Polymer filament

Abstract

A polymer filament comprising a polyolefin composition which comprises at least 10% by weight of one or more copolymer(s) (I) of propylene with one or more comonomers selected from ethylene, C.sub.4-C.sub.10 α-olefins and their combinations, said copolymer or copolymers (I) having MFR from 0.5 to 10 g/10 min. and containing units deriving from the said comonomers in a total amount of from 0.5 to 25% by weight with respect to the total amount of all momoner units in the copolymer, provided that, in the absence of comonomer units deriving from C.sub.6-C.sub.10 α-olefins, the amount of comonomer units deriving from ethylene or C.sub.4-C.sub.5 α-olefins or their combinations is at least 2.5% by weight.

Claims

1. A polymer filament comprising a polyolefin composition, wherein the polyolefin composition comprises: (A) 55-95 wt. % by weight, based upon the total weight of the polyolefin composition, of a copolymer (I) of propylene with at least one comonomer selected from ethylene and C.sub.4-C.sub.10 α-olefins and their combinations, said copolymer (I) having an MFR of 0.5-10 g/10 min., having a polymer fraction insoluble in xylene at room temperature of 60-90% by weight, a melting temperature equal to or greater than 120° C., and comprising units deriving from the said comonomers in a total amount of 0.5-25% by weight with respect to the total amount of all monomer units in the copolymer, provided that, in the absence of comonomer units deriving from C.sub.6-C.sub.10 α-olefins, the amount of comonomer units deriving from ethylene or C.sub.4-C.sub.5 α-olefins or their combinations is at least 2.5% by weight; and B) 5-45 wt. % by weight, based upon the total weight of the polyolefin composition, of a polyolefin composition having a flexural modulus equal to or less than 200 MPa, and wherein component B) is a heterophasic polyolefin composition comprising: (i) a crystalline propylene homopolymer, copolymer of propylene or combinations thereof, wherein the copolymer of propylene contains up to 10% by weight of ethylene and/or an α-olefin comonomer, and (ii) a copolymer of ethylene and an α-olefin, wherein the copolymer of ethylene and an α-olefin, optionally, contains a diene, and wherein the copolymer of ethylene and an α-olefin contains 15% or more, based upon the total weight of the copolymer of ethylene and an α-olefin, of ethylene; wherein the polymer filament has an elongation at break as measured by ASTM D882-02 at conditions of 25° C. and 500 mm/min of from 73% to 165%.

2. The polymer filament of claim 1, having a titre of at least 20 dTex.

3. The polymer filament of claim 1, stretched by drawing with a draw ratio from 1.5 to 10.

4. The polymer filament of claim 1, wherein component B) has at least one of the following features: Shore D hardness of at most 50 points; Shore A hardness of at most 90 points; and X-ray crystallinity from 0 to 40%.

5. The polymer filament of claim 1, wherein the copolymer of ethylene and an α-olefin contains 10 to 40% by weight, of the α-olefin.

6. The polymer filament of claim 5, wherein the α-olefin is a C.sub.3-C.sub.10 α-olefin.

7. A manufactured item containing the polymer filaments of claim 1.

8. An artificial turf structure, comprising a plurality of polymer filaments according to claim 1.

Description

EXAMPLES 1 TO 4 AND COMPARISON EXAMPLES 1 AND 2

(1) The following materials are used as components A) and B).

(2) Component A)

(3) PP-1: Propylene copolymer with MFR of 2 g/10 min., containing 6% by weight of ethylene, having melting temperature of 129.8° C. and an amount of fraction insoluble in xylene at room temperature of 85%;

(4) PP-2: Propylene copolymer with MFR of 1 g/10 min., containing 4% by weight of ethylene and 6% by weight of butene-1, having melting temperature of 132° C. and an amount of fraction insoluble in xylene at room temperature of 70%;

(5) PP-3: Propylene homopolymer with MFR of 2 g/10 min;

(6) Component B)

(7) Heco: heterophasic polyolefin composition having a MFR value of about 0.6 g/10 min., flexural modulus of 20 MPa and a content of fraction soluble in xylene at room temperature of 76% by weight, and comprising (weight percentages) 17% of a crystalline copolymer of propylene with 3.3% of ethylene, and 83% of an elastomeric fraction of propylene with ethylene containing 32% of ethylene.

(8) PB-1: butene-1/propylene copolymer containing 4.1% by weight of propylene (.sup.13C-NMR), having MFR of 0.5 g/10 min., density of 0.886 g/cm.sup.3, Flexural modulus (ISO 178) of 23.7 MPa, X-ray crystallinity of 25%, DSC TmII of 96° C., mmmm of 51.3, Mw/Mn of 6.4.

