Polymer production process and polymer

Abstract

The present invention relates to a polymer production process, a corresponding polymer and an article comprising a polymer as prepared by the process of the present invention.

Description

[0001] The present invention relates to a process for producing a polymer, a corresponding polymer, and an article comprising a polymer prepared by the process according to the present invention.

[0002] Unimodal polyethylene (PE) polymers (e.g., SSC products) are typically used in film applications. Unimodal PE polymers, for example, have good optical properties such as low haze. However, for example, from a production perspective, the melt processing of such polymers is not satisfactory and may also cause quality problems in the finished product. Multimodal PE polymers having two or more different polymer components are more easily processed. However, for example, there may be problems with the melt homogenization of multimodal PE, resulting in a non-uniform finished product, such as a high gel content in the finished product.

[0003] Borealis' EP1472298A discloses a multimodal PE polymer composition having two different comonomers. The polymerization of the multimodal PE polymer is carried out using a metallocene catalyst. The examples disclose multimodal PE polymers having two polymer components, for example, having different types of comonomers. The publication seems to define any range of the melt flow rate MFR 21 / MFR2 (FRR 21 / 2 ), however, the variation range of the melt flow rate of the exemplary polymers is 38 - 55.

[0004] To provide customized solutions, there is a continuous search for multimodal PE polymers with different performance balances to meet the growing needs of end - application producers, such as for reducing production costs and / or maintaining or even improving the properties of the finished product, especially the balance between, for example, the breaking stress and / or toughness and / or stiffness and toughness, and optical properties such as gloss and / or haze. To meet the evolving equipment technology requirements in end - application fields, customized polymer solutions are also needed. Summary of the Invention

[0005] The present invention relates to a process for producing a polymer, characterized in that the polymerization reaction in the first polymerization zone is carried out in a slurry using ethylene and hydrogen to obtain a first ethylene polymer component (A), and preferably the polymerization reaction of the second ethylene polymer component (B) in the second polymerization zone is carried out in a gas phase using ethylene and a comonomer to produce an ethylene multimodal polymer (a), and the ethylene multimodal polymer (a) has at least one comonomer selected from α - olefins having 4 to 10 carbon atoms,

[0006] - which has

[0007] a) MFR2 of 0.5 - 10 g / 10 min (according to ISO 1133, 190 °C, load 2.16 kg);

[0008] b) MFR 21 / MFR2 is 13 - 35 (MFR 21 , 190 °C, load 21.6 kg), and

[0009] c) MWD ≤ 5;

[0010] - It comprises at least

[0011] - Ethylene polymer component (A), and

[0012] - Ethylene polymer component (B),

[0013] wherein, according to ISO 1133, at 190 °C and a load of 2.16 kg, the MFR2 of the ethylene polymer component (A) is higher than the MFR2 of the ethylene polymer component (B), and the MFR2 of the ethylene polymer component (B) < 0.64 g / 10 min.

[0014] The process as described in the present invention can be particularly used for producing polymers for film applications, especially film applications requiring high toughness and / or good optical properties.

[0015] In the polymer production process as described in the present invention, the range of MFR2 of the ethylene polymer component (B) can be 0.0001 - 0.64 (excluding), preferably 0.001 - 0.60, more preferably 0.01 - 0.55, and further preferably 0.1 - 0.50 g / 10 min according to ISO 1133, at 190 °C and a load of 2.16 kg.

[0016] In the polymer production process as described in the present invention, the polymerization reaction in the first polymerization zone is carried out in a slurry of a second comonomer to obtain the first ethylene polymer component (A).

[0017] In the polymer production process as described in the present invention, the first polymerization zone can include at least one slurry loop reactor, and the second polymerization zone can include at least one gas phase reactor, and the reactors are preferably connected in series.

[0018] In the polymer production process as described in the present invention, the first polymerization zone can include two slurry loop reactors, which are preferably connected in series, and / or more preferably such that the ratio of the second comonomer to ethylene in the first loop is higher than that in the second loop.

[0019] In the polymer production process as described in the present invention, the first polymerization zone can include two series-connected slurry loop reactors, and hydrogen is added to the first slurry loop reactor and / or the second loop reactor, preferably only to the first loop reactor.

[0020] In the polymer production process as described in the present invention, the first polymerization zone may include two slurry loop reactors connected in series, whereby hydrogen is supplied only to the first slurry loop reactor, and the two slurry loop reactors operate under the same conditions or different conditions in other ways, preferably under the same conditions.

[0021] In the polymer production process as described in the present invention, the polymerization of the second ethylene polymer component (B) in the second polymerization zone is preferably carried out in the gas phase to maximize the molecular weight and / or without supplying hydrogen to the second polymerization zone. Maximizing the molecular weight may mean, for example, especially in the case of a chain transfer agent, especially when substantially no hydrogen or no hydrogen is supplied to the second polymerization zone, or the polymerization reaction in the second polymerization zone is carried out without substantially using hydrogen or without using hydrogen or without adding hydrogen to the second polymerization zone.

[0022] In the polymer production process as described in the present invention, the MFR2 of the ethylene polymer component (A) may be 1-50 g / 10 min, preferably 1-40 g / 10 min, more preferably 1-30 g / 10 min, or the ratio of the MFR2 of the ethylene polymer component (A) to the MFR2 of the ethylene final multimodal polymer (a) may be 2-50, preferably 5-40, preferably 10-30.

[0023] In the polymer production process as described in the present invention, a second comonomer can be used to produce the ethylene polymer component (A), and the comonomer and the second comonomer may be at least two α-olefin comonomers having 4 to 10 carbon atoms, preferably 1-butene and 1-hexene, and further preferably the α-olefin comonomer having 4 to 10 carbon atoms in the ethylene polymer component (A) may be different from the α-olefin comonomer having 4 to 10 carbon atoms in the ethylene polymer component (B). Preferably, the second α-olefin comonomer having 4 to 10 carbon atoms in the ethylene polymer component (A) may be 1-butene, and the α-olefin comonomer having 4 to 10 carbon atoms in the ethylene polymer component (B) may be 1-hexene.

[0024] In the polymer production process as described in the present invention, the ratio of [the content (mol%) of the α-olefin comonomer having 4 to 10 carbon atoms in the ethylene polymer component (A)] to [the content (mol%) of at least two α-olefin comonomers having 4 to 10 carbon atoms in the ethylene final multimodal polymer (a)] may be 0.2-0.6, preferably 0.24-0.5, and more preferably, the content (mol%) of the comonomer in the ethylene polymer component (A) may be lower than that in the ethylene polymer component (B).

[0025] In the polymer production process as described in the present invention, the content (mol%) of the α-olefin comonomer having 4 to 10 carbon atoms in the ethylene polymer component (A) can be 0.03 - 5.0 mol%, preferably 0.05 - 4.0 mol%, more preferably 0.1 - 3.0 mol%, and even more preferably 0.1 - 2.0 mol%.

[0026] In the polymer production process as described in the present invention, the ethylene multimodal polymer (a) can also be multimodal with respect to density. Preferably, the density of the ethylene polymer component (A) can be different from, preferably higher than, the density of the ethylene polymer component (B).

[0027] In the polymer production process as described in the present invention, the density of the ethylene polymer component (A) can be 925 - 950 kg / m 3 , preferably 930 - 945 kg / m 3 , or the density of the ethylene multimodal polymer (a) is 910 - 935 kg / m 3 , preferably 915 - 930 kg / m 3 or > 912 kg / m 3 and < 925 kg / m 3 , or the MFR 21 / MFR2 of the ethylene multimodal polymer (a) can be 13 - 30, preferably 15 - 30, or the ethylene multimodal polymer (a) can be multimodal with respect to MFR, the type of comonomer, comonomer content, and density, or when measured according to ISO 527 - 1 and ISO 527 - 3 and in accordance with the quality standards described under "Measurement Method" from a film sample (thickness 40 μm) composed of the polymer composition, the longitudinal (MD) tensile modulus of the ethylene multimodal polymer (a) can be 200 - 350 MPa, preferably 210 - 330 MPa, or when measured according to the "Dynamic Shear Measurement Method" in the quality standards described under "Measurement Method", the SHI 2.7 / 210 of the polymer composition (preferably the ethylene multimodal polymer (a)) can be 1.5 - 7, preferably 2 - 3.5.

