NON-WOVEN FABRIC CONTAINING POLYPROPYLENE FIBERS

Abstract

The present invention relates to a non-woven fabric comprising fibers which comprise a polypropylene composition comprising a polypropylene having a melt flow rate MFR.sub.2 (230? C./2.16 kg) measured according to ISO 1133 of 10 to 40 g/10 min, a melting temperature T.sub.m as determined by DSC according to ISO 11357 of >152.0? C. to <162.0? C., and a number of 2,1 and 3,1 regio defects as measured by .sup.13C NMR of from 0.01 to 0.85%,
to a process for producing the non-woven fabric, to the use of said non-woven fabric for the production of an article and to an article comprising the non-woven fabric.

Claims

1. A non-woven fabric comprising fibers which comprise a polypropylene composition comprising a polypropylene having a melt flow rate MFR.sub.2 (230? C./2.16 kg) measured according to ISO 1133 of 10 to 40 g/10 min, a melting temperature Tm as determined by DSC according to ISO 11357 of >152.0? C. to <162.0? C., and a number of 2.1 and 3.1 regio defects as measured by .sup.13C NMR of from 0.01 to 0.85%.

2. Non-woven fabric according to claim 1 wherein the polypropylene is a propylene homopolymer.

3. Non-woven fabric according to claim 1 wherein the polypropylene has a molecular weight distribution MWD of 2 to 4.5 as determined by GPC.

4. Non-woven fabric according to claim 1 wherein the polypropylene has a melting T.sub.m of 153.0 to 157.0? C.

5. Non-woven fabric according to claim 1 wherein the polypropylene has been produced in the presence of a single-site catalyst.

6. Non-woven fabric according to claim 1 wherein the polypropylene has a xylene cold soluble (XCS) fraction as determined according to ISO 16152 of from 0.1 to below 4 wt. %.

7. Non-woven fabric according to claim 1 wherein the polypropylene has a xylene cold soluble (XCS) fraction as determined according to ISO 16152 of from 0.1 to 2.5 wt. %.

8. Non-woven fabric according to claim 1 wherein the polypropylene has a melt flow rate MFR.sub.2 of 20 to 35 g/10 min.

9. Non-woven fabric according to claim 1 wherein the polypropylene comprises, or consists of, two polymer fractions (PPH-1) and (PPH-2) with the split between fractions (PPH-1) and (PPH-2) is from 30:70 to 70:30.

10. Non-woven fabric according to claim 1 wherein the polypropylene has a crystallization temperature T.sub.c as determined by DSC according to ISO 11357 in the range of 100 to 135? C.

11. Non-woven fabric according to claim 1 wherein the polypropylene has a flexural modulus as determined according to ISO 178 on injection moulded specimens of 1200 to 1800 MPa.

12. A process for producing a non-woven fabric wherein fibers are formed from a polypropylene composition comprising a polypropylene having a melt flow rate MFR.sub.2 (230? C./2.16 kg) measured according to ISO 1133 of 10 to 40 g/10 min, a melting temperature T.sub.m as determined by DSC according to ISO 11357 of >152.0? C. to <162.0? C., and a number of 2,1 and 3,1 regio defects as measured by .sup.13C NMR of from 0.01 to 0.85%, and wherein the fibers are formed into the non-woven fabric.

13. A production process of an article comprising non-woven fabric.

14. An article comprising the non-woven fabric according to claim 1.

15. The process of claim 13, wherein the article comprises a filtration medium (filter), diaper, sanitary napkin, panty liner, incontinence product for adults, protective clothing, surgical drape, surgical gown, and/or surgical wear.

16. The article of claim 13, wherein the article comprises a filtration medium (filter), diaper, sanitary napkin, panty liner, incontinence product for adults, protective clothing, surgical drape, surgical gown, and/or surgical wear.

Description

EXAMPLES

[0117] A polypropylene for producing a non-woven fabric in accordance with the invention (Inventive Examples, IE), using a single-site metallocene catalyst was prepared as follows:

Catalyst System IE

Metallocene (MC1) (rac-anti-dimethylsilandiyl(2-methyl-4-phenyl-5-methoxy-6-tert-butyl-indenyl)(2-methyl-4-(4-tert-butylphenypindenyl)zirconium dichloride)

[0118] ##STR00001##

was synthesized according to the procedure as described in WO 2013/007650, E2.

[0119] A MAO-silica support was prepared as follows: A steel reactor equipped with a mechanical stirrer and a filter net was flushed with nitrogen and the reactor temperature was set to 20? C. Next silica grade DM-L-303 from AGC Si-Tech Co, pre-calcined at 600? C. (7.4 kg) was added from a feeding drum followed by careful pressuring and depressurising with nitrogen using manual valves. Then toluene (32 kg) was added. The mixture was stirred for 15 min. Next 30 wt. % solution of MAO in toluene (17.5 kg) from Lanxess was added via feed line on the top of the reactor within 70 min. The reaction mixture was then heated up to 90? C. and stirred at 90? C. for additional two hours. The slurry was allowed to settle and the mother liquor was filtered off. The MAO treated support was washed twice with toluene (32 kg) at 90? C., following by settling and filtration. The reactor was cooled off to 60? C. and the solid was washed with heptane (32.2 kg). Finally MAO treated SiO2 was dried at 60? under nitrogen flow for 2 hours and then for 5 hours under vacuum (?0.5 barg) with stirring. MAO treated support was collected as a free-flowing white powder found to contain 12.6% Al by weight.

