Flame-retardant thermoplastic polyurethane

Abstract

The present invention relates to a composition comprising at least one thermoplastic polyurethane TPU-1 based on an aliphatic diisocyanate, a thermoplastic polyurethane TPU-2 based on an aromatic diisocyanate, a melamine cyanurate, a first phosphorus-containing flame retardant (F1) selected from the group consisting of derivatives of phosphoric acid and derivatives of phosphonic acid and a further phosphorus-containing flame retardant (F2) selected from the group consisting of derivatives of phosphinic acid. The present invention further relates to the use of such compositions for production of cable sheaths.

Claims

1. A composition, comprising: (i) a thermoplastic polyurethane TPU-1 based on an aliphatic diisocyanate, (ii) a thermoplastic polyurethane TPU-2 based on an aromatic diisocyanate, (iii) a melamine cyanurate, (iv) a first phosphorus-containing flame retardant F1 selected from the group consisting of a derivative of phosphoric acid and a derivative of phosphonic acid, and (v) a second phosphorus-containing flame retardant F2, which is a derivative of phosphinic acid; wherein a proportion of the melamine cyanurate ranges from 20% to 40% by weight based on total weight of the composition, a proportion of the flame retardant F1 ranges from 2% to 15% by weight based on total weight of the composition, and a proportion of the flame retardant F2 ranges from 3% to 15% by weight based on total weight of the composition, wherein the thermoplastic polyurethane TPU-1 is based on at least one aliphatic diisocyanate selected from the group consisting of hexamethylene diisocyanate and di(isocyanatocyclohexyl)methane and the thermoplastic polyurethane TPU-2 is based on diphenylmethane diisocyanate, and wherein a total proportion of the thermoplastic polyurethanes TPU-1 and TPU-2 ranges from 30% to 75% by weight based on a total weight of the composition, and wherein a mass ratio of flame retardants F1 and F2 to melamine cyanurate is in a range of 1:3 to 1:1.

2. The composition according to claim 1, wherein the phosphorus-containing flame retardant F2 is a phosphinate.

3. The composition according to claim 2, wherein the phosphinate is an aluminum phosphinate or a zinc phosphinate.

4. The composition according to claim 1, wherein the phosphorus-containing flame retardant F1 is a phosphoric ester.

5. The composition according to claim 1, wherein the flame retardant F1 is selected from the group consisting of resorcinol bis(diphenyl phosphate), bisphenol A bis(diphenyl phosphate) and diphenyl cresyl phosphate.

6. The composition according to claim 1, wherein the melamine cyanurate has a particle size ranging from 0.1 to 100 μm.

7. The composition according to claim 1, wherein the thermoplastic polyurethane TPU-1 has a Shore hardness ranging from 85 A to 65 D, determined in accordance with DIN ISO 7619-1.

8. The composition according to claim 1, wherein the thermoplastic polyurethane TPU-2 has a Shore hardness ranging from 70 A to 65 D, determined in accordance with DIN ISO 7619-1.

