(ULTRA)high molecular weight polyethylene-based block copolymer, manufacturing method thereof, and secondary battery separator fabricated using the same as raw material

Abstract

To provide an (ultra) high molecular weight polyethylene-based block copolymer and a secondary battery separator that are improved in the kneading property, film surface, and other physical properties compared to a heterogeneous composite secondary battery separator made of polyethylene and polypropylene processed by simple blending.SOLUTION: A high or ultrahigh molecular weight polyethylene-based block copolymer comprises, with respect to 100 wt.% of the block copolymer: 25 to 90 wt.% of high or ultrahigh molecular weight polyethylene; and 10 to 75 wt.% of ultrahigh molecular weight polypropylene. The high or ultrahigh molecular weight polyethylene has a viscosity average molecular weight of 400,000 to 5,000,000 g / mol. The ultrahigh molecular weight polypropylene has a viscosity average molecular weight of 1,000,000 to 4,000,000 g / mol. The block copolymer has a viscosity average molecular weight of 400,000 to 5,000,000 g / mol under conditions of adding no hydrogen or adding a trace amount of hydrogen.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an (ultra)high molecular weight polyethylene-based block copolymer, a manufacturing method thereof, and a secondary battery separator manufactured using the same as a raw material. More specifically, to solve the problem of reduced compatibility between polyethylene and polypropylene during the blending process of (ultra)high molecular weight polyethylene and ultra-high molecular weight polypropylene used in secondary battery separators, the present invention relates to an (ultra)high molecular weight polyethylene-based block copolymer having (ultra)high molecular weight polyethylene as a linear first-stage polymer manufactured through multi-stage polymerization, thereby improving uniformity and processing stability, a manufacturing method thereof, and a secondary battery separator manufactured using the same as a raw material. [Background technology]

[0002] Generally, polypropylene polymerization is carried out using magnesium chloride as a carrier, titanium chloride containing phthalate, diether, or succinate compounds as the main catalyst, alkylaluminum as a co-catalyst, and a silicon compound containing an alkoxy group as a co-catalyst, which is an external electron donor, and polymerization is carried out in various reaction forms such as slurry polymerization, bulk polymerization, and gas phase polymerization. Polyethylene polymerization is carried out by slurry polymerization, using a magnesium chloride-supported titanium catalyst as the main catalyst and alkylaluminum compounds as a co-catalyst.

[0003] Polyethylene and polypropylene produced in this way have low compatibility and are generally not compounded. However, for specific applications such as ropes, they can be partially mixed and compounded by using a polyethylene-polypropylene block copolymer as a compatibilizer to increase the kneadability.

[0004] Despite this lack of compatibility, separators have recently been produced by blending (ultra) high molecular weight polyethylene with polypropylene to improve the performance of secondary battery separators. However, general-purpose polypropylene has poor processability and mechanical properties due to its low viscosity, and the content of (ultra) high molecular weight polyethylene and ultra-high molecular weight polypropylene creates a heterogeneous system, limiting the production of separators with uniform performance. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] European Patent EP3157966B1 [Patent Document 2] Registered US Patent US8008417 [Patent Document 3] Korean Patent KR10-1161752 Summary of the Invention [Problem to be solved by the invention]

[0006] In order to solve the above-mentioned problems, the present invention aims to provide a method for selecting a main catalyst capable of polymerizing polyethylene and polypropylene, a combination ratio of the main catalyst, cocatalyst, promoter, etc., polymerization conditions for adjusting the molecular weight and basic properties of each polyethylene and polypropylene during multi-stage polymerization, an (ultra) high molecular weight polyethylene-based block copolymer for improving the performance of secondary battery separators, a method for manufacturing the same, and a secondary battery separator manufactured using the same as a raw material. [Means for solving the problem]

[0007] To achieve the above object, the present invention discloses a method for producing an (ultra)high molecular weight polyethylene block copolymer, comprising: (a) a step of mixing and charging a co-catalyst (x) which is an alkylaluminum compound, a main catalyst (y) which is a titanium compound, and a promoter (z) which is a silicon compound into a reactor in the presence of a hydrocarbon solvent having 1 to 20 carbon atoms; (b) a step of charging ethylene monomer alone or ethylene monomer and a trace amount of hydrogen into the mixed solution obtained in step (a) to perform a first-stage polymerization reaction; (c) a step of removing unreacted monomer from the reactor after the first-stage polymerization reaction; (d) a step of charging propylene monomer into the mixed solution obtained in step (c) to perform a second-stage polymerization reaction; and (e) a step of filtering and drying a polyethylene-polypropylene block copolymer powder from the reaction solution obtained in step (d).

[0008] Here, the cocatalyst (x) may be at least one compound selected from the group consisting of triethylaluminum, trimethylaluminum, triisobutylaluminum, trioctylaluminum, diethylaluminum chloride, diethylaluminum bromide, diethylaluminum iodide, diethylaluminum fluoride, ethylaluminum dichloride, dimethylaluminum chloride, methylaluminum dichloride, and ethylaluminum sesquichloride.

[0009] Here, the co-catalyst (z) is cyclohexylmethyldimethoxysilane (CMCD), cyclohexyl-n-propyldimethoxysilane (CPDM), cyclohexyl-i-propyldimethoxysilane (CIPDM), cyclohexyl-n-butyldimethoxysilane (CBDM), cyclohexyl-i-butyldimethoxysilane (CIBDM), cyclohexyl-n-hexyldimethoxysilane (CHDM), cyclohexyl-n-octyldimethoxysilane (CODM), cyclohexyl-n-decyldimethoxysilane (CDeDM), dimethyldimethoxysilane, dimethyldiethoxysilane, dicyclo The compound may be any one or more compounds selected from the group consisting of pentyldimethoxysilane, diisopropyldimethoxysilane, dicyclopentyldimethoxysilane, methylphenyldimethoxysilane, diphenyldiethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, vinyltriethoxysilane, phenyltriethoxysilane, butyltriethoxysilane, ethyltriisopropoxysilane, vinyltributoxysilane, and methyltriaryloxysilane.

[0010] Here, the co-catalyst (x) which is the alkylaluminum compound may contain 10 to 500 moles of Al per mole of Ti which is the main catalyst (y) which is the titanium compound.

[0011] Here, the co-catalyst (z) which is the silicon compound may contain 1 to 40 moles of Si per mole of Ti in the main catalyst (y) which is the titanium compound.

[0012] Here, the polymerization temperature in the first and second polymerization reactions may be within the range of 30 to 90°C.

[0013] Here, in the first and second stage polymerization reactions, the polymerization pressure may be within the range of 1 to 40 bar.

