KR20200077146A - Polypropylene resin compositions with high mechanical strength and heat resistance - Google Patents

Abstract

The present invention relates to a polypropylene resin composition, and specifically, to a polypropylene resin composition excellent in mechanical strength and heat resistance. The polypropylene resin composition according to the present invention has high mechanical strength by including a styrene-ethylene-butylene-styrene block copolymer, has high heat resistance by including a heat-resistant stabilizer and primary and secondary antioxidants, additionally includes a rigid nucleating agent not to lower rigidity, and thus can be advantageously used in manufacturing a molded article for a pressurized reservoir tank for an automobile. The polypropylene resin composition includes 93 to 99 wt% of homo-polypropylene and 1 to 7 wt% of a styrene-based thermoplastic elastomer block copolymer.

Description

Polypropylene resin composition excellent in mechanical strength and heat resistance{POLYPROPYLENE RESIN COMPOSITIONS WITH HIGH MECHANICAL STRENGTH AND HEAT RESISTANCE}

The present invention relates to a polypropylene resin composition, specifically to a polypropylene resin composition excellent in mechanical strength and heat resistance.

Polypropylene resin is a material used in various industrial fields such as automotive interior parts, home appliance parts, and industrial materials due to its excellent mechanical properties, chemical resistance, moldability and low cost. In general, homopolypropylene in which propylene is polymerized alone has excellent stiffness, hardness, and tensile strength, but when used as a material for injection molding products for automobiles and general liquids, it is not suitable for application due to insufficient impact strength, especially at low temperatures. There is this.

In general, a vehicle stores various fluids used for driving or convenience devices of a vehicle, for example, washer fluid for wiping windshield glass, steering oil for driving power steering, and brake oil used for hydraulic brake operation. Reservoir tanks are provided to do this, and these various fluids are stored in the reservoir tank, and inflow and outflow are repeated as necessary. There are two types of reservoir tanks: atmospheric open type and pressurized type. In the open air type, the pressure inside the tank is formed to atmospheric pressure, but the pressurized reservoir tank is applied with a pressurized system to prevent overflow. Currently, Lyondell Basell's H1850 product (homo polypropylene) is used exclusively as a raw material for pressurized reservoir tanks in automobiles, but the need for localization is increasing as demand for pressurized reservoir tanks increases.

As a method for improving the impact properties of polypropylene, there is a method of melt-mixing a rubber component material such as EPM (ethylene propylene copolymer) or EPDM (ethylene propylene diene copolymer) into polypropylene, but polypropylene and rubber There is a problem of deterioration in transparency due to a limitation in dispersibility control between component materials. In addition, while maintaining a considerable level of stiffness and applying a special nucleating agent as a method of improving the impact characteristics, there is a possibility that relatively different physical properties may be caused.

The Republic of Korea Patent Publication No. 10-2004-0065079 (published on July 21, 2004) relates to a polypropylene resin composition excellent in pressure resistance, impact resistance and transparency, homo polypropylene, ethylene-propylene random block copolymer, alpha olefin copolymer Disclosed is a polypropylene resin composition comprising a coalescence and a nucleating agent, and Korean Patent Publication No. 10-2016-0139904 (published on December 12, 2016) relates to a polypropylene resin composition excellent in transparency, heat resistance, and mechanical strength. A polypropylene resin composition comprising homopolypropylene and high-transparency random polypropylene.

Further, Japanese Patent Publication No. 2014-88475 (published May 15, 2014) relates to a polypropylene resin composition having high heat resistance and high impact, and a polypropylene resin composition comprising polypropylene, polycarbonate, and a styrene-based thermoplastic elastomer. Disclosed, Japanese Patent Application Publication No. 2015-110794 (published on June 18, 2015) relates to a resin composition for welding molding having a high strength of a welded surface and an excellent appearance of a welded portion, the resin composition comprising a propylene-based polymer and an elastomer. It is disclosed.

The above prior art discloses a polypropylene resin composition with improved physical properties that can be applied as a material for automobile storage containers, but the mechanical strength is weak, and there is still a problem that cannot compensate for the mechanical strength at low temperatures.

