Polypropylene resin composition having excellent low-temperature impact resistance and low volatile organic compound emission, and molded article made therefrom

Abstract

The present invention relates to a polypropylene resin composition having excellent impact resistance and low emission of volatile organic compounds, and a molded article made from the same. A polypropylene resin molded article prepared from the polypropylene resin composition according to an embodiment of the present invention has excellent impact resistance and low emission of volatile organic compounds, and thus can be effectively used as an automotive interior and exterior member, a toy for children, or a food storage container.

Description

Technical Field

[0001] The present invention relates to a polypropylene resin composition having excellent impact resistance and low volatile organic compound emissions, and a molded article made therefrom. Specifically, the present invention relates to a polypropylene resin composition having impact resistance at normal and low temperatures and low volatile organic compound emissions, which contains an ethylene-propylene block copolymer resin as a main component, and a molded article made therefrom. Background Art

[0002] As a general-purpose resin, polypropylene resin is widely used as a material for automotive interior and exterior parts, parts of electrical and household appliances, building and industrial materials, films, tubes, and wires due to its excellent economy, mechanical properties, moldability, and chemical resistance.

[0003] As a type of polypropylene, an ethylene-propylene block copolymer is a polymer in which an ethylene-propylene rubber copolymer is dispersed in a propylene homopolymer, so that the impact resistance of this resin is enhanced compared to that of a propylene homopolymer.

[0004] In particular, when the content of the ethylene-propylene rubber copolymer in the ethylene-propylene block copolymer is 25% by weight or more, the Izod impact strength measured at 23 °C is 50 kgf·cm / cm or more, and the Izod specimen will not be completely broken after the impact test, showing very excellent impact resistance. This high-impact polypropylene resin prepared in a reactor is called R-TPO (reactor made-thermoplastic olefin). Although R-TPO has excellent impact resistance at normal temperature (23 °C), its impact resistance at low temperature (e.g., 0 °C) is low, so its application is limited when low-temperature impact resistance is required.

[0005] For polypropylene resins with excellent impact resistance, it is difficult to have a high melt index. Therefore, peroxides are usually added to polypropylene resins to increase the final melt index. However, the residual peroxides have a strong odor and emit a large amount of volatile organic compounds, so they are not suitable for use in automotive parts or food containers. Therefore, it is necessary to develop a polypropylene resin composition that exhibits excellent impact resistance and high melt index characteristics and has low volatile organic compound emissions.

[0006]

Prior Art Documents

[0007]

Patent Documents

[0008] (Patent Document 1) Korean Patent Application Publication No. 10-2007-0098279. Summary of the Invention

[0009] Technical Problem

[0010] An object of the present invention is to provide a polypropylene resin composition having excellent impact resistance at normal and low temperatures and low volatile organic compound emissions.

[0011] Another object of the present invention is to provide a polypropylene resin molded article made of the above polypropylene resin composition, which has excellent impact resistance at normal and low temperatures and low volatile organic compound emissions.

[0012] Technical solution

[0013] To achieve the above object, according to an embodiment of the present invention, the present invention provides a polypropylene resin composition comprising: an ethylene-propylene block copolymer (A), which accounts for 85 to 97% by weight in the total weight of components (A) and (B), and is obtained by the stepwise polymerization of a propylene homopolymer and an ethylene-propylene rubber copolymer in a reactor; and polyethylene (B), which accounts for 3 to 15% by weight in the total weight of components (A) and (B), wherein when the ethylene-propylene block copolymer (A) is extracted with a xylene solvent at normal temperature, the content of the ethylene-propylene rubber copolymer obtained as an extract (xylene-soluble matter) is 25 to 40% by weight, the ethylene content in the xylene-soluble matter is 35 to 45% by weight, the ethylene content in the ethylene-propylene block copolymer (A) is 9 to 20% by weight, and when measured at a load condition of 2.16 kg at 230 °C, the melt flow rate (MFR T ) of the polypropylene resin composition and the matrix melt flow rate (MFR M ) of the ethylene-propylene block copolymer (A) ratio (MFR T / MFR M ) is 0.3 or less.

