Propylene copolymer for blow molded articles

Abstract

Propylene copolymer having a melt flow rate MFR.sub.2 (230 C.) in the range of more than 0.5 to below 2.5 g/10 min, a xylene cold soluble content (XCS) in the range of 30.0 to 40.0 wt-%, a comonomer content in the range of more than 7.5 to 12.0 wt.-%, wherein further the comonomer content of xylene cold soluble (XCS) fraction of the propylene copolymer is in the range of 16.0 to 28.0 wt.-%.

Claims

1. A Ziegler-Natta catalyzed propylene copolymer having: (a) a melt flow rate MFR.sub.2 at 230 C. measured according to ISO 1133 in the range of more than 0.5 to below 2.5 g/10 min, (b) a xylene cold soluble content (XCS) determined according ISO 16152 at 25 C. in the range of 30.0 to 40.0 wt. %, (c) a comonomer content in the range of more than 7.5 to 12.0 wt. %, wherein further; the comonomer content of xylene cold soluble (XCS) fraction of the propylene copolymer is in the range of 16.0 to 28.0 wt. %.

2. The propylene copolymer according to claim 1, wherein the propylene copolymer fulfills inequation (I): $\frac{\mathrm{Co}\left(\mathrm{total}\right)}{\mathrm{Co}\left(\mathrm{XCS}\right)}0.7$ wherein; Co (total) is the comonomer content [wt. %] of the propylene copolymer, and Co (XCS) is the comonomer content [wt. %] of the xylene cold soluble fraction (XCS) of the propylene copolymer.

3. The propylene copolymer according to claim 1, wherein the propylene copolymer has a melting temperature Tm determined by differential scanning calorimetry (DSC) in the range of 145 to 159 C.

4. The propylene copolymer according to claim 1, wherein the propylene copolymer has an intrinsic viscosity (IV) of the xylene cold soluble (XCS) fraction determined according to DIN ISO 1628/1 in Decalin at 135 C. in the range of more than 1.8 to below 3.5 dl/g.

5. The propylene copolymer according to claim 1, wherein the propylene copolymer has a flexural modulus measured according to ISO 178 of not more than 600 MPa.

6. The propylene copolymer according to claim 1, wherein the propylene copolymer is a heterophasic propylene copolymer comprising a matrix (M) and an elastomeric propylene copolymer (E) dispersed in said matrix (M), wherein said matrix (M) is a random propylene copolymer (R-PP).

7. The propylene copolymer according to claim 6, wherein the weight ratio between the matrix (M) and the elastomeric propylene copolymer (E) is 50/50 to 80/20.

8. The propylene copolymer according to claim 6, wherein the comonomer content of the random propylene copolymer (R-PP) is in the range of 1.0 to 9.0 wt. %.

9. The propylene copolymer according to claim 6, wherein the propylene copolymer fulfills inequation (II): $\frac{\mathrm{Co}\left(\mathrm{total}\right)}{\mathrm{Co}\left(\mathrm{RPP}\right)}1.1$ wherein; Co (total) is the comonomer content [wt. %] of the propylene copolymer, and Co (RPP) is the comonomer content [wt. %] of the random propylene copolymer (R-PP).

10. The propylene copolymer according to claim 6, wherein the random propylene copolymer (R-PP) has a xylene cold soluble (XCS) fraction in the range of 2.0 to 15.0 wt. %.

11. The propylene copolymer according to claim 6, wherein the random propylene copolymer (R-PP) comprises at least two different fractions, a first random propylene copolymer fraction (R-PP1) and a second random propylene copolymer fraction (R-PP2).

12. The propylene copolymer according to claim 11, wherein: (a) the weight ratio between the first random propylene copolymer fraction (R-PP1) and the second random propylene copolymer fraction (R-PP2) is 20/80 to 80/20, and/or (b) the first random propylene copolymer fraction (R-PP1) has a comonomer content in the range 0.5 to 5.0 wt. %, and/or (c) the second random propylene copolymer fraction (R-PP2) has a commoner content in the range 0.5 to 15.0 wt. %.

13. The propylene copolymer according to claim 6, wherein the elastomeric propylene copolymer (E) has a comonomer content in the range of 16.0 to 26.0 wt. %.

14. A blow molded article comprising the propylene copolymer according to claim 1.

15. The blow molded article according to claim 14, wherein the article is a bottle.

Description

EXAMPLES

1. Measuring Methods

(1) The following definitions of terms and determination methods apply for the above general description of the invention as well as to the below examples unless otherwise defined.