Republic of Korea Patent Publication No. 10-2004-0065079 Republic of Korea Patent Publication No. 10-2016-0139904 Japanese Patent Publication No. 2014-88475 Japanese Patent Publication No. 2015-110794

The present invention is to solve the above problems, a mixture of homo polypropylene and styrene-ethylene-butylene-styrene (styrene-ethylene-butylene-styrene, SEBS) block copolymer, antioxidant, heat stabilizer, rigidity It is an object to provide a polypropylene resin composition excellent in mechanical strength and heat resistance by further mixing a nucleating agent and a neutralizing agent.

The present invention comprises 93 to 99% by weight of homo polypropylene and 1 to 7% by weight of a styrenic thermoplastic elastomer block copolymer, and the homo polypropylene has a melt index of 0.2 to 0.2 according to ASTM D1238 (230°C, 2.16 kg). It provides a polypropylene resin composition, characterized in that 0.4 g/10 min.

In addition, the present invention provides a molded article made of the polypropylene resin composition.

The polypropylene resin composition according to the present invention has high mechanical strength by including a styrene-ethylene-butylene-styrene block copolymer, high heat resistance by including a heat stabilizer, and primary and secondary antioxidants, and additionally a rigid nucleating agent. Since the stiffness is not lowered by inclusion, it can be usefully used to manufacture molded articles for automobile pressurized reservoir tanks.

Hereinafter, the present invention will be described in more detail.

In the present invention, when a part “includes” a certain component, it means that the component may further include other components, not to exclude other components, unless otherwise stated.

<Polypropylene resin composition>

One aspect of the present invention comprises 93 to 99% by weight of homo polypropylene and 1 to 7% by weight of a styrenic thermoplastic elastomer block copolymer, wherein the homo polypropylene has a melt index measured according to ASTM D1238 (230° C., 2.16 kg). It is a polypropylene resin composition characterized in that 0.2 to 0.4 g/10 min.

(a) Homo polypropylene

The polypropylene resin composition according to the present invention comprises homo polypropylene. The homo polypropylene may have characteristics of high stiffness, dimensional stability and high crystallinity excellent in heat resistance.

The homo polypropylene according to the present invention is contained in an amount of 93 to 99% by weight, preferably in an amount of 94 to 98.5% by weight, and most preferably in an amount of 95 to 98% by weight. Specifically, if the content of the homo polypropylene is less than the above range, there is a possibility that mechanical properties are reduced, and if it is more than the above range, there is a possibility that flexibility is reduced.

In addition, as the homo polypropylene according to the present invention, a melt index measured according to ASTM D 1238 (230°C, 2.16 kg) is 0.2 to 0.4 g/10 min, and the melt index is preferably 0.23 to 0.38 g. /10 min is used, and most preferably, a melt index of 0.25 to 0.35 g/10 min is used. Specifically, if the melt index of the homo polypropylene is less than the above range, there is a possibility that unmolding occurs during product molding, and if it is more than the above range, there is a possibility that burr due to overcharging occurs during product molding.

(b) Styrene-based thermoplastic elastomer block copolymer

The polypropylene resin composition according to the present invention includes a styrene-based thermoplastic elastomer block copolymer.

The styrenic thermoplastic elastomer according to the present invention is preferably styrene-ethylene-butylene-styrene block copolymer, styrene-hydrogenated butadiene-styrene triblock copolymer, styrene-isoprene-styrene triblock copolymer, styrene-hydrogen One or more selected from the group consisting of additive isoprene-styrene triblock copolymer, styrene-hydrogenated butadiene diblock copolymer, styrene-hydrogenated isoprene diblock copolymer, and styrene-isoprene diblock copolymer may be used, Styrene-ethylene-butylene-styrene block copolymer (SEBS) may be most preferably used from the viewpoint of excellent flexibility and impact reinforcing effect.

The styrenic thermoplastic elastomer block copolymer according to the present invention is contained in an amount of 1 to 7% by weight, preferably in an amount of 1.5 to 6% by weight, most preferably in an amount of 2 to 5% by weight do. Specifically, if the content of the styrene-based thermoplastic elastomer block copolymer is less than the above range, there is a possibility that the impact strength is low, and if it is more than the above range, there is a possibility that physical properties such as tensile strength and heat deformation temperature are not good.

As the styrenic thermoplastic elastomer block copolymer according to the present invention, preferably, a melt index measured according to ISO 1133 (230° C., 2.16 kg) can be used in the range of 3 to 10 g/10 min, more preferably a melt index Can be used from 3.5 to 8 g/10 min, most preferably a melt index of 4 to 6 g/10 min. Specifically, if the melt index of the styrene-based thermoplastic elastomer block copolymer is less than the above range, there is a possibility that flexibility and impact resistance may decrease, and if it is more than the above range, mechanical rigidity may decrease.