[0028] In the polymer production process as described in the present invention, the ethylene multimodal polymer (a) can be produced using a single-site catalyst. Preferably, the ethylene polymer components (A) and (B) of the ethylene polymer (a) can be produced using the same single-site catalyst.

[0029] Thus, the use of a single-site catalyst in the polymerization reaction of at least one component (A) and / or (B) can mean that, for example, at least one or preferably at least two or preferably all of the components (A) and / or (B) and / or the multimodal polymer (a) can have, for example, an MWD = Mw / Mn of 1.5 - 6.5, preferably 2 - 5.5, more preferably >2 and <5 or <4.5 as determined by GPC.

[0030] The present invention also relates to articles or films comprising the polymer composition produced by the process as described in the present invention.

[0031] In the context of the ethylene polymer (a), the term "multimodal" as used herein refers to the multimodality with respect to the melt flow rate (MFR) of the ethylene polymer components (A) and (B), i.e., the ethylene polymer components (A) and (B) have different MFR values. With respect to one or more other properties between the ethylene polymer components (A) and (B), the (a) multimodal polymer (a) can have other multimodality, as described below.

[0032] The polymer composition as described herein is also referred to herein simply as "polymer composition".

[0033] "(a) Ethylene multimodal polymer having at least two different comonomers, wherein the comonomers are selected from α-olefins having 4 to 10 carbon atoms", or "ethylene multimodal polymer (a)" as defined above, below or in the claims is also referred to herein simply as "ethylene polymer (a)".

[0034] When mentioned simultaneously, the ethylene polymer component (A) and the ethylene polymer component (B) are also referred to as "ethylene polymer components (A) and (B)".

[0035] Surprisingly, the present invention also provides the flexibility to customize the polymer structure most suitable for the selected application.

[0036] Surprisingly, the present invention can thus provide, for example, a favorable balance between processability and improved homogeneity, wherein the processability is, for example, represented by a significantly reduced extruder pressure compared to a unimodal polymer, while the improved homogeneity is, for example, represented by a lower gel content compared to a "substantial" multimodal ethylene polymer.

[0037] Preferably, in addition to the above excellent property balance achieved by the present invention, it also relates to possibly improved mechanical properties, and compared to, for example, a unimodal ethylene polymer having the same final density, higher stiffness (represented, for example, by a higher longitudinal tensile modulus (MD)) can be obtained.

[0038] Even more preferably, the present invention can contribute to obtaining excellent sealing performance, expressed as, for example, a lower heat adhesion temperature at maximum heat adhesion force. The polymer composition provides an unsealing temperature even at a lower temperature.

[0039] Furthermore, the performance balance of the present invention can provide good optical properties, such as excellent haze values.

[0040] The obtained performance balance is highly desirable, for example, for film applications.

[0041] The preferred embodiments, properties, and subgroups of the process, polymer composition, ethylene polymer (a), and its ethylene polymer components (A) and (B) (including their preferred ranges) can be independently summarized, and thus the preferred embodiments of the process, polymer composition, and the article can be further defined in any order or combination.

[0042] Polymer composition, ethylene polymer (a), and ethylene polymer components (A) and ethylene polymer component (B)

[0043] As described above, since the ethylene polymer component (A) and the ethylene polymer component (B) are produced under different polymerization conditions that result in different MFRs (e.g., MFR2), the ethylene polymer (a) is referred to herein as "multimodal", i.e., the polymer composition is multimodal at least with respect to the MFR difference between the two ethylene polymer components (A) and (B). The term "multi" includes "bimodal" compositions consisting of two components having the MFR difference.

[0044] Preferably, the MFR2 of the ethylene polymer component (A) is 1 - 50 g / 10 min, preferably 1 - 40 g / 10 min, more preferably 1 - 30 g / 10 min, more preferably 2 - 20 g / 10 min, more preferably 2 - 15 g / 10 min, and even more preferably 2 - 10 g / 10 min. More preferably, the MFR2 of the ethylene polymer component (A) is higher than that of the ethylene polymer component (B).

[0045] Even more preferably, the ratio of the MFR2 of the ethylene polymer component (A) to the MFR2 of the final multimodal ethylene polymer (a) is 2 - 50, preferably 5 - 40, preferably 10 - 30, more preferably 10 - 25, and more preferably 15 - 25.

[0046] Preferably, the MFR2 of the polymer composition (preferably the ethylene polymer (a)) is preferably 0.5 - 7, preferably 0.5 - 5 g / 10 minutes. Preferably, the MFR of the polymer composition (preferably the ethylene polymer (a)) 21 / MFR2 is from 13 to 30, preferably from 15 to 30, more preferably from 15 to 25.

[0047] If it is not possible to measure the MFR2 of the ethylene polymer component (e.g., component (B)) because it cannot be separated from the mixture of at least the ethylene polymer components (A) or (B), the so-called formula ( (The Polymer Processing Society, Europe / Africa Region Meeting, Gothenburg, Sweden, August 19 - 21, 1997)) can be used for the calculation (MI2 below):

[0048]

[0049] According to the above formula, in the said formula (formula 3), for MFR2, a = 5.2 and b = 0.7. In addition, w is the weight fraction of the other ethylene polymer component (e.g., component (A)) having a higher MFR. Therefore, the ethylene polymer component (A) can be taken as the component 1 and the ethylene polymer component (B) as the component 2. MI b is the MFR2 of the final ethylene polymer (a). Then, when the MFR1 (MI1) of the ethylene polymer component (A) and the MFR2 (MI b ) of the final ethylene polymer (a) are known, the MFR2 (MI2) of the ethylene polymer component (B) can be solved from Equation 1.

[0050] The at least two α-olefin comonomers having 4 to 10 carbon atoms of the ethylene polymer (a) are preferably 1-butene and 1-hexene.

[0051] Naturally, in addition to the multimodality regarding the difference in MFR between the ethylene polymer components (A) and (B), the ethylene polymer (a) of the polymer composition of the present invention can also be multimodal with respect to one or both of two other properties, for example:

[0052] - Multimodality, that is, when referring to the following differences

[0053] - The comonomer type or the comonomer content in the ethylene polymer components (A) and (B), or the comonomer type and content in the ethylene polymer components (A) and (B); and / or

[0054] - The density of the ethylene polymer components (A) and (B).

[0055] Preferably, the ethylene multimodal polymer (a) of the polymer composition is also multimodal with respect to comonomer type and / or comonomer content (mol%), preferably, wherein the α-olefin comonomer having 4 to 10 carbon atoms of the ethylene polymer component (A) is different from the α-olefin comonomer having 4 to 10 carbon atoms of the ethylene polymer component (B), preferably, wherein the α-olefin comonomer having 4 to 10 carbon atoms of the ethylene polymer component (A) is 1-butene, and the α-olefin comonomer having 4 to 10 carbon atoms of the ethylene polymer component (B) is 1-hexene.

[0056] Preferably, the ratio of [the content (mol%) of the α-olefin comonomer having 4 to 10 carbon atoms in the ethylene polymer component (A)] to [the content (mol%) of at least two α-olefin comonomers having 4 to 10 carbon atoms in the final ethylene multimodal polymer (a)] is 0.2 - 0.6, preferably 0.24 - 0.5,

[0057] More preferably, the content (mol%) of the comonomer in the ethylene polymer component (A) is lower than that in the ethylene polymer component (B).

