Polypropylene

Abstract

The present invention relates to a polypropylene which exhibits high transparency and has a very low level of generation of volatile organic compounds, which has a total volatile organic compounds (TVOC) value of 60 g/g or less, which is measured according to VDA 277 standardized by the German Automobile Industry Association by heating the polypropylene for 12 to 5 hours and converting all hydrocarbons detected per 1 g into an acetone content, and a haze value of 5% or less.

Claims

1. A polypropylene having a TVOC (total volatile organic compounds) value of 60 g/g or less, which is measured according to VDA 277 standardized by the German Association of the Automobile Industry and means a value obtained by heating the polypropylene at 120 C. for 5 hours and converting all hydrocarbons detected per 1 g of the polypropylene into the content of acetone; having a haze of 5% or less; a weight average molecular weight of 100,000 to 145,000 g/mol; and a molecular weight distribution (Mw/Mn) of 2.9 or less.

2. The polypropylene of claim 1, wherein the polypropylene has a VOC (volatile organic compounds) value of 30 g/g or less, which is measured according to VDA 278 standardized by the German Association of the Automobile Industry, and means a value obtained by heating the polypropylene at 90 C. for 30 minutes and converting straight chain hydrocarbons having 1 to 25 carbon atoms detected per 1 g of the polypropylene into the content of toluene.

3. The polypropylene of claim 1, wherein the polypropylene has a FOG (fogging) value of 40 g/g or less, which is measured according to VDA 278 standardized by the German Association of the Automobile Industry, and means a value obtained by heating the polypropylene at 120 C. for 1 hour and converting straight chain hydrocarbons having 14 to 32 carbon atoms detected per 1 g of the polypropylene into the content of hexadecane.

4. The polypropylene of claim 1, wherein the polypropylene has a flexural strength (measured according to ASTM D790) of 400 kgf/cm.sup.2 or more.

5. The polypropylene of claim 1, wherein the polypropylene has a melting point (Tm) of 130 C. to 145 C., and a flexural modulus (measured according to ASTM D790) of 14,000 kgf/cm.sup.2 or more.

6. The polypropylene of claim 1, wherein the polypropylene has a MFR (measured at 230 C. under a load of 2.16 kg according to ASTM D1238) of 10 to 25 g/10 min.

7. The polypropylene of claim 1, wherein the polypropylene has a tensile strength (measured according to ASTM D790) of 300 to 400 kgf/cm.sup.2.

8. The polypropylene of claim 1, wherein the polypropylene is produced by polymerizing propylene in the presence of a hybrid supported catalyst comprising a compound represented by the following Chemical Formula 1, a compound represented by the following Chemical Formula 2 and a support: ##STR00009## in Chemical Formula 1, X is halogen, equal to or different from each other, R.sub.1 is C.sub.6-20 aryl substituted with C.sub.1-20 alkyl, R.sub.2, R.sub.3 and R.sub.4 are each independently hydrogen, halogen, C.sub.1-20 alkyl, C.sub.2-20 alkenyl, C.sub.1-20 alkylsilyl, C.sub.1-20 silylalkyl, C.sub.1-20 alkoxysilyl, C.sub.1-20 ether, C.sub.1-20 silyl ether, C.sub.1-20 alkoxy, C.sub.6-20 aryl, C.sub.7-20 alkylaryl, or C.sub.7-20 arylalkyl, A is carbon, silicon or germanium, R.sub.5 is C.sub.1-20 alkyl substituted with C.sub.1-20 alkoxy, and R.sub.6 is hydrogen, C.sub.1-20 alkyl or C.sub.2-20 alkenyl, ##STR00010## in Chemical Formula 2, X is halogen, equal to or different from each other, R.sub.1 is C.sub.6-20 aryl substituted with C.sub.1-20 alkyl, R.sub.2, R.sub.3 and R.sub.4 are each independently hydrogen, halogen, C.sub.1-20 alkyl, C.sub.2-20 alkenyl, C.sub.1-20 alkylsilyl, C.sub.1-20 silylalkyl, C.sub.1-20 alkoxysilyl, C.sub.1-20 ether, C.sub.1-20 silyl ether, C.sub.1-20 alkoxy, C.sub.6-20 aryl, C.sub.7-20 alkylaryl, or C.sub.7-20 arylalkyl, A is carbon, silicon or germanium, R.sub.5 is C.sub.1-20 alkyl substituted with C.sub.1-20 alkoxy, and R.sub.6 is hydrogen, C.sub.1-20 alkyl or C.sub.2-20 alkenyl.