[0014] In a specific embodiment of the present invention, when measured at a load condition of 2.16 kg at 230 °C, the melt flow rate of the ethylene-propylene block copolymer (A) may be 30 to 50 g / 10 min.

[0015] In a specific embodiment of the present invention, the polyethylene (B) may include low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), or high-density polyethylene (HDPE).

[0016] In a preferred embodiment of the present invention, the polyethylene (B) may include high-density polyethylene.

[0017] In a specific embodiment of the present invention, the polypropylene resin composition may further comprise one or more additives selected from antioxidants, neutralizing agents, slip agents, anti-blocking agents, reinforcing agents, fillers, weather stabilizers, antistatic agents, lubricants, nucleating agents, flame retardants, pigments, and dyes.

[0018] In a specific embodiment of the present invention, based on 100 parts by weight of the polypropylene resin composition, the polypropylene resin composition may further comprise 0.05 to 0.3 parts by weight of at least one antioxidant selected from pentaerythritol tetra(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, and tris(2,4-di-tert-butylphenyl) phosphite.

[0019] In a specific embodiment of the present invention, based on 100 parts by weight of the polypropylene resin composition, the polypropylene resin composition may further comprise 0.05 to 0.3 parts by weight of at least one neutralizing agent selected from hydrotalcite and calcium stearate.

[0020] In a specific embodiment of the present invention, when measured under a load condition of 2.16 kg at 230 °C, the melt index of the polypropylene resin composition may be 30 to 50 g / 10 min.

[0021] In a specific embodiment of the present invention, in the differential scanning calorimetry analysis of the polypropylene resin composition, the temperature of the first peak appearing during the second heating may be in the range of 125 °C to 130 °C.

[0022] According to another embodiment of the present invention, the present invention provides a polypropylene resin molded article formed from the above polypropylene resin composition.

[0023] In a specific embodiment of the present invention, the polypropylene resin molded article may be obtained by injection molding the polypropylene resin composition.

[0024] In a specific embodiment of the present invention, the Izod impact strength of the polypropylene resin molded article measured at 23 °C may be 50 kgf·cm / cm or more, and the Izod impact strength measured at 0 °C may be 50 kgf·cm / cm or more.

[0025] In a specific embodiment of the present invention, the total volatile organic compound emission of the polypropylene resin composition may be 400 ppm or less.

[0026] The polypropylene resin molded article according to the embodiment of the present invention may be an interior or exterior automotive component, a children's toy, or a food storage container.

[0027] Beneficial effects

[0028] The polypropylene resin molded article made of the polypropylene resin composition according to an embodiment of the present invention has excellent low-temperature impact resistance and low emissions of volatile organic compounds, and thus can be effectively used as interior and exterior automotive parts, children's toys, or food storage containers. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The differential scanning calorimetry heating curve of the resin composition of Example 1 is shown.

[0030] Figure 2 The differential scanning calorimetry heating curve of the resin composition of Comparative Example 1 is shown. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] Hereinafter, the present invention will be described in detail.

[0032] To achieve the above object, according to an embodiment of the present invention, the present invention provides a polypropylene resin composition comprising: propylene-ethylene block copolymer (A), which accounts for 85 to 97% by weight in the total weight of components (A) and (B), and is obtained by the stepwise polymerization of propylene homopolymer and propylene-ethylene rubber copolymer in a reactor; and polyethylene (B), which accounts for 3 to 15% by weight in the total weight of components (A) and (B), wherein when the propylene-ethylene block copolymer (A) is extracted with xylene solvent at room temperature, the content of the propylene-ethylene rubber copolymer obtained as an extract (xylene-soluble matter) is 25 to 40% by weight, the ethylene content in the xylene-soluble matter is 35 to 45% by weight, the ethylene content in the propylene-ethylene block copolymer (A) is 9 to 20% by weight, and when measured at a load condition of 2.16 kg at 230 °C, the melt index (MFR T ) of the polypropylene resin composition and the matrix melt index (MFR M ) of the propylene-ethylene block copolymer (A) ratio (MFR T / MFR M ) is 0.3 or less.