[0014] Here, in the first-stage polymerization reaction, the ethylene monomer can be introduced in an amount of 3 to 95% by weight, and in the second-stage polymerization reaction, the propylene monomer can be introduced in an amount of 6 to 98% by weight.

[0015] Meanwhile, in order to achieve the above object, the present invention further discloses a (ultra)high molecular weight polyethylene-based block copolymer, which comprises, relative to 100% by weight of the block copolymer, 25 to 90% by weight of (ultra)high molecular weight polyethylene; and 10 to 75% by weight of ultra-high molecular weight polypropylene, wherein the (ultra)high molecular weight polyethylene has a viscosity average molecular weight of 400,000 to 5,000,000 g / mol, and the ultra-high molecular weight polypropylene has a viscosity average molecular weight of 1,000,000 to 4,000,000 g / mol, and the block copolymer has a viscosity average molecular weight of 400,000 to 5,000,000 g / mol under conditions where no hydrogen or a very small amount of hydrogen is added.

[0016] Here, the block copolymer can be produced by carrying out a first-stage polymerization reaction in which only ethylene monomer is added to a mixed solution, or by adding ethylene monomer and a trace amount of hydrogen to the mixed solution, and then carrying out a second-stage polymerization reaction in which propylene monomer is added to the mixed solution, thereby having the (ultra) high molecular weight polyethylene as a first-stage polymer with a linear structure.

[0017] Here, the block copolymer has an apparent density of 0.30 to 0.50 g / cm 3 may be.

[0018] Here, the block copolymer may have an inorganic content of 1 to 30 ppm, and the inorganic substance may be used as a catalyst in the polymerization process.

[0019] Here, the block copolymer may have a particle size of 10 to 400 μm.

[0020] Meanwhile, to achieve the above object, the present invention further discloses a secondary battery separator produced from a (ultra)high molecular weight polyethylene-based block copolymer, wherein the (ultra)high molecular weight polyethylene-based block copolymer comprises, relative to 100% by weight of the block copolymer, 25 to 90% by weight of (ultra)high molecular weight polyethylene; and 10 to 75% by weight of ultra-high molecular weight polypropylene, wherein the (ultra)high molecular weight polyethylene has a viscosity-average molecular weight of 400,000 to 5,000,000 g / mol, and the ultra-high molecular weight polypropylene has a viscosity-average molecular weight of 1,000,000 to 4,000,000 g / mol, and the block copolymer has a viscosity-average molecular weight of 400,000 to 5,000,000 g / mol under conditions where no or a very small amount of hydrogen is added.

[0021] Here, the secondary battery separator may have a puncture strength of 300 to 600 gf.

[0022] Here, the secondary battery separator has a tensile strength of 800 to 2,000 kgf / cm 2 may be. [Effects of the Invention]

[0023] The (ultra) high molecular weight polyethylene-based block copolymer of the present invention can be used as a compatibilizer to increase the blending and processing of polyethylene and polypropylene, which have low compatibility, and also has the effect of improving blending properties, film surface properties, and other physical properties compared to secondary battery separators made of heterogeneous composite materials of polyethylene and polypropylene, which are simply blended and processed. DETAILED DESCRIPTION OF THE INVENTION

[0024] The terms used in this application are merely used to describe specific examples. Therefore, for example, singular expressions include plural expressions unless the context clearly requires otherwise. It should be noted that the terms "comprise" or "comprise" used in this application are used to clearly indicate the presence of features, steps, functions, components, or combinations thereof described in the specification, and do not preliminarily exclude the presence of other features, steps, functions, components, or combinations thereof.

[0025] On the other hand, unless otherwise defined, all terms used herein should be considered to have the same meaning as that commonly understood by a person of ordinary skill in the art to which the present invention pertains. Therefore, unless clearly defined herein, specific terms should not be construed in an overly ideal or formal sense.

[0026] To improve the performance of secondary battery separators made by blending ultra-high molecular weight polyethylene with polypropylene, a catalyst capable of multi-stage polymerization of ultra-high molecular weight polyethylene and ultra-high molecular weight polypropylene must be selected, and technology must be established to control the molecular weight of polyethylene and polypropylene and the degree of polymerization of polyethylene and polypropylene in multi-stage polymerization. Furthermore, to facilitate the production, supply, and processing of powder, adjustments to the powder's particle shape and size are required.

[0027] The present inventors have completed the present invention by confirming that it is possible to prepare an (ultra) high molecular weight polyethylene-based block copolymer with improved performance as a secondary battery separator by adjusting the molecular weight of polyethylene and polypropylene and performing multi-stage polymerization, as described below. Meanwhile, as used herein, the term "(ultra) high molecular weight" refers to a viscosity average molecular weight of 1,000,000 g / mol or more.

[0028] Furthermore, the term "high molecular weight" as used herein means a molecular weight having a viscosity average molecular weight of more than 400,000 g / mol and less than 1,000,000 g / mol.

[0029] Selection of titanium catalysts for the polymerization of polyethylene and polypropylene. To achieve the above-mentioned objectives, the present invention requires the selection of a main catalyst that can polymerize polyethylene and polypropylene and ensure a stable powder form, as well as the combination ratio of the main catalyst, co-catalyst, and promoter. The titanium chloride catalyst supported by Ziegler-Natta magnesium chloride results in different degrees of polymerization of polyethylene and polypropylene depending on the acid value of the titanium, which has a significant impact on molecular weight and granularity.

[0030] In particular, in the case of a trivalent titanium catalyst, polymerization of both polyethylene and polypropylene is possible. Therefore, the present invention selects a trivalent titanium catalyst as a catalyst capable of multi-stage polymerization of (ultra) high molecular weight polyethylene and ultra-high molecular weight polypropylene, and provides a method for adjusting the ratio of co-catalyst and promoter to control the molecular weight during polyethylene polymerization and ensure a stable particle shape.

[0031] More specifically, the present invention provides a multistage polymerization method for producing a (ultra)high molecular weight polyethylene block copolymer, using a trivalent titanium catalyst as the main catalyst, which is the magnesium titanium chloride compound, and varying the addition ratios of a co-catalyst, which is an alkylaluminum compound, and a promoter, which is a silicon compound containing an alkoxy group.

[0032] Method for producing (ultra) high molecular weight polyethylene block copolymers The present invention provides a multistage polymerization method for producing (ultra)high molecular weight polyethylene block copolymers, using a trivalent titanium catalyst as the main catalyst, which is the magnesium chloride-supported titanium compound, and varying the input ratios of a cocatalyst, which is an alkylaluminum compound, and a promoter, which is a silicon compound containing an alkoxy group.

[0033] In the method for producing the (ultra) high molecular weight polyethylene-based block copolymer of the present invention, the process for each step is as follows.

