KR102287154B1 - Metallocene polypropylene and expandable polypropylene comprising the same - Google Patents

Abstract

The present invention relates to a metallocene polypropylene and expanded polypropylene containing the same, wherein the metallocene polypropylene according to the present invention has a low melting point, so that high-magnification foaming is possible with a low processing temperature, and the expanded polypropylene manufactured therewith Since the silver strength is high, the metallocene polypropylene according to the present invention can produce expanded polypropylene having a low melting point and high strength.

Description

Metallocene polypropylene and expanded polypropylene comprising the same

The present invention relates to a metallocene polypropylene and expanded polypropylene comprising the same.

Expandable polypropylene (EPP) refers to spherical particles in which polypropylene is physically (non-crosslinkable) foamed without using a chemical foaming agent. Such expanded polypropylene has a cell structure, and due to the characteristics of the cell structure, it is used in various fields as an energy absorber, a heat insulator, a cushioning material, a lightweight box, and the like. In particular, as the demand for improved fuel efficiency and weight reduction of automobiles increases, the demand for low-density expanded polypropylene is gradually increasing.

Various studies have been conducted on polypropylene suitable for manufacturing expanded polypropylene, and in general, polypropylene satisfying both properties is required. One is that the higher the degree of foaming, the larger the internal cell structure and the higher the degree of weight reduction, the higher the foaming magnification should be possible. Because high-magnification foaming requires a high-temperature process, the melting point of polypropylene must be somewhat high. The other is that the strength of the expanded polypropylene produced by foaming should be high, and therefore the strength of the polypropylene itself should be high.

However, as the melting point of polypropylene increases, overall physical properties including strength are improved, but there is a problem in that the temperature of the process for high magnification foaming increases, thereby increasing the manufacturing cost. Therefore, the development of polypropylene having a low melting point and high strength is required.

On the other hand, polypropylene polymerization catalysts can be broadly classified into Ziegler-Natta and metallocene catalyst systems, and these two highly active catalyst systems have been developed according to their respective characteristics. Ziegler-Natta catalyst has been widely applied to existing commercial processes since its invention in the 1950s. There is a problem in that there is a limit in securing desired properties because the distribution is not uniform.

The metallocene catalyst consists of a combination of a main catalyst containing a transition metal compound as a main component and a cocatalyst containing an organometallic compound containing aluminum as a main component, and such a catalyst is a homogeneous complex catalyst and is a single site catalyst. A polymer with a narrow molecular weight distribution and uniform comonomer composition distribution is obtained according to the single active site characteristic, and the polymer's stereoregularity, copolymerization characteristics, molecular weight, crystallinity, etc. has properties that can change it.

Accordingly, in order to produce polypropylene having a low melting point and high strength, a metallocene catalyst system is more advantageous than a Ziegler-Natta catalyst system, and in particular, a catalyst system capable of producing polypropylene having a high molecular weight is advantageous.

Accordingly, the present inventors have intensively studied metallocene polypropylene suitable for the production of expanded polypropylene through various metallocene catalysts. As will be described later, the metallocene polypropylene according to the present invention has a low melting point and high strength. The present invention was completed by confirming that high expanded polypropylene could be produced.

An object of the present invention is to provide a metallocene polypropylene capable of producing expanded polypropylene having a low melting point and high strength.

In addition, the present invention is to provide an expanded polypropylene comprising the metallocene polypropylene.

In order to solve the above problems, the present invention provides a metallocene polypropylene having the following characteristics:

a weight average molecular weight of 20,000 to 200,000 g/mol,

a molecular weight distribution (Mw/Mn) of 1.5 to 3.5,

Melting temperature (Tm) is 120 to 155 ℃,

According to ASTM D1238, the melt flow rate (MFR) measured at 230° C. and a load of 2.16 kg is 3 to 30 g/10 min.

The metallocene polypropylene according to the present invention is a suitable material for the production of expanded polypropylene. The term 'expandable polypropylene (EPP)' used in the present invention means spherical particles in which polypropylene is physically (non-crosslinkable) foamed without using a chemical foaming agent.

Metallocene polypropylene that satisfies the above physical properties has a characteristic of being able to produce expanded polypropylene having a low melting point and high strength.