9. The polypropylene of claim 8, wherein the hybrid supported catalyst further includes at least one of the cocatalyst compounds represented by the following Chemical Formulas 3, 4 and 5,
[Al(R.sub.30)O].sub.m[Chemical Formula 3] in Chemical Formula 3, R.sub.30 is equal to or different from each other, and each independently represent a halogen; a hydrocarbonyl having 1 to 20 carbon atoms; or a hydrocarbonyl having 1 to 20 carbon atoms substituted with halogen; and m is an integer of 2 or more;
J(R.sub.31).sub.3[Chemical Formula 4] in Chemical Formula 4, R.sub.31 is as R.sub.30 defined in Chemical Formula 3; J is aluminum or boron;
[E-H].sup.+[ZA.sub.4].sup. or [E].sup.+[ZA.sub.4].sup.[Chemical Formula 5] in Chemical Formula 5, E is a neutral or cationic Lewis base; H is a hydrogen atom; Z is a Group 13 element; and A is equal to or different from each other, and each independently represents an aryl group having 6 to 20 carbon atoms or an alkyl group having 1 to 20 carbon atoms, in which one or more hydrogen atoms are substituted or unsubstituted with a halogen, a hydrocarbonyl having 1 to 20 carbon atoms, an alkoxy or a phenoxy.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

(1) Hereinafter, the invention will be described in more detail by way of examples. However, these examples are given for illustrative purposes only and the scope of the present invention is not limited by the examples.

Preparation Example 1

(2) ##STR00007##

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

(3) 2-Methyl-4-tert-butylphenyl indene (20.0 g, 76 mmol) was dissolved in a toluene/THF=10/1 solution (230 mL) and then 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. Then, (6-t-butoxyhexyl)dichloromethylsilane (1.27 g) was slowly added dropwise to the mixed solution at 78 C. After stirring for about 10 minutes, the mixture was 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.

(4) .sup.1H NMR (500 MHz, CDCl.sub.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)

(5) Step 2) Preparation of [(6-t-butoxyhexylmethylsilane-diyl)-bis(2-methyl-4-tert-butylphenylindenyl)]zirconium dichloride

(6) (6-t-butoxyhexyl)(methyl)-bis(2-methyl-4-tert-butyl-phenylindenyl)silane prepared in Step 1 was dissolved in a toluene/THF=5/1 solution, and then n-butyllithium solution (2.5 M, hexane solvent, 22 g) was slowly added dropwise thereto at 78 C. and stirred at room temperature for one day. Bis(N,N-diphenyl-1,3-propanediamido)dichlorozirconium bis (tetrahydrofuran))[Zr(C.sub.5H.sub.6NCH.sub.2CH.sub.2NC.sub.5H.sub.6)Cl.sub.2(C.sub.4H.sub.8O).sub.2] was dissolved in toluene (229 mL), and then slowly added dropwise to the reaction solution at 78 C., and the solution was stirred at room temperature for one day. After the reaction solution was cooled to 78 C., a HCl ether solution (1 M, 183 mL) was slowly added dropwise, and the solution was stirred 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 to obtain [(6-t-butoxyhexylmethylsilane-diyl)-bis(2-methyl-4-tert-butylphenylindenyl)]zirconium dichloride (20.5 g, total 61%)

(7) .sup.1H NMR (500 MHz, CDCl.sub.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)

Preparation Example 2

(8) ##STR00008##

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

(9) 150 g of 2-methyl-4-(4-t-butylphenyl)indene was added to a 3 L Schlenk flask and dissolved in toluene/THF (10:1, 1.73 L) solution at room temperature. After the above solution was cooled to 20 C., 240 mL of n-butyllithium solution (n-BuLi, 2.5 M in hexane) was slowly added dropwise and the solution was stirred at room temperature for 3 hours. Then, 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. The reaction solution was warmed up to room temperature, and then stirred for 12 hours, to which 500 mL of water was added. Then, the organic layer was separated, dehydrated with MgSO.sub.4 and filtered. The filtrate was distilled under reduced pressure to obtain a desired compound in the form of a yellow oil.

(10) .sup.1H NMR (500 MHz, CDCl.sub.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

(11) (6-t-butoxyhexyl)(methyl)-bis(2-methyl-4-(4-t-butylphenyl)indenyl)silane previously prepared was added to a 3 L Schlenk flask, and 1 L of ethyl ether 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 the mixture was stirred at room temperature for 3 hours. Then, the reaction solution was cooled to 78 C., and 92 g of hafnium chloride was added thereto. The reaction solution was warmed up to room temperature and stirred for 12 hours, and the solvent was removed under reduced pressure. 1 L of dichloromethane was added, and then insoluble inorganic salts and the like were removed by filtration. The filtrate was dried under reduced pressure, and 300 mL of dichloromethane was added again to precipitate crystals. The precipitated crystals were filtered and dried to obtain 80 g of rac-[(6-t-butoxyhexylmethylsilanediyl)-bis(2-methyl-4-(4-t-butylphenyl)indenyl)]hafnium dichloride (Rac:meso=50:1).