9. A cable sheath, made from the composition according to claim 1.

Description

EXAMPLES

(1) 1. Feedstocks Elastollan 1185A10: TPU of Shore hardness 85 A from BASF Polyurethanes GmbH, Elastogranstrasse 60, 49448 Lemforde, based on polytetrahydrofuran polyol (PTHF) having a molecular weight of 1000 g/mol, butane-1,4-diol, diphenylmethane 4,4′-diisocyanate. Elastollan 3090A10: TPU of Shore hardness 90 A from BASF Polyurethanes GmbH, Elastogranstrasse 60, 49448 Lemförde, based on polycarbonate polyol from Ube (Eternacoll PH-200D, based on pentane-1,5-diol and hexane-1,6-diol) having a molecular weight of 2000 g/mol, butane-1,4-diol, diphenylmethane 4,4′-diisocyanate. Elastollan L 1160D10N: TPU of Shore hardness 60 D from BASF Polyurethanes GmbH, Elastogranstrasse 60, 49448 Lemförde, based on polytetrahydrofuran polyol (PTHF) having a molecular weight of 1000 g/mol, butane-1,4-diol, 4,4′-diisocyanatod icyclohexylmethane. 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%</=50 μm, D50%<=4.5 μm, water content % (w/w)<0.2. Fyrolflex RDP: 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 % (w/w)<0.1. Exolit OP 1230: Aluminum diethylphosphinate, CAS #: 225789-38-8, Clariant Produkte (Deutschland) GmbH, Chemiepark Knapsack, 50351 Hürth, water content % (w/w)<0.2, average particle size (D50) 20-40 μm. Chisorb 622 LT: dimethyl butanedioate, polymer with 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinethanol, CAS #: 65447-77-0, BASF Polyurethanes GmbH, Postfach 1140, 49440 Lemfoerde, GERMANY. Tinuvin 234: 2-(2H-benzotriazol-2-yl)4,6-bis(1-ethyl-1-phenylethylphenol), CAS #: 70321-86-17, BASF SE, 67056 Ludwigshafen, GERMANY.

(2) 2. Production of the Mixtures 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. The compositions are summarized in Table 1 (figures in % by weight).

(3) TABLE-US-00001 TABLE 1 Composition 1 (CE) 2 (CE) 3 4 1185A10 56.2 55 40 3090A10 40 L1160D10 15 15 Disflamoll TOF Fyroflex RDP 5 5 5 5 Melapur 15 ED 29.8 29.8 29.8 29.8 Exolit OP 1230 9 9 9 9 Tinuvin 234 0.6 0.6 0.6 Chisorb 622 0.6 0.6 0.6 (CE): comparative example

(4) 3. Mechanical Properties 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 density, Shore hardness, tensile strength, tear propagation resistance, wear and elongation at break of the corresponding test specimens. All the compositions have good mechanical properties. The results are summarized in Table 2.

(5) TABLE-US-00002 TABLE 2 Standard mechanical properties 1 (CE) 2 (CE) 3 4 Density [g/cm.sup.3] 1.287 1.347 1.29 1.323 Shore hardness A 92 89 90 92 Tensile strength [MPa] 15 14 14 14 Elongation at break [%] 580 520 520 470 Tear propagation resistance [kN/m] 57 55 57 57 Wear [mm.sup.3] 90 131 107 134 (CE): comparative example Test methods: Density: DIN EN ISO 1183-1, A Shore hardness A: DIN 53505 Tensile strength: DIN EN ISO 527 Elongation at break: DIN EN ISO 527 Tear propagation resistance: DIN ISO 34-1, B (b Wear: DIN 53516

(6) 4. Discoloration on UV Exposure 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 delta E values (ASTM E313) of the corresponding specimens were measured after various exposure times by the method ASTM G155 Cy4. Lower delta E values were found for the TPU mixtures of the invention. The results are summarized in Table 3.

(7) TABLE-US-00003 TABLE 3 Exposure ASTM G155 Cy 4 Time 1 (CE) 2 (CE) 3 4 Color measurement in reflection 0 h (without specular reflection) Color separation delta E 0 0 0 0 Color measurement in reflection 0 h (with specular reflection) Color separation delta E 0 0 0 0 Color measurement in reflection 100 h (without specular reflection) Color separation delta E 4.8 1.9 1 0.5 Color measurement in reflection 100 h (with specular reflection) Color separation delta E 4.8 1.4 0.6 0.5 Color measurement in reflection 200 h (without specular reflection) Color separation delta E 9.3 4.5 1.5 1.4 Color measurement in reflection 200 h (with specular reflection) Color separation delta E 9.3 4.4 1.5 1.4 Color measurement in reflection 300 h (without specular reflection) Color separation delta E 14.9 8 2.4 2.7 Color measurement in reflection 300 h (with specular reflection) Color separation delta E 15 7.5 2.4 2.7 (CE): comparative example A small value for delta E represents lower discoloration caused by the test. The lower the discoloration in the test, the lower the discoloration to be expected in practical use, for example under insolation. The results show that the materials of the invention have improved properties, especially good long-term stability.