The styrene-based thermoplastic elastomer block copolymer according to the present invention preferably has a glass transition temperature (Tg) measured by DSC (differential scanning calorimetry) of -60 to -50°C. It can be used, more preferably, a glass transition temperature of -58 to -52°C can be used, and most preferably, a glass transition temperature of -56 to -53°C can be used. Specifically, if the melt index of the styrene-based thermoplastic elastomer block copolymer is less than the above range, there is a possibility that mechanical stiffness is reduced, and if it is more than the above range, there is a possibility that flexibility is reduced.

<Additive>

The polypropylene resin composition according to the present invention may preferably further include at least one selected from the group consisting of primary antioxidants, secondary antioxidants, heat stabilizers, rigid nucleating agents, and neutralizing agents.

(c) primary and secondary antioxidants

Antioxidants in the present invention may be added to prevent excessive oxidative deformation while imparting thermal stability of the base resin even in a high temperature or oxidizing atmosphere when the final manufactured resin composition is applied for high pressure/ultra high pressure. Therefore, in the present invention, the primary antioxidant that suppresses the generation of unstable free radicals generated by the oxidizing action or makes the free radicals in a stable form, and the hydroperoxide produced by combining unstable free radicals with oxygen ( Hydroperoxide) can be used in combination with secondary antioxidants to suppress the formation of another unstable free radical that may occur due to oxidation.

As the primary antioxidant, a phenol-based or amine-based antioxidant commonly used in the art to which the present invention pertains may be used, but preferably 2,6-di-tertiary-butyl-4-methylphenol (2 ,6-di-t-butyl-4-methylphenol), tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane (Tetrakis[methylene-3) -(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane), 2,2-methylenebis(4-methyl-6-tertiary-butylphenol)(2,2-methylenebis(4-methyl -6-t-butylphenol), octadecyl-3,5-di-tertiary-butyl-4-hydroxyhydrocinnamate, octadecyl-3,5-di-t-butyl-4-hydroxyhydrocinnamate, 1, 3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-tri On(1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione ) Can be used, and most preferably 1,3,5-tris(4-tertiary-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5- from the viewpoint of processing safety. Triazine-2,4,6-(1H,3H,5H)-trione can be used.

Further, as the secondary antioxidant, a phosphorus-based or thio-based antioxidant commonly used in the art to which the present invention pertains may be used, but preferably tris(2,4-di-tertiary-butylphenyl)phosphite (tris(2,4-di-t-butylphenyl)phosphite), bis(2,4-di-tertary-butyl)pentaerythritol diphosphite, Alkyl ester phosphite may be used, and tris(2,4-di-tertary-butylphenyl)phosphite may be most preferably used from the viewpoint of oxidation stability.

The primary antioxidant according to the present invention may preferably be included in an amount of 0.01 to 0.1 parts by weight, more preferably 0.02 to 0.08 parts by weight, and most preferably 0.03 to 0.06 parts by weight in 100 parts by weight of the polypropylene resin composition. It can be included as a wealth. Specifically, if the content of the primary antioxidant is less than the above range, there is a possibility that processing stability is low, and if it is more than the above range, there is a possibility that a problem occurs in appearance quality.

In addition, the secondary antioxidant according to the present invention may be preferably included in 0.2 to 0.6 parts by weight, more preferably in the range of 0.25 to 0.55 parts by weight, most preferably 0.3 to 100 parts by weight of the polypropylene resin composition. 0.5 parts by weight. Specifically, if the content of the secondary antioxidant is less than the above range, there is a possibility that the oxidation stability is low, and if it exceeds 0.6 parts by weight, there is a possibility that a problem occurs in appearance quality.

(d) Heat stabilizer

The polypropylene resin composition according to the present invention may preferably further include a heat-resistant stabilizer. The heat stabilizer may be used to improve long-term heat resistance when exposed to high temperatures.

The heat-resistant stabilizer according to the present invention may preferably be included in an amount of 0.4 to 0.8 parts by weight, more preferably in an amount of 0.45 to 0.75 parts by weight, and most preferably in an amount of 0.5 to 0.7 parts by weight. Can. Specifically, if the content of the heat stabilizer is less than the above range, the heat resistance is low, there is a possibility that the heat deflection temperature is not compensated, and if it is more than the above range, the physical properties are lowered, and there is a possibility that a problem occurs in appearance quality.

