Additional F determined according to ISO 16790:2005 compared to the melt strength (LMS). 30 Is the melt strength (AMS) [unit: cN]. MS(HMS-PP) is the F of high melt strength polypropylene (HMS-PP) determined according to ISO 16790:2005. 30 Is the melt strength [unit: cN]. LMS is the F of linear polypropylene having the same melt flow rate MFR2 (230 °C, 2.16 kg) as the high melt strength polypropylene (HMS-PP) determined according to ISO 1133. 30 Is the melt strength (LMS) [unit: cN]. F of the corresponding linear polypropylene having the same melt flow rate MFR2 and a polydispersity in the range of 3 to 5 as the high melt strength polypropylene (HMS-PP). 30 The melt strength (LMS) is determined according to formula (III). LMS = 17.35MFR -0.994 (III) In the formula, MFR is the melt flow rate MFR2 (230 °C, 2.16 kg) determined according to ISO 1133 of the high melt strength polypropylene (HMS-PP). The process described in Embodiment 1.

[0123] 3. The following a) A step of preparing a linear propylene homopolymer (H-PP), b) A step of irradiating the linear propylene homopolymer (H-PP) prepared in step a) with electron beam irradiation. Step b) includes at least two irradiation periods, There is a period without irradiation between each irradiation period. Each non-irradiation period is in the range of more than 0.01 minutes to 20 minutes, preferably 1.0 minutes to 20 minutes, and more preferably 2.0 minutes to 20 minutes. The process described in Embodiment 1 or Embodiment 2.

[0124] 4. The following a) A step of preparing a linear propylene polymer (L-PP), a1) A step of blending the linear propylene polymer (L-PP) prepared in step a) with a coupling agent (CA) containing a polyunsaturated organic compound. b) A step of irradiating the blend obtained in step a1) with electron beam irradiation. Step b) includes at least two irradiation periods, There is a period without irradiation between each irradiation period. Each non-irradiation period is in the range of more than 0.01 minutes to 20 minutes, preferably 1.0 minutes to 20 minutes, and more preferably 2.0 minutes to 20 minutes. The process described in any one of Embodiments 1 to 3.

[0125] 5. The following a) A step of preparing a linear propylene homopolymer (H-PP), a1) A step of blending the above linear propylene homopolymer (H-PP) with a coupling agent (CA) containing a polyunsaturated organic compound, b) A step of irradiating the blend obtained in step a1) with electron beam irradiation. Step b) includes at least two irradiation periods, There is a period without irradiation between each irradiation period. Each non-irradiation period is in the range of more than 0.01 minutes to 20 minutes, preferably 1.0 minutes to 20 minutes, and more preferably 2.0 minutes to 20 minutes. The process described in any one of Embodiments 1 to 4.

[0126] 6. The following a) A step of preparing a linear propylene polymer (L-PP), a1) A step of blending the above linear propylene polymer (L-PP) with a coupling agent (CA) containing polyunsaturated fatty acids, b) A step of irradiating the blend obtained in step a1) with electron beam irradiation. Step b) includes at least two irradiation periods, There is a period without irradiation between each irradiation period. Each non-irradiation period is in the range of more than 0.01 minutes to 20 minutes, preferably 1.0 minutes to 20 minutes, and more preferably 2.0 minutes to 20 minutes. The process described in any one of Embodiments 1 to 5.

[0127] 7. The following a) A step of preparing a linear propylene homopolymer (H-PP), a1) A step of blending the above linear propylene homopolymer (H-PP) with a coupling agent (CA) containing polyunsaturated fatty acids, b) A step of irradiating the blend obtained in step a1) with electron beam irradiation. Step b) includes at least two irradiation periods, There is a period without irradiation between each irradiation period. Each non-irradiation period is in the range of more than 0.01 minutes to 20 minutes, preferably 1.0 minutes to 20 minutes, and more preferably 2.0 minutes to 20 minutes. The process described in any one of Embodiments 1 to 6.

[0128] 8. The process according to any one of embodiments 4 to 7, wherein the blend obtained in step a1) contains 0.01 to 5.0% by weight, more preferably 0.1 to 2.0% by weight, of the coupling agent (CA) containing the polyunsaturated organic compound, based on the total weight of the blend obtained in step a1).

