[Citation with related applications] [2] This application claims the benefit of priority based on Korean Patent Application No. 10-2018-0037549 dated March 30, 2018 and Korean Patent Application No. 10-2018-0117838 dated October 02, 2018, All content disclosed in the literature is incorporated as a part of this specification. [3] [Technical field] [4] The present invention relates to a block copolymer composition, and more particularly, to a block copolymer composition including a diblock copolymer and a triblock copolymer including a polyolefin-based block and a polystyrene-based block. background [5] Polyolefin-polystyrene block copolymers, such as styrene-ethylene/butylene-styrene (SEBS) or styrene-ethylene/propylene-styrene (SEPS), currently have a global market of hundreds of thousands of tons. In addition, they have superior heat resistance and light resistance compared to Styrene-butadiene-styrene (SBS) or styrene-isoprene-styrene (SIS). It is used as an oil-gel used in communication materials, an impact modifier for engineering plastics, and a plasticizer or toughener for transparent polypropylene. Conventional SEBS is prepared through a two-step reaction of hydrogenating SBS obtained by anionic polymerization of styrene and butadiene. Conventional SEPS is also prepared through a two-step reaction in which SIS obtained by anionic polymerization of styrene and isoprene is hydrogenated. As described above, the process of saturating all double bonds included in the main chain by hydrogenation has a high process cost, so the unit price of SEBS and SEPS is significantly higher than that of SBS and SIS before hydrogenation. This may act as a limit to market expansion. In addition, it is virtually impossible to saturate all double bonds in the polymer chain through hydrogenation, so commercialized SEBS and SEPS contain some residual double bonds and their presence is often problematic (Journal of Polymer Science: Part A: Polymer Chemistry, 2002, 40, 1253; Polymer Degradation and Stability 2010, 95, 975). In addition, the conventional block copolymer prepared through two steps as described above has a very limited structure because the polyolefin block is formed through hydrogenation reaction after anionic polymerization of butadiene or isoprene. [6] Under this background, the production of a polyolefin-polystyrene block copolymer by a direct one-pot reaction from an olefin monomer and a styrene monomer is a challenging research topic with a large commercial ripple effect. In this regard, in the related art, polypropylene having a para-methylstyryl group is synthesized in a terminal by using para-methylstyrene as a molecular weight modifier during polymerization of para-methylstyrene to propylene, and then the methyl group of the terminal is dehydrogenated with butyllithium. An example of preparing a polyprefillene-polystyrene block copolymer by implementing styrene anionic polymerization after inducing the reaction has been reported (J. Am. Chem. Soc. 2001, 123, 4871; Macromolecules 2002, 35, 1622). As another example, an attempt to prepare a block copolymer by performing ethylene/propylene copolymerization by utilizing the living polymerization reactivity of a phenoxyimine catalyst and subsequently injecting styrene monomer has been reported (Marcomole. Rapid. Commun., 2006, 27). , 1009). However, the conventionally reported methods as described above have problems such as requiring a multi-step process, and thus have not been applied to commercial processes. DETAILED DESCRIPTION OF THE INVENTION technical challenge [7] An object of the present invention is to provide a block copolymer composition including a diblock copolymer and a triblock copolymer including a polyolefin-based block and a polystyrene-based block with improved melt processability. means of solving the problem [8] In order to solve the above problems, the present invention provides (1) a weight average molecular weight (Mw) of 70,000 g/mol to 120,000 g/mol; (2) a polydispersity index (PDI) of 1.0 to 2.0; (3) the glass transition temperature (Tg) is -55 ℃ to -30 ℃; (4) melt index (MI, 230 ℃, 5 kg load conditions) of 0.2 to 3.0 g / 10 minutes, to provide a block copolymer composition. Effects of the Invention [9] The block copolymer composition according to the present invention includes a diblock copolymer and a triblock copolymer including a polyolefin-based block and a polystyrene-based block, in which the structure and properties of each block of the block copolymer are controlled, Since the content of the triblock copolymer in the composition is maximized to simultaneously satisfy specific physical property conditions, excellent melt processability can be satisfied. Best mode for carrying out the invention [10] Hereinafter, the present invention will be described in more detail to help the understanding of the present invention. [11] The terms or words used in the present specification and claims should not be construed as being limited to their ordinary or dictionary meanings, and the inventor may properly define the concept of the term in order to best describe his invention. It should be interpreted as meaning and concept consistent with the technical idea of ​​the present invention based on the principle that there is. [12] As used herein, the term 'composition' includes reaction products and decomposition products formed from materials of the composition, as well as mixtures of materials comprising the composition. [13] As used herein, the term 'residual unsaturated bonds' refers to unsaturated bonds such as double bonds and triple bonds present in the polymer chain of the block copolymer included in the block copolymer composition, and the polymer chain is the block copolymer. contains the main chain and branched chain of the block copolymer, including unsaturated bonds generated during polymerization as well as unsaturated bonds contained in or derived from