[0033] (A) Propylene-ethylene block copolymer

[0034] The polypropylene resin composition according to an embodiment of the present invention contains a propylene-ethylene block copolymer (A). Among them, the propylene-ethylene block copolymer (A) may be a polymer obtained by the stepwise polymerization of propylene homopolymer and propylene-ethylene rubber copolymer in a reactor.

[0035] Specifically, when the propylene-ethylene block copolymer (A) is extracted with xylene solvent at room temperature, the content of the propylene-ethylene rubber copolymer obtained as the extract (xylene-soluble matter) is 25 to 40% by weight. Preferably, when the propylene-ethylene block copolymer (A) is extracted with xylene solvent at room temperature, the content of the propylene-ethylene rubber copolymer obtained as the extract (xylene-soluble matter) can be 26 to 38% by weight, more preferably 30 to 35% by weight. If the content of the propylene-ethylene rubber copolymer is less than 25% by weight, the Izod impact strength of the resin molded article at 23°C may decrease. If the content of the propylene-ethylene rubber copolymer exceeds 40% by weight, there is a risk that the flexural modulus of the resin molded article decreases and the Izod impact strength cannot be further improved.

[0036] In addition, the ethylene content in the above-mentioned xylene-soluble matter of the propylene-ethylene block copolymer (A) is 35 to 45% by weight. Preferably, the ethylene content in the above-mentioned xylene-soluble matter of the propylene-ethylene block copolymer (A) can be 36 to 44% by weight, more preferably 37 to 44% by weight. If the ethylene content in the xylene-soluble matter is less than 35% by weight or greater than 45% by weight, the Izod impact strength of the resin molded article at 23°C may decrease.

[0037] In addition, the ethylene content in the propylene-ethylene block copolymer (A) is 9 to 20% by weight. Preferably, the ethylene content in the propylene-ethylene block copolymer (A) can be 10 to 18% by weight, more preferably 12 to 16% by weight. If the ethylene content in the propylene-ethylene block copolymer (A) is less than 9% by weight, the Izod impact strength of the resin molded article at 23°C may decrease. If the ethylene content in the propylene-ethylene block copolymer (A) exceeds 20% by weight, the compatibility between the propylene homopolymer and the propylene-ethylene rubber copolymer is low, such that the propylene-ethylene rubber copolymer cannot be smoothly dispersed in the propylene homopolymer matrix, which may cause the balance of rigidity / impact resistance of the resin molded article to deteriorate.

[0038] In a specific embodiment of the present invention, when measured under a load condition of 2.16 kg at 230°C, the melt index of the propylene-ethylene block copolymer (A) is 30 to 50 g / 10 min. Preferably, when measured under a load condition of 2.16 kg at 230°C, the melt index of the propylene-ethylene block copolymer (A) can be 35 to 45 g / 10 min.

[0039] If the melt index is less than 30 g / 10 min, the fluidity of the resin composition during injection molding decreases, which may lead to a decrease in processability, and if the melt index exceeds 50 g / 10 min, the impact resistance of the resin molded article cannot be sufficiently improved.

[0040] Based on the total weight of component (A) and component (B), the polypropylene resin composition according to an embodiment of the present invention contains 85 to 97% by weight of an ethylene-propylene block copolymer (A). Preferably, based on the total weight of component (A) and component (B), the polypropylene resin composition may contain 90 to 97% by weight of an ethylene-propylene block copolymer (A). If the content of the ethylene-propylene block copolymer (A) is less than 85% by weight, the flexural modulus of the resin molded article may decrease. If the content of the ethylene-propylene block copolymer (A) exceeds 97% by weight, the IZOD impact strength of the resin molded article at 0 °C may decrease.