(2) Calculation of comonomer content of the second propylene copolymer fraction (R-PP2):

(3) $\begin{array}{cc}\frac{C\left(\mathrm{PP}\right)-w\left(\mathrm{PP}1\right)C\left(\mathrm{PP}1\right)}{w\left(\mathrm{PP}2\right)}=C\left(\mathrm{PP}2\right)& \left(I\right)\end{array}$
wherein w(PP1) is the weight fraction [in wt.-%] of the first propylene copolymer fraction (R-PP1), w(PP2) is the weight fraction [in wt.-%] of second propylene copolymer fraction (R-PP2), C(PP1) is the comonomer content [in wt.-%] of the first propylene copolymer fraction (R-PP1), C(PP) is the comonomer content [in wt.-%] of the random propylene copolymer (R-PP), C(PP2) is the calculated comonomer content [in wt.-%] of the second propylene copolymer fraction (R-PP2).

(4) Calculation of the xylene cold soluble (XCS) content of the second propylene copolymer fraction (R-PP2):

(5) $\begin{array}{cc}\frac{\mathrm{XS}\left(\mathrm{PP}\right)-w\left(\mathrm{PP}1\right)\mathrm{XS}\left(\mathrm{PP}1\right)}{w\left(\mathrm{PP}2\right)}=\mathrm{XS}\left(\mathrm{PP}2\right)& \left(\mathrm{II}\right)\end{array}$
wherein w(PP1) is the weight fraction [in wt.-%] of the first propylene copolymer fraction (R-PP1), w(PP2) is the weight fraction [in wt.-%] of second propylene copolymer fraction (R-PP2), XS(PP1) is the xylene cold soluble (XCS) content [in wt.-%] of the first propylene copolymer fraction (R-PP1), XS(PP) is the xylene cold soluble (XCS) content [in wt.-%] of the random propylene copolymer (R-PP), XS(PP2) is the calculated xylene cold soluble (XCS) content [in wt.-%] of the second propylene copolymer fraction (R-PP2), respectively.

(6) Calculation of melt flow rate MFR.sub.2 (230 C.) of the second propylene copolymer fraction (R-PP2):

(7) $\begin{array}{cc}\mathrm{MFR}\left(\mathrm{PP}2\right)={10}^{\left[\frac{\log \left(\mathrm{MFR}\left(\mathrm{PP}\right)\right)-w\left(\mathrm{PP}1\right)\log \left(\mathrm{MFR}\left(\mathrm{PP}1\right)\right)}{w\left(\mathrm{PP}2\right)}\right]}& \left(\mathrm{III}\right)\end{array}$
wherein w(PP1) is the weight fraction [in wt.-%] of the first propylene copolymer fraction (R-PP1), w(PP2) is the weight fraction [in wt.-%] of second propylene copolymer fraction (R-PP2), MFR(PP1) is the melt flow rate MFR.sub.2 (230 C.) [in g/10 min] of the first propylene copolymer fraction (R-PP1), MFR(PP) is the melt flow rate MFR.sub.2 (230 C.) [in g/10 min] of the random propylene copolymer (R-PP), MFR(PP2) is the calculated melt flow rate MFR.sub.2 (230 C.) [in g/10 min] of the second propylene copolymer fraction (R-PP2).

(8) Calculation of comonomer content of the elastomeric propylene copolymer (E), respectively:

(9) $\begin{array}{cc}\frac{C\left(\mathrm{RAHECO}\right)-w\left(\mathrm{PP}\right)C\left(\mathrm{PP}\right)}{w\left(E\right)}=C\left(E\right)& \left(\mathrm{IV}\right)\end{array}$
wherein w(PP) is the weight fraction [in wt.-%] of the random propylene copolymer (R-PP), i.e. polymer produced in the first and second reactor (R1+R2), w(E) is the weight fraction [in wt.-%] of the elastomeric propylene copolymer (E), i.e. polymer produced in the third and fourth reactor (R3+R4) C(PP) is the comonomer content [in wt.-%] of the random propylene copolymer (R-PP), i.e. comonomer content [in wt.-%] of the polymer produced in the first and second reactor (R1+R2), C(RAHECO) is the comonomer content [in wt.-%] of the propylene copolymer, i.e. is the comonomer content [in wt.-%] of the polymer obtained after polymerization in the fourth reactor (R4), C(E) is the calculated comonomer content [in wt.-%] of elastomeric propylene copolymer (E), i.e. of the polymer produced in the third and fourth reactor (R3+R4).