[0034] (a) mixing and charging a co-catalyst (x) which is an alkylaluminum compound, a main catalyst (y) which is a titanium compound, and a co-catalyst (z) which is a silicon compound into a reactor in the presence of a hydrocarbon solvent having 1 to 20 carbon atoms;

[0035] (b) adding only ethylene monomer or ethylene monomer and a trace amount of hydrogen to the mixed solution obtained in the step (a) to carry out a first-stage polymerization reaction;

[0036] (c) removing unreacted monomers from the reactor after the first-stage polymerization reaction;

[0037] (d) adding propylene monomer to the mixed solution obtained in step (c) to carry out a second-stage polymerization reaction; and

[0038] (e) filtering and drying a powder of the polyethylene block copolymer from the reaction solution obtained in step (d).

[0039] The present invention can produce an (ultra-)high molecular weight polyethylene-based block copolymer having (ultra-)high molecular weight polyethylene as a first-stage polymer with a linear structure by sequentially adding ethylene monomer in step (b) and then propylene monomer in step (d). That is, in the (ultra-)high molecular weight polyethylene-based block copolymer of the present invention, the (ultra-)high molecular weight polyethylene produced in the first polymerization stage can form a starting polymer chain with a linear structure, and then the ultra-high molecular weight polypropylene produced in the second polymerization stage can form a subsequent polymer chain linearly linked to the starting polymer chain.

[0040] Specifically, the (ultra) high molecular weight polyethylene can be the main chain of the (ultra) high molecular weight polyethylene-based block copolymer of the present invention, and the ultra-high molecular weight polypropylene can be a main chain continuous with one main chain of the (ultra) high molecular weight polyethylene-based block copolymer of the present invention.

[0041] The term "main chain" used in this specification means a backbone molecular chain that forms the backbone of a polymer, and means that a starting polymer chain and a subsequent polymer chain form one main chain. The present invention explains that (ultra) high molecular weight polyethylene and ultra-high molecular weight polypropylene, which are different polymers, form blocks within the same main chain.

[0042] Furthermore, after performing step (d), steps (b) to (d) are again performed to prepare the block copolymer according to the present invention through four-stage polymerization. In this case, a block copolymer having uniform mixing properties and improved physical properties compared to the two-stage polymerization according to the present invention, and a secondary battery separator prepared using the block copolymer as a raw material, can be obtained.

[0043] The multi-stage polymerization of the (ultra) high molecular weight polyethylene block copolymer according to the present invention can be repeated within a range of 1 to 5 times, but is not limited thereto.

[0044] Here, the step (a) is preferably carried out under a nitrogen atmosphere, i.e., the step (a) is preferably carried out in the presence of an inert gas, but is not limited thereto.

[0045] In the method for producing an (ultra) high molecular weight polyethylene-based block copolymer of the present invention, the hydrocarbon solvent having 1 to 20 carbon atoms in step (a) may include at least one solvent selected from the group consisting of aliphatic hydrocarbon solvents such as pentane, hexane, cyclohexane, methylcyclohexane, heptane, octane, decane, undecane, dodecane, tridecane, and tetradecane; aromatic hydrocarbon solvents such as benzene, toluene, xylene, and ethylbenzene; and halogenated hydrocarbon solvents such as dichloropropane, dichloroethylene, trichloroethylene, carbon tetrachloride, and chlorobenzene. Alternatively, gas phase polymerization or bulk polymerization may be performed in the presence of high pressure propylene without using a hydrocarbon.

[0046] In addition, in step (a) of the method for producing the (ultra) high molecular weight polyethylene-based block copolymer of the present invention, representative examples of the co-catalyst (x) include any one or more compounds selected from the group consisting of triethylaluminum, trimethylaluminum, triisobutylaluminum, trioctylaluminum, diethylaluminum chloride, diethylaluminum bromide, diethylaluminum iodide, diethylaluminum fluoride, ethylaluminum dichloride, dimethylaluminum chloride, metal aluminum dichloride, and ethylaluminum sesquichloride.

[0047] In step (a), the cocatalyst (x) is preferably added in an amount of 3 to 1,000 moles per mole of the main catalyst (y), but this is not a limitation. More specifically, the amount of Al in the cocatalyst (x), which is an alkylaluminum compound, is preferably 3 to 1,000 moles per mole of Ti in the main catalyst (y), which is a titanium compound. It is even more preferable that the amount of Al in the cocatalyst (x), which is an alkylaluminum compound, is 5 to 500 moles per mole of Ti in the main catalyst (y), which is a titanium compound. It is even more preferable that the amount of Al in the cocatalyst (x), which is an alkylaluminum compound, is 10 to 500 moles per mole of Ti in the main catalyst (y), which is a titanium compound. If the ratio of Al in the cocatalyst (x), which is an alkylaluminum compound, to 1 mole of Ti in the main catalyst (y), which is a titanium compound, is less than 5 moles, the polymerization reaction may not proceed sufficiently. Conversely, if the ratio of Al in the cocatalyst (x), which is an alkylaluminum compound, to 1 mole of Ti in the main catalyst (y), which is a titanium compound, exceeds 500 moles, the alkyl group in the cocatalyst may cause scission of the molecular main chain, making it impossible to obtain a high-molecular-weight polyethylene resin, and preventing the production of an (ultra-)high-molecular-weight polyethylene block copolymer with uniform kneadability and improved physical properties.

[0048] In step (a), the main catalyst (y) contains a silicon compound containing phthalate, diether, or succinate as an internal electron donor, and titanium trichloride is preferred as a Ziegler-Natta titanium chloride catalyst supported by magnesium chloride. A catalyst that provides high stereoregularity depending on the type of internal electron donor is more preferred, and a commonly available commercially available catalyst can be used.

[0049] In step (a), the co-catalyst (z) may be at least one compound selected from the group consisting of a compound represented by the following formula (1), a compound represented by the following formula (2), and a compound represented by the following formula (3): [ka] [ka] [ka] In the chemical formulas (1) to (3), R a , R 7 , R 8 and R 9 are each independently an alkyl group, a cycloalkyl group, an aryl group, an allyl group, or a vinyl group having 1 to 12 carbon atoms; R b is an alkyl or aryl group having 1 to 6 carbon atoms, R is an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group, an aryl group, an allyl group, or -OR c In this case, R c is an alkyl group or an aryl group having 1 to 6 carbon atoms, and n is an integer of 0 to 6.