The heat-resistant stabilizer according to the present invention may preferably use one or more selected from the group consisting of sulfur-based, phenol-based and phosphorus-based, more preferably sulfur-based antioxidants, most preferably from the viewpoint of heat stability. Distearyl thiodipropionate (DSTDP) can be used.

(e) rigid nuclear agent

The polypropylene resin composition according to the present invention may preferably further include a rigid nucleating agent. The stiffness nucleating agent may be used to reinforce stiffness deterioration due to the addition of a styrene-based thermoplastic elastomer, and may have characteristics of improving stiffness and having less thermal strain as having isotropy.

The rigid nucleating agent according to the present invention may be preferably included in 0.05 to 0.2 parts by weight, more preferably 0.1 to 0.18 parts by weight, and most preferably 0.12 to 0.16 parts by weight, based on 100 parts by weight of the polypropylene resin composition. Can. Specifically, when the content of the stiffness nucleating agent is less than the above range, the tensile strength is low, and there is a possibility that the thermal strain temperature is not compensated, and if it is more than the above range, there is a possibility that the physical properties are deteriorated.

As the rigid nucleating agent according to the present invention, preferably, a metal salt selected from the group consisting of aluminum salts, sodium salts and calcium salts can be used, and most preferably from the viewpoint of stiffness reinforcement and heat distortion prevention, dicarboxylate calcium salt Can be used.

(f) neutralizer

The polypropylene resin composition according to the present invention may preferably further include a neutralizing agent. The neutralizing agent can be used to prevent metal oxidation.

The neutralizing agent according to the present invention may be included in 100 parts by weight of the polypropylene resin composition, preferably 0.1 to 0.3 parts by weight, more preferably 0.15 to 0.25 parts by weight, and most preferably 0.18 to 0.22 parts by weight. have. Specifically, if the content of the neutralizing agent is less than the above range, there is a possibility that the effect of preventing metal oxidation is insufficient, and if it is more than the above range, there is a possibility that no further expression is achieved.

The neutralizing agent according to the present invention may preferably use calcium stearate or hydrotalcite, and most preferably from the viewpoint of preventing metal oxidation, calcium stearate.

Specifically, the polypropylene resin composition according to the present invention is 0.01 to 0.1 parts by weight, 0.2 to 0.6 parts by weight, and 0.4 to 0.8 parts by weight of the primary antioxidant, the secondary antioxidant, and the heat stabilizer, respectively, based on 100 parts by weight of the base resin. Can be used in combination. If the content is less than the above range, there is a possibility that the oxidation resistance of the final resin composition is weakened, and thus the heat resistance of the composition may be lowered. It can be migrated to the product surface, so there is a possibility that it is not good in appearance.

In addition, the content of the nucleating agent may be used in 0.05 to 0.2 parts by weight, respectively, based on 100 parts by weight of the base resin, and is effective for stiffness when applied in the above range, and if less than the above range, the effect may be insufficient, and the range If it is more than this, there is a possibility that no further expression can be achieved.

In addition, the content of the neutralizing agent may be used in 0.1 to 0.3 parts by weight, respectively, based on 100 parts by weight of the base resin, and the neutralizing agent content is effective for the expression of oxidation caused by metal ions when applied in the above range, and the effect is less than the above range There is a possibility that it is insufficient, and if it exceeds the above range, there is a possibility that no further expression is achieved.

The polypropylene resin composition according to the present invention can significantly increase impact resistance and heat resistance while maintaining tensile strength. The present invention can significantly increase not only the impact strength at room temperature, but particularly the impact strength at low temperatures.

The polypropylene resin composition according to the present invention preferably has an Izod impact strength of 80 J/m or more, more preferably 120 J/m or more, and most preferably 150 J measured at 23°C by the method of ASTM D256. /m or more. In addition, the Izod impact strength measured at -40°C by the method of ASTM D256 is preferably 32 J/m or more, more preferably 35 J/m or more, and most preferably 37 J/m or more. Specifically, if the Izod impact strength of the polypropylene resin composition is less than the above range, the impact characteristics are lowered, and there is a possibility of breaking at room temperature or low temperature.