[0058] The comonomer content of components (A) and (B) can be measured, or, in this case, preferably, one component is first produced in a so-called multistage process, and then the other component is produced in the case of using the obtained first component; subsequently, the comonomer content of the first component produced (such as component (A)) can be measured, and the comonomer content of the other component (such as component (B)) can be calculated according to the following formula:

[0059] Comonomer content in component B (mol%) = (Comonomer content in the finished product (mol%) - (Weight fraction of component A * Comonomer content in component A (mol%))) / (Weight fraction of component B)

[0060] Preferably, the content (mol%) of the α-olefin comonomer having 4 to 10 carbon atoms in the ethylene polymer component (A) is 0.03 - 5.0 mol%, preferably 0.05 - 4.0 mol%, more preferably 0.1 - 3.0 mol%, even more preferably 0.1 - 2.0 mol%, more preferably 0.15 - 1.5, even more preferably 0.15 - 1.0 mol%.

[0061] More preferably, the total content of the comonomer in the ethylene multimodal polymer (a) is 0.5 - 10 mol%, preferably 1.0 - 8 mol%, more preferably 1.0 - 5 mol%, more preferably 1.5 - 5.0 mol%.

[0062] Other specific multimodality, i.e., the difference in comonomer type and comonomer content between the ethylene polymer component (A) and the ethylene polymer component (B), further contributes to highly advantageous sealing properties, such as the improved hot tack as described above, and preferably an excellent peel temperature even at low temperatures. The optical properties (such as haze) are also at an advantageous level.

[0063] Even more preferably, the ethylene multimodal polymer (a) of the polymer composition is also multimodal with respect to the density difference between the ethylene polymer component (A) and the ethylene polymer component (B). Preferably, the density of the ethylene polymer component (A) is different from the density of the ethylene polymer component (B), preferably higher than the density of the ethylene polymer component (B). The density of the ethylene polymer component (A) is more preferably 925 - 950 kg / m 3 , preferably 930 - 945 kg / m 3 .

[0064] The ethylene multimodal polymer (a) is preferably linear low density polyethylene (LLDPE) having the well-known meaning. The density of the ethylene multimodal polymer (a) (preferably the density of the polymer composition) is even more preferably 910 - 935 kg / m 3 , preferably 915 - 930 kg / m 3 or > 912 kg / m 3 and < 925 kg / m 3 .

[0065] The multimodality with respect to density also helps the polymer composition to obtain beneficial mechanical properties.

[0066] In addition, the ethylene polymer (a) of the polymer composition can also be multimodal with respect to the difference between the (weight average) molecular weights of the ethylene polymer components (A) and (B). The multimodality with respect to the weight average molecular weight refers to the form of the molecular weight distribution curve of such multimodal polyethylene compared to the curves of the individual components, i.e., the appearance of the graph of the polymer weight fraction as a function of its molecular weight will show two or more maxima or at least a significant broadening.

[0067] More preferably, the ethylene multimodal polymer (a) has the multimodality as defined above, below or in the claims (including any preferred ranges or embodiments of the polymer composition) at least with respect to the differences between MFR2, comonomer type and comonomer content (mol%), and the density between the ethylene polymer component (A) and the ethylene polymer component (B).

[0068] Most preferably, the polymer composition of the present invention as defined above, below or in the claims comprises an ethylene multimodal polymer (a), wherein the ethylene multimodal polymer (a) comprises, preferably consists of, an ethylene polymer component (A) and an ethylene polymer component (B), wherein,

[0069] - The MFR2 of the ethylene polymer component (A) is higher than that of the ethylene polymer component (B);

[0070] - More preferably, the MFR2 of the ethylene polymer component (A) is 1 - 50 g / 10 min, preferably 1 - 40 g / 10 min, more preferably 1 - 30 g / 10 min, more preferably 2 - 20 g / 10 min, more preferably 2 - 15 g / 10 min, even more preferably 2 - 10 g / 10 min;

[0071] - Even more preferably, the ratio of the MFR2 of the ethylene polymer component (A) to the MFR2 of the final ethylene multimodal polymer (a) is 2 - 50, preferably 5 - 40, preferably 10 - 30, more preferably 10 - 25, more preferably 15 - 25;

[0072] And wherein,

[0073] - The ethylene polymer component (A) has a comonomer different from that of the ethylene polymer (B);

[0074] - More preferably, the comonomer content (mol%) of the ethylene polymer component (A) is lower than that of the ethylene polymer component (B), and even more preferably, the ratio of [the content (mol%) of the α-olefin comonomer having 4 to 10 carbon atoms in the ethylene polymer component (A)] to [the content (mol%) of at least two α-olefin comonomers having 4 to 10 carbon atoms in the final ethylene multimodal polymer (a)] is 0.2 - 0.6, preferably 0.25 - 0.5;

[0075] - Even more preferably, the α-olefin comonomer having 4 to 10 carbon atoms in the ethylene polymer component (A) is 1-butene, and the α-olefin comonomer having 4 to 10 carbon atoms in the ethylene polymer component (B) is 1-hexene;

[0076] And wherein,

[0077] - The density of the ethylene polymer component (A) is different from the density of the ethylene polymer component (B), preferably higher than the density of the ethylene polymer component (B);

[0078] - The density of the ethylene multimodal polymer (a) (preferably the density of the polymer composition) is more preferably 910 - 935 kg / m3 , preferably 915 - 930 kg / m 3 or > 912 kg / m 3 and < 925 kg / m 3 ;

[0079] - The density of the ethylene polymer component (A) is even more preferably 925 - 950 kg / m 3 , preferably 930 - 945 kg / m 3 .

[0080] When measured according to the "Dynamic Shear Measurement Method" as defined under "Measurement Method", the shear thinning value SHI of the polymer composition (preferably the ethylene multimodal polymer (a)) 2.7 / 210 is preferably 1.5 - 7, preferably 2 - 3.5.

[0081] When measured according to ISO 527 - 1 and ISO 527 - 3 and measured from a film sample (thickness 40 μm) composed of the polymer composition as described below under "Measurement Method", the longitudinal (MD) tensile modulus of the polymer composition (preferably the ethylene multimodal polymer (a)) is preferably 200 - 350 MPa, preferably 210 - 330 MPa.

[0082] The polymer composition (preferably the ethylene multimodal polymer (a)) preferably has the following correlation between the longitudinal tensile modulus of a 40 - μm film and the hot tack temperature (the lowest temperature at which the maximum hot tack force is obtained):

[0083] Hot tack temperature < 0.0794 MD tensile modulus + 83.

[0084] The definitions of the MD tensile modulus and the hot tack temperature measurement are as described under "Measurement Method".

[0085] When measured according to Method B in ASTM F 1921 - 98(2004) and measured from a film sample (thickness 40 μm) composed of the polymer composition as described above under "Measurement Method", the hot tack temperature of the polymer composition is preferably below 112 °C. The hot tack temperature is preferably 80 °C or higher. The hot tack temperature is more preferably 111 - 85 °C.

[0086] Further preferably, when measured according to Method B in ASTM F 1921 - 98(2004) and measured from a film sample (thickness 40 μm) composed of the polymer composition as described above under "Measurement Method", the hot tack force (maximum hot tack force) of the polymer composition is 1.95 N or greater. The hot tack force is preferably up to 5.0 N. The hot tack force is more preferably 2.1 - 5.0 N.

[0087] Based on the total content (100 wt%) of the ethylene polymer (a), the content of the ethylene polymer component (A) comprised in the ethylene multimodal polymer (a) is preferably 30 - 70 wt%, preferably 40 - 60 wt%, more preferably 35 - 50 wt%, more preferably 40 - 50 wt%, and the content of the ethylene polymer component (B) is 70 - 30 wt%, preferably 60 - 40 wt%, more preferably 50 - 65 wt%, more preferably 50 - 60 wt%. Most preferably, the ethylene polymer (a) consists of the ethylene polymer components (A) and (B) as the only polymer components. Thus, the ratio of the ethylene polymer component (A) to the ethylene polymer component (B) is (30 - 70):(70 - 30) wt%, preferably (40 - 60):(60 - 40) wt%, more preferably (35 - 50):(65 - 50) wt%, more preferably (40 - 50):(50 - 60) wt%.

[0088] The polymer composition may comprise other polymer components and optional additives and / or fillers. It should be noted herein that the additives may be present in and / or mixed with the ethylene polymer (a), for example, in the formulation step for producing the polymer composition. If the polymer composition comprises other polymer components, based on the total amount of the ethylene polymer (a) and the other polymer components, the content of the other polymer components generally varies within the range of 3 - 20 wt%.