[0050] Specifically, representative examples of the compound of the chemical formula (1) include cyclohexylmethyldimethoxysilane (CMCD), cyclohexyl-n-propyldimethoxysilane (CPDM), cyclohexyl-i-propyldimethoxysilane (CIPDM), cyclohexyl-n-butyldimethoxysilane (CBDM), cyclohexyl-i-butyldimethoxysilane (CIBDM), cyclohexyl-n-hexyldimethoxysilane (CHDM), cyclohexyl-n-octyldimethoxysilane (CODM), cyclohexyl-n-decyldimethoxysilane (CDeDM), dimethyldimethoxysilane, and dimethyldiethoxysilane. and at least one compound selected from the group consisting of silane, dicyclopentyldimethoxysilane, diisopropyldimethoxysilane, dicyclopentyldimethoxysilane, methylphenyldimethoxysilane, diphenyldiethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, vinyltriethoxysilane, phenyltriethoxysilane, butyltriethoxysilane, ethyltriisopropoxysilane, vinyltributoxysilane, and methyltriaryloxysilane. Representative examples of the compound of the above chemical formula (1) may preferably include one or more compounds selected from the group consisting of dimethyldimethoxysilane, dimethyldiethoxysilane, dicyclopentyldimethoxysilane, cyclohexylmethyldimethoxysilane, diisopropyldimethoxysilane, dicyclopentyldimethoxysilane, methylphenyldimethoxysilane, diphenyldiethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, vinyltriethoxysilane, phenyltriethoxysilane, butyltriethoxysilane, ethyltriisopropoxysilane, vinyltributoxysilane, and methyltriaryloxysilane.

[0051] Representative examples of the compound of the chemical formula (2) include 1,1,3,3-tetramethoxy-1,3-dimethyl-1,3-disilanepropane (TMDMDP), 1,1,3,3-tetramethoxy-1-methyl-3-hexyl-1,3-disilanepropane (TMMHDP), 1,1,3,3-tetramethoxy-1,3-di-n-hexyl-1,3-disilanepropane (TMDHDP), 1,1,3,3-tetramethoxy-1-methyl-3-cyclohexyl-1,3-disilanepropane (TMDHDP), Examples of suitable compounds include one or more compounds selected from the group consisting of 1,1,3-disilanepropane (TMMCDP), 1,1,3,3-tetramethoxy-1,3-dicyclohexyl-1,3-disilanepropane (TMDCDP), 1,1,8,8-tetramethoxy-1,8-dicyclohexyl-1,8-disilaneoctane (TMDCDO), and 1,1,3,3-tetramethoxy-1,3-dimethyldisiloxane (TMDMDS).

[0052] Representative examples of the compound of chemical formula (3) include one or more compounds selected from the group consisting of methyl(trimethylsilylmethyl)dimethoxysilane (MTDM), n-propyl(trimethylsilylmethyl)dimethoxysilane (PTDM), i-propyl(trimethylsilylmethyl)dimethoxysilane (IPTDM), n-butyl(trimethylsilylmethyl)dimethoxysilane (BTDM), i-butyl(trimethylsilylmethyl)dimethoxysilane (IBTDM), n-pentyl(trimethylsilylmethyl)dimethoxysilane (PnTDM), n-hexyl(trimethylsilylmethyl)dimethoxysilane (HTDM), cyclopentyl(trimethylsilylmethyl)dimethoxysilane (CpTDM), and cyclohexyl(trimethylsilylmethyl)dimethoxysilane (CTDM).

[0053] In step (a), the co-catalyst (z) is preferably added in an amount of 0.5 to 40 moles per mole of the main catalyst (y), but is not limited thereto. More specifically, the co-catalyst (z) preferably contains 0.5 to 40 moles of silicon per mole of titanium compound main catalyst Ti, and more preferably contains 1 to 40 moles of silicon per mole of titanium compound main catalyst Ti. Furthermore, it is even more preferable that the co-catalyst (z) contains 1 to 30 moles of silicon per mole of titanium compound main catalyst Ti. For example, if the ratio of Si in the silicon compound co-catalyst (z) to 1 mole of Ti in the titanium compound main catalyst (y) is less than 1 mole, the rapid reaction rate of ethylene in the first-stage polymerization reaction will cause rapid and uneven particle growth, blocking the catalytic active sites, and preventing sufficient polypropylene reaction in the second-stage polymerization reaction. Conversely, if the ratio of Si in the silicon compound co-catalyst to 1 mole of Ti in the titanium compound main catalyst (y) exceeds 40 moles, the oxygen atoms contained in the co-catalyst structure will act as catalyst poisons, causing a rapid decrease in activity, resulting in a low degree of polymerization that makes it impossible to obtain an ultra-high molecular weight polypropylene resin. Even if a polymerization reaction does occur, it may be difficult to obtain a sufficient amount of (ultra-)high molecular weight polyethylene-based block copolymer with uniform kneadability and improved physical properties.

[0054] In the first-stage polymerization reaction of step (b), the ethylene monomer is preferably added in an amount of 3 to 95% by weight, but is not limited thereto. For example, if the ethylene monomer is added in an amount of less than 3% by weight, the ethylene content during production of the block copolymer is low, a sufficient degree of polymerization is not ensured, and high-molecular-weight polyethylene is not polymerized. Conversely, if the ethylene monomer is added in an amount of more than 95% by weight, it becomes difficult to control the target copolymer composition during production of the block copolymer, and the activity sufficient for the polypropylene reaction to proceed in two stages cannot be ensured, making it impossible to obtain a copolymer resin.

[0055] Meanwhile, in step (b), the polymerization temperature for carrying out the first-stage polymerization reaction by adding only ethylene monomer or ethylene monomer and a trace amount of hydrogen to the mixed solution is preferably, but not limited to, within the range of 30 to 90°C. If the polymerization temperature is less than 30°C, the polymerization reaction may not proceed sufficiently. Conversely, if the polymerization temperature is more than 90°C, even if the polymerization reaction does occur, the rapid reaction rate will cause the produced resin to rapidly block the catalytic active sites, making it difficult to adjust the composition of the target copolymer and preventing sufficient activity for the second-stage polymerization.

[0056] In step (b), the polymerization pressure for the first-stage polymerization reaction, in which only ethylene monomer or ethylene monomer and a trace amount of hydrogen are added to the mixed solution, is preferably within the range of 1 to 40 bar, but is not limited thereto. If the polymerization pressure is less than 1 bar, the polymerization reaction may not proceed sufficiently. Conversely, if the polymerization pressure exceeds 40 bar, even if the polymerization reaction does proceed, the rapid reaction rate will cause the produced resin to rapidly block the catalytic active sites, making it difficult to adjust the target copolymer composition and preventing sufficient activity for the second-stage polymerization.