(10) MFR.sub.2 (230 C.) is measured according to ISO 1133 (230 C., 2.16 kg load).

(11) Comonomer content, especially ethylene content is measured with Fourier transform infrared spectroscopy (FTIR) calibrated with .sup.13C-NMR. When measuring the ethylene content in polypropylene, a thin film of the sample (thickness about 250 m) was prepared by hot-pressing. The area of absorption peaks 720 and 733 cm.sup.1 for propylene-ethylene-copolymers was measured with Perkin Elmer FTIR 1600 spectrometer. Propylene-1-butene-copolymers were evaluated at 767 cm.sup.1. The method was calibrated by ethylene content data measured by .sup.13C-NMR. See also IR-Spektroskopie fr Anwender; WILEY-VCH, 1997 and Validierung in der Analytik, WILEY-VCH, 1997

(12) Flexural Modulus: The flexural modulus was determined in 3-point-bending at 23 C. according to ISO 178 on 80104 mm.sup.3 test bars injection moulded in line with EN ISO 1873-2

(13) Intrinsic viscosity is measured according to DIN ISO 1628/1, October 1999 (in Decalin at 135 C.).

(14) The xylene solubles (XCS, wt.-%): Content of xylene cold solubles (XCS) is determined at 25 C. according ISO 16152; first edition; 2005-07-01

(15) Hexane Solubles

(16) 1 g of the sample was put into a 300 ml Erlenmeyer flask and 100 ml of hexane was added. The mixture was boiled under stirring in a reflux condenser for 4 h. The hot solution was immediately filtered through a folded filter paper N.sup.o 41 and dried (in a vacuum oven at 90 C.) and weighted (0.0001 g exactly) in a round shenk. The Erlenmeyer flask and the filter were washed with n-hexane. Then the hexane was evaporated under a nitrogen stream on a rotary evaporator. The round shenk was dried in a vacuum oven at 90 C. over night and was put into a desiccator for at least 2 hours to cool down. The shenk was weighted again and the hexane soluble was calculated therefrom.

(17) Melting temperature (T.sub.m) and heat of fusion (H.sub.f), crystallization temperature (T.sub.c) and heat of crystallization (H.sub.c): measured with Mettler TA820 differential scanning calorimetry (DSC) on 5 to 10 mg samples. DSC is run according to ISO 3146/part 3/method C2 in a heat/cool/heat cycle with a scan rate of 10 C./min in the temperature range of +23 to +210 C. Crystallization temperature and heat of crystallization (H.sub.c) are determined from the cooling step, while melting temperature and heat of fusion (H.sub.f) are determined from the second heating step

(18) Number Average Molecular Weight (M.sub.n), Weight Average Molecular Weight (M.sub.w) and Molecular Weight Distribution (MWD)

(19) are determined by Gel Permeation Chromatography (GPC) according to the following method:

(20) The weight average molecular weight Mw and the molecular weight distribution (MWD=Mw/Mn wherein Mn is the number average molecular weight and Mw is the weight average molecular weight) is measured by a method based on ISO 16014-1:2003 and ISO 16014-4:2003. A Waters Alliance GPCV 2000 instrument, equipped with refractive index detector and online viscosimeter was used with 3TSK-gel columns (GMHXL-HT) from TosoHaas and 1,2,4-trichlorobenzene (TCB, stabilized with 200 mg/L 2,6-Di tert butyl-4-methyl-phenol) as solvent at 145 C. and at a constant flow rate of 1 mL/min. 216.5 L of sample solution were injected per analysis. The column set was calibrated using relative calibration with 19 narrow MWD polystyrene (PS) standards in the range of 0.5 kg/mol to 11 500 kg/mol and a set of well characterized broad polypropylene standards. All samples were prepared by dissolving 5-10 mg of polymer in 10 mL (at 160 C.) of stabilized TCB (same as mobile phase) and keeping for 3 hours with continuous shaking prior sampling in into the GPC instrument.

(21) Transparency, haze and clarity were determined according to ASTM D1003-00 on 60601 mm.sup.3 plaques injection molded in line with EN ISO 1873-2 using a melt temperature of 200 C.

(22) Description/Dimension of the Bottles

(23) 1 l bottles, having an outer diameter of 90 mm, wall thickness: 0.6 mm; overall-height of 204 mm, height of the cylindrical mantle of 185 mm

(24) Drop Test on Bottles (Progressive)

(25) During the progressive drop test each container is dropped several times in a row from increasing heights. The test is stopped for each container when fracture occurs.