[0129] 9. The process according to any one of embodiments 4 to 8, wherein the amount of the polyunsaturated organic compound in the coupling agent (CA) containing the above-mentioned polyunsaturated organic compound is in the range of 20% to 100% by weight, preferably 30% to 90% by weight, and more preferably 40% to 80% by weight.

[0130] 10. The process according to any one of embodiments 4 to 9, wherein the coupling agent (CA) containing the polyunsaturated organic compound is selected from the group consisting of linseed oil, walnut oil, tung oil, and sunflower oil, and is preferably linseed oil, more preferably virgin linseed oil.

[0131] 11. The process according to any one of embodiments 4 to 10, wherein the blend of L-PP and CA obtained in step a1) further comprises an antioxidant in an amount ranging from 10 to 500 ppm, preferably 25 to 200 ppm, based on the total weight of the blend, and / or a process stabilizer in an amount ranging from 10 to 500 ppm, preferably 25 to 200 ppm, based on the total weight of the blend.

[0132] 12. The process according to any one of embodiments 1 to 11, wherein the maximum pressure in the process does not exceed 0.2 bar and is in the range of 0.0 to 0.2 bar.

[0133] 13. The process according to any one of embodiments 1 to 11, wherein the pressure in the process is greater than 0.2 bar, preferably in the range of greater than 0.2 bar to 2.0 bar.

[0134] 14. The process according to any one of embodiments 1 to 13, wherein the process further comprises a step c) after step b), the step c) comprising a temperature adjustment period, during which the irradiated mixture obtained in step b) is temperature-adjusted to a temperature in the range of 40 to 140°C, preferably 50 to 70°C.

[0135] 15. The process according to any one of embodiments 1 to 14, wherein the temperature adjustment period in step c) is in the range of 5 minutes to 120 minutes, preferably 45 minutes to 90 minutes.

[0136] 16. The process according to any one of embodiments 1 to 15, wherein in step b), the surface radiation dose applied during the first irradiation period of the at least two irradiation periods is in the range of 10 to 150 kGy, preferably 55 to 130 kGy, and more preferably 60 to 110 kGy.

[0137] 17. The process according to any one of embodiments 1 to 16, wherein in step b), the surface radiation dose applied during the second irradiation period of the at least two irradiation periods is in the range of 5 to 150 kGy, preferably 8 to 80 kGy, and more preferably 10 to 50 kGy.

[0138] 18. The process according to any one of embodiments 1 to 17, wherein in step b), the ratio of the surface radiation dose applied during the first irradiation period of the at least two irradiation periods to the surface radiation dose applied during the second irradiation period of the at least two irradiation periods is in the range of greater than 1.1 to 30, preferably 1.2 to 15, and more preferably 1.5 to 8.0.

[0139] 19. The process according to any one of embodiments 1 to 18, wherein the total surface radiation dose applied in the above process is in the range of 30 kGy to 200 kGy, preferably 50 kGy to 180 kGy, and more preferably 60 kGy to 130 kGy.

[0140] 20. The process according to any one of embodiments 1 to 19, wherein the electron beam for the electron beam irradiation is an electron beam having an acceleration voltage in the range of 5 MeV to 15 MeV, preferably 7 MeV to 13 MeV, and more preferably 8 MeV to 12 MeV.

[0141] 21. The process according to any one of embodiments 1 to 20, wherein step b) comprises two irradiation periods and a non-irradiation period in between, the non-irradiation period being in the range of 0.01 minutes to 20 minutes, preferably 1.0 minutes to 20 minutes, and more preferably 2.0 minutes to 20 minutes.

[0142] 22. The following a) A step of preparing a linear propylene polymer (L-PP), preferably a linear propylene homopolymer (H-PP), a1) A step of blending the above propylene polymer (L-PP) with a coupling agent (CA) containing a polyunsaturated organic compound, preferably a polyunsaturated fatty acid, b) A step of irradiating the blend obtained in step a1) with electron beam irradiation, c) A step of adjusting the temperature of the irradiated blend obtained in step b) to a temperature in the range of 50°C to 70°C. Step b) includes two irradiation periods and one non-irradiation period between these two irradiation periods, preferably consisting of these. The surface radiation dose applied during the first irradiation period is in the range of 60 kGy to 110 kGy. The surface radiation dose applied during the second irradiation period is in the range of 10 kGy to 50 kGy. The period without irradiation between the two irradiation periods mentioned above ranges from 2 to 20 minutes. The temperature adjustment period in step c) is in the range of 45 to 90 minutes. The process described in any one of Embodiments 1 to 21.