[0057] In the first polymerization reaction of step (b), ethylene monomer is added to the mixed solution, and a trace amount of hydrogen (H2), which is a molecular weight regulator, is added, or no hydrogen is added at all, to achieve the target molecular weight. The molecular weight range of the ultra-high molecular weight polyethylene polymer can be controlled by adding hydrogen to the first-stage polymerization reaction in an amount ranging from 0.001 to 500 mL under reactor conditions of 1 atmosphere, or at a pressure of 0.001 to 0.5 bar, or by adding hydrogen in a molar amount ranging from 0.1 to 50 vol% relative to the olefin monomer, but this is not limited thereto.

[0058] Step (c) corresponds to a process for removing unreacted monomer remaining in the reactor after the first-stage polymerization reaction. The unreacted monomer is preferably ethylene monomer. If propylene monomer is added first instead of ethylene monomer in step (b), the unreacted monomer may be propylene monomer. To effectively remove the unreacted monomer, a vacuum pump can be used. However, since the hexane in the reactor may be vaporized and removed, the vacuum level is limited to 30 torr. Alternatively, the reactor internal temperature is maintained above 60°C, and the reactor is filled with nitrogen up to 2 bar and completely vented to the atmosphere. This process is repeated at least three times.

[0059] In the second-stage polymerization reaction of step (d), the propylene monomer is preferably added in an amount of 6 to 98 wt % of the total amount of monomers added, but is not limited thereto. For example, if the propylene monomer is added in an amount of less than 6 wt %, the propylene content during block copolymer production is low, and the melting point of the block copolymer cannot reach 160°C or higher, which corresponds to polypropylene. Conversely, if the propylene monomer is added in an amount of more than 98 wt %, it becomes difficult to control the copolymer composition as desired during block copolymer production, and this can lead to problems such as reduced separator performance during production of secondary battery separators using the copolymer as a raw material.

[0060] Meanwhile, in step (d), the polymerization temperature at which propylene monomer is added to the mixed solution and the second-stage polymerization reaction is carried out is preferably, but not limited to, within the range of 30 to 90°C. If the polymerization temperature is below 30°C, the polymerization reaction may not proceed sufficiently. Conversely, if the polymerization temperature exceeds 90°C, even if the polymerization reaction does occur, polypropylene with low stereoregularity may be polymerized and dissolved in hexane, or the polymerization activity may decrease rapidly, making it difficult to control the desired copolymer composition. This may result in a decrease in the performance of the separator when producing a secondary battery separator using the copolymer as a raw material.

[0061] In step (d), the polymerization pressure at which the propylene monomer is added to the mixed solution and the second-stage polymerization reaction is carried out is preferably, but not limited to, within the range of 1 to 40 bar. If the polymerization pressure is less than 1 bar, the polymerization reaction may not proceed sufficiently. Conversely, if the polymerization pressure exceeds 40 bar, even if the polymerization reaction does proceed, it may be difficult to adjust the composition of the copolymer to the desired level, which may result in a decrease in the performance of the separator when the copolymer is used as a raw material for producing a secondary battery separator.

[0062] In addition, when propylene monomer is added to the mixed solution in the second polymerization reaction of step (d) and hydrogen (H2) as a molecular weight regulator is added, ultra-high molecular weight polypropylene is polymerized. In this case, the molecular weight range of the target ultra-high molecular weight polypropylene polymer and the molecular weight range of the final ultra-high molecular weight polyethylene block copolymer can be controlled by adjusting the ratio of the main catalyst, co-catalyst, and promoter to control the molecular weight range.

[0063] Meanwhile, the polymerization reaction in steps (b) and (d) may be carried out in liquid, slurry, bulk, or gas phase, but is not limited thereto. Preferably, steps (b) and (d) are carried out in a suspension polymerization reactor (autoclave), and may be carried out in two or more consecutive reactors. In this case, the operating conditions of each reactor can be the same or different to adjust the physical properties of the polymer.

[0064] Step (e) is a step of filtering and drying a powder of a polyethylene-based block copolymer from the reaction solution obtained in step (d). More specifically, the (ultra)high molecular weight polyethylene-based block copolymer produced is mixed with a polar organic solvent, and separated, purified, and dried using distilled water (y) or filtered water (y').

[0065] In this case, the mixing ratio of the polar organic solvent with the (ultra) high molecular weight polyethylene-based block copolymer prepared may be 0.1 to 10 times the weight of the polar organic solvent as prepared block copolymer, and preferably 0.5 to 3 times the weight of the polar organic solvent as prepared block copolymer.

[0066] That is, it is preferable to mix 10 to 1000 parts by weight of a polar organic solvent with 100 parts by weight of the produced block copolymer, and it is more preferable to mix 50 to 300 parts by weight of a polar organic solvent with 100 parts by weight of the produced block copolymer.

[0067] In this case, the polar organic solvent may be a compound represented by the following formula (4): R-OH····Chemical formula (4) HO-R1-R2-OH·····Chemical formula (5)

[0068] In the chemical formula (4), R is a linear or branched alkyl group having 1 to 12 carbon atoms. Specifically, representative examples of the compound corresponding to the chemical formula (4) may include one or more compounds selected from the group consisting of linear alkalis such as methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, and dodecanol, and branched alkyl groups such as isopropanol, isobutanol, and isopentanol.

[0069] In the chemical formula (5), R1 and R2 are linear alkyl groups having 0 to 6 carbon atoms. Specifically, representative examples of the compound corresponding to the chemical formula (5) may include one or more compounds selected from the group consisting of methanediol, ethanediol, propanediol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, undecanediol, and dodecanediol.

[0070] The water used to separate the polar organic solvent dissolving the catalyst residue from the produced block copolymer may be distilled water or filtered water, and may be used in an amount 1 to 30 times, and preferably 5 to 20 times, the weight of the polar organic solvent used.

[0071] That is, it is preferable to use 100 to 3,000 parts by weight of distilled water or filtered water per 100 parts by weight of polar organic solvent, and it is even more preferable to use 500 to 2,000 parts by weight of distilled water or filtered water per 100 parts by weight of polar organic solvent. The mixture of the produced block copolymer and polar organic solvent undergoes layer separation after contact with water, where the molecular polar organic solvent is mixed in the aqueous layer and the produced block copolymer floats on top of the water. This is separated using filter paper or a filter and then dried in a dryer at 90 to 105°C to obtain a (ultra)high molecular weight polyethylene-based block copolymer from which inorganic substances such as magnesium, titanium, aluminum, and silicon used as catalysts in the polymerization process have been removed.

[0072] (Ultra)high molecular weight polyethylene block copolymer Meanwhile, the present specification further discloses a (ultra) high molecular weight polyethylene-based block copolymer produced by the method for producing a (ultra) high molecular weight polyethylene-based block copolymer of the present invention.