Preferably, the weight average molecular weight (g/mol) is 50,000 or more, 60,000 or more, 70,000 or more, 80,000 or more, 90,000 or more, 100,000 or more, 110,000 or more, 120,000 or more, 130,000 or more, or 140,000 or more. Also preferably, the weight average molecular weight (g/mol) is 190,000 or less, 180,000 or less, 170,000 or less, 160,000 or less, or 150,000 or less.

Preferably, the molecular weight distribution (Mw/Mn) is 1.6 or more, 1.7 or more, 1.8 or more, 1.9 or more, 2.0 or more, 2.1 or more, 2.2 or more, 2.3 or more, 2.4 or more, 2.5 or more, 2.6 or more, 2.7 or more, 2.8 or more. or more, 2.9 or more, 3.0 or more, 3.1 or more, or 3.2 or more. Also preferably, the molecular weight distribution (Mw/Mn) is 3.4 or less, or 3.3 or less.

Preferably, the melting temperature (Tm, ℃) is 121 or more, 122 or more, 123 or more, 124 or more, 125 or more, 126 or more, 127 or more, 128 or more, 129 or more, 130 or more, 131 or more, or 132 or more. . Also preferably, the melting temperature (Tm, °C) is 150 or less, 145 or less, 140 or less, 139 or less, 138 or less, 137 or less, 136 or less, or 135 or less.

Preferably, the melt flow index (MFR, g/10 min) is between 10 and 20 g/10 min.

Preferably, the metallocene polypropylene has a flexural modulus measured according to ASTM D790 of 10,000 kg/cm 2 or more. The flexural modulus is better as its value is higher, so there is no upper limit for it, but for example, 15,000 kg/cm2 or less, 14,000 kg/cm2 or less, 13,000 kg/cm2 or less, 12,000 kg/cm2 or less, or 11,000 kg/cm2 or less. can

In addition, the metallocene polypropylene is a copolymer including a comonomer other than propylene. The content of the comonomer is preferably 0.5 to 5% by weight compared to the metallocene polypropylene. As the comonomer, an alpha-olefin having 2 to 10 carbon atoms other than propylene may be used, for example, ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1 and at least one selected from the group consisting of -decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, and mixtures thereof.

The metallocene polypropylene may be prepared by polymerization with propylene and the comonomer in the presence of at least one compound represented by the following formula (1):

[Formula 1]

In the above formula,

M is Zr or Hf,

X is the same or different halogens,

R ₁ is C _6-20 aryl substituted with _{C 1-20 alkyl,}

R ₂ , R ₃ and R ₄ are each independently hydrogen, halogen, C _1-20 alkyl, C _2-20 alkenyl, C _1-20 alkylsilyl, C _1-20 silylalkyl, C _1-20 alkoxysilyl, C _1-20 ether, C _1-20 silyl ether, C _1-20 alkoxy, C _6-20 aryl, C _7-20 alkylaryl, or C _7-20 arylalkyl,

A is carbon, silicon or germanium,

R ₅ is C _1-20 alkyl substituted with C _1-20 alkoxy;

R ₆ is hydrogen, C _1-20 alkyl or C _2-20 alkenyl.

The compound of Formula 1 has an ansa-metallocene structure and includes two indenyl groups as ligands. In particular, since a functional group capable of serving as a Lewis base as an oxygen-donor is substituted in a bridge group connecting the ligand, there is an advantage in maximizing the activity as a catalyst. In addition, since a _{bulky group such as C 6-20} aryl (R _{1 ) substituted with C 1-20} alkyl in the indenyl group is substituted, steric hindrance is imparted to suppress the formation of the meso form. Accordingly, when the compound represented by Formula 1 is supported by itself or on a carrier, and used as a catalyst for the metallocene polypropylene according to the present invention, polypropylene having desired physical properties can be more easily prepared.

Preferably, R ₁ is phenyl substituted with tert-butyl. More preferably, R ₁ is 4-tert-butyl-phenyl.

Also preferably, R ₂ , R ₃ and R ₄ are hydrogen.

Also preferably, A is silicone.

Also preferably, R ₅ is 6-tert-butoxy-hexyl and R ₆ is methyl.

Also preferably, the metallocene polypropylene may be prepared by polymerization with propylene or, if necessary, the comonomer in the presence of two of the compounds represented by Formula 1 above. More preferably, the structures of the two types of compounds are identical to each other except for M.

