STRETCHED FLUOROPOLYMERS

Abstract

The present invention is directed to stretched filaments based on fluoropolymers, where the filaments were stretched at a temperature between 70° C. and the Vicat temperature and where the filaments are cooled under full tensile load to room temperature.

Claims

1. A process for producing stretched filaments comprising at least 80% by weight of at least one fluoropolymer, the process comprising: stretching raw filaments with a stretching factor greater than or equal to 3 at a temperature between 70° C. and a Vicat temperature of the at least one fluoropolymer, which is determined in accordance with DIN EN ISO 306:2004-10 B50, and cooling the raw filaments after stretching under full tensile load to below 50° C., wherein the stretched filaments have a rectangular cross section where a thickness thereof is less than a width thereof, wherein the stretched filaments are made of non-perfluorinated polymers.

2. The process according to claim 1, where the at least one fluoropolymer is selected from the group consisting of polyvinylidene fluoride (PVDF), ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-chlorotrifluoroethylene copolymer (E-CTFE), polychlorotrifluoroethylene (PCTFE), ETFE modified by a tercomponent or modified by vinylidene fluoride, and copolymers based on vinylidene fluoride which comprise up to 40% by weight of other monomers.

3. The process according to claim 1, where the Vicat temperature of the at least one fluoropolymer is at least 80° C.

4. Stretched filaments produced by the process according to claim 1, having a width to thickness ratio of at least 25.

5. A composite comprising the stretched filaments according to claim 4.

6. A winding layer comprising the stretched filaments according to claim 4.

Description

EXAMPLES

[0058] Materials:

[0059] PVDF: Solef® 1006, trademark of Solvay, USA

[0060] PVDF: Solef® 6008, trademark of Solvay, USA

[0061] FEP: Neoflon® NP-20, trademark of Daikin Industries, Japan

[0062] Methods

[0063] DSC:

[0064] Perkin Elmer Diamond, automatic peak recognition and integration by a method based on DIN EN

[0065] ISO 11357-1: 2010, heating rate 20 K/min.

[0066] Vicat:

[0067] DIN EN ISO 306:2004-10, Method B, 50 N (loading 5 kg).

Example 1a, Production of Specimens

[0068] An extruder (Collin E45M) was used at a temperature of 260° C. to extrude PVDF (Solef 1006), which was calendered to give a ribbon of thickness 650 μm and width 35 mm and cooled to 57° C. Take-off speed was 1.4 m/min.

[0069] E 1,* are samples made of PVDF Solef 1006;

[0070] E 2,* are samples made of FEP.

Example 1 b, Production of Specimens

[0071] An extruder (Collin CE20) was used at a temperature of 240° C. to extrude PVDF (Solef 6008), which was calendered to give a ribbon of thickness 150 μm and width 120 mm and cooled to 89° C.; take-off speed was 2.1 m/min.

[0072] E 3,* are samples of this Example 1 b.

Example 2, Stretching of Specimens

[0073] Method 1:

[0074] Specimens according to Example 1a were stretched in a tensile tester (Zwick, Z101-K) at 10 mm/min at 140° C. Before the tensile load was released, the specimens were cooled to below 50° C.

[0075] Method 2:

[0076] An endless specimen according to Example 1a was provided on a reel and stretched on a continuously operating machine (Retech drawing machine) at a material-feed rate of 4 rpm with a tension rate of up to 32 rpm to give a stretching factor (SF) of 8. The stretching temperature was 140° C.

[0077] Method 3:

[0078] Specimens according to Example 1a were stretched in a tensile tester (Zwick, Z101-K) at 10 mm/min at 100, 120 and 140° C. Before the tensile load was released, the specimens were cooled to below 50° C. The stretched specimens thus produced were again clamped into the machine and were again stretched at 100, 120 and 140° C. at 10 mm/min.

[0079] Table 2 presents the results.

[0080] Method 4:

[0081] An endless specimen according to Example 1 b was provided on a reel and stretched on a continuously operating machine (Retech drawing machine) at a material-feed rate of 1.5 m/min and at variable tension rates to realize various stretching factors (SF). The stretching temperatures were 120° C.

[0082] Table 3 presents the results.

[0083] Method 5:

[0084] An endless specimen according to Method 4 (stretched with SF=6) was provided on a reel and stretched on a continuously operating machine (Retech drawing machine) at a material-feed rate of 1.5 m/min and at variable tension rates to realize various stretching factors (SF). The stretching temperatures were 120° C.

[0085] Table 4 presents the results.

Example 3a, Mechanical Tests

[0086] Tensile Tests

[0087] Dumbbell specimens in accordance with DIN 527-2:2012 (specimen type 1BA) were punched out of the stretched (Method 1) ribbons; the thickness resulted from the stretching test and was not altered.

[0088] Test equipment from Zwick was used to test tensile strength at a temperature of 23° C. and relative humidity of 50%. Test speed=10 mm/min, clamped length=120 mm and measurement length of incremental gauge=75 mm.

[0089] The results are provided in Table 1, and also in FIGS. 1 and 2.

[0090] The results are the arithmetic average from 3 specimens.

Example 3b, Mechanical Tests

[0091] Tensile Tests

[0092] Tensile strength in accordance with DIN 527-2:2012 was measured from the stretched (Methods 4 and 5) ribbons; the thickness resulted from the stretching test and was not altered.

[0093] Test equipment from Zwick was used to test tensile strength at a temperature of 23° C. and relative humidity of 50%. Test speed=60 mm/min, clamped length=100 mm.

[0094] The results are provided in Table 4, and also in FIGS. 3 and 4.

[0095] The results are the arithmetic average from 3 specimens.

TABLE-US-00001 TABLE 1 T = 23° C., results of the tensile tests according to Example 3a. E 1.0 E 1.1 E 1.2 E 1.3 Stretching factor 1 1.4 3.0 4.5 Modulus of elasticity [MPa] 2144 2965 3367 3323 Max strength (stress) σ.sub.m [MPa] 58.02 173.34 248.60 284.64

TABLE-US-00002 TABLE 2 Results of the stretching tests according to Example 2, Method 3. Stretching temperature [° C.] Stretching procedure 100 120 140 Stretching factor during 1st 5.00 5.34 5.12 stretching procedure Stretching factor during 2.03 2.17 2.45 2nd stretching procedure Overall stretching factor 10.15  11.59  12.54 

TABLE-US-00003 TABLE 3 Results of the stretching tests according to Example 2, Method 4. Speed of stretching reel Stretching Speed of 1st reel [m/min] [m/min] factor 1.5  9.0 6.0 1.5 10.6 7.1 1.5 12.0 8.0 1.5 13.6 9.0 1.5 15.2 10.1 

TABLE-US-00004 TABLE 5 Results of the stretching tests according to Example 2, Method 5. Stretching procedure E 3.1 E 3.2 E 3.3 Stretching factor during 1st 6 6 6 stretching procedure Stretching factor during 1.21 1.32 2.15 2nd stretching procedure Overall stretching factor 7.30 7.96 8.63

TABLE-US-00005 TABLE 4 Results of the tensile tests according to Example 3b. E 3.4 E 3.5 E 3.6 E 3.7 Stretching factor 1 6 7.3 8.6 Modulus of elasticity [MPa] 1200 2160 2390 2670 Max strength (stress) σ.sub.m [MPa] 49.6 301 350 370