[0073] In the (ultra) high molecular weight polyethylene-based block copolymer of the present invention, the content of the (ultra) high molecular weight polyethylene is 5 to 95% by weight, and the content of the ultra-high molecular weight polyethylene is preferably 5 to 95% by weight, but is not limited thereto.

[0074] Furthermore, in the (ultra)high molecular weight polyethylene-based block copolymer of the present invention, the viscosity average molecular weight of the (ultra)high molecular weight polyethylene is preferably 400,000 to 5,000,000 g / mol, and more preferably 800,000 to 4,000,000 g / mol.

[0075] In the (ultra)high molecular weight polyethylene block copolymer of the present invention, the viscosity average molecular weight of the ultra-high molecular weight polyethylene is preferably 1,000,000 to 4,000,000 g / mol, and more preferably 1,200,000 to 3,000,000 g / mol.

[0076] Furthermore, the (ultra)high molecular weight polyethylene-based block copolymer of the present invention may have a viscosity average molecular weight of 400,000 to 5,000,000 g / mol, more preferably 900,000 to 4,000,000 g / mol, under conditions where no hydrogen or a very small amount of hydrogen is added, preferably under conditions where no hydrogen is added.

[0077] In addition, the (ultra)high molecular weight polyethylene-based block copolymer of the present invention can be produced by carrying out a first-stage polymerization reaction in which only ethylene monomer is added to a mixed solution, or by adding ethylene monomer and a trace amount of hydrogen to the mixed solution, and then carrying out a second-stage polymerization reaction in which propylene monomer is added to the mixed solution, thereby having the (ultra)high molecular weight polyethylene as a linear one-stage polymer.

[0078] Furthermore, the (ultra)high molecular weight polyethylene-based block copolymer of the present invention can maintain the inorganic content at a level of 30 ppm or less by undergoing the catalyst residue removal process as described above. More specifically, the inorganic content of the (ultra)high molecular weight polyethylene-based block copolymer of the present invention is preferably 1 to 30 ppm, and more preferably 5 to 20 ppm.

[0079] Furthermore, as described above, the particle size of the (ultra)high molecular weight polyethylene-based block copolymer of the present invention can be maintained at a level of 400 μm or less by adjusting the particle size and degree of polymerization of the catalyst. More specifically, the particle size of the (ultra)high molecular weight polyethylene-based block copolymer of the present invention is preferably 10 to 400 μm, and more preferably 50 to 300 μm.

[0080] The (ultra) high molecular weight polyethylene block copolymer of the present invention has an apparent density of 0.30 to 0.50 g / cm 3 is preferred, but is not limited to this.

[0081] Secondary battery separators made from (ultra) high molecular weight polyethylene block copolymers In addition, the (ultra) high molecular weight polyethylene-based block copolymer according to the present invention has increased kneadability compared to conventional copolymers of polyethylene and polypropylene, and therefore, a separator for a secondary battery having excellent performance can be produced using the block copolymer according to the present invention as a raw material.

[0082] The secondary battery separator manufactured using the (ultra) high molecular weight polyethylene-based block copolymer according to the present invention as a raw material preferably has a puncture strength of 300 to 600 gf, but is not limited thereto.

[0083] In addition, the secondary battery separator manufactured using the (ultra) high molecular weight polyethylene block copolymer according to the present invention as a raw material has a tensile strength of 800 to 2,000 kgf / cm 2 That is Although preferred, this is not a limitation.

[0084] In addition, the secondary battery separator manufactured using the (ultra) high molecular weight polyethylene-based block copolymer according to the present invention as a raw material preferably has a tensile elongation (Elong) of 25 to 90%, but is not limited thereto. [Example]

[0085] The present specification will be described in more detail with reference to the accompanying drawings and examples. However, the drawings and examples presented in this specification can be modified in various ways by those skilled in the art to have various forms, and the contents of this specification should not be construed as limiting the present invention to the specific disclosed forms, but should be considered as including all equivalents or alternatives within the spirit and technical scope of the present invention. The accompanying drawings are presented to help those skilled in the art to more accurately understand the present invention, and may be exaggerated or reduced in size.

[0086] {Examples and Evaluation} Example 1 A 2L stainless steel reactor equipped with a stirrer was evacuated at room temperature, and 900mL of hexane was poured in as an organic solvent, followed by stirring. At room temperature, 900mg of triethylaluminum as a co-catalyst and 90mg of dicyclopentyldimethoxysilane as a promoter were added, along with 30mg of titanium compound catalyst as the main catalyst. The reactor was then placed in a thermostatic bath maintained at 70°C and heated to 60°C. a. First stage polymerization After adding 200 mL of hydrogen as a molecular weight regulator, gaseous ethylene monomer is added using a mass flow meter at a rate of 1,050 mL / min for 85 minutes to polymerize at 70°C. b. Removing unreacted ethylene monomer. c. After removing the unreacted ethylene monomer, without adding hydrogen, gaseous propylene monomer was added using a mass flow meter at a rate of 500 mL / min for 120 minutes to polymerize at 70°C. After the reaction was completed, the unreacted propylene monomer was removed, the reactor was opened, and the organic solvent and polymerized resin were filtered and separated. The resin was then dried in a dryer to obtain an (ultra)high molecular weight polyethylene block copolymer resin.

[0087] Example 2 The same procedures as in Example 1 were carried out, except that after 100 mL of hydrogen gas was introduced during a. first-stage polymerization, the introduction rate of gas-phase ethylene was adjusted to 500 mL / min, and c. the introduction rate of gas-phase propylene during second-stage polymerization was adjusted to 750 mL / min.

[0088] Example 3 The same procedures as in Example 1 were carried out, except that in a. the first-stage polymerization, 300 mL of hydrogen gas was introduced, and then gas-phase ethylene was introduced at a rate of 1,100 mL / min for 120 minutes, and in c. the second-stage polymerization, gas-phase propylene was introduced at a rate of 500 mL / min for 60 minutes.

[0089] Example 4 The same procedures as in Example 1 were carried out, except that a. 20 mL of hydrogen gas was introduced during the first-stage polymerization, and then gas-phase ethylene was introduced at a rate of 300 mL / min for 30 minutes, and c. gas-phase propylene was introduced at a rate of 730 mL / min for 150 minutes during the second-stage polymerization.

[0090] Example 5 The same procedures as in Example 1 were carried out, except that in a. the first-stage polymerization, 380 mL of hydrogen gas was introduced, and then gas-phase ethylene was introduced at a rate of 1,400 mL / min for 120 minutes, and in c. the second-stage polymerization, gas-phase propylene was introduced at a rate of 200 mL / min for 30 minutes.