[0143] 23. The process according to any one of embodiments 1 to 22, wherein the linear polypropylene (L-PP) prepared in step a) or the blend obtained in step a1) is placed in a sealable containment facility before irradiation in step b).

[0144] 24. The process according to embodiment 23, wherein the sealable containment facility containing the linear polypropylene (L-PP) prepared in step a) or the blend obtained in step a1) is flushed with nitrogen inside the containment facility until an atmosphere with oxygen in the range of 1 to 1000 ppm, preferably 50 to 400 ppm, more preferably 100 to 300 ppm is achieved.

[0145] 25. The process according to any one of embodiments 1 to 24, wherein the process comprises a further step d) after step b) or step c), the step d) comprising homogenizing the irradiated L-PP or irradiated blend obtained in step b) or step c).

[0146] 26. The process according to embodiment 25, wherein an additive (AD) may be added to the irradiated L-PP or irradiated blend obtained in step b) or step c) before or during the homogenization described above.

[0147] 27. The process according to embodiment 25, wherein the additive (AD) is applied to the surface of homogenized irradiated L-PP or homogenized irradiated blend.

[0148] 28. i) Propylene, and ii) At least one polyunsaturated fatty acid High melt strength polypropylene (HMS-PP) containing units that can be derived from, The above high melt strength polypropylene (HMS-PP) has a crystallization temperature Tc measured according to DSC in the range of over 120°C, preferably 120°C to 132°C. F measured by Rheotens according to ISO 16790:2005 at 200℃, 120 mm / sec acceleration, and standard shear (die pressure 30 bar). 30The melt strength is greater than 26 cN, preferably in the range of greater than 26 cN to 50 cN. The melt flow rate MFR2 (230°C, 2.16 kg), determined according to ISO 1133, is in the range of 1.0 to 2.4 g / 10 min. Complex shear viscosity η at a frequency of 285 rad / s, determined by dynamic shear measurements in accordance with ISO standards 6721-1 and 6721-10. * The pressure is greater than 170 Pa·s, preferably in the range of greater than 170 Pa·s to 220 Pa·s. High melt strength polypropylene (HMS-PP).

[0149] 29. The high melt-strength polypropylene (HMS-PP) according to Embodiment 28, wherein the HMS-PP is obtained by the process described in any one of Embodiments 1 to 27.

[0150] 30. High melt strength polypropylene (HMS-PP) according to embodiment 28 or 29, wherein the units that can be derived from at least one polyunsaturated fatty acid are derived from linseed oil as a coupling agent (CA) containing a polyunsaturated organic compound.

[0151] 31. An article comprising high melt strength polypropylene (HMS-PP) as described in any one of embodiments 28 to 30.

[0152] 32. Use of high melt strength polypropylene (HMS-PP) according to any one of claims 28 to 30 for foam applications, preferably extruded foam, bead foam, injection-molded foam or coated foam. [Examples]

[0153] Measurement method The following definitions and methods of determining terms apply to the above general description of the present invention and the following embodiments, unless otherwise specified.

[0154] MFR2 (230°C) is measured according to ISO 1133 (230°C, 2.16 kg load).

[0155] GPC measurement A gel permeation chromatograph (GPC) manufactured by PolymerChar (Valencia, Spain) was used, equipped with an infrared detector (IR5), an online four-capillary bridge viscometer, and a multi-angle light scattering (MALS) detector (Dawn Helios 2) from Wyatt Technology (Santa Barbara, USA) with 18 angle settings ranging from approximately 22.5° to 147.0°. Three Agilent Olexis columns and one Olexis Guard column were used as the stationary phase, and 1,2,4-trichlorobenzene (TCB, stabilized with 250 mg / L of 2,6-di-tert-butyl-4-methylphenol) was applied as the mobile phase at a constant flow rate of 1 mL / min at 160°C. Polymer samples were dissolved in TCB at a concentration of 1 mg / ml for 150 minutes at 160°C. 200 μl of polymer solution was injected for each analysis. The injection concentration of the polymer solution at 160°C (c 160℃ The following method was used to determine this.

