FLAME-RETARDANT THERMOPLASTIC POLYURETHANE

Abstract

The present invention relates to compositions comprising at least one thermoplastic polyurethane, at least melamine cyanurate, at least one first phosphorus-containing flame retardant (F1) selected from the group consisting of derivatives of phosphoric acid and derivatives of phosphonic acid and at least one further phosphorus-containing flame retardant (F2) selected from the group consisting of derivatives of phosphinic acid, and to the use of such a composition for production of cable sheaths.

Claims

1-15. (canceled)

16: A composition, comprising: at least one thermoplastic polyurethane, at least one melamine cyanurate, at least one first phosphorus-containing flame retardant (F1) selected from the group consisting of a phosphoric acid compound and a phosphonic acid compound, and at least one further phosphorus-containing flame retardant (F2) selected from the group consisting of a phosphinic acid compound, wherein the phosphorus-containing flame retardant (F1) is a phosphoric ester, and wherein the phosphorus-containing flame retardant (F2) is a phosphinate.

17: The composition according to claim 16, wherein the phosphinate is selected from the group consisting of an aluminum phosphinate and a zinc phosphinate.

18: The composition according to claim 16, wherein the flame retardant (F1) is selected from the group consisting of resorcinol bis(diphenyl phosphate) (RDP), bisphenol A bis(diphenyl phosphate) (BDP) and diphenyl cresyl phosphate (DPK).

19: The composition according to claim 16, wherein the melamine cyanurate has a particle size in the range from 0.1 to 100 m.

20: The composition according to claim 16, wherein the phosphinate is selected from the group consisting of an aluminum phosphinate and a zinc phosphinate, wherein the flame retardant (F1) is selected from the group consisting of resorcinol bis(diphenyl phosphate) (RDP), bisphenol A bis(diphenyl phosphate) (BDP) and diphenyl cresyl phosphate (DPK), and wherein the melamine cyanurate has a particle size in the range from 0.1 to 100 m.

21: The composition according to claim 16, wherein the thermoplastic polyurethane is selected from the group consisting of a thermoplastic polyurethane based on at least one diisocyanate and at least one polycarbonatediol, and a thermoplastic polyurethane based on at least one diisocyanate and polytetrahydrofuran polyol.

22: The composition according to claim 16, wherein the thermoplastic polyurethane has a mean molecular weight (M.sub.w) in the range from 50 000 to 500 000 Da.

23: The composition according to claim 16, wherein the thermoplastic polyurethane is based on diphenylmethane diisocyanate (MDI).

24: The composition according to claim 16, wherein the thermoplastic polyurethane has a Shore hardness in the range from 80 A to 100 A, determined in accordance with DIN 53505.

25: The composition according to claim 16, wherein the proportion of the thermoplastic polyurethane in the composition is in the range from 30% to 75% by weight based on the overall composition.

26: The composition according to claim 16, wherein the proportion of the melamine cyanurate in the composition is in the range from 20% to 40% by weight based on the overall composition.

27: The composition according to claim 16, wherein the proportion of the flame retardant (F2) in the composition is in the range from 3% to 15% by weight based on the overall composition.

28: The composition according to claim 16, wherein the proportion of the flame retardant (F1) is in the range from 2% to 15% by weight based on the overall composition.

29: A method of making a cable sheath, the method comprising: passing a core comprising at least one wire through an extruder device; and coating the core with a composition according to claim 16 during said passing.

Description

EXAMPLES

[0120] The examples show the improved flame retardancy of the compositions of the invention, the good mechanical properties and the lower smoke gas density.