In addition, the present invention provides a method for preparing a compound represented by the formula (1), as represented by the following Scheme 1:

[Scheme 1]

Step 1 is a step of preparing the compound represented by Formula 4 by reacting the compound represented by Formula 2 with the compound represented by Formula 3 above. It is preferable to use alkyllithium (for example, n-butyllithium) in the reaction, and the reaction temperature is -200 to 0°C, more preferably -150 to 0°C. Toluene, THF, etc. can be used as a solvent. At this time, after separating the organic layer from the product, the step of vacuum-drying the separated organic layer and removing excess reactants may be further performed.

Step 2 is a step of preparing the compound represented by Formula 1 by reacting the compound represented by Formula 4 with the compound represented by Formula 5. It is preferable to use alkyllithium (for example, n-butyllithium) in the reaction, and the reaction temperature is -200 to 0°C, more preferably -150 to 0°C. As a solvent, ether, hexane, etc. can be used.

The compound represented by Formula 1 may be supported on a carrier. The carrier is not particularly limited because a conventional one in the art to which the present invention pertains may be used, but preferably one or more carriers selected from the group consisting of silica, silica-alumina and silica-magnesia may be used. On the other hand, when supported on a carrier such as silica, the silica carrier and the functional group of the compound represented by Formula 1 are chemically bonded and supported. There is no fouling of the reactor wall or polymer particles sticking together during manufacturing.

Specifically, as the carrier, silica dried at high temperature, silica-alumina, etc. may be used, and these are typically Na ₂ O, K ₂ CO ₃ , BaSO ₄ , Mg(NO ₃ ) ₂ Oxides, carbonates, sulfates, etc.; It may contain a nitrate component.

In addition, the catalyst may further include a co-catalyst composed of alkylaluminoxane. When using such a cocatalyst, X bonded to the metal element (M) of the compound represented by Formula 1 may be used as a catalyst in which an alkyl _{group, for example, C 1-20 alkyl is substituted.}

The co-catalyst is also not particularly limited because it may be used in the art to which the present invention pertains, but preferably one or more co-catalysts selected from the group consisting of silica, silica-alumina, and organoaluminum compounds may be used.

In addition, the present invention provides a method for preparing a metallocene polypropylene by polymerization with propylene and the comonomer in the presence of the catalyst.

The polymerization may be carried out by reacting at a temperature of 25 to 500° C. and a pressure of 1 to 100 kgf/cm 2 for 1 to 24 hours. At this time, the polymerization reaction temperature is preferably 25 to 200 °C, more preferably 50 to 100 °C. Further, the polymerization reaction pressure is preferably 1 to 70 kgf/cm 2 , more preferably 5 to 40 kgf/cm 2 . The polymerization reaction time is preferably 1 to 5 hours.

The polymerization process can control the molecular weight range of the finally produced polymer product according to hydrogenation or non-hydrogenation conditions. In particular, high molecular weight metallocene polypropylene can be prepared under conditions in which hydrogen is not added, and when hydrogen is added, low molecular weight metallocene polypropylene can be prepared even with a small amount of hydrogenation. At this time, the hydrogen content added to the polymerization process is in the range of 0.07 L to 4 L under reactor conditions 1 atm, or is supplied at a pressure of 1 bar to 40 bar, or is supplied at 168 ppm to 8,000 ppm in the hydrogen molar content range compared to the monomer. can

The present invention also provides, expandable polypropylene (EPP) comprising the metallocene polypropylene according to the present invention. In general, the expanded polypropylene comprises at least 95% by weight of the metallocene polypropylene according to the present invention, preferably the expanded polypropylene consists of the metallocene polypropylene according to the present invention.

A method for producing expanded polypropylene may be a conventional method in the art to which the present invention pertains, except that the metallocene polypropylene according to the present invention is used. For example, expanded polypropylene may be produced by a batch method. Specifically, mixing the metallocene polypropylene and other additives for imparting functionality; uniformly dispersing the mixed raw materials and extruding them into pellets of a certain size; A foaming step of discharging the foam in the form of beads by putting the pellets in a batch, adding water, a dispersing agent, a foaming agent, etc., and raising the temperature and pressurization; Foamed polypropylene can be manufactured by a method comprising a washing step to remove foreign substances from the bead surface and a drying step to remove moisture. In addition, in order to manufacture a final product, the bead may be injected into the mold of the final product and fused with high-temperature steam to obtain a final finished product, a foam product.