[0156] GPC-VISC-MALS The IV detector was calibrated according to NIST1475a using a nominal IV of 1.01 dl / g. The inter-detector volume between different detectors—concentration (IR) detector, LS detector, and viscometer detector—was achieved by analyzing a narrow-distribution PS standard with a molar mass of 30,000 g / mol. For determining MWD using GPC-VISC-MALS technology, normalization of different MALS angles was obtained using a narrow-distribution PS standard with a molar mass of 30,000 g / mol. The MALS detector was calibrated with the certified PE standard NIST1475a with a Mw of 54,000 g / mol, using a laser wavelength of 660 nm (λ0) and a dn / dc of 0.094 ml / mg. For molecular weight calculations, a laser wavelength of 660 nm (λ0) and a dn / dc of 0.094 ml / mg for PP in TCB solution were used. Due to higher baseline noise and frequent disturbances, the MALS signals for the three smallest angles were not used in all calculations. The second virial coefficient (A2=0) was ignored due to the low sample concentrations used. Absolute Mw and corresponding radius of inertia (R) in each chromatographic slice are given. g The values ​​were obtained from the slope and intercept of the Debye plot. i The Zimm formula was used to extrapolate the corresponding Rayleigh ratio (R(θ)) for different angles. The average molecular weight (Mz(LS), Mw(LS), and Mn(LS)), molecular weight distribution (MWD), and its extent (polydispersibility, described by PD(LS) = Mw(LS) / Mn(LS) (wherein Mn(LS) is the number-average molecular weight and Mw(LS) is the weight-average molecular weight obtained from GPC-LS)) were calculated by gel permeation chromatography (GPC) using the following formula.

number

number

[0157] Conventional GPC The column set was calibrated using universal calibration with 19 polystyrene (PS) standards having a narrow molecular weight distribution (MWD) ranging from 0.5 kg / mol to 11500 kg / mol. The PS standards were dissolved at 160°C for 30 minutes. The conversion of polystyrene peak molecular weight to polypropylene molecular weight was achieved using the Mark Houwink formula and the following Mark Houwink constants. K PS = 19 × 10 -3 mL / g, α PS =0.655 K PP = 19 × 10 -3 mL / g, α PP =0.725 The calibration data was fitted using cubic polynomial fitting. The average molecular weight (Mz, Mw, and Mn), molecular weight distribution (MWD), and its extent (described by the polydispersity index, PDI = Mw / Mn (where Mn is the number-average molecular weight and Mw is the weight-average molecular weight)) were determined by gel permeation chromatography (GPC) using the following formula.

number

[0158] gpcBR index The gpcBR index is calculated using the following formula.

number

[0159] Concentration of grafted coupling agent (alpha-linolenic acid) after irradiation 1 Determination by 1H-NMR 1. Soxhlet extraction to remove ungrafted coupling agent Weigh 2.5 g of the pulverized sample into a Soxhlet sleeve. Add 200 ml of n-hexane to a round-bottom flask (250 ml) and insert the sleeve into the Soxhlet. Extraction of the ungrafted coupling agent is carried out under reflux cooling for 24 hours. Dry the residue overnight in a vacuum drying oven at 90°C and cool to room temperature. 1 It is used in 1H NMR spectroscopy.

[0160] 2. 1 Method of 1H NMR spectroscopy quantitative 1 ¹H NMR spectra were recorded in solution using a Bruker AVNEO 400 NMR spectrometer operating at 400.15 MHz. All spectra were recorded at 125°C. 13Recording was performed using nitrogen gas for all pneumatic pressures with a 10 mm selective excitation probe head optimized for 1C. Approximately 200 mg of material was dissolved in approximately 3 ml of 1,2-tetrachloroethane-d2 (TCE-d2) using approximately 3 mg of Hostanox O3 (CAS 32509-66-3) as a stabilizer. Standard single-pulse excitation was employed using a 30° pulse, a 3-second relaxation delay, and a 10 Hz sample rotation. A total of 64k data points were collected per FID with a sampling interval of 61 μs, corresponding to a spectral window of approximately 20 ppm. 512 transient signals per spectrum were acquired using four dummy scans. This setting was chosen for high sensitivity, resolution, and stability with respect to unsaturated species. quantitative 1 The H spectra were processed and integrated using an exponential window function with line broadening at 0.3 Hz, and the relevant ratios were determined from the intensity of the integral. All chemical shifts were indirectly referenced to 0.00 ppm TMS using the signal from 5.95 ppm residual protonated solvent {Resconi L., Cavallo L., Fait A., Piemontesi F., Chem. Rev. 2000, 100, 1253} and the intensity of the aliphatic bulk signal (I bulk ) was set to 100000. Table 1 summarizes the specific structural groups corresponding to the presence of the listed structural groups. 1 Characteristic signals were observed in the 1H NMR chemical shift {Resconi L., Piemontesi F., Camurati I., Sudmeijer O., Nifantef IE, Ivschenko PV, Kuzmina LG, J.Am.Soc. 1998, 120, 2308-2321}.