[0120] The final catalyst system was prepared as follows: 30 wt. % MAO in toluene (2.2 kg) was added into a steel nitrogen blanked reactor via a burette at 20? C. Toluene (7 kg) was then added under stirring. Metallocene MC1 (286 g) was added from a metal cylinder followed by flushing with 1 kg toluene. The mixture was stirred for 60 minutes at 20? C. Trityl tetrakis(pentafluorophenyl) borate (336 g) was then added from a metal cylinder followed by a flush with 1 kg of toluene. The mixture was stirred for 1 h at room temperature. The resulting solution was added to a stirred cake of MAO-silica support prepared as described above over 1 hour. The cake was allowed to stay for 12 hours, followed by drying under N2 flow at 60? C. for 2 h and additionally for 5 h under vacuum (?0.5 barg) under stirring. Dried catalyst was sampled in the form of pink free flowing powder containing 13.9 wt % Al and 0.26 wt % Zr.

[0121] The polymerization for preparing the polypropylene of the inventive examples was performed in a Borstar pilot plant with a 2-reactor set-up (loopgas phase reactor (GPR 1)) and a pre-polymerizer, using the catalyst system as described above.

[0122] For the production of a comparative non-woven fabric (Comparative Example 1 (CE1)) commercially available resin Lumicene MR2001 was used. In Table 1, the polymerization conditions for the resin of the inventive examples IE and the final properties of the resins of the inventive examples and CE1 are given.

TABLE-US-00001 TABLE 1 IE CE1 Prepolymerizer Temperature ? C. 25 Pressure kPa 5153 Loop Temperature ? C. 75 Pressure kPa 5400 Feed H2/C3 mol/kmol 0.48 Split wt % 62 MFR g/10 min 26.2 GPR1 Temperature ? C. 80 H2/C3 mol/kmol 3 Split wt % 38 MFR (final PP) g/10 min 27 Final polymer MFR g/10 min 27 25 XCS wt % 0.9 Tm 153 151 Tc 115 2, 1e mol % 0.7 2, 1t mol % 0 3, 1 mol % 0 FM MPa 1450 1300 MWD 3.4

[0123] The polymer powders were compounded in a co-rotating twin-screw extruder Coperion ZSK 57 at 220? C. 0.1 wt % antioxidant (Irgafos 168FF); 0.1 wt % of a sterically hindered phenol (Irganox 1010FF), 0.05 wt % of Ca-stearat).

[0124] Using the compounded resin of the inventive examples and of CE1 as described above, polypropylene fibers and spunbonded fabrics were produced as follows:

[0125] The polypropylene homopolymers were converted into spunbonded fabrics on a Reicofil 4 line using a spinneret having 7377 holes of 0.6 mm exit diameter and 6827 holes per meter. The details of the process are in Table 2. The product is fixed as 10 g/m.sup.2. The properties are also shown in Table 2.

TABLE-US-00002 TABLE 2 Extruder melt Cabin calander Die temper- melt cabin monomer engraved/ throughput line Extruder temper- ature pressure pressure pressure extraction draw nip smooth per hole speed temper- ature die die extruder (SET) (SET) S-roll pressure roll temp. [g/min*hole] [m/min] ature[? C.] [? C.] [? C.] [bar] [bar] [Pa] [%] [%] [N/mm] (oil) [? C.] IE1 0.54 355.0 245 250 244 66 79 4500 11 4.0 80 147 IE2 0.54 355.0 245 250 244 66 79 4500 11 4.0 80 152 IE3 0.54 355.0 245 250 244 66 79 5500 9 4.0 80 152 IE4 0.42 282.0 275 280 270 45 73 4500 12 3.0 80 152 CE1 0.54 355.0 245 250 243 71 80 4500 12 4.0 80 152 calander HOT- engr./ HOT- measured data S-roll smooth S-roll filament tensile tensile temp. roll surface filament filament diameter strength strength elongation elongation fabric (oil) surface temp. fineness fineness [?m] - MD CD MD CD weight [? C.] temp. [? C.] [? C.] [dtex] [den] Filament [N] [N] [%] [%] [gsm] IE1 145 135 134 1.55 1.4 14.75 22.5 12.8 87.8 98.2 10.1 IE2 150 139 139 1.55 1.4 14.75 22.7 12.9 88.8 87.1 9.8 IE3 150 139 138 1.55 1.39 14.72 23.8 12.5 72.2 85.4 9.7 IE4 150 140 138 1.28 1.15 13.37 25.7 14.3 80.3 97.3 10.3 CE1 150 139 138 1.7 1.53 15.41 20.9 10.3 69.1 70.9 9.9

[0126] As can be seen, the non-woven fabric of the invention comprise fibers which are significantly finer than those of the comparative non-woven fabric, therefore the mechanical properties (force and elongation) are improved, especially along the CD direction.