The metallocene polypropylene according to the present invention has a low melting point, enabling high-magnification foaming at a low processing temperature, and the expanded polypropylene prepared therewith has high strength. The metallocene polypropylene according to the present invention has a low melting point. It is possible to manufacture expanded polypropylene with high strength while still being.

As described above, the metallocene polypropylene according to the present invention is characterized in that it can produce expanded polypropylene having a low melting point and high strength.

Hereinafter, preferred examples are presented to help the understanding of the present invention. However, the following examples are only provided for easier understanding of the present invention, and the content of the present invention is not limited thereto.

manufacturing example One

Step 1) Preparation of (6-t-butoxyhexyl)(methyl)-bis(2-methyl-4-(4-t-butylphenyl)indenyl))silane

150 g of 2-methyl-4-(4-t-butylphenyl)-indene was placed in a 3 L schlenk flask, and a toluene/THF (10:1, 1.73 L) solution was added thereto and dissolved at room temperature. . After the solution was cooled to -20°C, 240 mL of n-butyllithium solution (n-BuLi, 2.5 M in hexane) was slowly added dropwise and stirred at room temperature for 3 hours. After that, the reaction solution was cooled to -20°C, and then 82 g of (6-t-butoxyhexyl)dichloromethylsilane and 512 mg of CuCN were slowly added dropwise. After raising the temperature of the reaction solution to room temperature, the mixture was stirred for 12 hours, and 500 mL of water was added. After that, the organic layer was separated, dehydrated with _{MgSO 4 and filtered.} The filtrate was distilled under reduced pressure to obtain a yellow oil.

¹ H NMR (500 MHz, CDCl ₃ , 7.26 ppm): -0.09 - -0.05 (3H, m), 0.40 - 0.60 (2H, m), 0.80 - 1.51 (26H, m), 2.12 - 2.36 (6H, m) ), 3.20~3.28 (2H, m), 3.67 - 3.76 (2H, m), 6.81 - 6.83 (2H, m), 7.10 - 7.51 (14H, m)

Step 2) Preparation of rac-[(6-t-butoxyhexylmethylsilanediyl)-bis(2-methyl-4-(4-t-butylphenyl)indenyl)]hafnium dichloride

(6-t-butoxyhexyl) (methyl) bis (2-methyl-4- (4-t-butylphenyl)) indenylsilane prepared previously in a 3 L schlenk flask was added, 1 L of ethyl ether was added and dissolved at room temperature. After the solution was cooled to -20°C, 240 mL of n-butyllithium solution (n-BuLi, 2.5 M in hexane) was slowly added dropwise and stirred at room temperature for 3 hours. After that, the reaction solution was cooled to -78°C, and then 92 g of hafnium chloride was added thereto. The reaction solution was heated to room temperature, stirred for 12 hours, and the solvent was removed under reduced pressure. 1 L of dichloromethane was added, and then undissolved inorganic salts were removed by filtration. The filtrate was dried under reduced pressure, and 300 mL of dichloromethane was added thereto to precipitate crystals. The precipitated crystals were filtered and dried, and 80 g of rac-[(6-t-butoxyhexylmethylsilanediyl)-bis(2-methyl-4-(4-t-butylphenyl)indenyl)]hafnium dichloride was obtained (rac:meso = 50:1).

¹ H NMR (500 MHz, CDCl ₃ , 7.26 ppm): 1.19 - 1.78 (37H, m), 2.33 (3H, s), 2.34 (3H, s), 3.37 (2H, t), 6.91 (2H, s) , 7.05 - 7.71 (14H, m)

manufacturing example 2

Step 1) Preparation of (6-t-Butoxyhexyl)(methyl)-bis(2-methyl-4-tert-butyl-phenylindenyl)silane

After dissolving 2-methyl-4-tert-butylphenylindene (20.0 g, 76 mmol) in toluene/THF=10/1 solution (230 mL), n-butyllithium solution (2.5 M, hexane solvent, 22 g) was slowly added dropwise at 0° C., and then stirred at room temperature for one day. Thereafter, (6-t-butoxyhexyl)dichloromethylsilane (1.27 g) was slowly added dropwise to the mixed solution at -78°C, stirred for about 10 minutes, and then stirred at room temperature for one day. Then, water was added to separate the organic layer, and the solvent was distilled under reduced pressure to obtain (6-t-butoxyhexyl)(methyl)-bis(2-methyl-4-tert-butyl-phenylindenyl)silane.