[0161] [Table 1]

[0162] The ratio of the intensities of specific groups was calculated to compensate for the influence of other groups. Ratio x / z = x / (zw) Ratio x / y = x / (y - (h / 4 × 4²))

[0163] Quantification of fine structure by NMR spectroscopy Quantitative nuclear magnetic resonance (NMR) spectroscopy was performed as described in the international publication brochure No. 2022 / 238520A1.

[0164] Intrinsic viscosity (IV) was measured according to DIN ISO 1628 / 1, October 1999 (in decalin, 135°C).

[0165] Melting temperature Tm, crystallization temperature Tc, and enthalpy of fusion Hm The melting temperature Tm was determined by differential scanning calorimetry (DSC) according to ISO 11357-3 using a TA-Instruments 2920 Dual-Cell equipped with an RSC cooler and data station. A heating rate of 10°C / min was applied to the heating / cooling / heating cycle between +23°C and +210°C. The crystallization temperature (Tc) was determined from the cooling step, while the melting temperature (Tm) and enthalpy of melting (Hm) were determined from the second heating step.

[0166] F 30 and F 200 Melt strength and v 30 Melt-stretchable The tests described herein conform to ISO 16790:2005. The strain-curing behavior was determined by the method described in the paper "Rheotens-Mastercurves and Drawability of Polymer Melts" by M.H. Wagner, Polymer Engineering and Science, Vol. 36, pp. 925-935. The strain-curing behavior of the polymer was analyzed using a Rheotens apparatus (Siemensstr. 2, 74711 Buchen, Goettfert, Germany). In this apparatus, the molten strands are stretched by pulling them down at a specified acceleration. The Rheotens experiment simulates industrial spinning and extrusion processes. In principle, a molten material is compressed or extruded through a circular die to extract the resulting strand. The stress on the extruded product is recorded as a function of the molten material properties and measurement parameters (particularly the ratio of output to extraction speed, practically a measure of elongation). For the results shown below, the material was extruded using an experimental HAAKE Polylab system extruder and a gear pump equipped with a cylindrical die (L / D = 6.0 / 2.0 mm). 30 Melt strength and v 30 To measure melt-stretchability, the pressure at the extruder outlet (=gear pump inlet) is set to 30 bar by bypassing a portion of the extruded polymer. 200 To measure the melt strength, the pressure at the extruder outlet (=gear pump inlet) is set to 200 bar by bypassing a portion of the extruded polymer. The gear pump was pre-adjusted to extrude the strand at a speed of 5 mm / s, and the melting temperature was set to 200°C. The spinline 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 match the speed of the extruded polymer strand (zero tensile force). Then, the winding speed of the Rheotens wheel was slowly increased until the polymer filament broke, and the experiment began. The wheel acceleration was kept small enough so that the tensile force could be measured in a quasi-steady state. The acceleration of the pulled-down melt strand was 120 mm / s². 2 This Rheotens was operated in combination with the PC program "EXTENS". This is a real-time data acquisition program that displays and saves measurement data of tensile force and drawdown speed. The endpoints of the Rheotens curve (force vs. pulley rotation speed) where the polymer strand breaks are defined as F 30 Melt strength and v 30 Melt-stretchability value, or F 200 This will be defined as the melt strength.

