Unoriented film based on soft polypropylene

Abstract

Unoriented film comprising at least one layer of a polymer composition comprising a styrenic based elastomer and a propylene copolymer.

Claims

1. Unoriented film comprising at least one layer (L1), said layer (L1) comprises at least 70 wt. % of a polymer composition (Co), said composition (Co) comprises: (a) a propylene copolymer (A) having (a1) a melt flow rate MFR.sub.2 (230 C.) measured according to ISO 1133 in the range of more than 2.0 to 15.0 g/10 min, (a2) a comonomer content in the range of more than 7.5 to 16.5 wt. %, (a3) a xylene cold soluble content (XCS) determined according ISO 16152 (25 C.) in the range of 20.0 to 55.0 wt. %, and (a4) a melting temperature in the range of 146 to 151 C., wherein (a5) the comonomer content of xylene cold soluble (XCS) fraction of the propylene copolymer is in the range of 14.0 to 30.0 wt. %, and (b) a styrenic based elastomer(s) (B) having a styrene content in the range of 5 to equal or below 15 wt. %.

2. Unoriented film according to claim 1, wherein the unoriented film is a mono-layer or at least a three layer film comprising the layers (L1), (L2) and (L3) with the stacking order (L2)/(L1)/(L3).

3. Unoriented film according to claim 1, wherein the weight ratio of propylene copolymer (A) and the styrenic based elastomer(s) (B) [(A)/(B)] in the composition (Co) is in the range of 9/1 to 3/2.

4. Unoriented film according to claim 1, wherein the propylene copolymer (A) (a) has a melt flow rate MFR.sub.2 (230 C.) measured according to ISO 1133 in the range of more than 2.5 to below 5.0 g/10 min, and/or (b) fulfills inequation (I): $\begin{array}{cc}0.3\frac{\mathrm{Co}\left(\mathrm{total}\right)}{\mathrm{Co}\left(\mathrm{XCS}\right)}0.7& \left(I\right)\end{array}$ wherein, Co (total) is the comonomer content [wt. %] of the propylene copolymer (A), Co (XCS) is the content of the xylene cold soluble fraction (XCS) [wt. %] of the propylene copolymer (A), and/or (c) fulfills inequation (II): $\begin{array}{cc}\frac{\mathrm{Co}\left(\mathrm{total}\right)}{\mathrm{XCS}}0.30& \left(\mathrm{II}\right)\end{array}$ wherein, Co (total) is the comonomer content [wt.-%] of the propylene copolymer (A), and XCS is the content of the xylene cold soluble fraction (XCS) [wt. %] of the propylene copolymer (A).

5. Unoriented film according to claim 1, wherein the xylene cold insoluble (XCI) fraction of the propylene copolymer (A) has a comonomer content in the range of 1.5 to 6.0 wt. %.

6. Unoriented film according to claim 1, wherein the propylene copolymer (A) has an intrinsic viscosity (IV) of the xylene cold soluble (XCS) fraction in the range of equal or more than 1.5 to equal or below 3.0 dl/g, wherein the intrinsic viscosity (IV) is determined according to DIN ISO 1628/1.

7. Unoriented film according to claim 1, wherein the styrenic based elastomer(s) (B) is(are) (a) styrene-ethylene/butylene-styrene (SEBS) block copolymer(s) (B-1) and/or (a) hydrogenated styrene-vinyl isoprene (SIS) block rubber(s) (B-2).

8. Unoriented film according to claim 1, wherein the polymer composition (Co) comprises as styrenic based elastomer(s) (B) only (a) styrene-ethylene/butylene-styrene (SEBS) block copolymer(s) (B-1) and/or (a) hydrogenated styrene-vinyl isoprene (SIS) block rubber(s) (B-2).

9. Unoriented film according to claim 1, wherein the styrenic based elastomer (B) has: (a) a melt flow rate MFR.sub.2 (230 C.) of below 10.0 g/10 min, and/or (b) a density of below 0.905 g/m.sup.3.