[0089] The optional additives and fillers and their amounts used are conventional in the field of film applications. Examples of such additives are especially antioxidants, process stabilizers, UV stabilizers, dyes, fillers, antistatic additives, antiblocking agents, nucleating agents, acid scavengers, and polymer processing aids (PPA).

[0090] It should be understood herein that any of the said additives and / or fillers may optionally be added to a so-called masterbatch, wherein the masterbatch comprises the corresponding additive and a carrier polymer. In this case, based on the total amount (100 wt%) of the polymer composition, the carrier polymer is not counted as a polymer component of the polymer composition but is counted towards the amount of the corresponding additive.

[0091] Preferably, based on the total amount (100 wt%) of the polymer composition and optional, preferred additives, the polymer composition comprises at least 80 wt% of the ethylene polymer (a).

[0092] It should be noted in this text that the ethylene polymer (a) may optionally include a prepolymer component with a content of up to 20 wt%, which has a meaning well-known in the art. In this case, based on the total amount of the ethylene polymer (a), the prepolymer component in one of the ethylene polymer components (A) or (B) is calculated, preferably the content of the ethylene polymer component (A).

[0093] Therefore, the ethylene multimodal polymer (a) is preferably produced using a coordination catalyst. More preferably, the ethylene polymer components (A) and (B) of the ethylene polymer (a) are preferably produced using single-site catalysts, where the single-site catalysts include metallocene catalysts and non-metallocene catalysts, and these terms have meanings well-known in the art. The term "single-site catalyst" as used herein refers to a catalytically active metallocene compound or complex used in combination with a cocatalyst. The metallocene compound or complex is also referred to as an organometallic compound (C) herein.

[0094] The organometallic compound (C) includes transition metals (M) in Groups 3 to 10 of the Periodic Table of Chemical Elements (IUPAC 2007), or actinide elements or lanthanide elements.

[0095] The term "organometallic compound (C)" as described in the present invention includes any metallocene or non-metallocene compound of a transition metal, which has at least one organic (coordination) ligand and exhibits catalytic activity alone or in combination with a cocatalyst. The transition metal compounds are well-known in the art, and the present invention encompasses metal compounds of Groups 3 to 10 (e.g., Groups 3 to 7, or Groups 3 to 6, such as Groups 4 to 6) of the Periodic Table of Chemical Elements (IUPAC 2007), as well as lanthanide elements or actinide elements.

[0096] In one embodiment, the organometallic compound (C) is represented by the following formula (I):

[0097] (L) m R n MX q (i)

[0098] Wherein,

[0099] "M" is a transition metal (M) in Groups 3 to 10 of the Periodic Table of Chemical Elements (IUPAC 2007);

[0100] Each "X" is independently a monoanionic ligand, such as a σ-ligand;

[0101] Each "L" is independently an organic ligand coordinated with the transition metal "M";

[0102] "R" is a bridging group that connects the above-mentioned organic ligand (L);

[0103] "m" is 1, 2 or 3, preferably 2;

[0104] "n" is 0, 1 or 2, preferably 1;

[0105] "q" is 1, 2 or 3, preferably 2, and

[0106] m + q is equal to the valence of the transition metal (M).

[0107] "M" is preferably selected from the group consisting of zirconium (Zr), hafnium (Hf) or titanium (Ti), more preferably selected from the group consisting of zirconium (Zr) and hafnium (Hf). "X" is preferably a halogen, most preferably Cl.

[0108] The organometallic compound (C) is most preferably a metallocene complex, which comprises a transition metal compound as defined above, and the transition metal compound comprises a cyclopentadienyl, indenyl or fluorenyl ligand as the substituent "L". In addition, the ligand "L" may have substituents such as alkyl, aryl, arylalkyl, alkylaryl, silyl, silyloxy, alkoxy or other heteroatom groups, etc. Suitable metallocene catalysts are known in the art and are disclosed, inter alia, in WO-A-95 / 12622, WO-A-96 / 32423, WO-A-97 / 28170, WO-A-98 / 32776, WO-A-99 / 61489, WO-A-03 / 010208, WO-A-03 / 051934, WO-A-03 / 051514, WO-A-2004 / 085499, EP-A-1752462 and EP-A-1739103.

[0109] The most preferred single-site catalyst is a metallocene catalyst, which refers to the metallocene complex having catalytic activity as described above and a cocatalyst, wherein the metallocene catalyst is also called an activator. Suitable activators are metal alkyl compounds, especially alkylaluminum compounds known in the art. Particularly suitable activators for use with metallocene catalysts are alkylaluminoxane compounds such as methylaluminoxane (MAO), tetra-isobutylaluminoxane (TIBAO) or hexa-isobutylaluminoxane (HIBAO).

[0110] Therefore, a suitable single-site catalyst can be particularly a single-site catalyst prepared by the following steps:

[0111] 130 g of the metallocene complex bis(1-methyl-3-n-butylcyclopentadienyl)zirconium dichloride (CAS No.: 151840-68-5) was mixed with 9.67 kg of a toluene solution of 30% commercially available methylaluminoxane (MAO), and 3.18 kg of dry purified toluene was added. The resulting complex solution was added to 17 kg of silica support Sylopol 55SJ (supplied by Grace) by very slowly and uniformly spraying over 2 hours. The temperature was maintained below 30 °C. After adding the complex at 30 °C, the mixture was reacted for 3 hours.

[0112] More preferably, the ethylene polymer components (A) and (B) of the ethylene polymer (a) are produced (i.e., present) using the same metallocene catalyst.

[0113] The ethylene multimodal polymer (a) can be produced using any suitable polymerization process known in the art. Ethylene, an optional inert diluent, and optional hydrogen and / or comonomer are also introduced into the polymerization zone. The ethylene polymer component (A) is preferably produced in a first polymerization zone, while the ethylene polymer component (B) is produced in a second polymerization zone. The first polymerization zone and the second polymerization zone can be connected in any order, i.e., the first polymerization zone can precede the second polymerization zone, or the second polymerization zone can precede the first polymerization zone, or the polymerization zones can be in parallel. However, it is preferred to operate the polymerization zones in a cascade mode. The polymerization zones can be operated under slurry, solution, or gas-phase conditions or a combination thereof. Suitable processes including cascade slurry and gas-phase polymerization stages are disclosed in WO-A-92 / 12182 and WO-A-96 / 18662.

[0114] It is generally preferred to remove the reactants of the previous polymerization stage from the polymer before introducing the polymer of the previous polymerization stage into the subsequent polymerization stage. Preferably, the above operation is carried out when transferring the polymer from one polymerization stage to another.

[0115] The catalyst can be transferred into the polymerization zone by any means known in the art. For example, the catalyst can be suspended in a diluent and maintained as a homogeneous slurry, the catalyst can be mixed with a viscous mixture of fats and oils, and the resulting paste can be added to the polymerization zone or the catalyst can be allowed to stand and a portion of the resulting catalyst slurry can be introduced into the polymerization zone.

[0116] The polymerization reaction of the first polymerization zone (preferably the ethylene polymer component (A)) is preferably carried out in a slurry. Then the polymer particles formed in the polymerization, together with the catalyst fragmented and dispersed within the particles, are suspended in the liquid hydrocarbon. The slurry is stirred to enable the reactants to transfer from the fluid to the particles.

[0117] The polymerization usually occurs in an inert diluent, usually a hydrocarbon diluent such as methane, ethane, propane, n-butane, isobutane, pentane, hexane, heptane, octane, etc., or a mixture thereof. Preferably, the diluent is a low-boiling hydrocarbon having 1 to 4 carbon atoms or a mixture of such hydrocarbons, and a preferred diluent is propane.

[0118] The ethylene content in the liquid phase of the slurry can be 2 to 50 mol%, preferably 2 to 20 mol%, especially 3 to 12 mol%.