The polypropylene resin composition according to the present invention has a heat deflection temperature (HDT) measured by the method of ASTM D648 is preferably 112°C or higher, more preferably 115°C or higher, and most preferably 119°C That's it. Specifically, if the heat deflection temperature of the polypropylene resin composition is less than the above range, there is a possibility that there is a limitation in use at high temperatures.

The polypropylene resin composition according to the present invention preferably has a tensile strength measured by the method of ASTM D638 of 25 MPa or more, more preferably 30 MPa or more, and most preferably 37 MPa or more. Specifically, if the tensile strength of the polypropylene resin composition is less than the above range, there is a possibility that there is a limitation in use at high pressure.

Examples of the method for producing the polypropylene resin composition of the present invention include a method of melt-kneading each component, for example, a method of using a kneader such as a single-screw extruder, twin-screw extruder, van barry mixer, heat roll, or the like. Can be lifted.

Examples of the shape of the polypropylene-based resin composition obtained in the present invention include a strand shape, a sheet shape, a flat plate shape, and a pellet shape in which the strand is cut to an appropriate length. In order to apply the polypropylene-based resin composition of the present invention to molding processing, it is preferably a pellet having a length of 1 to 50 mm as a shape from the viewpoint of production stability of the obtained molded body.

<Molded product>

Another aspect of the present invention is a molded article made of the polypropylene resin composition.

The molded article can be produced by various molding methods using the polypropylene-based resin composition of the present invention, and the shape, size, etc. of the molded body can be appropriately determined.

Examples of the method for producing the molded body include an injection molding method, a press molding method, a vacuum molding method, a foam molding method, an extrusion molding method, etc., which are commonly used in industry, and the polypropylene-based resin composition of the present invention can be used depending on the purpose. And a molding method in which polypropylene-based resins of the same kind or different kinds are mixed with other resins, a method of co-extrusion molding, and the like.

Examples of the use of the molded body include automobile materials, home appliance materials, and building materials.

Automotive materials include, for example, interior trims such as door trims, fillers, instrument panels, consoles, rocker panels, armrests, door panels, spare tire covers, and exterior parts such as bumpers, spoilers, fenders, and side steps, and other air intakes. And parts such as ducts, coolant reserve tanks, wing liners, sirocco fans, air conditioner cases, fan shrouds, under deflectors, and integrally molded parts such as front end panels.

In addition, as a household appliance material, for example, a material for a washing machine, a material for a dryer, a material for a vacuum cleaner, a material for a rice cooker, a material for a pot, a material for a warmer, a material for a dishwasher, a material for an air cleaner, a material for an air conditioner, a material for lighting equipment, etc Can be mentioned. Further, examples of the building materials include indoor floor members, wall members, and window frame members.

The polypropylene resin composition according to the present invention and the molded article produced therefrom can be preferably used in a pressurized reserve tank for automobiles from the viewpoint of excellent mechanical strength and heat resistance.

Hereinafter, examples will be described in detail to specifically describe the present specification. However, the embodiments according to the present specification may be modified in various other forms, and the scope of the present specification is not interpreted to be limited to the embodiments described below. The embodiments of the present specification are provided to more fully describe the present specification to those skilled in the art. In addition, "%" and "part" which represents content below are on a weight basis unless otherwise specified.

Examples 1-3 and Comparative Example 1: Preparation of polypropylene resin composition

A polypropylene resin composition was prepared by varying the component ratios of the styrene-ethylene-butylene-styrene block copolymer.

Specifically, the components described below were prepared at the component ratios shown in Table 1 below. This was mixed for 3 minutes at 400 rpm using a Super Mixer, then mixed for 2 minutes at 600 rpm, and the mixture was extruded at 210° C. using a single extruder.

[Components]

1) Homo polypropylene: Homo polypropylene (Lotte Chemical Co. Ltd.) having a melt index of 0.3 g/10 min measured according to ASTM D1238 (230° C., 2.16 kg).

