Polypropylene resin composition and article produced therefrom

Abstract

A polypropylene resin composition according to the present invention is characterized by comprising: a polypropylene resin; and a melt blend of about 65 to about 99 weight% of an ultra-low density polyethylene having a density of about 0.88 to about 0.91 g / cm3 as measured in accordance with ISO 1183-1, and about 1 to about 35 weight% of a styrene-based thermoplastic elastomer. The polypropylene resin composition has excellent impact resistance, rigidity, hardness, and thermal deformation properties, and an excellent balance of these physical properties.

Description

Polypropylene resin composition and molded article manufactured therefrom

[0001] The present invention relates to a polypropylene resin composition and a molded article manufactured therefrom. More specifically, the present invention relates to a polypropylene resin composition having excellent impact resistance, rigidity, hardness, thermal deformation characteristics, and a balance of these physical properties, and a molded article manufactured therefrom.

[0002]

[0003] Polyolefin resin has excellent chemical resistance, weather resistance, and processability, making it easy to manufacture into injection molded products, films, and blow molded products, and is a widely used material in fields such as electrical components, automobiles, and building materials.

[0004] However, among these polyolefin resins, block polypropylene resin has limited application in automotive safety parts due to its lack of impact resistance, and random polypropylene resin (propylene-ethylene random copolymer) has limited application in large-sized molded products or in frozen or refrigerated conditions due to its lack of flexural modulus or heat resistance.

[0005] In order to improve the impact resistance of polypropylene resin, a method of applying a rubber-based substance to polypropylene resin is being used.

[0006] However, in the case of conventional rubber component materials, compatibility with polypropylene resin is poor, and accordingly, there is a concern that the heat deformation properties of the resin composition and molded product may deteriorate.

[0007] Therefore, there is a need to develop a polypropylene resin composition with excellent impact resistance, rigidity, hardness, thermal deformation characteristics, and a balance of these properties.

[0008] The background technology of the present invention is disclosed in Korean Patent No. 10-0842162, etc.

[0009]

[0010] The purpose of the present invention is to provide a polypropylene resin composition having excellent impact resistance, rigidity, hardness, thermal deformation characteristics, and a balance of these physical properties.

[0011] Another object of the present invention is to provide a molded article formed from the polypropylene resin composition.

[0012] The above and other objects of the present invention can all be achieved by the present invention described below.

[0013]

[0014] 1. One aspect of the present invention relates to a polypropylene resin composition. The polypropylene resin composition comprises: a polypropylene resin; and a density measured according to ISO 1183-1 of about 0.88 to about 0.91 g / cm. 3 A melt blend of about 65 to about 99 wt% of an ultra-low density polyethylene and about 1 to about 35 wt% of a styrenic thermoplastic elastomer.

[0015] 2. In the above 1 specific example, the polypropylene resin composition may include about 100 parts by weight of the polypropylene resin; and about 0.1 to about 50 parts by weight of the melt blend.

[0016] 3. In the above 1 or 2 specific examples, the polypropylene resin may include at least one of a homo polypropylene resin, a block polypropylene resin, and a random polypropylene resin.

[0017] 4. In the above specific examples 1 to 3, the polypropylene resin may have a melt flow index of about 10 to about 1,500 g / 10 min, measured under conditions of 230°C and 2.16 kg load, according to ASTM D1238.

[0018] 5. In the above specific examples 1 to 4, the ultra-low density polyethylene may have a melt flow index of about 1 to about 20 g / 10 min, measured under conditions of 230°C and 2.16 kg load, according to ASTM D1238.

[0019] 6. In the above 1 to 5 specific examples, the styrene-based thermoplastic elastomer may include at least one of a styrene-ethylene-butylene-styrene block copolymer, a styrene-ethylene-propylene-styrene block copolymer, a styrene-butadiene-styrene block copolymer, a styrene-isoprene-styrene block copolymer, and a styrene-butadiene-butylene-styrene block copolymer.

[0020] 7. In the above 1 to 6 specific examples, the styrene-based thermoplastic elastomer may have a content of styrene-based monomer of about 5 to about 50 wt%.

[0021] 8. In the above specific examples 1 to 7, the styrene-based thermoplastic elastomer may have a weight average molecular weight of about 100,000 to about 450,000 g / mol.

