FLEXIBLE, FIREPROOF THERMOPLASTIC COMPOSITIONS WITH HIGH THERMOMECHANICAL STRENGTH AND IMPROVED THERMAL AGEING

Abstract

The present invention relates to compositions comprising a copolymer comprising at least one segment of a polyolefin and at least one segment of a polyamide, said composition additionally comprising piperazine pyrophosphate and, if appropriate, a coloring additive. The present invention also relates to a method for the manufacture of these compositions and to the use of the latter in the manufacture of jacket for metal cables, of electrical parts, such as electrical connectors or electrical engineering housings, of thermal protection jackets or sleeves, of injection-molded parts for electronic equipment, such as computers and telephones, of monolayer or multilayer tubes or of bellow tubes, preferably in the manufacture of jacket for metal cables. Finally, it also relates to the electronic, electrical or thermal protection components comprising said composition.

Claims

1. A composition comprising: a copolymer comprising at least one segment of a polyolefin and at least one segment of a polyamide, said polyamide having a molar mass Mn of between 500 and 10 000 g/mol, piperazine pyrophosphate, optionally a coloring additive, and optionally a molecular sieve.

2. The composition as claimed in claim 1, comprising: a copolymer comprising at least one polyolefin segment and, on average, at least one segment of a polyamide attached to said at least one segment of a polyolefin by the residues of at least one unsaturated monomer (X), piperazine pyrophosphate, optionally a coloring additive, and optionally a molecular sieve.

3. The composition as claimed in claim 1, wherein the composition does not comprise a halogenated compound.

4. The composition as claimed in claim 1, wherein said polyolefin is chosen from ethylene/maleic anhydride and ethylene/alkyl (meth)acrylate/maleic anhydride copolymers.

5. The composition as claimed in claim 1, wherein said copolymer comprises, on average, at least 1.3 mol of residues of the unsaturated monomer (X) attached to said polyolefin segment per mole of polyolefin segment.

6. The composition as claimed in claim 1, wherein said polyamide has a molar mass Mn of between 1000 and 5000 g/mol.

7. The composition as claimed in claim 1, additionally comprising a molecular sieve.

8. The composition as claimed in claim 1, wherein piperazine pyrophosphate is the only flame retardant.

9. The composition as claimed in claim 1, comprising from 5% to 50% by weight of said piperazine phosphate, with respect to the total weight of the composition.

10. The composition as claimed in claim 1, additionally comprising at least one polyolefin which may be maleated or nonmaleated.

11. The composition as claimed in claim 1, not comprising a coloring additive.

12. An article of manufacture comprising a composition as claimed in claim 1, where the article of manufacture is a jacket for metal cables, of electrical parts, a thermal protection jackets or sleeves, injection-molded parts for electronic equipment, monolayer or multilayer tubes, or bellow tubes.

13. A method for the preparation of a composition as claimed in claim 1, comprising: a) preparation of said copolymer; b) mixing: the copolymer obtained in stage a); said piperazine pyrophosphate; optionally, said coloring additive; and optionally, a molecular sieve.

14. The method as claimed in claim 13, in which stages a) and b) are carried out simultaneously.

15. Electronic, electrical or thermal protection components comprising the composition as defined in claim 1.

Description

EXAMPLES

1) Process for the Preparation of the Compositions

[0107] The formulations described in detail in table 1 below were prepared from the different ingredients mentioned below using an extruder of Leistriz model LSM30.34 type. It is a self-cleaning engaging corotating twin-screw extruder with a diameter of 34 mm and a length corresponding to 32 times its diameter. The screws are temperature-regulated according to a flat profile at 220 C. A rotational speed of 200 rpm and a throughput of 15 kg/h are displayed. The rods are subsequently extruded, cooled in a water tank and finally granulated.

[0108] Bondine HX8290, Lotader 5500 and Lotader 4210 are terpolymers of ethylene, of alkyl acrylate and of maleic anhydride sold by the applicant company.

[0109] EVA 2403 is a copolymer of ethylene and of vinyl acetate having an MFI (190 C., 2.16 kg) of 3 g/10 min and a content by weight of vinyl acetate of 24%.