10. Unoriented film according to claim 1, wherein the propylene copolymer (A) is a heterophasic propylene copolymer (RAHECO) 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).

11. Unoriented film according to claim 10, wherein; (a) the weight ratio between the matrix (M) and the elastomeric propylene copolymer (E) is 50/50 to 90/10, and/or (b) the comonomer content of the random propylene copolymer (R-PP) is in the range of 3.0 to 12.5 wt. %, and/or (c) the random propylene copolymer (R-PP) has a xylene cold soluble (XCS) fraction in the range of 5.0 to 50.0 wt. %.

12. Unoriented film according to claim 1, wherein the unoriented film is a cast film or a blown film.

13. Unoriented film according to claim 12, wherein the cast film or blown film is rapidly cooled by water or sleeve touch technology.

14. A container, comprising the unoriented film according to claim 1.

15. The container according to claim 14, wherein the container or the film has been subjected to a sterilisation treatment.

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

(2) $\begin{array}{cc}\frac{C\left(\mathrm{PP}\right)-w\left(\mathrm{PP}1\right)C\left(\mathrm{PP}1\right)}{w\left(\mathrm{PP}2\right)}=C\left(\mathrm{PP}2\right)& \left(I\right)\end{array}$
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).
Calculation of the xylene cold soluble (XCS) content of the second propylene copolymer fraction (R-PP2):

(3) $\begin{array}{cc}\frac{\mathrm{XS}\left(\mathrm{PP}\right)-w\left(\mathrm{PP}1\right)\mathrm{XS}\left(\mathrm{PP}1\right)}{w\left(\mathrm{PP}2\right)}=\mathrm{XS}\left(\mathrm{PP}2\right)& \left(\mathrm{II}\right)\end{array}$
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.
Calculation of melt flow rate MFR.sub.2 (230 C.) of the second propylene copolymer fraction (R-PP2):

(4) $\begin{array}{cc}\mathrm{MFR}\left(\mathrm{PP2}\right)={10}^{\left[\frac{l\mathrm{og}\left(\mathrm{MFR}\left(\mathrm{PP}\right)\right)-w\left(\mathrm{PP}1\right)l\mathrm{og}\left(\mathrm{MFR}\left(\mathrm{PP}1\right)\right)}{w\left(\mathrm{PP}2\right)}\right]}& \left(\mathrm{III}\right)\end{array}$
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).
Calculation of comonomer content of the elastomeric propylene copolymer (E), respectively:

(5) $\begin{array}{cc}\frac{C\left(\mathrm{RAHECO}\right)-w\left(\mathrm{PP}\right)C\left(\mathrm{PP}\right)}{w\left(E\right)}=C\left(E\right)& \left(\mathrm{IV}\right)\end{array}$
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).
MFR.sub.2 (230 C.) is measured according to ISO 1133 (230 C., 2.16 kg load). 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.
Styrene Content

(6) The styrene content is measured by Fourier transform infrared spectroscopy (FTIR). A thin film of 300 m thickness is prepared from pelletized material by hot-pressing (190 C., 100 bar, 1 minute). Per sample, two films are prepared. The so prepared film-samples are measured by a Perkin Elmer IR-Spectrophotometer System 2000FTIR. The peak at 1602 cm.sup.1 (Phenyl-Absorption) is integrated and evaluated by using an internally established calibration curve. The arithmetic mean of two measurements is given as result.

(7) Calibration: Various polypropylene-compounds consisting of PP and a styrene-containing elastomer (of known styrene-content) are prepared and measured according to the method described above.

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

(9) The xylene solubles (XCS, wt.-%): Content of xylene cold solubles (XCS) is determined at 25 C. according ISO 16152; first edition; 2005-Jul.-1. The part which remains insoluble is the xylene cold insoluble (XCI) fraction.