[0041] The method for preparing the above-mentioned ethylene-propylene block copolymer (A) is not particularly limited, and the preparation methods of ethylene-propylene block copolymers known in the technical field to which the present invention pertains can be directly used, or used after appropriate improvement. For example, bulk polymerization, solution polymerization, slurry polymerization, gas-phase polymerization, etc. can be used, and batch or continuous methods can be adopted.

[0042] In addition, if necessary, in order to increase the molecular weight distribution of the ethylene-propylene block copolymer (A), a plurality of polymerization reactors for polymerizing propylene polymers can be arranged in series, and each polymerization reactor has a different degree of polymerization, and polymerization is carried out in sequence.

[0043] Specifically, the preparation of the ethylene-propylene block copolymer (A) can be carried out in a commercial process according to the polymerization methods known to those skilled in the art, such as the Spherizone preparation process of LyondellBasell, the Hypol preparation process of Mitsui, or the Unipol preparation process of Grace.

[0044] The Spherizone process can be a process capable of continuous polymerization by an annular reactor called a multizone circulating reactor (MZCR) and a gas-phase reactor connected in series. Specifically, an ethylene homopolymer can be produced by injecting propylene alone into the MZCR reactor. In the subsequent gas-phase reactor, block copolymerization of an ethylene-propylene rubber component can be carried out by adding propylene and ethylene, thereby obtaining an ethylene-propylene block copolymer. The melt index of the resulting copolymer can be controlled by injecting hydrogen into each reactor.

[0045] The Hypol process can be a process capable of continuous polymerization through two bulk reactors or slurry reactors connected in series and two gas-phase reactors. Specifically, propylene homopolymer can be produced by injecting propylene alone into the first to third reactors. In the subsequent fourth reactor, propylene-ethylene rubber components can be block copolymerized by adding propylene and ethylene to obtain a propylene-ethylene block copolymer. The melt index of the resulting copolymer can be controlled by injecting hydrogen into each reactor.

[0046] The Unipol process can achieve continuous polymerization by connecting two or more gas-phase reactors in series. Specifically, in the case of a process connecting two gas-phase reactors in series, propylene homopolymer can be produced by injecting propylene alone into the first reactor. In the subsequent second reactor, propylene-ethylene rubber components can be block copolymerized by adding propylene and ethylene to obtain a propylene-ethylene block copolymer. The melt index of the resulting copolymer can be controlled by injecting hydrogen into each reactor.

[0047] The propylene-ethylene block copolymer (A) can be polymerized in the presence of a Ziegler-Natta catalyst or a metallocene catalyst.

[0048] Specifically, the Ziegler-Natta catalyst can be prepared using phthalates, succinates, or diether internal electron donors, or two or more of them can be used in combination for preparation.

[0049] More specifically, a catalyst for propylene polymerization can be prepared by reacting dialkoxymagnesium with a titanium compound and phthalates, succinates, or diether internal electron donors in the presence of an organic solvent. In the presence of this catalyst, propylene monomers are reacted with a cocatalyst and an external electron donor to polymerize the propylene-ethylene block copolymer (A).

[0050] For example, catalysts, alkyl aluminums, and suitable external electron donors mentioned in Korean Patent Application Publication Nos. 2006-0038101, 2006-0038102, 2006-0038103, etc. can be selected and combined to construct a catalyst system. In particular, in order to maximize the balance between the rigidity / impact resistance of the resin molded article of the present invention, a catalyst capable of increasing the stereoregularity index is preferably used.

[0051] (B) Polyethylene

[0052] The polypropylene resin composition according to an embodiment of the present invention contains polyethylene (B). Among them, polyethylene (B) can be a polymer obtained by polymerizing ethylene monomers substantially alone or copolymerizing a small amount of C 4-8 α-olefins with ethylene.