¹ H NMR (500 MHz, CDCl ₃ , 7.26 ppm): -0.20-0.03 (3H, m), 1.26 (9H, s), 0.50-1.20 (4H, m), 1.20-1.31 (11H, m), 1.40 -1.62 (20H, m), 2.19-2.23 (6H, m), 3.30-3.34 (2H, m), 3.73-3.83 (2H, m), 6.89-6.91 (2H, m), 7.19-7.61 (14H, m)

Step 2) Preparation of [(6-t-Butoxyhexylmethylsilane-diyl)-bis(2-methyl-4-tert-butylphenylindenyl)]zircholium dichloride

The (6-t-butoxyhexyl)(methyl)-bis(2-methyl-4-tert-butyl-phenylindenyl)silane prepared in step 1 was dissolved in toluene/THF=5/1 solution (95 mL). After dissolution, n-butyllithium solution (2.5 M, hexane solvent, 22 g) was slowly added dropwise at -78°C, followed by stirring at room temperature for one day. Bis(N,N'-diphenyl-1,3-propanediamido)dichlorozirconium bis(tetrahydrofuran)[Zr(C ₅ H ₆ NCH ₂ CH ₂ NC ₅ H ₆ )Cl ₂ (C ₄ H ₈ O) ₂ ] was dissolved in toluene (229 mL), and then slowly added dropwise at -78°C and stirred at room temperature for one day. After the reaction solution was cooled to -78°C, HCl ether solution (1 M, 183 mL) was slowly added dropwise, followed by stirring at 0°C for 1 hour. After filtration and vacuum drying, hexane was added and stirred to precipitate crystals. The precipitated crystals were filtered and dried under reduced pressure, and [(6-t-butoxyhexylmethylsilane-diyl)-bis(2-methyl-4-tert-butylphenylindenyl)]zircolium dichloride (20.5 g, total 61) %) was obtained.

¹ H NMR (500 MHz, CDCl ₃ , 7.26 ppm): 1.20 (9H, s), 1.27 (3H, s), 1.34 (18H, s), 1.20-1.90 (10H, m), 2.25 (3H, s) , 2.26 (3H, s), 3.38 (2H, t), 7.00 (2H, s), 7.09-7.13 (2H, m), 7.38 (2H, d), 7.45 (4H, d), 7.58 (4H, d) ), 7.59 (2H, d), 7.65 (2H, d)

Example One

Step 1) Preparation of supported catalyst

After weighing 3 g of silica L203F in a shrink flask in advance, 10 mmol of methylaluminoxane (MAO) was added and reacted at 95° C. for 24 hours. After precipitation, the upper layer was removed and washed once with toluene. After dissolving 60 μmol of the compound prepared in Preparation Example 2 in toluene, it was reacted at 75° C. for 5 hours. When the precipitation was completed after the reaction was completed, the upper layer solution was removed and the remaining reaction product was washed once with toluene. Then, 20 μmol of the compound prepared in Preparation Example 1 was dissolved in toluene, and then reacted at 75° C. for 2 hours. When the precipitation was completed after the reaction was completed, the upper layer solution was removed and the remaining reaction product was washed once with toluene. 64 μmol of dimethylanilinium tetrakis (pentafluorophenyl) borate was added and reacted at 75° C. for 5 hours. After completion of the reaction, the mixture was washed with toluene, washed again with hexane, and then vacuum dried to obtain a silica-supported metallocene catalyst in the form of solid particles.

Step 2) Polypropylene production

The 2L stainless reactor was vacuum dried at 65° C. and then cooled, and 1.5 mmol of triethylaluminum was added at room temperature, 0.37 L of hydrogen was added, and 1.5 L of propylene and ethylene were sequentially added. After stirring for 10 minutes, the metallocene-supported catalyst prepared in step 1 was introduced into the reactor under nitrogen pressure. Thereafter, the temperature of the reactor was raised to 70° C. within 5 minutes, and then polymerization was carried out for 1 hour. After completion of the reaction, unreacted propylene was vented.