[0022] 9. In the above 1 to 8 specific examples, the polypropylene resin composition has a notched Izod impact strength of about 10 to about 50 kJ / m of a specimen measuring 80 mm × 10 mm × 4 mm at 23°C, as measured according to ISO 180. 2 It could be.

[0023] 10. In the above 1 to 9 specific examples, the polypropylene resin composition may have a tensile strength of 20 to 40 MPa of a 4 mm thick specimen measured under 50 mm / min conditions according to ISO 527-1A standard, and a tensile elongation of about 100 to about 350% of a 4 mm thick specimen measured under 50 mm / min conditions according to ISO 527.

[0024] 11. In the above 1 to 10 specific examples, the polypropylene resin composition may have a flexural modulus of about 1,300 to about 1,900 MPa of a specimen measuring 80 mm × 10 mm × 4 mm, measured under a crosshead speed condition of 2 mm / min according to ISO 178.

[0025] 12. In the above 1 to 11 specific examples, the polypropylene resin composition may have a Shore A hardness of about 70 to about 110 of a 6 mm thick specimen measured with a Shore A hardness tester according to ISO 7619-1.

[0026] 13. In the above 1 to 12 specific examples, the polypropylene resin composition may have a heat distortion temperature (HDT) of about 90 to about 120°C of a specimen measuring 80 mm × 10 mm × 4 mm, measured under conditions of 0.45 MPa and a heating rate of 120°C / hr, according to ISO 75.

[0027] 14. In the above 1 to 13 specific examples, the polypropylene resin composition may be in a form in which the polypropylene resin is a continuous phase, the ultra-low density polyethylene is a dispersed phase, and the styrene-based thermoplastic elastomer is present at the interface of the continuous phase and the dispersed phase.

[0028] 15. Another aspect of the present invention relates to a molded article. The molded article is characterized in that it is formed from a polypropylene resin composition according to any one of 1 to 14.

[0029]

[0030] The present invention has the effect of providing a polypropylene resin composition having excellent impact resistance, rigidity, hardness, heat deformation characteristics, and a balance of these physical properties, and a molded article formed therefrom.

[0031]

[0032] Hereinafter, the present invention will be described in detail as follows.

[0033] A polypropylene resin composition according to the present invention comprises (A) a polypropylene resin; and (B) a melt blend of ultra-low density polyethylene and a styrenic thermoplastic elastomer.

[0034] In this specification, “a to b” indicating a numerical range is defined as “≥a and ≤b”.

[0035]

[0036] (A) Polypropylene resin

[0037] A polypropylene resin according to one specific example of the present invention can be applied together with a melt blend of ultra-low density polyethylene and a styrene-based thermoplastic elastomer, etc., to improve the impact resistance, rigidity, hardness, heat deformation characteristics, and physical property balance of the polypropylene resin composition, and a polypropylene resin applied to a typical thermoplastic resin composition can be used.

[0038] In a specific example, the polypropylene resin may include at least one of a homopolypropylene resin, a block polypropylene resin, and a random polypropylene resin. Here, the block polypropylene resin may be a block polypropylene resin composed of a homopolypropylene block and an ethylene-propylene copolymer block and / or a homopolyethylene block, and the random polypropylene resin may be a propylene-ethylene random copolymer.

[0039] In a specific example, the polypropylene resin may have a melt flow index (MI) of about 10 to about 1,500 g / 10 min, for example, about 15 to about 1,400 g / 10 min, measured under conditions of 230°C and a load of 2.16 kg according to ASTM D1238. Within this range, the mechanical properties, moldability, etc. of the polypropylene resin composition may be excellent.

[0040]

[0041] (B) Melt blend of ultra-low density polyolefin and styrenic thermoplastic elastomer

[0042] A melt blend of ultra-low-density polyolefin and styrenic thermoplastic elastomer according to one specific example of the present invention can be applied together with a polypropylene resin or the like to improve the impact resistance, rigidity, hardness, thermal deformation characteristics, and balance of these physical properties of the polypropylene resin composition.