(10) 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 11357-3:1999 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

(11) Tensile modulus in machine and transverse direction was determined according to ISO 527-3 at 23 C. on film as described in the examples below. Testing was performed at a cross head speed of 1 mm/min.

(12) Total Penetration Energy:

(13) The impact strength of films is determined by the Dynatest method according to ISO 7725-2 on films as described in the examples below. The value Wbreak [J/mm] represents the total penetration energy per mm thickness that a film can absorb before it breaks. The higher this value, the tougher the material is.

(14) Haze is determined according to ASTM D1003-00 on films as described in the examples below

(15) Steam sterilization was performed in a Systec D series machine (Systec Inc., USA). The samples were heated up at a heating rate of 5 C./min starting from 23 C. After having been kept for 30 min at 121 C., they were removed immediately from the steam sterilizer and stored at room temperature till processed further.

2. Examples

(16) The catalyst used in the polymerization process for examples RAHECOS 1 and 2 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

(17) For RAHECO 2 the catalyst was prepolymerized with vinyl cyclohexane in an amount to achieve a concentration of 200 ppm poly(vinyl cyclohexane) (PVCH) in the final polymer. The resulting polymer was visbroken in a co-rotating twin-screw extruder (type: Coperion ZSK 57) with suitable amounts of 2,5-dimethyl-2,5-di-(tert. butylperoxy)hexane (Trigonox 101 supplied by AKZO Nobel, Netherlands) added to the extruder as concentrate of 1 wt.-% on polypropylene powder. 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 polymer in the same step.

(18) TABLE-US-00001 TABLE 1 Polymerization conditions and properties for the RAHECOs 1 and 2 RAHECO 1 RAHECO 2 TEAL/D [mol/mol] 10 15 Loop MFR.sub.2 [g/10 min] 1.4 2.5 C2 content [wt.-%] 2.0 4.2 XCS [wt.-%] 4.0 3.6 C2/C3 ratio [mol/kmol] 4.8 5.1 1 GPR MFR.sub.2 [g/10 min] 1.0 0.7 C2 content [wt.-%] 7.3 11.2 XCS [wt.-%] 29.5 38.9 C2/C3 ratio [mol/kmol] 117 200 2 GPR MFR.sub.2 [g/10 min] 1.2 1.5 C2 content [wt.-%] 10.1 XCS [wt.-%] 33.7 48.7 C2 of XCS [wt.-%] 20.2 19.3 C2/C3 ratio [mol/kmol] 304 154 3 GPR MFR.sub.2 [g/10 min] 1.1 1.8 C2 content [wt.-%] 11.8 12.1 XCS [wt.-%] 42.7 50.9 C2 of XCS [wt.-%] 22.5 19.2 IV of XCS [dl/g] 1.9 2.2 C2/C3 ratio [mol/kmol] 304 159 Split Loop [wt.-%] 41.4 36.1 1 GPR [wt.-%] 39.9 44.3 (2 GPR + 3 GPR) [wt.-%] 18.7 19.6 Visbreaking POX [wt.-%] 0.01 0.015 MFR.sub.2 [g/10 min] 3.4 3.5 Tm [ C.] 147 151 XCS [wt.-%] 41.0 48.0 IV of XCS [dl/g] 1.9 2.1 C2 ethylene IV intrinsic viscosity H.sub.2/C3 ratio hydrogen/propylene ratio C2/C3 ratio ethylene/propylene ratio POX 2,5-dimethyl-2,5-di-(tert. butylperoxy)hexane 1/2/3 GPR 1/2/3 gas phase reactor Loop Loop reactor

(19) TABLE-US-00002 TABLE 2 Properties of the styrene-ethylene/butylene-styrene (SEBS) block copolymer SEBS type Kraton G 1645M styrene [wt.-%] 12.5 Shore A [] 35 MFR.sub.2 (230 C.) [g/10 min] 2.0 density [g/cm.sup.3] 0.900 Kraton G 1645M is supplied by Kraton Polymers LLC