[0167] The additional melt strength (AMS) is calculated according to equation (II). AMS = MS(HMS-PP)-LMS (II) In the above formula (II), AMS is a linear polypropylene having a melt flow rate MFR2 (230°C, 2.16 kg) determined according to the same ISO 1133 as high melt strength polypropylene (HMS-PP). 30 Additional F determined according to ISO 16790:2005 when compared to melt strength (LMS) 30 The melt strength (AMS) [unit: cN] is defined as F of high melt strength polypropylene (HMS-PP) as determined according to ISO 16790:2005. 30 The melt strength [unit: cN] is that LMS is a linear polypropylene having a melt flow rate MFR2 (230℃, 2.16kg) determined according to the same ISO 1133 as high melt strength polypropylene (HMS-PP). 30 It has a melt strength (LMS) [unit: cN] and the same melt flow rate and polydispersity in the range of 3-5 as the corresponding linear polypropylene F 30 The melt strength (LMS) is determined according to equation (III), LMS = 17.35 MFR -0.994 (III) In formula (III) above, MFR is the melt flow rate MFR2 (230°C, 2.16 kg) determined according to ISO 1133 for high melt strength polypropylene (HMS-PP). Formula (III) is the melt flow rate MFR2 (230°C, 2.16 kg) of a commercially available linear propylene homopolymer tested by Rheotens, determined according to ISO 1133, and F as defined above. 30 This is the fitting function for melt strength. The melt flow rate and F of the above commercially available linear propylene homopolymer manufactured by Borealis. 30 The melt strengths are summarized in Table 2.

[0168] [Table 2]

[0169] Shear thinning index (SHI) The characterization of polymer molten materials by dynamic shear measurement was performed in accordance with ISO standards 6721-1 and 6721-10. Measurements were conducted using an Anton Paar MCR501 stress-controlled rotational rheometer with a 25 mm parallel plate configuration. Measurements were performed on compression-molded plates under a nitrogen atmosphere, with strain set within the linear viscoelastic region. Vibration shear tests were conducted at 200°C with a frequency range of 0.01 to 300 rad / s, a gap of 0.5 mm, and a vibration shear test. In dynamic shear experiments, the probe is subjected to uniform deformation under sinusoidal shear strain or shear stress (modes where strain and stress are controlled, respectively). In controlled strain experiments, the probe is subjected to sinusoidal strain, which can be expressed by the following equation. γ(t)=γ0sin(ωt) (1) If the applied strain is within the linear viscoelastic region, the resulting sinusoidal stress response can be given by the following equation. σ(t)=σ0sin(ωt+δ) (2) In the above equation, σ0 and γ0 are the stress amplitude and strain amplitude, respectively, ω is the angular frequency, δ is the phase difference (the loss angle between the applied strain and the stress response), and t is time. Dynamic test results typically yield several different rheological functions, namely the shear storage modulus G', the shear loss modulus G'', and the complex shear modulus G''. * , complex shear viscosity η * The rheological function is expressed in terms of the dynamic shear viscosity η', the heterophase component η'' of the complex shear viscosity, and the loss tangent tanη, and can be expressed as follows.

number

[0170] The so-called shear fluidity index, which correlates with MWD and is independent of Mw, is determined as shown in Equation 9.

number

number

[0171] Examples of Inventions Examples IE1 to IE5 and comparative examples CE1 and CE2 were prepared as follows. precursor material The linear precursor is produced by a slurry process using a Ziegler-Natta catalyst, at a rate of 0.6 g / 10 min (230°C, 2.16 kg / cm³). 2MFR2 (ISO1133), melting point 161°C, crystallization temperature 116°C, isotacticity 97.3% ( 13 Borealis' linear polypropylene homopolymer HA001 was used, which has a pentad concentration (determined by 13C NMR) and contains 50 ppm by weight of Irganox 1076 (an antioxidant by BASF). 30 The melt strength is 35 cN. The linseed oil was purchased from Lausitzer Oelmuehle Hoyerswerda GmbH and is a cold-pressed linseed oil containing 99g of fat, 23g of monounsaturated fatty acids, 60g of polyunsaturated fatty acids, 15g of saturated fatty acids, and 0.22g of protein per 100mL.

[0172] Preparation of formulations Borealis propylene homopolymer fluff HA001 was blended with 0.25% by weight linseed oil and 0.05% by weight calcium stearate into pellets (PP pellets) under nitrogen using a Prism TSE 24MC twin-screw extruder at a rate of 10 kg / h and a screw rotation speed of 200 rpm. The additives were added to the extruder either by pre-blending or direct addition. The extruder temperature was set to 220°C. The MFR2 of the formulation containing linseed oil and calcium stearate used in the irradiation test was 1.0 g / 10 min (230°C, 2.16 kg / cm²). 2 It was ISO1133).