[0043] In a specific example, the ultra-low density polyethylene (VLDPE) has a density of about 0.88 to about 0.91 g / cm as measured according to ISO 1183-1. 3 , for example, about 0.883 to about 0.90 g / cm 3 It can be. The density of the above ultra-low density polyethylene is about 0.88 g / cm 3 If it is less than 0.90 g / cm, there is a risk that the rigidity and thermal deformation characteristics of the polypropylene resin composition (molded product) may deteriorate, and if it is less than 0.90 g / cm, there is a risk that the rigidity and thermal deformation characteristics of the polypropylene resin composition (molded product) may deteriorate. 3 If it exceeds, there is a risk that the rigidity and impact resistance of the polypropylene resin composition may deteriorate.

[0044] In a specific example, the ultra-low density polyethylene may have a melt flow index of about 1 to about 20 g / 10 min, measured under conditions of 190°C and a load of 2.16 kg, according to ASTM D1238. Within this range, the moldability of the polypropylene resin composition may be excellent.

[0045] In a specific example, the ultra-low density polyethylene may have a weight average molecular weight measured by gel permeation chromatography (GPC) of about 100,000 to about 550,000 g / mol, for example, about 150,000 to about 500,000 g / mol. Within this range, the mechanical properties, elasticity, etc. of the polypropylene resin composition may be excellent.

[0046] In a specific example, the ultra-low density polyethylene may be included in an amount of about 65 to about 99 wt%, for example, about 70 to about 95 wt%, based on 100 wt% of the total melt blend. If the amount of the ultra-low density polyethylene is less than about 65 wt%, based on 100 wt% of the total melt blend, there is a concern that the rigidity, heat deformation characteristics, etc. of the polypropylene resin composition may be reduced, and if it exceeds about 99 wt%, there is a concern that the rigidity, impact resistance, etc. of the polypropylene resin composition may be reduced.

[0047] In specific examples, the styrene-based thermoplastic elastomer may be a styrene-ethylene-butylene-styrene block copolymer, a styrene-ethylene-propylene-styrene block copolymer, a styrene-butadiene-styrene block copolymer, a styrene-isoprene-styrene block copolymer, a styrene-butadiene-butylene-styrene block copolymer, or a combination thereof.

[0048] In a specific example, the styrenic thermoplastic elastomer may have a styrenic monomer content of about 5 to about 50 wt%, for example, about 5 to about 45 wt%. Within this range, the mechanical properties, elasticity, etc. of the polypropylene resin composition may be excellent.

[0049] In a specific example, the styrene-based thermoplastic elastomer may have a weight average molecular weight measured by gel permeation chromatography (GPC) of about 100,000 to about 450,000 g / mol, for example, about 150,000 to about 400,000 g / mol. Within this range, the mechanical properties, moldability, etc. of the polypropylene resin composition may be excellent.

[0050] In a specific example, the styrenic thermoplastic elastomer may be included in an amount of about 1 to about 35 wt%, for example, about 5 to about 30 wt%, based on 100 wt% of the total molten blend. If the content of the styrenic thermoplastic elastomer is less than about 1 wt%, based on 100 wt% of the total molten blend, there is a concern that the rigidity, impact resistance, etc. of the polypropylene resin composition may be reduced, and if it exceeds about 35 wt%, there is a concern that the rigidity, heat deformation characteristics, etc. of the polypropylene resin composition may be reduced.

[0051] In a specific example, the melt blend may be manufactured according to a manufacturing method including the steps of: mixing the ultra-low density polyethylene and the styrenic thermoplastic elastomer to manufacture a mixture; and melt-extruding the mixture.

[0052] In a specific example, the melt extrusion may be performed using a conventional twin-screw extruder at a temperature of about 150 to about 250°C, for example, about 170 to about 230°C. Within this range, the mechanical properties, thermal deformation characteristics, hardness, and balance of these properties of the polypropylene resin composition may be excellent.

[0053] In a specific example, the molten blend may be manufactured in the form of pellets, and the manufactured pellets may be applied to various thermoplastic resin compositions and molded articles (products), and the molten blend alone may be manufactured into molded articles (products) through various molding methods such as injection molding, extrusion molding, vacuum molding, and casting molding. Such molding methods are well known to those skilled in the art to which the present invention pertains.