(20) TABLE-US-00003 TABLE 3 Properties of PP1 PP1 MFR total [g/10 min] 3.9 MFR matrix [g/10 min] 3.9 XCS [wt.-%] 23 C2 of XCS [wt.-%] 25 IV of XCS [dl/g] 1.3 C2 total [wt.-%] 8.0 Tm [ C.] 141 PP1 is the commercial product Bormed SC820CF of Borealis AG.
Preparation of Mono-Layer Water-Quenched Blown Film

(21) The film examples according to table 5 are produced on a water quenched blown film line. The film is blown downwards and water is used to quench the bubble in order to decrease the cooling time (by a factor 30 compared to air cooled). The detailed film processing conditions are shown in table 4.

(22) TABLE-US-00004 TABLE 4 Processing conditions for the water quenched blown film examples Tubular water quenching mono layer blown film 150 m IE1BF Material Unit 75% RAHECO 1 + 25% SEBS Melting temperature [ C.] 221 Melt pressure [bar] 195 Output [kg/h] 70 CE2BF Material 100% RAHECO 2 Melting temperature [ C.] 223 Melt pressure [bar] 205 Output [kg/h] 70 IE2 BF Material 75% RAHECO 2 + 25% SEBS Melting temperature [ C.] 222 Melt pressure [bar] 198 Output [kg/h] 70 CE2 BF Material 100% PP1 Melting temperature [ C.] 223 Melt pressure [bar] 207 Output [kg/h] 70 CE3 BF Material 75% PP1 + 25% SEBS Melting temperature [ C.] 221 Melt pressure [bar] 200 Output [kg/h] 70 valid Die temperature [ C.] 225 for all Colling water temp. [ C.] 10 C. films BUR [] 1:1.3 Take off speed winder [m/min] 9.6 Die diameter: [mm] 220 Die gap [mm] 2.4

(23) TABLE-US-00005 TABLE 5 Properties of mono-layer water-quenched blown films (150 m) IE 1 CE 1 IE 2 CE 2 CE 3 BF BF BF BF BF RAHECO 1 [wt.-%] 75 RAHECO 2 [wt.-%] 100 75 PP 1 [wt.-%] 100 75 SEBS [wt.-%] 25 25 25 Haze, b.s. [%] 1.8 9.3 4.6 4.3 2.4 Haze, a.s. [%] 8.9 32.6 14.3 14.3 7.2 delta Haze [%] 7.1 23.3 10.3 10.0 5.2 Wbreak 0 C., b.s. [J/mm] 17 11 15 11 15 Wbreak 0 C., a.s. [J/mm] 15 13 16 14 16 Tensile modulus MD, b.s. [MPa] 56 200 57 302 107 Tensile modulus MD, a.s. [MPa] 74 234 58 556 187
Preparation of Three-Layer Cast Film

(24) The films according to table 7 are produced on a multi layer cast film line equipped with 3 extruders. All three extruders are equipped with a notched feeding zone and a 3 zone screw with mixing and shear parts. The diameter of the cylinder of extruder A is 40 mm and the screw length 25D. Extruder B has a cylinder diameter of 60 mm and a screw length of 30D and extruder C a cylinder diameter of 45 mm and a screw length of 25D. Each extruder is fed by a gravimetric dosing system. A feed block with lamellas and following distribution was used as co-extrusion adapter: Extruder A 10% (outer layer air knife side), extruder C 80% (core layer) and extruder B 10% (inner layer chill roll side=sealing layer of the film). A coat hanger die with automatic die gap regulation was used, die width 800 mm and die gap 0.5 mm. The chill roll unit has a diameter of 450 mm and the 2.sup.nd cooling roll 250 mm. The detailed processing parameters are shown in tables 6.