[0110] The PA6 (polyamide 6) prepolymer is a PA6 having a number-average molecular weight of 2500 g/mol and terminated by a single primary amine functional group.

[0111] Siliporite NK10AP is a zeolite of 4A type produced by CECA.

[0112] Irganox 1010 is a primary antioxidant produced by BASF.

[0113] Alkanox 240 is a secondary antioxidant produced by Chemtura Great Lakes.

[0114] Budit 3178 is a flame retardant based on ammonium polyphosphate produced by Budenheim.

[0115] ADK STAB FP2500S is a flame retardant based on piperazine pyrophosphate sold by ADK.

[0116] PE48/5/4025F is a blue masterbatch produced by Colloids.

[0117] Compositions 5 and 6 constitute counterexamples.

2) Protocol Used to Measure the Elongation at Break, the Aging and the Fire Properties (UL94 and LOI)

[0118] The granules resulting from the preparation stage are subsequently formed according to the following methods: [0119] Injection molding on a molding machine of Battenfeld type having a clamping force of 80 t at a temperature of 230 C. in a mold thermally regulated at 30 C. and according to an injection flow rate of 30 cm.sup.3/s. [0120] Extrusion of films (thickness of 500 m) at 210 C. by virtue of a twin-screw extruder comprising conical counterrotating screws of Haake Rheocord 40 type provided with a flat die with a thickness of 1 mm and a width of 10 cm.

[0121] Standardized test specimens are thus formed according to the following international standards: [0122] Elongation at break: Test specimens of IFC (Institut Francais du Caoutchouc [French Institute of Rubber]) type cut out with a hollow punch from the films extruded on the Haake [0123] Test according to UL94: Injection-molded test specimens with a size of 127 mm12.7 mm and having a thickness of 1.6 mm [0124] Test according to LOI: Injection-molded test specimens with a size of 127 mm12.7 mm and having a thickness of 3.2 mm.

[0125] The thermal aging conditions are as follows: The IFC test specimens cut out with a hollow punch are placed for a certain time in a temperature-regulated air circulation oven.

TABLE-US-00001 TABLE 1 Composition 1 2 3 4 5 6 7 8 9 10 11 Bondine HX8290 42.7 39.2 48.8 12.81 42.7 46.2 43.89 48.8 42.7 58.8 Lotader 5500 42.7 Lotader 4210 29.89 EVA 2403 10 10 10 10 10 10 10 10 10 PA6 prepolymer 18.3 16.8 12.2 18.3 18.3 18.3 19.8 18.81 12.2 18.3 14.7 Siliporite NK10AP 2 2 2 2 2 2 2 1.9 2 2 2 Irganox 1010 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.425 1.5 1.5 1.5 Alkanox 240 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.475 0.5 0.5 0.5 Budit 3178 25 25 ADK STAB 25 30 25 25 30 28.5 25 25 12.5 FP-2500S PE48/5/4025F 5 Total 100 100 100 100 100 100 100 100 100 100 100

[0126] The characteristics are measured as follows:

[0127] Elongation at break obtained after tensile testing of the IFC test specimens at a rate of 50 mm/min 23 C. on a Zwick universal testing machine.

[0128] The flame propagation test is carried out according to the standard UL94 on injection-molded test specimens.

[0129] The material tested is classified as V0 if:

[0130] A) None of the five samples burns for more than 10 seconds after the flame of the burner has been removed.

[0131] B) The total combustion time over the 10 tests does not exceed 50 seconds.

[0132] C) None of the samples tested burns, either with a flame or by glowing, as far as the holding jaw.

[0133] D) No glowing drop, which can ignite the cotton cloth placed below, falls from any sample.

[0134] E) No sample exhibits a glowing time exceeding 30 seconds.

[0135] The material tested is classified as V1 if:

[0136] A) None of the five samples burns for more than 30 seconds after the flame of the burner has been removed.

[0137] B) The total combustion time over the 10 tests does not exceed 250 seconds.