[0054] In a specific example, the molten blend may be in the form of a mixture of ultra-low density polyethylene as a continuous phase and a styrenic thermoplastic elastomer as a dispersed phase, and the average particle size of the dispersed phase as measured by a transmission electron microscope may be about 0.1 to about 3 ㎛, for example, about 0.3 to about 1 ㎛.

[0055] In a specific example, the molten blend may be included in an amount of about 0.1 to about 50 parts by weight, for example, about 1 to about 30 parts by weight, and specifically about 5 to about 25 parts by weight, relative to about 100 parts by weight of the polypropylene resin. When the content of the molten blend is less than about 0.1 parts by weight relative to about 100 parts by weight of the polypropylene resin, there is a concern that the impact resistance, rigidity, etc. of the polypropylene resin composition may be reduced, and when it exceeds about 50 parts by weight, there is a concern that the rigidity, hardness, thermal deformation characteristics, etc. of the polypropylene resin composition may be reduced.

[0056]

[0057] A polypropylene resin composition according to one specific embodiment of the present invention may further include additives included in conventional thermoplastic resin compositions. Examples of the additives include, but are not limited to, flame retardants, anti-drip agents, stabilizers, slip agents, pigments, dyes, and mixtures thereof. When the additives are used, the content thereof may be from about 0.001 to about 40 parts by weight, for example, from about 0.1 to about 10 parts by weight, based on about 100 parts by weight of the polypropylene resin, but is not limited thereto.

[0058]

[0059] A polypropylene resin composition according to one specific example of the present invention may be in the form of pellets obtained by mixing the above components and melt-extruding them at about 180 to about 320°C, for example, about 200 to about 300°C, using a conventional twin-screw extruder.

[0060] In a specific example, the polypropylene resin composition may be in a form in which the polypropylene resin is a continuous phase, the ultra-low-density polyethylene is a dispersed phase, and the styrenic thermoplastic elastomer is present at the interface of the continuous phase and the dispersed phase. Specifically, the dispersed phase (ultra-low-density polyethylene) may be viewed as forming a core-shell form (a shell form in which the styrenic thermoplastic elastomer covers at least a portion of an ultra-low-density polyethylene core) with the continuous phase (polypropylene resin) and the styrenic thermoplastic elastomer at the interface of the dispersed phase.

[0061] In a specific example, the core-shell type dispersed phase may have an average particle size of about 0.1 to about 3 μm, for example, about 0.3 to about 1 μm, as measured by transmission electron microscopy (TEM, manufacturer: JEOL, device name: JEM-1400) after a thin-sectioned specimen using a cryomicrotome is stained with 0.5% ruthenium tetroxide. In this range, the mechanical properties of the polypropylene resin composition may be excellent.

[0062] In a specific example, the polypropylene resin composition has a notched Izod impact strength of about 10 to about 50 kJ / m for a specimen measuring 80 mm × 10 mm × 4 mm at 23° C. according to ISO 180. 2 , for example, from about 10.5 to about 45 kJ / m 2 It could be.

[0063] In a specific example, the polypropylene resin composition may have a tensile strength of about 20 to about 40 MPa, for example, about 20 to about 30 MPa, of a 4 mm thick specimen measured under 50 mm / min conditions according to ISO 527-1A standard.

[0064] In a specific example, the polypropylene resin composition may have a tensile elongation of about 100 to about 350%, for example, about 110 to about 300%, of a 4 mm thick specimen measured under conditions of 50 mm / min according to ISO 527.

[0065] In a specific example, the polypropylene resin composition may have a flexural modulus of about 1,300 to about 1,900 MPa, for example, about 1,350 to about 1,850 MPa, of a specimen measuring 80 mm × 10 mm × 4 mm in size, measured under a crosshead speed condition of 2 mm / min according to ISO 178.

[0066] In a specific example, the polypropylene resin composition may have a Shore A hardness of about 70 to about 110, for example, about 75 to about 100, of a 6 mm thick specimen measured using a Shore A durometer according to ISO 7619-1.

[0067] In a specific example, the polypropylene resin composition may have a heat distortion temperature (HDT) of about 90 to about 120°C, for example, about 90 to about 110°C, of ​​a specimen measuring 80 mm × 10 mm × 4 mm, measured under conditions of 0.45 MPa and a heating rate of 120°C / hr according to ISO 75.