2) Styrene-ethylene-butylene-styrene (SEBS) block copolymer: The melt index measured according to ISO 1133 (230°C, 2.16 kg) is 5 g/10 min, DSC (differential scanning calorimetry) Styrene-ethylene-butylene-styrene block copolymer (SEPTON 2004, Kuraray) with Tg (Glass Transition Temperature) measured by)

3) Primary antioxidant: 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6- (1H,3H,5H)-trion (1790, Songwon Industry)

4) Secondary antioxidant: tris(2,4-di-tertary-butylphenyl)phosphite (1680, Songwon Industry)

5) Heat stabilizer: DSTDP (Distearyl thiodipropionate) (Songwon Industry)

6) Rigid nucleating agent: Dicarboxylate calcium salt (HPN-20E, Milliken)

7) Neutralizing agent: Calcium Stearate (SC-120, Songwon Industry)

division Example 1 Example 2 Example 3 Example 4 Comparative example Suzy Homo polypropylene (parts by weight) 99 97 95 93 100 SEBS (parts by weight) One 3 5 7 0 Primary antioxidant (parts by weight) 0.05 0.05 0.05 0.05 0 Secondary antioxidant (parts by weight) 0.4 0.4 0.4 0.4 0 Heat stabilizer (parts by weight) 0.6 0.6 0.6 0.6 0 Rigid nucleating agent (parts by weight) 0.15 0.15 0.15 0.15 0 Neutralizing agent (parts by weight) 0.2 0.2 0.2 0.2 0

Experimental Example 1. Measurement of physical properties

The properties of the polypropylene resin compositions prepared in Examples 1 to 4 and Comparative Example 1 were measured using the experimental methods described below.

[Experiment method]

1) Tensile strength and elongation: Measured at room temperature by the method of ASTM D638.

2) Izod impact strength: measured at 23°C or -40°C by the method of ASTM D256.

3) Heat deflection temperature (HDT): measured by the method of ASTM D648.

division Example 1 Example 2 Example 3 Example 4 Comparative example Tensile strength (MPa) 38 37 30 25 40 Elongation (%) 120 140 190 250 80 Izod impact strength [23℃](J/m) 150 160 180 205 73 Izod impact strength [-40℃] (J/m) 37 39 40 42 30 HDT(℃) 119 120 115 112 111

As a result, as described in Table 2, the polypropylene resin compositions prepared in Examples 1 to 4 were improved in elongation, impact strength, and heat distortion temperature as compared to Comparative Examples. Particularly, Example 2 had the highest heat deflection temperature of 120°C compared to Examples 1, 3, and 4, so there was no restriction in use at high temperatures, and excellent tensile strength and impact strength properties at high or low temperatures.

Therefore, by mixing SEBS with homo polypropylene, the impact strength, in particular, the impact strength at low temperature can be improved, and by adding a heat stabilizer and primary and secondary antioxidants, the thermal deformation temperature can be improved, and the rigid nucleating agent. It was confirmed that the addition of to compensate for the decrease in tensile strength.

Claims (7)

It contains 93 to 99% by weight of homo polypropylene and 1 to 7% by weight of a styrenic thermoplastic elastomer block copolymer. Homo polypropylene has a melt index of 0.2 to 0.4 g/measured according to ASTM D1238 (230°C, 2.16 kg). Polypropylene resin composition characterized in that it is 10 min. According to claim 1,
The styrene-based thermoplastic elastomer block copolymer is styrene-ethylene-butylene-styrene block copolymer, styrene-hydrogenated butadiene-styrene triblock copolymer, styrene-isoprene-styrene triblock copolymer, styrene-hydrogenated isoprene-styrene Polypropylene characterized by comprising at least one member selected from the group consisting of triblock copolymers, styrene-hydrogenated butadiene diblock copolymers, styrene-hydrogenated isoprene diblock copolymers, and styrene-isoprene diblock copolymers. Resin composition. According to claim 2,
The styrene-ethylene-butylene-styrene block copolymer is a polypropylene resin composition, characterized in that the melt index measured according to ISO 1133 (230 ℃, 2.16kg) is 3 to 10 g/10 min. According to claim 1,
The polypropylene resin composition is a polypropylene resin composition, characterized in that it further comprises at least one selected from the group consisting of primary antioxidants, secondary antioxidants, heat stabilizers, rigid nucleating agents and neutralizing agents. The method according to any one of claims 1 to 4,
A polypropylene resin composition, characterized in that the Izod impact strength measured at 23°C is 80 J/m or higher by the method of ASTM D256, and the Izod impact strength measured at -40 °C is 32 J/m or higher. The method according to any one of claims 1 to 4,
A polypropylene resin composition characterized in that the heat deflection temperature (HDT) measured by the method of ASTM D648 is 112°C or higher. A molded article for a pressurized reservoir tank made of the polypropylene resin composition according to any one of claims 1 to 4.