(26) The drop test is performed on extrusion blow moulded 1 l bottles, having an outer diameter of 90 mm, a wall thickness of 0.6 mm, an overall-height of 204 mm and a height of the cylindrical mantle of 185 mm. The bottles are filled up to their shoulder with water. For each test series at least 12 containers are required. 4 containers are dropped simultaneously from a starting height which is chosen according to the following table, where the expected fracture drop height has been determined in pretests or has been chosen from experience:

(27) TABLE-US-00001 Expected fracture drop height [m] 0.3-1.0 1.0-2.5 2.5-5.0 Starting drop height [m] 0.2 0.5 2.0

(28) Those bottles that show fracture are discarded and the test is continued with the remaining bottles at increasing heights. The size of the steps by which the height is increased depends on the starting height. Below a starting height of 0.5 m the step size is 0.1 m while equal to or above 0.5 m the step size is 0.25 m. The fracture drop height is noted for each bottle and from the single values the average fracture drop height is calculated according to the following formula:
h.sub.p=(h.sub.i)/n.sub.g
wherein
h.sub.p=average fracture drop height
h.sub.i=individual fracture drop height
n.sub.g=total number of dropped containers
Transparency, Clarity and Haze Measurement on Bottles
Instrument: Haze-gard plus from BYK-Gardner
Testing: according to ASTM D1003 (as for injection molded plates)
Method: The measurement is done on the outer wall of the bottles. The top and bottom of the bottles are cut off. The resulting round wall is then split in two, horizontally. Then from this wall six equal samples of app. 6060 mm are cut from close to the middle. The specimens are placed into the instrument with their convex side facing the haze port. Then the transparency, haze and clarity are measured for each of the six samples and the haze value is reported as the average of these six parallels.
Tensile Test on Bottles

(29) The top and bottom of the bottles is cut off 12 specimen according to ISO527/1B are punched along the remaining cylinder. Tensile modulus and tensile stress are then determined according to ISO 527-2, applying a traction speed of 1 mm/min for the modulus and 100 mm/min for yield strength.

(30) Compression Test on Bottles

(31) Aim of this measurement is to determine the stiffness of 1 liter round bottles. Determined by this method is the deformation force at 1 mm, 2 mm and 3 mm deformation of the round bottle. Additionally the maximum force F.sub.max and the deformation in mm at F.sub.max are determined

(32) The bottles have a height of 203 mm. The bottles are produced according to the description given below.

(33) Before testing, the bottles are conditioned for 7 days at a temperature of 23 C. and at 10 relative humidity of 50% (+/5%). The burr of the bottle orifice is removed.

(34) Top load is tested at universal testing machine of the class 1 according to DIN 51221. Bottles to be tested are put between two parallel buffed plates of hardened steel, one plate is fixed and the other plate is moving. Force is recorded and results 15 are given as F.sub.max(N) and Deformation at Maximum Force (mm)

(35) Eight bottles are tested with speed of 10 mm/min by using 2.5 kN load cell. The test results of the eight tested bottles give the average value.

2. Examples

(36) The catalyst used in the polymerization process for examples E1, E2, CE1 and CE2 has been produced as follows: First, 0.1 mol of MgCl.sub.23 EtOH was suspended under inert conditions in 250 ml of decane in a reactor at atmospheric pressure. The solution was cooled to the temperature of 15 C. and 300 ml of cold TiCl.sub.4 was added while maintaining the temperature at said level. Then, the temperature of the slurry was increased slowly to 20 C. At this temperature, 0.02 mol of dioctylphthalate (DOP) was added to the slurry. After the addition of the phthalate, the temperature was raised to 135 C. during 90 minutes and the slurry was allowed to stand for 60 minutes. Then, another 300 ml of TiCl.sub.4 was added and the temperature was kept at 135 C. for 120 minutes. After this, the catalyst was filtered from the liquid and washed six times with 300 ml heptane at 80 C. Then, the solid catalyst component was filtered and dried. Catalyst and its preparation concept is described in general e.g. in patent publications EP491566, EP591224 and EP586390. As co-catalyst triethyl-aluminium (TEAL) and as donor dicyclo pentyl dimethoxy silane (D-donor) was used. The aluminium to donor ratio is indicated in table 1. As additives 0.04 wt. % synthetic hydrotalcite (DHT-4A supplied by Kisuma Chemicals, Netherlands) and 0.15 wt % Irganox B 215 (1:2-blend of Irganox 1010 (Pentaerythrityl-tetrakis(3-(3,5-di-tert.butyl-4-hydroxytoluoyl)-propionate and tris(2,4-di-t-butylphenyl) phosphate) phosphite) of BASF AG, Germany were added to the polymers in the same step.