[0068]

[0069] The molded article according to the present invention is formed from the polypropylene resin composition. The polypropylene resin composition can be manufactured in the form of pellets, and the manufactured pellets can be manufactured into various molded articles (products) through various molding methods such as injection molding, extrusion molding, vacuum molding, and casting molding. Such molding methods are well known to those skilled in the art to which the present invention pertains.

[0070] In a specific example, the molded product has excellent impact resistance, rigidity, thermal deformation characteristics, hardness, and balance of these properties, and is useful as an interior / exterior material for automobiles, a housing for home appliances, etc.

[0071]

[0072] Hereinafter, the present invention will be described in more detail through examples; however, these examples are for the purpose of explanation only and should not be construed as limiting the present invention.

[0073]

[0074] Example

[0075] Below, the specifications of each component used in the examples and comparative examples are as follows.

[0076] (A) Polypropylene resin

[0077] Polypropylene resin (Manufacturer: Polymirae, Product Name: EA5074, Melt-flow index: approximately 30 g / 10 min) was used.

[0078] (B) Ultra-low density polyethylene and styrenic thermoplastic elastomers

[0079] (B1) Density is about 0.885 g / cm 3 A melt blend was used, which was melt-extruded at approximately 200°C using a twin-screw extruder, containing 85 wt% of ultra-low density polyethylene and 15 wt% of styrene-ethylene-butylene-styrene block copolymer (manufacturer: SINOPEC, product name: YH-503T).

[0080] (B2) Density is about 0.865 g / cm 3 A melt blend was used, which was melt-extruded at approximately 200°C using a twin-screw extruder, containing 85 wt% of ultra-low density polyethylene and 15 wt% of styrene-ethylene-butylene-styrene block copolymer (manufacturer: SINOPEC, product name: YH-503T).

[0081] (B3) Density is about 0.912 g / cm 3A melt blend was used, which was melt-extruded at approximately 200°C using a twin-screw extruder, containing 85 wt% of ultra-low density polyethylene and 15 wt% of styrene-ethylene-butylene-styrene block copolymer (manufacturer: SINOPEC, product name: YH-503T).

[0082] (B4) Density is about 0.885 g / cm 3 A melt blend was used, which was melt-extruded at approximately 200°C using a twin-screw extruder, containing 50 wt% of ultra-low density polyethylene and 50 wt% of styrene-ethylene-butylene-styrene block copolymer (manufacturer: SINOPEC, product name: YH-503T).

[0083] (B5) Density is about 0.885 g / cm 3 A melt blend was used, which was melt-extruded at approximately 200°C using a twin-screw extruder, containing 99.5 wt% of ultra-low density polyethylene and 0.5 wt% of styrene-ethylene-butylene-styrene block copolymer (manufacturer: SINOPEC, product name: YH-503T).

[0084] (B6) Density is about 0.885 g / cm 3 85 wt% of ultra-low density polyethylene and 15 wt% of styrene-ethylene-butylene-styrene block copolymer (manufacturer: SINOPEC, trade name: YH-503T) were simply mixed.

[0085]

[0086] Examples 1 to 3 and Comparative Examples 1 to 7

[0087] Each of the above components was added in the amounts shown in Tables 1, 2, and 3 below, and then extruded at about 250°C to produce pellets. The extrusion was performed using a twin-screw extruder with an L / D of 48 and a diameter of 75 mm. The manufactured pellets were dried at about 80°C for about 2 hours or more, and then injected into a 110-ton injection molding machine (molding temperature: about 210°C, mold temperature: about 50°C) to produce test pieces. The physical properties of the manufactured test pieces were evaluated using the following methods, and the results are shown in Tables 1, 2, and 3 below.

[0088]

[0089] Method of measuring physical properties

[0090] (1) Notched Izod impact strength (unit: kJ / m) 2 ): The notched Izod impact strength of a specimen measuring 80 mm × 10 mm × 4 mm at 23°C was measured according to ISO 180.

[0091] (2) Tensile strength (unit: MPa): The tensile strength of a 4 mm thick specimen was measured under 50 mm / min conditions according to ISO 527-1A standard.