[0119] The temperature in the slurry polymerization is usually 50 - 115 °C, preferably 60 - 110 °C, especially 70 - 100 °C. The pressure is 1 - 150 bar, preferably 10 - 100 bar.

[0120] The slurry polymerization can be carried out in any known reactor for slurry polymerization. Such reactors include continuous stirred reactors and loop reactors. It is particularly preferred to carry out the polymerization in a slurry loop reactor. In such a reactor, the slurry is circulated at high speed along a closed pipeline by a circulation pump. Loop reactors are generally known in the art and examples are given, for example, in US-A-4582816, US-A-3405109, US-A-3324093, EP-A-479186 and US-A-5391654.

[0121] Sometimes it is advantageous to carry out the slurry polymerization at a temperature and pressure above the critical temperature and pressure of the fluid mixture. Such an operation is as described in US-A-5391654. In such an operation, the temperature is usually 85 - 110 °C, preferably 90 - 105 °C, and the pressure is 40 - 150 bar, preferably 50 - 100 bar.

[0122] The slurry can be withdrawn from the reactor continuously or intermittently. A preferred intermittent withdrawal method is to use a settling branch pipe to concentrate the slurry before withdrawing a batch of the concentrated slurry from the reactor. Continuous withdrawal is advantageously combined with a suitable concentration method (for example, the methods disclosed in EP-A-1310295 and EP-A-1591460).

[0123] Hydrogen can be added to the reactor to control the molecular weight of the polymer known in the art. In addition, one or more α-olefin comonomers are added to the reactor, thereby, for example, controlling the density of the polymer product. The actual feed amounts of such hydrogen and comonomers depend on the catalyst used and the expected melt index (or molecular weight) and density (or comonomer content) of the resulting polymer.

[0124] The polymerization in the second polymerization zone (preferably the ethylene polymer component (B)) is preferably carried out under gas phase conditions, preferably in a gas phase reactor, more preferably in a gas phase fluidized bed reactor, a gas phase fast fluidized bed reactor or a gas phase sedimentation bed reactor, or any combination thereof. The polymerization in the second polymerization zone is more preferably carried out in a fluidized bed gas phase reactor, in which ethylene and at least one comonomer are polymerized under the action of a polymerization catalyst, and preferably the reaction mixture in the first polymerization zone containing the ethylene polymer component (A) is used for polymerization in the upward gas flow. The reactor generally includes a fluidized bed, and the fluidized bed includes growing polymer particles, and the growing polymer particles contain the active catalyst located above the fluidization grid.

[0125] With the help of the fluidizing gas, the polymer bed is fluidized, where the fluidizing gas contains the olefin monomer, the final comonomer, an optional chain growth control agent or chain transfer agent (such as hydrogen), and finally an inert gas. The fluidizing gas is introduced into the inlet chamber at the bottom of the reactor. One or more of the above components can be continuously added to the fluidizing gas to compensate for gas losses caused by reactions or product withdrawal, among other things.

[0126] The fluidizing gas passes through the fluidized bed. The superficial velocity of the fluidizing gas must be higher than the minimum fluidization velocity of the particles contained in the fluidized bed, otherwise fluidization will not occur. On the other hand, the velocity of the gas should be lower than the starting velocity of the pneumatic conveying device, otherwise the entire fluidized bed will be carried away by the fluidizing gas.

[0127] When the fluidizing gas contacts the fluidized bed containing the active catalyst, the active components of the gas, such as monomers and chain transfer agents, react under the action of the catalyst to form the polymer product. At the same time, the gas is heated by the heat of reaction.

[0128] The unreacted fluidizing gas is discharged from the top of the reactor and cooled in a heat exchanger to remove the heat of reaction. The gas is cooled to a temperature lower than that of the fluidized bed to prevent the reaction from heating the fluidized bed. The gas can be cooled to a temperature at which a part of it condenses. When entering the reaction zone, the droplets will evaporate. The heat of vaporization helps to remove the heat of reaction. This operation is called the condensation mode, and its variants are disclosed, among other things, in WO-A-2007 / 025640, US-A-4543399, EP-A-699213 and WO-A-94 / 25495. As disclosed in EP-A-696293, a condensing agent can also be added to the circulating gas stream. The condensing agent is a non-polymerizable component, such as n-pentane, isopentane, n-butane or isobutane, which at least partially condenses in the cooler.

[0129] The gas is then compressed and recycled to the inlet chamber of the reactor. Before entering the reactor, fresh reactants are introduced into the fluidized gas stream to compensate for the gas losses due to the reaction and the withdrawal of the product. It is generally known to analyze the composition of the fluidized gas and introduce the gas components to keep the composition constant. The actual composition depends on the desired properties of the product and the catalyst used in the polymerization.

[0130] The catalyst can be introduced into the reactor in various ways, continuously or intermittently. When the gas-phase reactor is part of a cascade reactor, the catalyst is usually dispersed within the polymer particles of the previous polymerization stage. As disclosed in EP-A-1415999 and WO-A-00 / 26258, the polymer particles can be introduced into the gas-phase reactor. In particular, if the foregoing reactor is a slurry reactor, it is advantageous to feed the slurry directly into the fluidized bed of the gas-phase reactor, as disclosed in EP-A-887379, EP-A-887380, EP-A-887381 and EP-A-991684.

[0131] The polymer product can be withdrawn from the gas-phase reactor continuously or intermittently. Combinations of these methods can also be used. Among others, continuous withdrawal methods are disclosed in WO-A-00 / 29452. Among others, intermittent withdrawal methods are disclosed in US-A-4621952, EP-A-188125, EP-A-250169 and EP-A-579426.

[0132] If desired, antistatic agents such as water, ketones, aldehydes and alcohols can also be introduced into the gas-phase reactor. The reactor can also include a mechanical stirrer to further promote mixing within the fluidized bed.

[0133] The fluidized bed polymerization reactor generally operates in the temperature range of 50 - 100 °C, preferably 65 - 90 °C. The pressure is suitably 10 - 40 bar, preferably 15 - 30 bar.

[0134] Before carrying out the polymerization reaction of at least the ethylene polymer component (A) and the ethylene polymer component (B) in the first polymerization zone and the second polymerization zone, a prepolymerization step can be carried out first. The purpose of the prepolymerization reaction is to polymerize a small amount of polymer onto the catalyst at low temperature and / or low monomer concentration. The performance of the catalyst in the slurry can be improved and / or the properties of the final polymer can be changed through the prepolymerization reaction. The prepolymerization step can be carried out in slurry or in the gas phase. Preferably, the prepolymerization reaction is carried out in slurry, preferably in a slurry loop reactor. Then the prepolymerization reaction is preferably carried out in an inert diluent, and the diluent is preferably a low-boiling hydrocarbon having 1 to 4 carbon atoms or a mixture of such hydrocarbons.

[0135] The temperature in the prepolymerization step is generally 0 - 90 °C, preferably 20 - 80 °C, more preferably 40 - 70 °C.

[0136] The pressure is not critical and is generally 1 - 150 bar, preferably 10 - 100 bar.

[0137] Preferably, all the catalyst components are introduced into the prepolymerization step. Preferably, subsequently, the reaction product of the prepolymerization step is introduced into the first polymerization zone. Also preferably, as described above, the prepolymer component is included in the content of the ethylene polymer component (A).

[0138] It is within the knowledge of those skilled in the art to obtain the ethylene multimodal polymer (a) claimed in this claim by adjusting the polymerization conditions, feed streams and residence times in each step.

[0139] The ethylene multimodal polymer (a) containing at least and preferably only the ethylene polymer components (A) and (B) obtained from the second polymerization zone is subjected to a conventional post-reactor treatment to remove unreacted components, wherein the second polymerization zone is preferably a gas-phase reactor as described above.