[0121] 1. Feedstocks [0122] Elastollan 1185A10: TPU of Shore hardness 85 A from BASF Polyurethanes GmbH, Elastogranstrasse 60, 49448 Lemfrde, based on polytetrahydrofuran polyol (PTHF) having a molecular weight of 1000, butane-1,4-diol, MDI. [0123] Melapur MC 15 ED: Melamine cyanurate (1,3,5-triazine-2,4,6(1H,3H,5H)-trione, compound with 1,3,5-triazine-2,4,6-triamine (1:1)), CAS #: 37640-57-6, BASF SE, 67056 Ludwigshafen, GERMANY, particle size D99%<1=50 m, D50%<=4.5 m, water content [0124] Fyrolflex ROP: Resorcinol bis(diphenylphosphate), CAS #: 125997-21-9, Supresta Netherlands B.V., Office Park De Hoef, Hoefseweg 1, 3821 AE Amersfoort, the Netherlands, viscosity at 25 C.=700 mPas, acid number <0.1 mg KOH/g, water content [0125] Disflamoll DPK: Cresyl diphenyl phosphate, CAS #: 026444-49-5, LANXESS Deutschland GmbH, 51369 Leverkusen, Germany, acid number<0.1 mg KOH/g, water content % [0126] Exolit OP 1230: Aluminum diethylphosphinate, CAS#: 225789-38-8, Clariant Produkte (Deutschland) GmbH, Chemiepark Knapsack, 50351 Hrth, water content % (w/w)<0.2, average particle size (D50) 20-40 m.

[0127] 2. Production of the Mixtures

[0128] Table 1 below lists compositions in which the individual constituents are stated in parts by weight (PW). The mixtures were each produced with a Berstorff ZE 40 A twin-screw extruder having a screw length of 35 D divided into 10 barrel sections.

TABLE-US-00001 TABLE 1 Mixtures I II III* IV* 1185A10 55 55 60 59 Melapur MC 15ED 30 30 40 33 Fyrolflex RDP 5 8 Disflamoll DPK 5 Exolit OP 1230 10 10 Mechanical properties MFR 200 C./21.6 kg [g/10 min] DIN EN ISO 1133 100 70 50 40 Density [g/cm.sup.3] DIN EN ISO 1183-1, A 1.27 1.26 1.29 1.27 Shore hardness [A] DIN 53505 91 91 94 91 TS [MPa] DIN EN ISO 527 17 17 15 25 EB [%] DIN EN ISO 527 540 540 400 600 TPR [kN/m] DIN ISO 34-1, B (b) 65 58 60 65 Abrasion [mm.sup.3] DIN ISO 4649 85 72 54 40 Flame tests VW1 test conducted/passed 3/3 3/3 0/3 1/3 UL 94V UL 94V, 1.6 mm pass pass fail pass LOI [%] ISO 4589-2, 1.6 mm 30 30 24 23 *comparative example

[0129] 3. Mechanical Properties [0130] The mixtures were extruded with an Arenz single-screw extruder having a three-zone screw with a mixing section (screw ratio 1:3) to give films having a thickness of 1.6 mm. The parameters measured were MFR of the pellets used, density, Shore hardness, tensile strength, tear propagation resistance and elongation at break of the corresponding test specimens.

[0131] 4. Flame Retardancy [0132] In order to assess flame retardancy, a test specimen having a thickness of 1.6 mm is tested in accordance with UL 94V (UL Standard for Safety for Tests for Flammability of Plastic Materials for Parts in Devices and Appliances). [0133] In order to assess flame retardancy, cables were produced on a conventional extrusion line (smooth tube extruder, extruder diameter 45 mm) for cable insulation and cable sheathing. A conventional three-zone screw with a compression ratio of 2.5:1 was employed. [0134] First of all, the cores (8 twisted individual wires) were insulated with the respective mixtures with 0.1 mm of the respective mixtures in a tubular method. The diameter of the insulated cores was 1.0 mm. Three of these cores were stranded and a shell (shell thickness 1 mm) was applied by extrusion in a tubular method. The external diameter of the overall cable was 5 mm. [0135] Then a VW 1 test (UL Standard 1581, 1080-VW-1 (vertical specimen) flame test) was conducted on the cables. The test was conducted on 3 cables in each case.