[0092] (3) Tensile elongation (unit: %): The tensile elongation of a 4 mm thick specimen was measured under conditions of 50 mm / min according to ISO 527.

[0093] (4) Flexural modulus (unit: MPa): According to ISO 178, the flexural modulus of a specimen measuring 80 mm × 10 mm × 4 mm was measured under a crosshead speed condition of 2.0 mm / min.

[0094] (5) Shore A hardness: Shore A hardness of a 6 mm thick specimen was measured using a Shore A hardness tester (manufacturer: Mitutoyo, device name: 810-220K) according to ISO 7619-1.

[0095] (6) Heat distortion temperature (unit: ℃): According to ISO 75, the heat distortion temperature (HDT) of a specimen measuring 80 mm × 10 mm × 4 mm was measured using a heat distortion temperature measuring device (manufacturer: Toyoseiki, device name: 533) under conditions of 0.45 MPa and a heating rate of 120℃ / hr.

[0096]

[0097] Example 123 (A) (parts by weight) 100 100 100 (B) (parts by weight) (B1) 517.525 (B2) --- (B3) --- (B4) --- (B5) --- (B6) Notched Izod impact strength 10.52 8.534 Tensile strength 272 320.8 Tensile elongation 118 168 210 Flexural modulus 1,760 1,430 1,350 Shore A hardness 988 881 Heat deflection temperature 1039 590

[0098]

[0099] Comparative Example 1234 (A) (weight parts) 100 100 100 100 (B) (weight parts) (B1) 0.0155--(B2)--17.5-(B3)---17.5 (B4)----(B5)----(B6)----Notched Izod impact strength 5.3 NB 29.6 12.4 Tensile strength 28 14.6 18.8 24.2 Tensile elongation 10600↑17148 Flexural modulus 1,790 892 1,208 1,540 Shore A hardness 995 88690 Heat deflection temperature 1176 48799

[0100]

[0101] Comparative Example 567 (A) (weight parts) 100 100 100 (B) (weight parts) (B1)--(B2)--(B3)--(B4) 17.5-(B5)-17.5 (B6)--17.5 Notched Izod impact strength 32.6 19.8 19.7 Tensile strength 18.9 23.4 23.4 Tensile elongation 2456 292 Flexural modulus 1,345 1,502 1,492 Shore A hardness 80 898 6 Heat deflection temperature 899 793

[0102]

[0103] From the above results, it can be seen that the polypropylene resin composition of the present invention has excellent impact resistance (notched Izod impact strength), rigidity (tensile strength, tensile elongation, flexural modulus), hardness (Shore A hardness), heat deformation characteristics (heat deformation temperature), and a balance of these physical properties.

[0104] On the other hand, in the case of Comparative Example 1, in which the content of the melt blend of ultra-low density polyethylene and styrenic thermoplastic elastomer is less than the range of the present invention, it can be seen that impact resistance, rigidity, etc. are reduced, and in the case of Comparative Example 2, in which the content of the melt blend of ultra-low density polyethylene and styrenic thermoplastic elastomer is more than the range of the present invention, it can be seen that rigidity, hardness, heat deformation characteristics, etc. are reduced.

[0105] In addition, in the case of Comparative Example 3, which applied a melt blend (B2) using ultra-low density polyethylene having a density below the range of the present invention instead of the melt blend of the present invention, it can be seen that the rigidity, heat deformation characteristics, etc. are deteriorated, in the case of Comparative Example 4, which applied a melt blend (B3) using ultra-low density polyethylene having a density exceeding the range of the present invention, it can be seen that the rigidity, etc. are deteriorated, in the case of Comparative Example 5, which applied a melt blend (B4) having an ultra-low density polyethylene content below the range of the present invention, it can be seen that the rigidity, heat deformation characteristics, etc. are deteriorated, in the case of Comparative Example 6, which applied a melt blend (B5) having an ultra-low density polyethylene content exceeding the range of the present invention, it can be seen that the rigidity, etc. are deteriorated, and in the case of Comparative Example 7, which applied (B6), which is a simple mixture of ultra-low density polyethylene and a styrene-based thermoplastic elastomer, it can be seen that the rigidity, etc. are deteriorated.