[0173] Sample preparation Two kilograms of the above-mentioned PP pellets were placed in an aluminum cylinder with a wall thickness of 2 mm and an outer diameter of 100 mm, equipped with a safety valve to ensure a maximum pressure of 0.2 bar. Before irradiation, the cylinder was flushed with nitrogen, and approximately 70 L of N2 / kg PP was used to bring the oxygen concentration in the gas phase to 200 ppm at equilibrium.

[0174] Electron beam irradiation General procedure of the present invention for IE1-IE5: An aluminum cylinder containing PP pellets and a nitrogen atmosphere with a specified O2 concentration of 200-300 ppm is placed on a belt at 25°C. The cylinder is then moved at a first belt speed V1, passing a 10 MeV electron beam (IBA TT200 with a beam current of 5 mA) through it, thereby applying a first surface radiation dose to the sample. The belt is then stopped for a specific period (reaction time), and then moved in the reverse direction at a second belt speed V2, thereby passing the electron beam through again and applying a second surface radiation dose to the sample (see Table 1 for precise reaction parameters). After that, the cylinder is stored at 60°C for 1 hour to complete the reaction (radical deactivation), and the sample is cooled by flushing the cylinder with nitrogen.

[0175] Comparative examples CE1~CE2: The procedure is the same as inventive examples IE1 to IE5, except that the sample is exposed to only one surface radiation dose and then directly stored at a temperature of 60°C for 1 hour. For stabilization, each of the obtained products was blended with 0.3 wt% Irganox 1010 (antioxidant by BASF) and 0.3 wt% Irgafos 168 (processing stabilizer by BASF) in a Prism TSE 24MC twin-screw extruder with a barrel length of L / D 40, under nitrogen, at a rate of 10 kg / h, a screw speed of 300 rpm, and a temperature of 220°C.

[0176] [Table 3]

[0177] [Table 4]

[0178] [Table 5]

[0179] As can be seen from Table 4, HMS-PP IE1 to IE5 obtained by the process of the present invention have higher F and F melt strength compared to CE1 and CE2 with only one irradiation period. Furthermore, the lower MFR2 and higher gpcBR of the inventive examples indicate that a higher degree of branching is achieved. A higher shear hardening index (SHI) is also achieved. 30 and F 200 As can be seen from Table 4, HMS-PP IE1 to IE5 obtained by the process of the present invention have higher F and F melt strength compared to CE1 and CE2 with only one irradiation period. Furthermore, the lower MFR2 and higher gpcBR of the inventive examples indicate that a higher degree of branching is achieved. A higher shear hardening index (SHI) is also achieved.

Claims

1. A method for producing high melt strength polypropylene (HMS-PP), a) A step of preparing a linear propylene polymer (L-PP), preferably a linear propylene homopolymer (H-PP), a1) Optionally, a step of blending the propylene polymer (L-PP) with a coupling agent (CA) containing a polyunsaturated organic compound, preferably a polyunsaturated fatty acid, b) A step of irradiating the L-PP prepared in step a) or the blend obtained in step a1) with electron beam irradiation. It includes the above in the order, Step b) includes at least two irradiation periods, There is a period without irradiation between each irradiation period. A method wherein each non-irradiation period is in the range of 0.01 minutes to 20 minutes, preferably 1.0 minutes to 20 minutes, and more preferably 2.0 minutes to 20 minutes.

2. In step b), the surface radiation dose applied during the first irradiation period of the at least two irradiation periods is in the range of 10 to 150 kGy, preferably 50 kGy to 130 kGy, and more preferably 60 kGy to 110 kGy. And / or the surface radiation dose applied during the second of the at least two irradiation periods is in the range of 5 kGy to 150 kGy, preferably 8 kGy to 80 kGy, more preferably 10 kGy to 50 kGy. And / or the ratio of the surface radiation dose applied during the first irradiation period of the at least two irradiation periods to the surface radiation dose applied during the second irradiation period of the at least two irradiation periods is in the range of greater than 1.1 to 30, preferably 1.2 to 15, and more preferably 1.5 to 8.

0. And / or the total surface radiation dose applied in the above method is in the range of 30 kGy to 200 kGy, preferably 50 kGy to 180 kGy, and more preferably 60 kGy to 130 kGy. The method according to claim 1.