[0053] The type of polyethylene (B) is not particularly limited, and the polyethylene may include low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), or high-density polyethylene (HDPE). Preferably, polyethylene (B) may include high-density polyethylene.

[0054] Based on the total weight of components (A) and (B), the polypropylene resin composition according to one embodiment of the present invention contains 3 to 15% by weight of polyethylene (B).

[0055] Preferably, based on the total weight of components (A) and (B), the polypropylene resin composition may contain 3 to 10% by weight of polyethylene (B). If the content of polyethylene (B) is less than 3% by weight, the Izod impact strength of the resin molded article at 0°C may decrease. Conversely, if the content of polyethylene (B) exceeds 15% by weight, the flexural modulus of the resin molded article may decrease.

[0056] Within the scope not departing from the present invention, the polypropylene resin composition according to an embodiment of the present invention may further contain conventional additives. For example, the polypropylene resin composition may further contain one or more additives selected from antioxidants, neutralizing agents, slip agents, anti-blocking agents, reinforcing agents, fillers, weather stabilizers, antistatic agents, lubricants, nucleating agents, flame retardants, pigments, and dyes, but is not particularly limited thereto.

[0057] In a specific embodiment of the present invention, the polypropylene resin composition may further contain an antioxidant to increase its heat resistance stability. At this time, based on 100 parts by weight of the polypropylene resin composition, the content of the antioxidant may be 0.05 to 0.3 parts by weight, preferably 0.05 to 0.2 parts by weight. If the content of the antioxidant is less than 0.05 parts by weight, it is difficult to ensure long-term heat resistance stability. If the content of the antioxidant exceeds 0.3 parts by weight, not only the heat resistance stability cannot be further improved, but also the economy of the product will be reduced, so it is not preferred.

[0058] As the above antioxidant, phenolic antioxidants, phosphite antioxidants, etc. can be used. Specifically, it may include one or more selected from pentaerythritol tetra(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, and tris(2,4-di-tert-butylphenyl)phosphite, but is not particularly limited thereto.

[0059] In a specific embodiment of the present invention, the polypropylene resin composition may further comprise a neutralizing agent to remove residual catalyst components in the polypropylene resin composition. At this time, based on 100 parts by weight of the polypropylene resin composition, the content of the neutralizing agent may be 0.05 to 0.3 parts by weight, preferably 0.05 to 0.2 parts by weight. If the content of the neutralizing agent is less than 0.05 parts by weight, it is difficult to sufficiently remove the residual catalyst components. If the content of the neutralizing agent exceeds 0.3 parts by weight, not only the effect of removing the residual catalyst components cannot be further improved, but also the economy of the product will be reduced, so it is not preferred.

[0060] The above-mentioned neutralizing agent may comprise one or more selected from hydrotalcite and calcium stearate, but is not particularly limited thereto.

[0061] The method for preparing the polypropylene resin composition according to an embodiment of the present invention is not particularly limited, and a blending method well-known in the technical field to which the present invention belongs can be directly used, or used after appropriate improvement.

[0062] Specifically, for example, a required amount of the above-mentioned propylene-ethylene block copolymer and polyethylene resin and additives can be added to a kneader, a roll, a Banbury mixer or other kneading machines or a single-screw / double-screw extruder, etc., and then the polypropylene resin composition of the present invention can be prepared according to the method of blending the added raw materials using these machines.

[0063] When measured under a load condition of 2.16 kg at 230 °C, the melt index of the polypropylene resin composition according to an embodiment of the present invention may be 30 to 50 g / 10 min. Preferably, when measured under a load condition of 2.16 kg at 230 °C, the melt index of the polypropylene resin composition may be 35 to 45 g / 10 min. If the melt index of the polypropylene resin composition is less than 30 g / 10 min, poor molding may occur during the injection molding process due to the low melt fluidity of the resin composition, and if the melt index exceeds 50 g / 10 min, the impact resistance of the resin molded product may be reduced.