[0140] Thereafter, the resulting polymer is usually extruded and pelletized. The extrusion can be carried out in a manner well-known in the art, preferably in a twin-screw extruder. An example of a suitable twin-screw extruder is a co-rotating twin-screw extruder. Among other things, the extruders are all produced by Coperion or Japan Steel Works, Ltd. Another example is a counter-rotating twin-screw extruder. Among other things, such extruders are all produced by Kobe Steel, Ltd. and Japan Steel Works, Ltd. Prior to the extrusion, as described above, it is preferred to mix at least a portion of the required additives with the polymer. The extruder generally includes a melting section and a mixing section, wherein the melting section is used to melt the polymer and the mixing section is used for homogenization of the polymer melt. Melting and homogenization are achieved by introducing energy into the polymer. A suitable specific energy input (SEI) level is from ~150 to ~450 kWh / ton of polymer, preferably 175 - 350 kWh / ton.

[0141] Measurement method

[0142] Unless otherwise specified in the description or experimental section, the following methods are used to determine the properties of the polymer compositions, polar polymers, and / or any sample solutions thereof specified in the main text or experimental section.

[0143] Melt flow rate

[0144] The melt flow rate (MFR) is determined according to ISO 1133 and expressed in g / 10 min. The MFR represents the fluidity of the polymer and thus indicates its processability. The higher the melt flow rate, the lower the viscosity of the polymer. The MFR of polyethylene is determined at a temperature of 190 °C. The MFR can be determined at different loads, such as 2.16 kg (MFR2), 5 kg (MFR5) or 21.6 kg (MFR 21 )

[0145] Density

[0146] The polymer density measurement is carried out on a molded specimen prepared according to EN ISO 1872-2 (February 2007) according to Method B (equilibrium density at 23 °C) of ASTM; D792, in kg / m 3 expressed. Molecular weight, molecular weight distribution (Mn, Mw, MWD) - GPC

[0147] The PL 220 (Agilent) GPC equipped with refractive index (RI), an on-line four-capillary bridge viscometer (PL-BV400-HT), and a dual light scattering detector at 15° and 90° angles (PL-LS15 / 90 light scattering detector) were used. At a temperature of 160 °C and a constant flow rate of 1 mL / min, Agilent 3×Olexis and 1x Olexis Guard chromatographic columns were used as the stationary phase, and 1,2,4-trichlorobenzene (TCB, stabilized with 250 mg / L 2,6-di-tert-butyl-4-methyl-phenol) was used as the mobile phase. 200 μL of the sample solution was injected for each analysis. The preparation method of all samples was as follows: 8.0 - 12.0 mg of the polymer was dissolved in 10 mL (at 160 °C) of stabilized TCB (the same as the mobile phase), and gently shaken continuously at 160 °C for 2.5 hours (PP) or 3 hours (PE). The injection concentration of the polymer solution at 160 °C (c 160℃ ) was determined as follows.

[0148]

[0149] w 25 (polymer weight) and V 25 (the volume of TCB at 25 °C).

[0150] Narrow PS standards with a molar mass of 132900 g / mol and a viscosity of 0.4789 dl / g (MWD = 1.01) were used to determine the corresponding detector constants and the inter-detector delay volume. The corresponding dn / dc of the PS standards used in TCB was 0.053 cm 3 / g. Calculations were performed using Cirrus Multi-Offline SEC-Software 3.2 (Agilent).

[0151] The molar mass of each elution layer was calculated using a 15° light scattering angle. Data acquisition, data processing, and calculations were performed using Cirrus Multi SEC-Software 3.2. The molecular weight was calculated using the option in Cirrus software (field “Sample calculation option subfield slice MW data table” and “Use LS15 degree angle”). The dn / dc for determining the molecular weight was calculated based on the detector constant of the RI detector, the sample concentration c, and the area of the detector response value of the analyzed sample.

[0152] According to C. Jackson and H. G. Barth (C. Jackson and H. G. Barth, “Molecular Weight Sensitive Detectors” in: Handbook of Size Exclusion Chromatography and related techniques, C.-S. Wu, 2 nd nd ed., Marcel Dekker, New York, 2004, p. 103), the molecular weight of each slice is calculated at a low angle. For the low molecular weight and high molecular weight regions where the LS detector or RI detector respectively gives less signal, a linear fit is used to relate the elution volume to the corresponding molecular weight. The linear fit region is adjusted according to the sample.

[0153] According to ISO 16014-4:2003 and ASTM D 6474-99, the number average molecular weight (Mn), weight average molecular weight (Mw), z-average molecular weight (Mz), molecular weight distribution (MWD) and its breadth (as described by the polydispersity index, PDI = Mw / Mn where Mn is the number average molecular weight and Mw is the weight average molecular weight) are determined by gel permeation chromatography (GPC) using the following formula:

[0154]

[0155] For a constant elution volume interval ΔV i , where A i and M i are the chromatographic peak slice area and the polyolefin molecular weight (MW) determined by GPC-LS.

[0156] Comonomer content:

[0157] Quantification of microstructure by nuclear magnetic resonance spectroscopy

[0158] The comonomer content of the polymer is quantified by quantitative nuclear magnetic resonance (NMR) spectroscopy.

[0159] Using a Bruker Advance III 500 NMR spectrometer, quantitative 1 H and 13 C are recorded at 500.13 and 125.76 MHz respectively in the molten state 13 C{ 1 H} NMR spectra. Using 13The C-optimized 7 mm magic angle spinning (MAS) probe was used to record all pneumatic spectra at 150 °C using nitrogen. Approximately 200 mg of the material was loaded into a 7 mm outer diameter zirconia MAS rotor and spun at 4 kHz. This setting was chosen mainly to obtain the high sensitivity required for rapid identification and accurate quantification. {klimke06, parkinson07, castignolles09} Standard single pulse excitation was employed, using the NOE with short recycle delays {pollard04, klimke06} and the RS-HEPT decoupling scheme {fillip05, griffin07}. A total of 1024 (1k) transients were acquired for each spectrum.

[0160] For the quantitative 13 C{ 1 H} NMR spectra were processed, integrated, and the relevant quantitative properties were determined by integration. All chemical shifts were referenced internally to the methylene stock solution signal (δ+) at 30.00 ppm.

[0161] The ethylene content was quantified using the number of methylene (δ+) site integrals at 30.00 ppm per monomer reporting site:

[0162] E = I δ+ / 2

[0163] Based on the number of separated comonomer units, the presence of separated comonomer units was corrected:

[0164] E 总计 = E + (3*B + 2*H) / 2

[0165] where B and H are defined as the respective comonomers. If there are consecutive and non-consecutive comonomer incorporations, the correction is made in a similar manner.

[0166] Characteristic signals corresponding to 1-butene incorporation were observed, and the comonomer fraction was calculated as the fraction of 1-butene in the polymer relative to all monomers in the polymer:

[0167] fB 总计 = (B 总计 / (E 总计 + B 总计 + H 总计 )

[0168] The separated 1-butene content incorporated in the EEBEE sequence was quantified using the number of integrals at the *B2 site at 38.3 ppm per comonomer reporting site:

[0169] B = I *B2

[0170] The content of 1-butene in the continuously bonded EEBBEE sequence is quantified using the integral of the ααB2B2 site at 39.4 ppm as a proportion of the number of reporting sites for each comonomer:

[0171] BB = 2 * IααB2B2

[0172] The content of non-continuously bonded 1-butene in the EEBEBEE sequence is quantified using the integral of the ββB2B2 site at 24.7 ppm as a proportion of the number of reporting sites for each comonomer:

[0173] BEB = 2 * IββB2B2

[0174] Since the *B2 and *βB2B2 sites of the separated (EEBEE) and non-continuously bonded (EEBEBEE) 1-butene overlap respectively, the total amount of separated 1-butene binding is corrected according to the amount of non-continuous 1-butene:

[0175] B = I* B2 -2 * I ββB2B2

[0176] The total content of 1-butene is calculated based on the sum of the separated, continuously bonded, and non-continuously bonded 1-butene:

[0177] B 总计 = B + BB + BEB

[0178] Then the total molar fraction of 1-butene in the polymer is calculated as:

[0179] fB = (B 总计 / (E 总计 + B 总计 + H 总计 )

[0180] Characteristic signals corresponding to 1-hexene binding are observed, and the comonomer fraction is calculated as the fraction of 1-hexene in the polymer relative to all monomers in the polymer:

[0181] fH 总计 = (H 总计 / (E 总计 + B 总计 + H 总计 )

[0182] The content of separated 1-hexene in the EEHEE sequence is quantified using the integral of the *B4 site at 39.9 ppm as a proportion of the number of reporting sites for each comonomer:

[0183] H = I *B4

[0184] Quantify the content of continuously incorporated 1-hexene in the EEHHEE sequence using the integral at the ααB4B4 site at 40.5 ppm as a fraction of the number of each comonomer reporting site:

[0185] HH = 2 * IααB4B4

[0186] Quantify the content of non - continuously incorporated 1 - hexene in the EEHEHEE sequence using the integral at the ββB4B4 site at 24.7 ppm as a fraction of the number of each comonomer reporting site:

[0187] HEH = 2 * IββB4B4

[0188] Then calculate the total mole fraction of 1 - hexene in the polymer as:

[0189] fH=(H 总计 / (E 总计 +B 总计 +H 总计 )

[0190] Calculate the comonomer incorporation mole percentage based on the mole fraction:

[0191] B[mol%]=100 * fB

[0192] H[mol%]=100 * fH

[0193] Calculate the comonomer incorporation weight percentage based on the mole fraction:

[0194] B[wt%]=100*(fB * 56.11) / ((fB * 56.11)+(fH * 84.16)+((1-(fB + fH))*28.05))

[0195] H[wt%]=100*(fH * 84.16) / ((fB * 56.11)+(fH * 84.16)+((1-(fB + fH))*28.05))

[0196] Rheological properties:

[0197] Dynamic shear measurement (frequency sweep measurement)

[0198] Characterize the polymer melt by dynamic shear measurement in accordance with ISO6721 - 1 and 6721 - 10. Perform the measurement on an Anton Paar MCR501 stress - controlled rotational rheometer equipped with a 25 mm parallel - plate geometry. Use a nitrogen environment for the measurement of the compression mold, and set the strain within the linear viscoelastic range. Conduct an oscillatory shear test at 190 °C with a frequency range of 0.0154 - 500 rad / s and a gap of 1.2 mm.

[0199] In a dynamic shear experiment, the probe undergoes uniform deformation under a sinusoidally varying shear strain or shear stress (strain- and stress-controlled modes, respectively). In a controlled strain experiment, the probe is subjected to a sinusoidal strain, expressed as

[0200] γ(t) = γ0 sin(ωt) (1)

[0201] If the applied strain is within the linear viscoelastic region, the resulting sinusoidal stress response can be obtained from the following equation:

[0202] σ(t) = σ0 sin(ωt +δ) (2)

[0203] where σ0 and γ0 are the stress and strain amplitudes, respectively; ω is the angular frequency; δ is the phase shift (loss angle between the applied strain and the stress response); and t is time.

[0204] The results of dynamic tests are usually represented by several different rheological functions, namely the shear storage modulus G', the shear loss modulus G", the complex shear modulus G*, the complex shear viscosity η*, the dynamic shear viscosity η', the out-of-phase component of the complex shear viscosity η", and the loss tangent tanη, which can be expressed as follows:

[0205]

[0206] G ＊ =G′+iG“ [Pa] (5)

[0207] η ＊ =η′-iη″ [Pa·s] (6)

[0208]

[0209] In addition to the above rheological functions, other rheological parameters can be determined, such as the so-called elastic index EI(x). The elastic index EI(x) is the value of the storage modulus G' determined according to the value of the loss modulus G" at x kPa, as shown in Equation 9.

[0210] EI(x) = G’ for (G” = x kPa) [Pa] (9)

[0211] For example, EI(5 kPa) is defined by the value of the storage modulus G' at 5 kPa.

[0212] As shown in Equation 10, the so-called shear thinning index is determined.

[0213]

[0214] For example, SHI (2.7 / 210)Defined as the complex viscosity value (Pa·s) determined according to the value of G* = 2.7 kPa divided by the complex viscosity value (Pa·s) determined according to the value of G* = 210 kPa.

[0215] Obtain the functional relationships of the storage modulus (G’), loss modulus (G”), complex modulus (G*), and complex viscosity (η*) with respect to the frequency (ω).

[0216] Thus, for example, η* 300rad / s (eta* 300rad / s ) is used as an abbreviation for the complex viscosity at a frequency of 300 rad / s, while η* 0.05rad / s (eta* 0.05rad / s ) is used as an abbreviation for the complex viscosity at a frequency of 0.05 rad / s.

[0217] Determine each value by the single-point interpolation method defined by Rheoplus software. In the case where the given G* value is not reached in the experiment, use the same method as before to determine the value by extrapolation. In both cases (interpolation or extrapolation), the Rheoplus options "Interpolate y values to x values for parameters" and "Logarithmic interpolation type" are applied.

[0218] Tensile test: According to ISO 527-3 (crosshead speed 1 mm / min), conduct a tensile test (flexural modulus, nominal fracture strain, and fracture stress in the machine) on a 40-μm film at 23°C.

[0219] Gloss and haze: Measure the gloss at 45° in gloss units (GU) on a 40-μm film according to ASTM D2457. Measure the haze (%) on a 40-μm film according to ASTM D1003.

[0220] Tear strength: Measure the transverse (TD) and longitudinal (MD) tear strengths on a 40-μm film according to ISO 6383 / 2.

[0221] Drop dart impact test (DDI): Conduct the measurement on a 40-μm film according to ISO 7765-1 or ASTM D1709. Detailed implementation

[0222] Preparation of the catalyst

[0223] 130 g of the metallocene complex bis(1-methyl-3-n-butylcyclopentadienyl)zirconium dichloride (CAS No.: 151840-68-5) was mixed with 9.67 kg of a toluene solution of 30% commercially available methylaluminoxane (MAO), and 3.18 kg of dry purified toluene was added. The resulting complex solution was added very slowly and uniformly by spraying over 2 hours into 17 kg of silica support Sylopol 55SJ (supplied by Grace). The temperature was maintained below 30 °C. After adding the complex at 30 °C, the mixture was reacted for 3 hours.

[0224] Comparative Example

[0225] 100 g / h of propane and 0.2 g / h of hydrogen were added to a 50 dm 3 loop reactor. The operating temperature was 50 °C and the operating pressure was 57 bar. The single-site catalyst prepared as described above was continuously fed to the loop reactor at a rate of 27.36 g / h.

[0226] The slurry was taken out from the reactor and transferred to a 150 dm 3 loop reactor. The reactor was operated at 85 °C and 55 bar. Ethylene, 1-butene, propane diluent and hydrogen were continuously added to the reactor to make the MFR2 of the polymer 2.7 g / 10 min and the polymer density 939 kg / m 3 .

[0227] The slurry was transferred to a second 300 dm 3 loop reactor. The reactor was operated at 85 °C and 54 bar. Ethylene, 1-butene, propane diluent and hydrogen were continuously added to the reactor to make the MFR2 of the polymer 18 g / 10 min and the polymer density 943 kg / m 3 .

[0228] The slurry was continuously withdrawn from the reactor until the flash stage, where hydrocarbons were removed from the polymer. Then the polymer was transferred to a gas-phase reactor where the polymerization reaction continued. The reactor was operated at 75 °C and 20 bar. Ethylene, hydrogen, 1-butene and 1-hexene were added to the reactor to obtain reaction conditions where the polymer MFR2 was 0.83 g / 10 min and the density was 902 kg / m 3 .

[0229] The yield of the catalyst was 3.8 kg / g catalyst.

[0230] The ratio of the amounts of polymer produced in the slurry loop reactor 1, the slurry loop reactor 2, and the gas phase reactor 3 is 19.7:19.9:57.6 (the remainder is produced from the prepolymerization reaction).

[0231] Example 1

[0232] 100 g / h of propane and 0.2 g / h of hydrogen were added to a 50 dm 3 loop reactor. The operating temperature was 50 °C and the operating pressure was 57 bar. The single-site catalyst prepared as described above was continuously fed to the loop reactor at a rate of 27.33 g / h.