3. The method comprises step a1), wherein the blend obtained in step a1) comprises a coupling agent (CA) containing the polyunsaturated organic compound in an amount of 0.01 to 5.0% by weight, more preferably 0.1 to 2.0% by weight, based on the total weight of the blend obtained in step a1), And / or the amount of the polyunsaturated organic compound in the coupling agent (CA) containing the polyunsaturated organic compound is in the range of 20% to 100% by weight, preferably 30% to 90% by weight, and more preferably 40% to 80% by weight. And / or the coupling agent (CA) containing the polyunsaturated organic compound is selected from the group consisting of linseed oil, walnut oil, tung oil, and sunflower oil, preferably linseed oil, and more preferably virgin linseed oil. The method according to claim 1 or claim 2.

4. The maximum pressure in the above method does not exceed 0.2 bar, and is preferably in the range of 0.0 to 0.2 bar. Alternatively, the pressure in the above method is greater than 0.2 bar, preferably in the range of greater than 0.2 bar to 2.0 bar. The method according to any one of claims 1 to 3.

5. The method includes a further step c) after step b), the step c) including a temperature adjustment period, during which the irradiated L-PP or irradiated blend obtained in step b) is temperature-adjusted to a temperature in the range of 40 to 140°C, preferably 50 to 70°C. And / or the temperature adjustment period in step c) is in the range of 5 minutes to 120 minutes, preferably 45 minutes to 90 minutes. The method according to any one of claims 1 to 4.

6. The method according to any one of claims 1 to 5, wherein the electron beam for electron beam irradiation is an electron beam having an acceleration voltage in the range of 5 MeV to 15 MeV, preferably 7 MeV to 13 MeV, more preferably 8 MeV to 12 MeV.

7. The method according to any one of claims 1 to 6, wherein step b) comprises two irradiation periods and a non-irradiation period between them, the non-irradiation period being in the range of 0.01 minutes to 20 minutes, preferably 1.0 minutes to 20 minutes, and more preferably 2.0 minutes to 20 minutes.

8. The method according to any one of claims 1 to 7, wherein the L-PP prepared in step a) or the blend obtained in step a1) is placed in a sealable containment facility before irradiation in step b).

9. The method according to claim 8, wherein the sealable containment facility containing the L-PP prepared in step a) or the blend obtained in step a1) is flashed with nitrogen until an atmosphere having an amount of oxygen in the range of 1 to 1000 ppm, preferably 50 to 400 ppm, more preferably 100 to 300 ppm, is reached inside the containment facility.

10. The method according to any one of claims 1 to 9, wherein the method comprises a further step d) after step b) or step c), the step d) comprising homogenizing the irradiated L-PP or irradiated blend obtained in step b) or step c).

11. Additives (AD) may be added to the irradiated L-PP or irradiated blend obtained after step b) or step c) before or during homogenization in step d), and / or The additive (AD) is applied to the surface of the homogenized irradiated L-PP or homogenized irradiated blend obtained after step d). The method according to claim 10.

12. i) Propylene, and ii) At least one polyunsaturated fatty acid High melt strength polypropylene (HMS-PP) containing units that can be derived from, The aforementioned high melt strength polypropylene (HMS-PP) has a crystallization temperature Tc determined according to DSC in the range of over 120°C, preferably 120°C to 132°C. F measured by Rheotens according to ISO 16790:2005 at 200°C, 120 mm / s acceleration, and standard shear (die pressure 30 bar). ３０ The melt strength is greater than 26 cN, preferably in the range of greater than 26 cN to 50 cN. Melt flow rate MFR determined in accordance with ISO 1133 ２ (230℃, 2.16kg) is in the range of 1.0 to 2.4 g / 10 min. Complex shear viscosity η at a frequency of 285 rad / s, determined by dynamic shear measurements in accordance with ISO standards 6721-1 and 6721-10. ＊ This refers to high melt strength polypropylene (HMS-PP) having a pressure of more than 170 Pa·s, preferably in the range of more than 170 Pa·s to 220 Pa·s.

13. The HMS-PP is obtained by the method described in any one of claims 1 to 11, the high melt strength polypropylene (HMS-PP) according to claim 12.

14. An article comprising high melt strength polypropylene (HMS-PP) as described in claim 12 or claim 13.

15. Use of high melt strength polypropylene (HMS-PP) according to claim 12 or 13 for foam applications, preferably extruded foams, bead foams, injection-molded foams, or coated foams.

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