[0106]

[0107] The present invention has been described with reference to exemplary embodiments. Those skilled in the art will appreciate that the present invention can be implemented in modified forms without departing from its essential characteristics. Therefore, the disclosed embodiments should be considered illustrative rather than limiting. The scope of the present invention is set forth in the claims, not the foregoing description, and all differences within the scope equivalent thereto should be construed as being encompassed by the present invention.

Claims

1. Polypropylene resin; and A density of about 0.88 to about 0.91 g / cm as measured according to ISO 1183-1. 3 A polypropylene resin composition comprising a melt blend of about 65 to about 99 wt % of an ultra-low density polyethylene and about 1 to about 35 wt % of a styrenic thermoplastic elastomer.

2. A polypropylene resin composition according to claim 1, characterized in that it comprises about 100 parts by weight of the polypropylene resin; and about 0.1 to about 50 parts by weight of the molten blend.

3. A polypropylene resin composition according to claim 1 or 2, characterized in that the polypropylene resin comprises at least one of a homo polypropylene resin, a block polypropylene resin, and a random polypropylene resin.

4. A polypropylene resin composition according to any one of claims 1 to 3, characterized in that the polypropylene resin has a melt flow index of about 10 to about 150 g / 10 min as measured under conditions of 230° C. and 2.16 kg load according to ASTM D1238.

5. A polypropylene resin composition according to any one of claims 1 to 4, wherein the ultra-low density polyethylene has a melt flow index of about 1 to about 20 g / 10 min as measured under conditions of 190° C. and 2.16 kg load according to ASTM D1238.

6. A polypropylene resin composition according to any one of claims 1 to 5, wherein the styrene-based thermoplastic elastomer comprises at least one of a styrene-ethylene-butylene-styrene block copolymer, a styrene-ethylene-propylene-styrene block copolymer, a styrene-butadiene-styrene block copolymer, a styrene-isoprene-styrene block copolymer, and a styrene-butadiene-butylene-styrene block copolymer.

7. A polypropylene resin composition according to any one of claims 1 to 6, wherein the styrene-based thermoplastic elastomer has a content of a styrene-based monomer of about 5 to about 50 wt%.

8. A polypropylene resin composition according to any one of claims 1 to 7, characterized in that the styrene-based thermoplastic elastomer has a weight average molecular weight of about 100,000 to about 450,000 g / mol.

9. In any one of claims 1 to 8, the polypropylene resin composition has a notched Izod impact strength of about 10 to about 50 kJ / m of a specimen measuring 80 mm × 10 mm × 4 mm at 23° C. according to ISO 180. 2 A polypropylene resin composition characterized by:

10. A polypropylene resin composition according to any one of claims 1 to 9, characterized in that the polypropylene resin composition has a tensile strength of 20 to 40 MPa of a 4 mm thick specimen measured under the condition of 50 mm / min according to ISO 527-1A, and a tensile elongation of about 100 to about 350% of a 4 mm thick specimen measured under the condition of 50 mm / min according to ISO 527.

11. A polypropylene resin composition according to any one of claims 1 to 10, characterized in that the polypropylene resin composition has a flexural modulus of about 1,300 to about 1,900 MPa of a specimen measuring 80 mm × 10 mm × 4 mm when measured under a crosshead speed condition of 2 mm / min according to ISO 178.

12. A polypropylene resin composition according to any one of claims 1 to 11, characterized in that the polypropylene resin composition has a Shore A hardness of about 70 to about 110 of a 6 mm thick specimen measured by a Shore A durometer according to ISO 7619-1.

13. A polypropylene resin composition according to any one of claims 1 to 12, characterized in that the polypropylene resin composition has a heat distortion temperature (HDT) of about 90 to about 120°C of a specimen measuring 80 mm × 10 mm × 4 mm, measured under conditions of 0.45 MPa and a heating rate of 120°C / hr according to ISO 75.

14. A polypropylene resin composition according to any one of claims 1 to 13, wherein the polypropylene resin composition is characterized in that the polypropylene resin is a continuous phase, the ultra-low-density polyethylene is a dispersed phase, and the styrene-based thermoplastic elastomer is present at the interface between the polypropylene resin and the ultra-low-density polyethylene.

15. A molded product characterized by being formed from a polypropylene resin composition according to any one of claims 1 to 14.