[0091] Example 6 The same procedure as in Example 1 was carried out except that no hydrogen was added during the first stage of polymerization.

[0092] Example 7 The same procedure as in Example 1 was carried out, except that a. hydrogen was not introduced during the first-stage polymerization and the reaction temperature of the second-stage polymerization was adjusted to 55°C.

[0093] Example 8 After the preparatory steps for polymerization in Example 1, a. gas-phase ethylene for the first-stage polymerization was fed at a rate of 700 mL / min for 60 minutes, and c. gas-phase propylene for the second-stage polymerization was fed at a rate of 500 mL / min for 60 minutes, and then the first and second stages of polymerization were repeated again to perform four-stage polymerization, in the same manner as in Example 1.

[0094] Example 9 The same procedure as in Example 1 was repeated except that the amount of cocatalyst was reduced from 900 mg to 300 mg and the amount of promoter was reduced from 90 mg to 30 mg.

[0095] Example 10 The same procedure as in Example 1 was carried out except that the amount of cocatalyst was reduced from 900 mg to 300 mg.

[0096] Example 11 The same procedure as in Example 6 was carried out, except that the polymerization temperature in the first and second stages was lowered from 70°C to 30°C.

[0097] Comparative Example 1 VH035 (viscosity average molecular weight: 400,000) manufactured by Daehan Petrochemical Co., Ltd. and UHMWPP (viscosity average molecular weight: 1.5 million) were mixed at a ratio of 50:50.

[0098] Comparative Example 2 U015 (viscosity average molecular weight: 1.5 million) and UHMWPP (viscosity average molecular weight: 1.5 million) manufactured by Daehan Petrochemical Co., Ltd. were mixed at a ratio of 50:50.

[0099] Comparative Example 3 VH100U (viscosity average molecular weight 1,000,000) manufactured by Daehan Petrochemical Co., Ltd. and UHMWPP (viscosity average molecular weight 1,500,000) were mixed at a ratio of 45:55.

[0100] Comparative Example 4 VH100U (viscosity average molecular weight 1,000,000) manufactured by Daehan Petrochemical Co., Ltd. and UHMWPP (viscosity average molecular weight 1,500,000) were mixed at a ratio of 40:60.

[0101] Comparative Example 5 The same procedure as in Example 1 was repeated except that the amount of cocatalyst was reduced from 900 mg to 10 mg and the amount of promoter was reduced from 90 mg to 30 mg.

[0102] Comparative Example 6 The same procedure as in Example 1 was carried out, except that the amount of cocatalyst was increased from 900 mg to 1,730 mg.

[0103] Comparative Example 7 The same procedure as in Example 1 was repeated except that the amount of the cocatalyst was reduced from 90 mg to 3 mg.

[0104] Comparative Example 8 The same procedure as in Example 1 was carried out, except that the amount of the cocatalyst was increased from 90 mg to 130 mg.

[0105] Measurement method for physical properties of (ultra)high molecular weight polyethylene block copolymers (1) Viscosity average molecular weight (Mv): The viscosity average molecular weight was measured by obtaining the intrinsic viscosity using the intrinsic viscosity measurement method defined by ASTM D5020 and ISO 1628-3, and the value was calculated using the Margolies Equation. Mv=5.37×10 4 ×[η] 1.49 η: Intrinsic viscosity

[0106] (2) Polyethylene / Polypropylene Content: NMRC 13 The values ​​analyzed in were integrated and expressed.

[0107] (3) Apparent density (g / cm 3 ): After removing the moisture from the block copolymer resin powder, dry The apparent density was measured using an automatic density meter (AccuPycII 1340TC-10CC; Shimadzu Corporation; carrier gas: helium). Measurements were repeated until the measured values ​​were equal five or more times in succession.

[0108] Measurement method for the physical properties of secondary battery separators (1) Puncture strength (gf): A puncture test was conducted using a Kato Tech KES-G5 handy compression tester with a needle tip curvature radius of 0.5 mm and a puncture speed of 2 mm / sec. The maximum puncture load was taken as the puncture strength. The sample was fixed in a metal frame (sample holder) with a hole of 11.3 mm diameter, together with a rubber gasket.

[0109] (2) Tensile strength (kgf / cm 2): According to ASTM D882 (1997), The tensile strength of the secondary battery separator was measured. An Instron-type tensile tester was used under the following conditions. The average value of five measurement results was taken as the tensile strength in the present invention. Test specimens for measuring tensile strength were prepared by cutting the secondary battery separator into a rectangle measuring 10 mm in length and 50 mm in width. The tensile speed was 100 mm / min, and the measurement environment was a temperature of 23°C and a humidity of 65% RH.

[0110] (3) Tensile elongation (Elong.%): A half-sized test piece of JIS K7113 No. 2 stamped from a 1 mm thick press sheet was used as the evaluation sample, and the measurement was carried out at a tension speed of 30 mm / min in an atmosphere of 23°C. An AGS-50G manufactured by Shimadzu Corporation was used for the measurement.

[0111] Measurement results of physical properties of (ultra) high molecular weight polyethylene block copolymer The polyethylene and polypropylene contents in the block copolymers prepared in Examples 1 to 11 and Comparative Examples 1 to 8, the viscosity average molecular weights after the first to fourth polymerization stages, and the properties of the secondary battery separators were evaluated and are shown in Table 1 below.

[0112] [Table 1]

[0113] Referring to Table 1, the characteristics of the secondary battery separator depending on the content and molecular weight of polyethylene and polypropylene in the ultra-high molecular weight polyethylene-based block copolymer according to one embodiment of the present invention can be seen, and the improved physical properties and surface can be seen compared to the comparative example of a simply mixed heterogeneous composite resin.

[0114] The (ultra) high molecular weight polyethylene block copolymers of the present invention according to Examples 1 to 11 contain 10 to 500 moles of Al as a co-catalyst which is an alkylaluminum compound and 1 to 40 moles of Si as a promoter which is a silicon compound, per mole of Ti as a main catalyst which is a titanium compound, and can be produced with viscosity control under the conditions where a trace amount of hydrogen (H2) as a molecular weight regulator is added or not added. It can be confirmed that the average molecular weight is 400,000 to 5,000,000 g / mol.

[0115] Furthermore, from Examples 6 and 11, it can be confirmed that when the (ultra) high molecular weight polyethylene-based block copolymer of the present invention is produced at a polymerization temperature of 30 to 90°C, it is possible to produce an (ultra) high molecular weight polyethylene-based block copolymer having a viscosity average molecular weight of 400,000 to 5,000,000 g / mol.