Step 3) Manufacture of expanded polypropylene foam

1) Mini-pellet manufacturing

According to the required physical properties of the final product, 2,000 to 5,000 ppm of an antistatic agent, 1,000 to 2,000 ppm of an antioxidant, and 2,000 to 3,000 ppm of silica were added to the polypropylene prepared in step 2 above and mixed sufficiently, and then put into the extruder. A strand was extruded at an extruder temperature of 180 to 220° C. at an input rate of 10 to 30 kg/hr, and the diameter of the finally obtained mini pellets was 1 to 2 mm.

2) EPP bead preparation

500 mL of water as a dispersion medium was filled in the autoclave reactor, 5 g of the previously prepared mini pellets were injected, and then the mini pellets were uniformly dispersed in water with a stirrer. At this time, 1,000 to 3,000 ppm of aluminum sulfite was added as a dispersion stabilizer to prevent the mini pellets from sticking to each other, and the temperature of the reactor was set to 140 to 150° C., and then CO2 was injected into the reactor as a foaming gas. At this time, the pressure in the reactor was set to be 500 psi or more, and after staying for 1 to 2 hours depending on the expansion ratio, the valve was opened and sent out of the reactor to obtain EPP beads.

3) Foam molding

The previously prepared EPP beads were fed into a foam molding machine, and the EPP beads were filled into a steam molding machine. The mold was closed and steam was injected inside, and at this time, a steam pressure of 10 to 20 bar was applied. After cooling the surface of the prepared foam, the mold was opened to obtain a finished foam molded article.

Example 2

Step 1) Preparation of supported catalyst

After weighing 3 g of silica in a shrink flask in advance, 52 mmol of methylaluminoxane (MAO) was added and reacted at 90° C. for 24 hours. After precipitation, the upper layer was removed and washed twice with toluene. 240 μmol of the compound synthesized in Preparation Example 1 was dissolved in toluene, and then reacted at 70° C. for 5 hours. After completion of the reaction and the completion of precipitation, the upper layer solution was removed, and the remaining reaction product was washed with toluene, washed again with hexane, and then vacuum dried to obtain 5 g of a silica-supported metallocene catalyst in the form of solid particles.

Step 2) Polypropylene production

The 2L stainless reactor was vacuum dried at 65° C. and then cooled, and 1.5 mmol of triethylaluminum was added at room temperature, 0.37 L of hydrogen was added, and 1.5 L of propylene and ethylene were sequentially added. After stirring for 10 minutes, the metallocene-supported catalyst prepared in step 1 was introduced into the reactor under nitrogen pressure. Thereafter, the temperature of the reactor was raised to 70° C. within 5 minutes, and then polymerization was carried out for 1 hour. After completion of the reaction, unreacted propylene was vented.

Step 3) Manufacture of expanded polypropylene foam

An expanded polypropylene foam was prepared in the same manner as in step 3 of Example 1.

comparative example

Ziglo-Natta polypropylene (R3410, LG Chem) was used as Comparative Example 1 and polypropylene (T3410, LG Chem) was used as Comparative Example 2, and expanded polypropylene was prepared as in step 3 of Example 1, respectively. .

Experimental example

(1) Evaluation of physical properties of polypropylene

The physical properties of the polypropylene prepared in Examples and Comparative Examples were measured as follows, and the results are shown in Table 1 below.

1) Mn, Mw, and MWD: The sample was pretreated by dissolving it in 1,2,4-Trichlorobenzene containing 0.0125% BHT at 160°C for 10 hours using PL-SP260, and measuring temperature 160°C using PL-GPC220 The number average molecular weight and weight average molecular weight were measured in The molecular weight distribution was expressed as the ratio of the weight average molecular weight to the number average molecular weight.

2) Recrystallization temperature (Trc), melting point (Tm) and heat of fusion (ΔH): Using a Differential Scanning Calorimeter (DSC, device name: DSC 2920, manufacturer: TA instrument), the recrystallization temperature, melting point, and The heat of fusion was measured. Specifically, the polymer was heated to 220° C. and maintained at that temperature for 5 minutes, then lowered to 20° C. and then increased again. At this time, the temperature rise and fall rates were adjusted to 10° C./min, respectively.

3) Tensile Strength (TS): It was measured at a speed of 50 mm/min according to ASTM D638.

4) Flexural Modulus (FM): The flexural modulus was measured according to ASTM D790.