[0064] In addition, the ratio (MFR T ) of the melt index (MFR M ) of the polypropylene resin composition to the matrix melt index (MFR T ) of the propylene-ethylene block copolymer (A) satisfies the condition of 0.3 or less, that is, MFR M / MFR T / MFR M≤0.3. At this time, each melt index is measured under the condition of a load of 2.16 kg at 230°C. If this condition is met, the emission of volatile organic compounds from the polypropylene resin composition can be maintained at a low level.

[0065] At this time, the melt index of the matrix of the propylene-ethylene block copolymer (A) can be measured by sampling the propylene homopolymer before the propylene-ethylene rubber component undergoes block copolymerization in the above preparation process.

[0066] In a specific embodiment of the present invention, in the differential scanning calorimetry of the polypropylene resin composition, the temperature of the first peak appearing during the second heating can satisfy the range of 125°C to 130°C.

[0067] In another embodiment of the present invention, the present invention provides a polypropylene resin molded article, which is made by molding the polypropylene resin composition of the present invention.

[0068] The method for preparing a molded article using the polypropylene resin composition according to the embodiment of the present invention is not particularly limited, and methods well-known in the technical field to which the present invention pertains can be used. For example, the polypropylene resin composition according to the embodiment of the present invention can be molded by conventional methods such as injection molding, extrusion molding, and casting molding to prepare a polypropylene resin molded article. Preferably, a polypropylene resin molded article can be prepared by injection molding the polypropylene resin composition.

[0069] In a specific embodiment of the present invention, the Izod impact strength of the polypropylene resin molded article measured at 23°C can be 50 kgf·cm / cm or more, and the Izod impact strength measured at 0°C can be 50 kgf·cm / cm or more.

[0070] In a specific embodiment of the present invention, the total volatile organic compound emission of the polypropylene resin can be 400 ppm or less. In the present invention, the melt index of the final resin composition can be increased without adding peroxides, thereby showing a low emission of volatile organic compounds.

[0071] The polypropylene resin molded article according to the embodiment of the present invention has excellent low-temperature impact resistance and reduced emission of volatile organic compounds, and thus can be effectively used as automotive interior and exterior parts, children's toys, or food storage containers.

[0072] In particular, the polypropylene resin molded article according to the embodiment of the present invention has excellent impact resistance even at low temperatures, so it is suitable for use as an automotive bumper and can replace polyolefin thermoplastic elastomers in the polypropylene composite resin composition, thereby achieving the effect of cost reduction.

[0073]

Example

[0074] Hereinafter, the present invention will be described in more detail through examples and comparative examples. However, the following examples are only for illustrating the present invention, and the scope of the present invention is not limited thereto.

[0075] Example 1 and Comparative Examples 1 to 2

[0076] In the Unipol process of Grace, the Consista C601 catalyst of Grace was used to prepare propylene-ethylene copolymer (A). Specifically, propylene was added to the first-stage gas-phase reactor to prepare a propylene homopolymer matrix, and in the subsequent second-stage gas-phase reactor, propylene and ethylene were copolymerized in the presence of the propylene homopolymer matrix to prepare propylene-ethylene copolymer (A). The composition of the obtained propylene-ethylene block copolymer is shown in Table 1.

[0077] The propylene-ethylene block copolymer resin in Table 1 and polyethylene resin (B) (HDPE C430A of Hanwha Total Energy; MFR (190 °C / 2.16 kg) is 1.7 g / 10 min) were formulated according to the composition shown in Table 2 below, and then 500 / 500 ppm of antioxidant (Irganox 1010 / Irgafos 168) and 400 ppm of neutralizer (calcium stearate) were added and kneaded. Pellets of the polypropylene resin composition were prepared using a twin-screw kneading extruder (SM Platek TEK-30, L / D 36, 30 mm twin-screw extruder), and then No. 4 injection test pieces according to ASTM were made using a Woojin injection molding machine (SELEX-TE 150, 150 tons, screw diameter 36 mm). Then, its physical properties were measured according to the following method and summarized in Table 3 below.