[0116] Furthermore, the (ultra) high molecular weight polyethylene-based block copolymers of the present invention according to Examples 1 to 11 have an apparent density of 0.30 to 0.50 g / cm 3 It can be confirmed that

[0117] On the other hand, the polyethylene and polypropylene block copolymers of Comparative Examples 5 to 8 all had an apparent density of 0.30 g / cm 3 It can be confirmed that it is less than

[0118] Furthermore, it can be confirmed that the secondary battery separators manufactured using the (ultra) high molecular weight polyethylene-based block copolymers of the present invention according to Examples 1 to 11 have improved mechanical properties, with a puncture strength of 300 to 600 gf, compared to the secondary battery separators manufactured using the block copolymers according to Comparative Examples 1 to 4.

[0119] On the other hand, it can be seen that the secondary battery separators manufactured using the polyethylene-polypropylene block copolymer according to Comparative Examples 1 to 4 all had a puncture strength of less than 300 gf.

[0120] In addition, the secondary battery separators produced using the (ultra) high molecular weight polyethylene-based block copolymers of the present invention as raw materials according to Examples 1 to 10 have a tensile strength of 800 to 2,000 kgf / cm 2 The tensile elongation (Elong) is 25 to 90%, and thus, the comparative examples 1 to 4 It can be seen that the polymer has uniform mixing properties and improved physical properties compared to secondary battery separators prepared using the same block copolymer as the raw material.

[0121] Meanwhile, the secondary battery separators manufactured using the polyethylene and polypropylene block copolymers according to Comparative Examples 1 to 4 had a tensile strength and elongation of 600 kgf / cm 2 It can be confirmed that the saturation is less than 100% and less than 60%.

[0122] In particular, the secondary battery separator manufactured using the (ultra) high molecular weight polyethylene-based block copolymer of the present invention as a raw material according to Example 8 has a puncture strength of 559 gf and a tensile strength of 1,811 kgf / cm 2 The tensile elongation (Elong) is 81%, making it the best separator for secondary batteries. It was found that the composition had excellent kneadability and improved physical properties.

[0123] From this, it can be seen that compared to a second-stage polymerization in which ethylene monomer and propylene monomer are each added once and polymerized, a fourth-stage polymerization in which ethylene monomer and propylene monomer are each added once and then polymerized again by additionally adding ethylene monomer and propylene monomer can improve the kneadability and mechanical properties of the produced block copolymer and the secondary battery separator produced using such a block copolymer as a raw material.

[0124] The (ultra) high molecular weight polyethylene-based block copolymer of the present invention can be used as a compatibilizer to increase the blending and processing of polyethylene and polypropylene, which have low compatibility, and also has the effect of improving blending properties, film surface properties, and other physical properties compared to secondary battery separators made of heterogeneous composite materials of polyethylene and polypropylene, which are simply blended and processed.

[0125] The above description is merely an illustrative example of the technical concept of the present invention, and various modifications and variations can be made by a person having ordinary knowledge in the technical field to which the present invention pertains without departing from the essential characteristics of the present invention.

[0126] Therefore, the embodiments disclosed in the present invention are for illustrative purposes only and are not intended to limit the technical idea of ​​the present invention, and the scope of the technical idea of ​​the present invention should not be limited by such embodiments. The scope of protection of the present invention should be interpreted by the following claims, and any technical idea within the scope equivalent thereto should be interpreted as being included in the scope of the present invention. [Industrial Applicability]

[0127] According to the present invention, it is possible to provide a secondary battery separator having improved mixability, film surface, and other physical properties compared to a secondary battery separator made of a heterogeneous composite material of polyethylene and polypropylene, which is simply mixed and processed, as well as by using a compatibilizer to increase mixability during mixing and processing of polyethylene and polypropylene, which have low compatibility.

Claims

1. In a high molecular weight or ultra-high molecular weight polyethylene-based block copolymer, 25 to 90% by weight of high molecular weight or ultra-high molecular weight polyethylene and 10 to 75% by weight of ultra-high molecular weight polypropylene, based on 100% by weight of the block copolymer; The high-molecular-weight or ultra-high-molecular-weight polyethylene has a viscosity-average molecular weight of 400,000 to 5,000,000 g / mol, and the ultra-high-molecular-weight polypropylene has a viscosity-average molecular weight of 1,000,000 to 4,000,000 g / mol; The block copolymer is a high-molecular-weight or ultra-high-molecular-weight polyethylene-based block copolymer having a viscosity-average molecular weight of 400,000 to 5,000,000 g / mol under conditions where no hydrogen is added or a very small amount of hydrogen is added.

2. 2. The high-molecular-weight or ultra-high-molecular-weight polyethylene-based block copolymer according to claim 1, wherein the block copolymer is produced by carrying out a first-stage polymerization reaction in which only ethylene monomer is added to a mixed solution, or by adding ethylene monomer and a trace amount of hydrogen to the mixed solution, and then carrying out a second-stage polymerization reaction in which propylene monomer is added to the mixed solution, thereby comprising the high-molecular-weight or ultra-high-molecular-weight polyethylene as a first-stage polymer having a linear structure.

3. The block copolymer has an apparent density of 0.30 to 0.50 g / cm 3 2. The high-molecular-weight or ultra-high-molecular-weight polyethylene-based block copolymer according to claim 1, wherein

4. 2. The high molecular weight or ultra-high molecular weight polyethylene-based block copolymer according to claim 1, wherein the block copolymer has an inorganic content of 1 to 30 ppm, and the inorganic substance is used as a catalyst in a polymerization process.

5. 2. The high-molecular-weight or ultra-high-molecular-weight polyethylene-based block copolymer according to claim 1, wherein the block copolymer has a particle size of 10 to 400 μm.

6. A secondary battery separator manufactured from a high-molecular-weight or ultra-high-molecular-weight polyethylene-based block copolymer, the high-molecular-weight or ultra-high-molecular-weight polyethylene-based block copolymer comprising, relative to 100% by weight of the block copolymer, 25 to 90% by weight of high-molecular-weight or ultra-high-molecular-weight polyethylene; and 10 to 75% by weight of ultra-high-molecular-weight polypropylene, the high-molecular-weight or ultra-high-molecular-weight polyethylene having a viscosity-average molecular weight of 400,000 to 5,000,000 g / mol, the ultra-high-molecular-weight polypropylene having a viscosity-average molecular weight of 1,000,000 to 4,000,000 g / mol, and the block copolymer having a viscosity-average molecular weight of 400,000 to 5,000,000 g / mol under conditions where no hydrogen or a trace amount of hydrogen is added.

7. The secondary battery separator according to claim 6, wherein the secondary battery separator has a puncture strength of 300 to 600 gf.

8. The secondary battery separator has a tensile strength of 800 to 2,000 kgf / cm 2 The secondary battery separator according to claim 6 or 7,

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