5) Melt index (MFR, 2.16 kg): Measured at 230°C under a load of 2.16 kg according to ASTM D1238, and expressed as the weight (g) of the polymer melted for 10 minutes.

Mw
(g/mol) MWD Trc
(℃) Tm
(℃) ΔH
(J/g) TS (@yield)
(kg/cm2) FM
(kg/cm2) MFR
(g/10 min) Example 1 148,287 3.2 96.7 132.4 66 253 9253 8.4 Example 2 149,971 3.3 99.5 134.6 72 275 10439 6.4 Comparative Example 1 148,403 3.9 106.0 144.2 70 279 10118 7.1 Comparative Example 2 151,671 4.5 97.8 134.0 67 253 8893 7.2

(2) Evaluation of properties of expanded polypropylene

The physical properties of the expanded polypropylene foam prepared in Examples and Comparative Examples were measured as follows, and the results are shown in Table 2 below.

1) Melting point (Tm): The melting point of the expanded polypropylene was measured using a Differential Scanning Calorimeter (DSC, device name: DSC 2920, manufacturer: TA instrument). Specifically, the polymer was heated to 220°C and maintained at that temperature for 5 minutes, then lowered to 20°C, and then the temperature was increased again.

2) Compressive strength (kg/cm 2 ): Measured according to ASTM D1621.

Tm(℃) Steam pressure 20% compressive strength (kg/㎠) 50% compressive strength (kg/㎠) magnification 1 ^{1 )} magnification 2 ^{2 )} magnification 3 ^{3 )} magnification 1 ^{1 )} magnification 2 ^{2 )} magnification 3 ^{3 )} Comparative Example 1 142.0 - 2.18 3.15 8.01 3.17 4.51 11.19 Example 2 134.6 15% reduction 2.24 3.04 7.05 3.37 4.76 11.73 1) Magnification 1: Foaming magnification 8 times
2) Magnification 2: 20 times the foaming magnification
3) Magnification 3: Foaming magnification 30 times

Claims (8)

a weight average molecular weight of 140,000 to 150,000 g/mol,
a molecular weight distribution (Mw/Mn) of 3.0 to 3.5,
Melting temperature (Tm) is 120 to 155 ℃,
A melt flow rate (MFR) of 3 to 30 g/10 min measured at 230° C. and a load of 2.16 kg according to ASTM D1238,
Metallocene polypropylene-ethylene.
According to claim 1,
Flexural Modulus (Flexural Modulus) measured by ASTM D790 is 10,000 kg / ㎠ or more,
Metallocene polypropylene-ethylene.
According to claim 1,
0.5 to 5% by weight of ethylene as a comonomer,
Metallocene polypropylene-ethylene.
According to claim 1,
Metallocene polypropylene-ethylene prepared by polymerizing propylene and a comonomer in the presence of at least one of the metallocene compounds represented by the following formula (1):
[Formula 1]

In the above formula,
M is Zr or Hf,
X is the same or different halogens,
R ₁ is C _6-20 aryl substituted with _{C 1-20 alkyl,}
R ₂ , R ₃ and R ₄ are each independently hydrogen, halogen, C _1-20 alkyl, C _2-20 alkenyl, C _1-20 alkylsilyl, C _1-20 silylalkyl, C _1-20 alkoxysilyl, C _1-20 ether, C _1-20 silyl ether, C _1-20 alkoxy, C _6-20 aryl, C _7-20 alkylaryl, or C _7-20 arylalkyl,
A is carbon, silicon, or germanium,
R ₅ is C _1-20 alkyl substituted with C _1-20 alkoxy;
R ₆ is hydrogen, C _1-20 alkyl, or C _2-20 alkenyl.
5. The method of claim 4,
R ₁ is phenyl substituted with tert-butyl,
Metallocene polypropylene-ethylene.
5. The method of claim 4,
R ₂ , R ₃ and R ₄ are hydrogen, characterized in that
Metallocene polypropylene-ethylene.
5. The method of claim 4,
The metallocene compound represented by Formula 1 is supported on at least one carrier selected from the group consisting of silica, silica-alumina and silica-magnesia,
Metallocene polypropylene-ethylene.
According to any one of claims 1 to 7, wherein any one of the metallocene polypropylene- containing ethylene, expanded polypropylene (Expandable polypropylene, EPP).