(25) TABLE-US-00006 TABLE 6 a: Processing conditions for the 3 layer cast film of Example CE1-CF Extruder A Extruder C Extruder B Layer thickness [m] 20 m 140 m 30 m Layer function [] outer layer core layer sealing layer Material [] HD800CF RAHECO 1 RB801CF Melting temperature [ C.] 2.55 247 264 Melt pressure [bar] 50 50 59 Screw speed [U/min] 8 41 11 Output [kg/h] 6.3 44.4 9.3 b: Processing conditions for the 3 layer cast film ofExample IE1-CF Extruder A Extruder C Extruder B Layer thickness [m] 20 m 140 m 30 m Layer function [] outer layer core layer sealing layer Material [] HD800CF 75% RB801CF RAHECO 1 + 25% SEBS Melting temperature [ C.] 226 244 255 Melt pressure [bar] 69 67 96 Screw speed [U/min] 9 63 11 Output [kg/h] 6.3 44.4 9.3 c: Processing conditions for the 3 layer cast film of Example CE2-CF Extruder A Extruder C Extruder B Layer thickness [m] 20 m 140 m 30 m Layer function [] outer layer core layer sealing layer Material [] HD800CF RAHECO 2 RB801CF Melting temperature [ C.] 258 245 265 Melt pressure [bar] 63 78 93 Screw speed [U/min] 9 34 9 Output [kg/h] 6.3 44.4 9.3 d: Processing conditions for the 3 layer cast film of Example IE2-CF Extruder A Extruder C Extruder B Layer thickness [m] 20 m 140 m 30 m Layer function [] outer layer core layer sealing layer Material [] HD800CF 75% RB801CF RAHECO 2 + 25% SEBS Melting temperature [ C.] 244 251 273 Melt pressure [bar] 51 43 60 Screw speed [U/min] 10 61 11 Output [kg/h] 6.3 44.4 9.3 e: Processing conditions for the 3 layer cast film of Example CE3-CF Extruder A Extruder C Extruder B Layer thickness [m] 20 m 160 m 20 m Layer function [] outer layer core layer sealing layer Material [] HD800CF PP1 RD801CF Melting temperature [ C.] 248 242 241 Melt pressure [bar] 64 78 51 Screw speed [U/min] 10 44 9 Output [kg/h] 6 48 6 f: Further processing conditions for the 3 layer cast films as produced in tables 6a to 6e Coex adapter temperature [ C.] 260 Die temperature [ C.] 250 Chill roll temperature [ C.] 12 2nd cooling roll temperature [ C.] 21 Take off speed winder [m/min] 8.4

(26) TABLE-US-00007 TABLE 7 Properties of three layer cast films (20 m/140 m/30 m) CE 1 IE 1 CE 2 IE 2 CE 3 CF CF CF CF CF Core layer (140 m) RAHECO 1 [wt.-%] 100 75 RAHECO 2 [wt.-%] 100 75 PP 1 [wt.-%] 100 SEBS [wt.-%] 25 25 Properties 3 layer film Haze, b.s. [%] 17 17 21 18 7 Haze, a.s. [%] 18 16 23 21 15 delta Haze [%] 1 1 2 3 8 Wbreak 23 C., b.s. [J/mm] 16 28 12 35 Wbreak 0 C., b.s. [J/mm] 11 15 11 15 Tensile modulus MD, b.s. [MPa] 242 142 251 153 343 Tensile modulus TD, b.s. [MPa] 217 125 232 140 293

(27) The polymer used for the outer layer is the polypropylene homopolymer Bormed HD800CF (HD800CF), commercially available from Borealis AG, with a MFR.sub.2 of 8 g/10 min and a melting temperature Tm of 164 C. The polymer used as sealing layer is the polypropylene random co-polymer Bormed RB801CF (RB801CF), commercially available from Borealis AG, with a MFR.sub.2 of 1.9 g/10 min and a melting temperature Tm of 140 C.