raw materials such as monomers, multimers, initiators, catalysts, etc. used to prepare the block copolymer do. [14] As used herein, the term 'halogen' means fluorine, chlorine, bromine or iodine, unless otherwise noted. [15] As used herein, the term 'alkyl' refers to a straight-chain, cyclic or branched hydrocarbon moiety, unless otherwise indicated. [16] The term 'aryl' as used herein, unless otherwise specified, refers to an aromatic group including phenyl, naphthyl anthryl, phenanthryl, chrysenyl, pyrenyl, and the like. [17] In the present specification, silyl may be silyl unsubstituted or substituted with alkyl having 1 to 20 carbon atoms, for example, silyl, trimethylsilyl or triethylsilyl. [18] [19] The block copolymer composition of the present invention has (1) a weight average molecular weight (Mw) of 70,000 g/mol to 120,000 g/mol; (2) a polydispersity index (PDI) of 1.0 to 2.0; (3) the glass transition temperature (Tg) is -55 ℃ to -30 ℃; (4) Melt index (MI, 230°C, 5 kg load condition) satisfies the condition of 0.2 to 3.0 g/10 min, and excellent melt processability can be satisfied by simultaneously satisfying the above physical property conditions. [20] The block copolymer composition of the present invention simultaneously satisfies the conditions of (1) to (4), thereby exhibiting a high molecular weight and a wide molecular weight distribution, and has excellent heat resistance and fluidity, and thus has excellent processability, particularly excellent melt processability. can indicate [21] [22] The block copolymer composition has (1) a weight average molecular weight (Mw) of 70,000 g/mol to 120,000 g/mol, specifically 72,000 g/mol to 110,000 g/mol, and more specifically 74,000 g/mol to 103,000 g/mol. g/mol can be satisfied. In the present invention, the weight average molecular weight (Mw) is a polystyrene equivalent molecular weight analyzed by gel permeation chromatography (GPC). [23] In addition, the block copolymer composition may satisfy (2) a polydispersity index (PDI) of 1.0 to 2.0, specifically 1.2 to 1.8, and more specifically 1.4 to 1.7. In the present invention, the polydispersity index refers to a ratio of Mw/Mn, Mw is a weight average molecular weight, and Mn is a number average molecular weight. [24] In addition, the block copolymer composition (3) the glass transition temperature (Tg) satisfies -55 ℃ to -30 ℃, specifically -55 ℃ to -39 ℃, more specifically -52 ℃ to -39 ℃ can be satisfied The glass transition temperature (Tg) may be measured using a dynamic mechanical analyzer (DMA). [25] In addition, the block copolymer composition (4) melt index (MI, 230 ℃, 5 kg load condition) satisfies 0.2 to 3.0 g/10 min, specifically 0.3 to 2.5 g/10 min, more specifically 0.3 to 2.1 g/10 min. [26] The melt index (MI) affects the mechanical properties, impact strength, and moldability of the block copolymer. In the present specification, the melt index may be measured at 230° C. and a load of 5 kg according to ASTM D1238 (ISO 1133). [27] [28] The block copolymer composition may include a diblock copolymer including a polyolefin-based block and a polystyrene-based block; and a triblock copolymer including a polyolefin-based block and a polystyrene-based block, for example, (1) reacting an organozinc compound with one or more olefinic monomers under a transition metal catalyst to form an olefinic polymer block to form an intermediate manufacturing; and (2) reacting the intermediate obtained in step (a) with a styrenic monomer in the presence of an alkyllithium compound to form a styrenic polymer block. [29] [30] (1) preparing an intermediate by reacting an organic zinc compound with at least one olefinic monomer under a transition metal catalyst to form an olefinic polymer block [31] [32] In step (a), the olefinic monomer may be inserted between Zn and A of the organic zinc compound to be polymerized to form an olefinic polymer block. [33] In an example of the present invention, the olefin-based polymer block formed by polymerization of one or more olefin-based monomers may include a repeating unit represented by the following formula (1), and in the present specification, a repeating unit represented by the following formula (1) The olefinic polymer block containing is represented as a first block. [34] In step (a), the olefinic monomer may form a first block including at least one repeating unit represented by the following Chemical Formula 1. [35] [Formula 1] [36] [37] In Formula 1, [38] R 1 is hydrogen; alkyl having 1 to 20 carbon atoms; alkyl having 1 to 20 carbon atoms substituted with silyl; arylalkyl having 7 to 20 carbon atoms; or arylalkyl having 7 to 20 carbon atoms substituted with silyl; [39] n may be an integer from 10 to 10,000. [40] In addition, in an example of the present invention, R 1 is hydrogen; It may be an alkyl having 3 to 20 carbon atoms. [41] In addition, in an example of the present invention, R 1 is hydrogen; Alternatively, it may be an alkyl having 3 to 12 carbon atoms, and specifically, R 1 may be hydrogen or an alkyl having 4 to 12 carbon atoms. [42] In addition, n may be an integer of 10 to 10,000, specifically, may be an integer of 500 to 7,000. [43] On the other hand, in the formulas shown in the specification of the present invention, "*" represents a linking site as a terminal site of the repeating unit. [44] [45] In an example of the present invention, when the first block includes two or more types of repeating units represented by Chemical Formula 1, the first block may include repeating units represented by Chemical Formula 2 below. [46] [Formula 2] [47] [48] In Formula 2, [49] R 1 ′ and R 1 ″ are each independently hydrogen, alkyl having 1 to 20 carbon atoms ; alkyl having 1 to 20 carbon atoms substituted with silyl; arylalkyl having 7 to 20 carbon atoms; or aryl having 7 to 20 carbon atoms substituted with silyl. alkyl; wherein R 1 ' and R 1 "are different from each other, [50] 0