[0078] 1. Melt flow rate (g / 10 min)

[0079] According to ASTM D1238, the melt flow rate of the propylene resin and the composition was measured at 230 °C under a load of 2.16 kg.

[0080] 2. Content (wt%) of xylene solvent extract (xylene-soluble matter)

[0081] It was measured according to ASTM D5492. Specifically, the propylene resin was dissolved in xylene at a concentration of 1 wt% at 140 °C (for 1 hour), and then after standing at room temperature (23 °C) for 2 hours, the extracted weight was measured. The obtained weight was expressed as a percentage relative to the weight of the propylene resin.

[0082] 3. Ethylene content (wt%)

[0083] Determined by FT-IR according to ASTM D3900.

[0084] 4. Flexural modulus

[0085] The flexural modulus was determined at 23 °C according to ASTM D770.

[0086] 5. Izod impact strength

[0087] The Izod impact strength was determined at 0 °C and 23 °C according to ASTM D256 using a notched specimen with a thickness of 3.2 mm.

[0088] 6. Generation amount of total volatile organic compounds

[0089] The resin pellets were equilibrated at a certain temperature (180 °C) using a Static Head Space Sampler (7697A from Agilent Technologies), and then the generated volatile components were qualitatively analyzed using GC / FID (7890B from Agilent Technologies) and evaluated using n-hexane as a reference substance.

[0090] 7. Temperature at the first peak during the second heating

[0091] Exothermic and endothermic curves were obtained using a differential scanning calorimeter. Specifically, the sample was placed in an aluminum pan, first heated to 200 °C at 40 °C / min, held at 200 °C for 10 minutes, cooled to 30 °C at 10 °C / min and held for 10 minutes, and then reheated to 200 °C at 10 °C / min again. The temperature at the first peak appearing in the endothermic curve at this time was determined.

[0092] [Table 1]

[0093] A-1 A-2 A-3 Melt index of copolymer resin matrix (g / 10 min) 170 100 95 Melt index of copolymer resin (g / 10 min) 42 43 42 Xylene solubles (wt%) 33.4 31.6 31.5 Ethylene content in xylene solubles (wt%) 39.0 47.5 37.8 Ethylene content in propylene-ethylene block copolymer (wt%) 12.3 17.1 11.1

[0094] [Table 2]

[0095] Example 1 Comparative Example 1 Comparative Example 2 A-1 97 - - A-2 - 100 - A-3 - - 97 B 3 0 3

[0096] [Table 3]

[0097] Example 1 Comparative Example 1 Comparative Example 2 Melt index of composition (g / 10 min) 40 43 37 <![CDATA[MFR T / MFR M > 0.23 0.43 0.38 <![CDATA[Flexural modulus (kgf / cm 2 )]]> 7,200 7,400 7,550 Izod impact strength (23°C, kgf·cm / cm) 60 62 60 Izod impact strength (0°C, kgf·cm / cm) 57 19 60 Total volatile organic compounds (ppm) 370 530 490

[0098] As can be seen from Tables 1 to 3, the molded article made of the polypropylene resin composition of Example 1 within the scope of the present invention has excellent flexural modulus, Izod impact strength at 23 °C and 0 °C. Moreover, it was also confirmed that the emission amount of total volatile organic compounds is low.

[0099] In contrast, in the case of the resin composition of Comparative Example 1 that does not contain polyethylene resin, the Izod impact strength at 0 °C decreases. In the case of Comparative Example 2, although the Izod impact strengths at 23 °C and 0 °C are both excellent, the MFR T / MFR M exceeds the scope of the present invention, and thus a large amount of total volatile organic compounds are emitted.