[0138] C) None of the samples tested burns, either with a flame or by glowing, as far as the holding jaw.

[0139] D) No glowing drop, which can ignite the cotton cloth placed below, falls from any sample.

[0140] E) No sample exhibits a glowing time exceeding 60 seconds.

[0141] The material tested is classified as V2 if:

[0142] A) None of the five samples burns for more than 30 seconds after the flame of the burner has been removed.

[0143] B) The total combustion time over the 10 tests does not exceed 250 seconds.

[0144] C) None of the samples tested burns, either with a flame or by glowing, as far as the holding jaw.

[0145] D) A few fragments may become detached from the sample tested, burning temporarily, and some of which may ignite the cotton cloth placed below.

[0146] E) No sample exhibits a glowing time exceeding 60 seconds.

[0147] In all the other cases, the material is unclassified.

[0148] The Limiting Oxygen Index (LOI) test is carried out according to the standard ASTM D2863 on injection-molded test specimens.

3 Results

[0149] 3.1. Coloration after 10 d at 175 C., Elongation at t.sub.0 and Fire Properties

TABLE-US-00002 TABLE 2 Color Elongation before After 240 h at t.sub.0 LOI aging at 175 C. [%] UL94 [%] Composition Beige Beige 200 V1 35 1 Composition Beige Beige 103 V0 37 2 Composition Beige Beige 250 V1 34 3 Composition Beige Beige 165 V1 35 4 Composition Beige Black 280 V0 37 5 Composition Beige Black 320 V0 37 6 Composition Beige Beige 80 V1 37 7 Composition Blue Green 90 V1 37 8 Composition Beige Beige 300 V1 34 9 Composition Beige Beige 230 V1 35 10 Composition Beige Beige >250 Unclassified ND 11
3.2. Comparison of the Elongation at Break Before and after Aging

[0150] The elongation at break was measured before and after aging for compositions 6 to 11. The results are reported in Table 3 below.

TABLE-US-00003 TABLE 3 Elongation at Elongation at break break at t.sub.0 after 240 h at 175 C. Difference [%] [%] [%] Composition 320 240 25 6 Composition 80 70 10 7 Composition 90 70 20 8 Composition 300 170 45 9 Composition 230 90 60 10

[0151] The materials according to the invention exhibit satisfactory performance qualities for the targeted applications (initial elongation at break, retention of these elongations at break after aging tests for 240 hours at 175 C., flame retardancy according to flame propagation test UL94 and Limiting Oxygen Index). On the other hand, unlike the counterexamples based on ammonium polyphosphate, only the examples based on piperazine pyrophosphate have the property of remaining distinguishable in color after a thermal oxidation aging for 240 hours at 175 C.

3.3. Fire-On-Cable Test

[0152] The fire-on-cable resistance was measured on two samples obtained by coating a cable with a diameter of 1.7 mm and 1.9 mm respectively with a layer with a thickness of 0.3 mm of compositions 3 and 11.

[0153] The tests were carried out on a test bench equipped with a propane gas burner and provided with a 45 support at a temperature of 23 C. without air displacement. Five samples of cable based on compositions 3 and 11 with a length of 600 mm each were positioned on the support, so as to be inclined by 45 with respect to the horizontal, and then exposed for a duration of 30 seconds to the flame of the burner forming a right angle with the sample and targeting the lower end of the cable (length of the flame: 100 mm, with a blue inner cone of 50 mm with a temperature of 990 C.). After removal of the flame, the combustion time and also the length of insulator which has remained intact are measured.

[0154] The test is regarded as positive when: [0155] combustion is continued for a duration of less than 70 seconds after the removal of the flame; and when [0156] the upper end of the cable tested has remained intact over, at a minimum, a length of 50 mm.

[0157] The results of the tests on the samples are reported in Table 4 below.

TABLE-US-00004 TABLE 4 Extinguishing time Intact length of the cable [s] [mm] Composition 0 470 3 Composition 20 400 11

[0158] These results reveal that the material according to the invention exhibits satisfactory performance qualities in terms of resistance to fire, including when it is present in a small amount.