[0233] The slurry was withdrawn from the reactor and transferred to a 150 dm 3 loop reactor. The reactor was operated at 85 °C and 55 bar. Ethylene, 1-butene, propane diluent, and hydrogen were continuously added to the reactor to give an MFR2 of 1.0 g / 10 min for the polymer and a polymer density of 928.5 kg / m 3 .

[0234] The slurry was transferred to a second 300 dm 3 loop reactor. The reactor was operated at 85 °C and 54 bar. Ethylene, 1-butene, propane diluent, and hydrogen were continuously added to the reactor to give an MFR2 of 67 g / 10 min for the polymer and a polymer density of 951 kg / m 3 .

[0235] The slurry was continuously withdrawn from the reactor until the flash stage, where hydrocarbons were removed from the polymer. The polymer was then transferred to a gas phase reactor where the polymerization reaction continued. The reactor was operated at 75 °C and 20 bar. Ethylene, hydrogen, 1-butene, and 1-hexene were added to the reactor to obtain reaction conditions for a polymer MFR2 of 0.46 g / 10 min and a density of 902 kg / m 3 .

[0236] The catalyst productivity was 3.8 kg / g catalyst.

[0237] The ratio of the amounts of polymer produced in the slurry loop reactor 1, the slurry loop reactor 2, and the gas phase reactor 3 is 17.8:17.8:61.8 (the remainder is produced from the prepolymerization reaction).

[0238] The polymer was then mixed with 1500 ppm calcium stearate and 3000 ppm Irganox B225 (a mixture of an organic phosphate and a hindered phenolic antioxidant).

[0239] The properties of the composite resin are shown in Table 1, in which the reaction conditions for producing the base resin are also given (the density and MFR values shown in Table 1 are the density and MFR values of the overall product obtained after polymerization in one or more reactors).

[0240] The composite material was made into a film. The test results of the film are shown in Table 2.

[0241] Table 1 Polymerization reaction conditions:

[0242]

[0243]

[0244] Using a Collin 30 blown film line, a 40 μm film was prepared at a melt temperature of 192 °C, a screw speed of 95 rpm, and an initial speed of 6.3 m / min, with a blow-up ratio (BUR) of 1:3 and a frost line distance (FLD) of 120 mm.

[0245] Table 2

[0246]

[0247] As shown in the above table, compared with Comparative Example CE, the toughness of Example 1 measured by DDI was significantly improved, while the stiffness measured by the tensile modulus remained at a good level. Similarly, optical properties such as gloss and haze were also improved. In addition, the fracture stress was also improved.

Claims

1. A polymer production process, characterized in that, The polymerization reaction in the first polymerization zone is carried out in the presence of ethylene, hydrogen, and a comonomer to obtain a first ethylene polymer component (A). Before the polymerization reaction, a prepolymerization step is carried out. The first polymerization zone includes two slurry loop reactors connected in series; wherein the ratio of the comonomer to ethylene in the first slurry loop reactor is higher than that in the second slurry loop reactor; and the polymerization reaction of the second ethylene polymer component (B) in the second polymerization zone is carried out in the gas phase of ethylene and the comonomer to produce an ethylene multimodal polymer (a). The ethylene multimodal polymer (a) has at least one comonomer selected from α-olefins having 4 to 10 carbon atoms, - which has a) MFR2 is 0.5 - 10 g / 10 min (according to ISO 1133, 190 °C, load 2.16 kg); b) MFR 21 / MFR2 is 13 - 35 (MFR 21 , 190 °C, load 21.6 kg), and c) MWD ≤ 5; - which at least includes - the ethylene polymer component (A), and - the ethylene polymer component (B), Among them, according to ISO 1133, at 190 °C and a load of 2.16 kg, the MFR2 of the ethylene polymer component (A) is higher than that of the ethylene polymer component (B), and the density of the ethylene polymer component (A) is 925 to 950 kg / m 3 , and the range of MFR2 of the ethylene polymer component (B) is 0.01 - 0.6 g / 10 min.

2. The polymer production process according to claim 1, characterized in that, The density of the polymer fraction prepared in the first slurry loop reactor is lower than that of the polymer fraction prepared in the second slurry loop reactor.

3. The polymer production process according to claim 1, characterized in that, At least one of the components (A), (B), or the multimodal polymer (a) has a MWD = Mw / Mn of 1.5 - 6.5 as determined by GPC.

4. The polymer production process according to claim 1, characterized in that, The first polymerization zone includes two slurry loop reactors connected in series, and hydrogen is added to the first slurry loop reactor and / or the second slurry loop reactor.

5. The polymer production process according to claim 4, characterized in that, The hydrogen is only supplied to the first slurry loop reactor.

6. The polymer production process according to claim 1, characterized in that, The polymerization reaction of the second ethylene polymer component (B) in the second polymerization zone is carried out without supplying hydrogen to the second polymerization zone.

7. The polymer production process according to claim 1, characterized in that, The polymerization reaction of the second ethylene polymer component (B) in the second polymerization zone is carried out under the condition that the H2 / C2 ratio (mol / kmol) > 0 and < 0.

15.

8. The polymer production process according to claim 1, wherein the MFR2 of the ethylene polymer component (A) is 1 - 50 g / 10 min.

9. The polymer production process according to claim 1, wherein the ratio of the MFR2 of the ethylene polymer component (A) to the MFR2 of the final ethylene multimodal polymer (a) is 2 - 50.

10. The polymer production process according to claim 1, wherein the α-olefin comonomer having 4 to 10 carbon atoms in the ethylene polymer component (A) is different from the α-olefin comonomer having 4 to 10 carbon atoms in the ethylene polymer component (B).

11. The polymer production process according to claim 10, wherein the ratio of [the content (mol%) of the α-olefin comonomer having 4 to 10 carbon atoms in the ethylene polymer component (A)] to [the content (mol%) of at least two α-olefin comonomers having 4 to 10 carbon atoms in the final ethylene multimodal polymer (a)] is 0.1 or 0.2 - 0.

6.

12. The polymer production process according to claim 10, wherein the content (mol%) of the α-olefin comonomer having 4 to 10 carbon atoms in the ethylene polymer component (A) is 0.03 - 5.0 mol%.

13. The polymer production process according to claim 1, wherein the density of the ethylene polymer component (A) is higher than the density of the ethylene polymer component (B).

14. The polymer production process according to claim 1, wherein the density of the ethylene multimodal polymer (a) is 910 - 935 kg / m 3 or > 912 kg / m 3 and < 925 kg / m 3 .

15. The polymer production process according to claim 1, wherein the MFR 21 / MFR2 of the ethylene multimodal polymer (a) is 13 - 30.

16. The polymer production process according to claim 1, wherein the ethylene multimodal polymer (a) can be multimodal with respect to MFR, the type of comonomer, comonomer content, and density.

17. The polymer production process according to claim 1, wherein when measured according to ISO 527 - 1 and ISO 527 - 3 and in accordance with the quality standards described under "Measurement Method" from a film sample (thickness 40 μm) composed of the polymer composition, the longitudinal (MD) tensile modulus of the ethylene multimodal polymer (a) is 150 - 400 MPa.

18. The polymer production process according to claim 1, wherein when measured according to the "Dynamic Shear Measurement Method" in the quality standards described under "Measurement Method", the SHI 2.7 / 210 of the ethylene multimodal polymer (a) is 1.5 - 7.

19. The polymer production process according to claim 1, wherein the glossiness of the polymer composition at 45° is measured to be > 20 - 50.

20. The polymer production process according to claim 1, wherein the DDI range of the polymer composition is 1000 - 2500 g.

21. The polymer production process according to claim 1, wherein the haze value of the polymer composition is 0 - 30 (excluding).

22. The polymer production process according to claim 1, wherein the longitudinal (MD) fracture stress of the polymer composition is 50 - 70 MPa.

23. The polymer production process as claimed in claim 1, the polymer production process, wherein the ethylene multimodal polymer (a) is produced using the same single-site catalyst.

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