(12) .sup.1H NMR (500 MHz, CDCl.sub.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)

Preparation Example 3Preparation of Hybrid Supported Catalyst

(13) 3 g of silica L203F was pre-weighed into a Schlenk flask to which 10 mmol of methylaluminoxane (MAO) was added and then reacted at 95 C. for 24 hours. After precipitation, the upper layer was removed and washed once with toluene. 60 mol of the compound prepared in Preparation Example 2 was dissolved in toluene and then reacted at 75 C. for 5 hours. After completion of the reaction, when the precipitation was completed, the upper layer solution was removed and the residual reaction product was washed once with toluene. 20 mol of the compound prepared in Preparation Example 1 was dissolved in toluene and then further reacted at 75 C. for 2 hours. After completion of the reaction, when the precipitation was completed, the upper layer solution was removed and the residual reaction product was washed once with toluene. 64 mol of dimethylanilinium tetrakis(pentafluorophenyl)borate was added and then reacted at 75 C. for 5 hours. After completion of the reaction, the reaction product was washed with toluene, washed again with hexane and dried under vacuum to obtain a silica-supported metallocene catalyst in the form of solid particles.

Example 1

(14) A 2 L stainless steel reactor was dried under vacuum at 65 C. and then cooled, to which 1.5 mmol of triethylaluminum, 337 ppm of hydrogen and 770 g of propylene were added at room temperature. Then, after stirring for 10 minutes, 0.04 g of the supported catalyst prepared in Preparation Example 3 was dissolved in 20 mL of TMA-formulated hexane and added to the reactor under nitrogen pressure. Then, the reactor temperature was gradually increased to 70 C. and then allowed to polymerize for 1 hour. After completion of the reaction, unreacted propylene was vented.

Example 2

(15) An olefin monomer was polymerized in the same manner as in Example 1, except that the amount of hydrogen added was changed to 200 ppm in Example 1.

Comparative Example 1

(16) A 2 L stainless steel reactor was vacuum dried at 65 C., cooled, and then 1.5 mmol of triethylaluminum, 500 ppm of hydrogen and 770 g of propylene were added at room temperature. After stirring for 10 minutes, 0.01 g of Ziegler-Natta catalyst was dissolved in 20 mL of TMA-formulated hexane and added to the reactor under nitrogen pressure. Then, the reactor temperature was gradually elevated to 70 C., and polymerization was carried out for 1 hour. After completion of the reaction, unreacted propylene was vented.

Comparative Example 2

(17) An olefin monomer was polymerized in the same manner as in Comparative Example 1, except that the amount of hydrogen added was changed to 725 ppm in Comparative Example 1.

Experimental Example

(18) The following physical properties were measured for the polypropylene of Examples and Comparative Examples.

(19) 1) Mn, Mw, and MWD: A sample was pretreated with PL-SP260 in 1,2,4-trichlorobenzene containing 0.0125% BHT at 160 C. for 10 hours, and the number average molecular weight and the weight average molecular weight were measured using PL-GPC220 at the measurement temperature of 1600 C. The molecular weight distribution is expressed by a ratio of the weight average molecular weight to the number average molecular weight.

(20) 2) Melt Index (MFR, 2.16 kg): Measured at 230 C. under 2.16 kg load according to ASTM D 1238 and shown in weight (g) of the polymer obtained by melting for 10 minutes.

(21) 3) Melting point (Tm): The melting point of the polymer was measured using Differential Scanning Calorimeter (DSC, device name: DSC 2920, manufacturer: TA Instrument). Specifically, the polymer was heated up to 220 C. and then maintained at the same temperature for 5 minutes. After cooling to 20 C., the temperature was again increased. At this time, the increasing speed and the lowering speed of the temperature was adjusted to 10 C./min, respectively.

(22) 4) Tensile Strength: The tensile strength was measured according to ASTM D790.

(23) 5) Flexural modulus and flexural strength: Flexural modulus and flexural strength were measured according to ASTM D790.

(24) 6) Impact strength: After fixing a test specimen with V-Notch according to ASTM D256, the strength of the specimen required until the specimen was broken by applying a pendulum was measured at 23 C.

(25) 7) Haze: The degree (%) of refraction of light when light was shot to 1 T (1 mm) and 2 T (2 mm) of a test specimen in accordance with ASTM D1003 was measured. The haze value can be measured with Td (refracted light)/Tt (passed light)*100, and the transparency of the specimen can be evaluated.