(37) For the production of 1 liter round bottles like used for testing in the inventive work a Fischer Mller Blow Molding Machine was used. The main processing parameters for the production are as follows: Temperature profile: 180 to 200 C. applied in extruder, adapter and head Melt temperature measured: 190 to 200 C. Speed of extruder (revolution per minute; rpm): 13 to 16 rpm Die gap: the die gap was adjusted to get a bottle with a weight of 40 g with Borealis grade RB307MO (random propylene copolymer with a density of 902 kg/m.sup.3 and a MFR.sub.2 of 1.5 g/10 min) Cycle time: 12 to 16 seconds

(38) TABLE-US-00002 TABLE 1 Polymerization conditions CE1 CE2 E1 E2 TEAL/D [mol/mol] 15 15 15 15 Loop MFR.sub.2 [g/10 min] 2.7 0.9 1.5 2.3 C2 content [wt.-%] 1.7 2.1 2.4 2.4 XCS [wt.-%] 5.3 5.0 6.8 6.8 H.sub.2/C3 ratio [mol/kmol] 1.70 0.66 0.64 1.55 C2/C3 ratio [mol/kmol] 3.51 3.40 3.74 3.20 1 GPR MFR.sub.2 [g/10 min] 3.7 1.0 1.5 1.7 C2 content [wt.-%] 2.1 4.9 2.4 3.2 XCS [wt.-%] 4.7 4.7 4.9 7.5 H.sub.2/C3 ratio [mol/kmol] 28.9 11.2 11.2 17.7 C2/C3 ratio [mol/kmol] 15.5 19.8 16.0 15.6 2 GPR MFR.sub.2 [g/10 min] 1.8 1.0 1.6 1.2 C2 content [wt.-%] 10.5 12.3 8.9 10.0 XCS [wt.-%] 29.1 34.7 33.9 35.6 C2 of XCS [wt.-%] 28.0 29.0 19.0 22.0 H.sub.2/C3 ratio [mol/kmol] 177 352 455 222 C2/C3 ratio [mol/kmol] 306 319 188 177 3 GPR MFR.sub.2 [g/10 min] 1.2 1.2 1.4 1.4 C2 content [wt.-%] 13.9 13.9 9.4 9.7 XCS [wt.-%] 40.6 40.9 38.9 35.5 C2 of XCS [wt.-%] 30.0 30.0 20.0 22.0 IV of XCS [dl/g] 2.6 2.2 2.4 3.0 Tm [ C.] 152 152 151 150 H.sub.2/C3 ratio [mol/kmol] 179 344 454 223 C2/C3 ratio [mol/kmol] 309 314 189 178 Split Loop [wt.-%] 28.4 23.8 27.5 26.6 1GPR [wt.-%] 36.6 35.2 35.6 36.3 (2GPR + 3GPR) [wt.-%] 35.0 40.9 36.9 37.1

(39) TABLE-US-00003 TABLE 2 Properties CE1 CE2 IE1 IE2 C2 of XCI [wt.-%] 5.1 4.1 IV of XCI [dl/g] 2.7 2.4 MWD of XCI [] 4.9 Flex Modulus [MPa] 439 403 400 442 C6-Solubles [wt.-%] 11.9 18.5 14.1 7.9 Transparency [%] 73 73 79 77 Haze [%] 87 50 36 59 Clarity [%] 90 94 96 95

(40) TABLE-US-00004 TABLE 3 Properties on bottles IE1 IE2 CE1 CE2 CE3 CE4 Average of drop [m] 5.5 5.5 5.5 5.5 3.5 5.5 height (23 C.) Average of drop [m] 5.5 5.5 5.5 5.5 3.5 3.0 height (0 C.) Transparency [%] 80 80 76 72 92 87 Haze [%] 49 65 88 61 47 34 Clarity [%] 56 30 9 54 67 89 Tensile modulus [MPa] 380 442 447 395 515 279 Compression [N] 131 405 131 test-force M X. CE3 is the commercial ethylene propylene random copolymer RB801CF of Borealis AG CE4 is the commercial LDPE LE6609PH of Borealis AG