[0100] The polypropylene resin composition according to the examples within the scope of the present invention has excellent impact resistance and low emissions of total volatile organic compounds, and thus the molded article made therefrom can be effectively used as interior and exterior automotive parts, children's toys, or food storage containers.

Claims

1. A polypropylene resin composition, comprising: A propylene-ethylene block copolymer (A), which accounts for 85 to 97% by weight of the total weight of the components (A) and (B), and is obtained by staged polymerization of a propylene homopolymer and a propylene-ethylene rubber copolymer in a reactor; and Polyethylene (B), accounting for 3 to 15% by weight of the total weight of components (A) and (B), in, When the propylene-ethylene block copolymer (A) is extracted with a xylene solvent at room temperature, the content of the propylene-ethylene rubber copolymer obtained as a xylene soluble matter is 25 to 40% by weight, the ethylene content in the xylene soluble matter is 35 to 45% by weight, the ethylene content in the propylene-ethylene block copolymer (A) is 9 to 20% by weight, and the melt index (MFR) of the polypropylene resin composition when measured at 230° C. under a load of 2.16 kg is 2.5 T ) and the matrix melt index (MFR) of the propylene-ethylene block copolymer (A) M ) ratio (MFR T / MFR M ) is less than 0.

3.

2. The polypropylene resin composition according to claim 1, wherein The melt index of the propylene-ethylene block copolymer (A) is 30 to 50 g / 10 min when measured at 230°C under a load of 2.16 kg.

3. The polypropylene resin composition according to claim 1, wherein The polyethylene (B) includes low-density polyethylene, linear low-density polyethylene or high-density polyethylene.

4. The polypropylene resin composition according to claim 1, wherein The polyethylene (B) includes high-density polyethylene.

5. The polypropylene resin composition according to claim 1, wherein The polypropylene resin composition further comprises one or more additives selected from antioxidants, neutralizers, slip agents, antiblocking agents, reinforcing agents, fillers, weathering stabilizers, antistatic agents, lubricants, nucleating agents, flame retardants, pigments and dyes.

6. The polypropylene resin composition according to claim 5, wherein The polypropylene resin composition further comprises 0.05 to 0.3 parts by weight of at least one antioxidant selected from pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene and tris(2,4-di-tert-butylphenyl)phosphite, based on 100 parts by weight of the polypropylene resin composition.

7. The polypropylene resin composition according to claim 5, wherein The polypropylene resin composition further comprises 0.05 to 0.3 parts by weight of at least one neutralizing agent selected from the group consisting of hydrotalcite and calcium stearate, based on 100 parts by weight of the polypropylene resin composition.

8. The polypropylene resin composition according to claim 1, wherein The melt index of the polypropylene resin composition is 30 to 50 g / 10 min when measured at 230° C. under a load of 2.16 kg.

9. The polypropylene resin composition according to claim 1, wherein In the differential scanning calorimetry analysis of the polypropylene resin composition, the temperature of the peak that first appears in the secondary temperature increase is in the range of 125°C to 130°C. 10 . A polypropylene resin molded article produced by molding the polypropylene resin composition according to claim 1 .

11. The polypropylene resin molded article according to claim 10, wherein It is produced by injection molding a polypropylene resin composition.

12. The polypropylene resin molded article according to claim 10, wherein The polypropylene resin molded article has an Izod impact strength of 50 kgf·cm / cm or more when measured at 23°C, and an Izod impact strength of 50 kgf·cm / cm or more when measured at 0°C.

13. The polypropylene resin molded article according to claim 10, wherein The total volatile organic compound emissions of polypropylene resin molded products are less than 400ppm.

14. The polypropylene resin molded article according to claim 10, wherein Polypropylene resin molded products are used as automotive interior and exterior parts, children's toys or food storage containers.

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