(26) 8) Amount of Volatile Organic Compound Emission: TVOC (total volatile organic compounds) and VOC/FOG (volatile organic compounds/fogging) emissions were measured under the following conditions.

(27) (1) VDA277

(28) The olefin polymer was heated for 5 hours at 120 C. using headspace-GC-FID according to VDA 277 standardized by the German Association of the Automobile Industry, and all hydrocarbons detected per 1 g of sample was converted into the content (g) of acetone.

(29) Specifically, as shown in Equation 1 below, the integrated value (blank value) of the total peak area of hydrocarbons detected in an empty headspace vessel is subtracted from the integrated value of the total peak area of hydrocarbons detected from the sample, and then the obtained value was divided by the constant (k (G)) obtained from the acetone calibration. Then, the obtained value is multiplied by the weight ratio value (0.6204) of carbon between the standard amount of acetone used (2 g of acetone per 1 g of sample) and the total weight of acetone, thereby determining the content (EG) in which hydrocarbons detected per 1 g of sample are converted into acetone.

(30) The thus converted value is prescribed as the TVOC value and is shown in Table 2 below.

(31) $\begin{array}{cc}{E}_G=\frac{\mathrm{Total}\mathrm{peak}\mathrm{area}-\mathrm{Blank}\mathrm{value}}{k\left(G\right)}20.6204& \left[\mathrm{Equation}1\right]\end{array}$

(32) (2) VDA278

(33) The olefin polymer was heated for 30 minutes at 90 C. using purge & trap-GC-MSD according to VDA 278 according to VDA 278 standardized by the German Association of the Automobile Industry, and hydrocarbons (up to n-C25) detected per 1 g of sample was converted into the content (g) of toluene.

(34) The thus converted value is prescribed as the VOC value and is shown in Table 2 below.

(35) Meanwhile, the olefin polymer was heated at 120 C. for 1 hour using purge & trap-GC-MSD according to VDA 278 standardized by the German Association of the Automobile Industry, and hydrocarbons (n-C14n-C32) detected per 1 g of sample was converted into the content (g) of hexadecane. The thus converted value is prescribed as the FOG value and is shown in Table 2 below

(36) Specifically, as shown in Equation 2 below, the integrated value (peak area) of the total peak area of hydrocarbons detected from sample is divided by the content of sample used. Then, in the case of VOC, the obtained value is multiplied by Rf (response factor) of toluene, and in the case of FOG, by RF of hexadecane, and thereby hydrocarbons detected per 1 g of sample is converted into the content (g) of toluene or hexadecane.

(37) $\begin{array}{cc}\mathrm{Emission}=\mathrm{Rf}\left(\mathrm{toluene}\mathrm{or}\mathrm{hexadecane}\right)\frac{\mathrm{Peak}\mathrm{area}}{1000\mathrm{Test}\mathrm{portion}\mathrm{sample}}& \left[\mathrm{Equation}2\right]\end{array}$

(38) The measurement results are shown in Tables 1 and 2 below.

(39) TABLE-US-00001 TABLE 1 Physical property Mw Mn MFR Tm unit g/mol g/mol Mw/Mn g/10 min C. Example 1 131,600 41,100 2.9 21.7 144.0 Example 2 145,000 38,000 2.8 13.5 144.0 Comparative 153,000 26,100 5.9 16.0 148.4 Example 1 Comparative 125,300 21,700 5.8 28.8 148.6 Example 2

(40) TABLE-US-00002 TABLE 2 Physical property Impact Tensile Flexural Flexural strength TVOC VOC FOG strength Modulus Strength (23 C.) Haze (VDA277) (VDA278) (VDA278) Unit kgf/cm.sup.2 kgf/cm.sup.2 kgf/cm.sup.2 kg-cm/cm % g/g g/g g/g Example 1 324 15,071 433 4.5 4.6 27 15 18 Example 2 327 16,200 462 4.7 4.4 31 18 20 Comparative 311 13,200 374 5.2 6.0 183 260 275 Example 1 Comparative 300 12,650 359 4.8 5.2 192 285 302 Example 2

(41) As shown in Tables 1 and 2 above, the polypropylene of Examples produced in the presence of a hybrid supported catalyst comprising two types of metallocene compounds containing specific transition metals have not only superior mechanical properties such as flexural modulus and flexural strength but also very low volatile organic compound emissions and excellent transparency, as compared with the polypropylene of Comparative Examples produced in the presence of a Ziegler-indicated catalyst. Therefore, the polypropylene of Examples is advantageously applied to products such as injection containers or beverage cups which can make direct contact with a human body.