(9) The said Heco is obtained by sequential polymerization in the presence of a Ziegler-Natta catalyst, as described above.

(10) The said components A) and B) are melt-blended in an extruder TR 14/24D USF B.V.O (MAC GI XIV), with screw diameter of 14 mm and screw length/diameter ratio of 24:1, under the following conditions: extrusion temperature of 210-220° C.; screw rotation speed of 60 rpm.

(11) All the polyolefin materials used for preparing the filaments, be them a single polymer or a composition prepared as above described, are extruded in a Plasticizers MKII extruder equipped with a flat extrusion die, with die opening width and height of 80 mm and 250 nm respectively, thus obtaining a precursor tape.

(12) The main extrusion conditions are: Melt temperature of 250° C.; Screw speed of 40 rpm; Melt pressure as reported in following Table I; Output of about 1 kg/hour.

(13) After cooling at room temperature through chill rolls, the precursor tape is heated by feeding it through hot rolls having a temperature of about 70° C. and drawn by feeding it through rolls with different rotation speeds. A draw ratio of 4 is obtained.

(14) The cutting treatment is not carried out, as it is not required for testing the final properties.

(15) Such cutting treatment is required in practice to obtain filaments having the desired width and consequently the desired titre, which in the present case could for instance range from 2 to 15 mm and from 300 to 2000 dTex respectively, but does not affect the tested properties.

(16) The final properties of the so obtained precursor tape, measured after at least 7 days from extrusion, are reported in Table I, together with the relative amounts of the polyolefin components. Table II reports the creep resistance measurements on the precursor tapes of Example 1 and Comparison Example 1.

(17) TABLE-US-00002 TABLE I Example No. 1 2 3 4 Comp. 1 Comp. 2 PP-1 (wt %) 100 80 PP-2 (wt %) 100 80 PP-3 (wt %) 100 80 Heco (wt %) 20 20 PB-1 (wt %) 20 Conditions and Properties Melt pressure (bar) 132 133 158 172 139 145 Tape thickness (μm) 72 80 72 74 78 83 Tear resistance 173 118.9 162.9 186.4 0.96 9.1 (N/mm) Stress at break 96.3 85.6 97.7 107.5 114 112.2 (MPa) Elongation at 105 150 144 165 62 152 break (%) Tangent modulus 656 363 629 490 1625 972 (MPa)

(18) TABLE-US-00003 TABLE II Example No. 1 Comp. 1 PP-1 (wt %) 100 PP-3 (wt %) 100 Draw ratio 4 4 Applied stress (MPa) 50 70 Elongation (%) after 1 hour 24 64 after 3 hours — 100 after 96 hours 102 200

EXAMPLES 5 TO 10 AND COMPARISON EXAMPLE 3

(19) Precursor tapes are prepared as in the preceding examples, with the draw ratios specified in the following Tables III and IV.

(20) The following materials are used as components A) and B.sup.I).

(21) Component A)

(22) PP-1: As previously specified;

(23) PP-3: As previously specified;

(24) PP-4: Propylene copolymer with MFR of 1.5 g/10 min., containing 1.5% by weight of hexene-1;

(25) PP-5: Propylene copolymer with MFR of 1.6 g/10 min., containing 7% by weight of hexene-1.

(26) Component B.sup.I)

(27) PB-2: butene-1 homopolymer having MFR of 0.4 g/10 min. and flexural modulus of 450 MPa.

(28) The final properties of the so obtained precursor tape, measured after at least 7 days from extrusion, are reported in Tables III and IV, together with the relative amounts of the polyolefin components.

(29) TABLE-US-00004 TABLE III Example No. 5 6 7 8 PP-1 (wt %) 80 50 20 PP-5 (wt %) 50 PB-2 (wt %) 20 50 80 50 Draw ratio 4 4 4 4 Applied stress (MPa) 48 70 50 70 Elongation (%) after 1 hour 22 20 6 16 after 3 hours 26 20 6 18 after 96 hours 42 26 6 22 Stress at yield (MPa) 120 — — — Elongation at yield (%) 33 — — — Stress at break (MPa) 125 150 151 154 Elongation at break (%) 96 80 40 73

(30) TABLE-US-00005 TABLE IV Comp. 3 9 10 PP-1 (wt %) PP-3 (wt %) 100 PP-4 (wt %) 100 PP-5 (wt %) 100 Draw ratio 8 8 8 Applied stress (MPa) 163 163 163 Elongation (%) after 1 hour 6 6 8 after 24 hours 10 after 96 hours 20 14 14 Stress at break (MPa) 487 434 310 Elongation at break (%) 18 21 16