Fire-retardant composition of an alloy of polyamide and polyester resins

Abstract

The present invention relates to a composition comprising at least a thermoplastic polyamide resin, a thermoplastic polyester resin, a reinforcing or bulking filler and a fire retardant. Said composition does not comprise any compatibilizer for the polyamide and the polyester, such as an agent of polymeric type, and especially no epoxy resin. Such a fire-retardant polyamide/polyester composition shows good compatibility and good mechanical and fire-retardant properties, especially a good capacity not to form flames in the presence of glowing agents, for example in the field of domestic electrical appliances, electrics and electronics.

Claims

1. A composition consisting of: (a) from 40 to 70% by weight (wt %) of a thermoplastic polyamide resin; (b) from 5 to 40 wt % of a thermoplastic polyester resin; (c) a reinforcing or bulking filler; (d) a fire retardant; and (e) an impact modifier consisting of ethylene/acrylic ester/maleic anhydride terpolymer, wherein the amount of (a) to (e) total 100 wt % based on the composition, and the composition does not comprise any epoxy resin compatibilizer for the polyamide and the polyester.

2. The composition as claimed in claim 1, wherein said polyamide resin is one or more compounds selected from the group consisting of polyamide-6, polyamide-66, polyamide-610, polyamide-11, polyamide-12, polyterephthalamide, polyisophthalamide and polyaramids.

3. The composition as claimed in claim 1, wherein said polyester resin or more compounds selected from the group consisting of polybutylene terephthalate, polybutylene (terephthalate/isophthalate), polybutylene (terephthalate/adipate), polybutylene (terephthalate/sebacate), polybutylene (terephthalate/decanedicarboxylate), polybutylene naphthalate, polyethylene terephthalate, polyethylene (terephthalate/isophthalate), polyethylene (terephthalate/adipate), polyethylene (terephthalate/5-sodiumsulfoisophthalate), polybutylene (terephthalate/5-sodiumsulfoisophthalate), polypropylene terephthalate, polyethylene naphthalate, and polycyclohexanedimethylene terephthalate.

4. The composition as claimed in claim 1, wherein said polyester resin is a recycled resin.

5. The composition as claimed in claim 1, wherein the reinforcing or bulking filler is a fibrous filler.

6. The composition as claimed in claim 5, wherein the fibrous filler is selected from the group consisting of: glass fibers, carbon fibers, natural fibers, aramid fibers, and nanotubes.

7. The composition as claimed in claim 1, wherein the reinforcing or bulking filler is present in an amount ranging from 1% to 60% by weight of the composition.

8. The composition as claimed in claim 1, wherein the fire retardant is selected from the group consisting of: phosphorus-bearing fire retardants; fire retardants of organonitrogen compound; and halogenated fire retardants.

9. The composition as claimed in claim 1, wherein the fire retardant is a combination of phosphorus-bearing compounds, and nitrogenous derivatives.

10. The composition as claimed in claim 8, wherein the fire retardant is at least one phosphorous-bearing fire retardant selected from the group consisting of phosphine oxides, phosphonic acids or salts thereof, phosphinic acids or salts thereof, cyclic phosphonates, organic phosphates, inorganic phosphates, and red phosphorus.

11. The composition as claimed in claim 8, wherein the fire retardant is an organonitrogen compound selected from the group consisting of triazines, cyanuric acid and/or isocyanuric acid, tri(hydroxyethyl) isocyanurate, benzoguanamine, guanidine, allantoin, glycoluril, and melamine or derivatives thereof selected from the group consisting of melamine cyanurate, melamine oxalate, melamine phthalate, melamine borate, melamine sulfate, melamine phosphate, melamine polyphosphate, melamine pyrophosphate, melem, melam, and melon.

12. The composition as claimed in claim 1, wherein the fire retardant is at least one halogenated fire retardant selected from the group consisting of brominated fire retardants and chlorinated fire retardants.

13. The composition as claimed in claim 9, wherein the fire retardant is a combination of: a phosphorus-bearing compound, selected from phosphine oxides, phosphonic acids or salts thereof, phosphinic acids or salts thereof, and cyclic phosphonates, and a nitrogenous derivative selected from melam, melem, melamine phosphate, melamine polyphosphates, melamine pyrophosphates, and ammonium polyphosphates.

14. The composition as claimed in claim 1, wherein the composition has a flame retardancy rating of V-0 according to UL 94, 0.8 mm.

15. The composition as claimed in claim 1 wherein the fire retardant is present in an amount ranging from 1-10 wt. % of the composition.

Description

EXPERIMENTAL SECTION

(1) In the examples and the comparative examples that follow, the resin alloy composition of the present invention and the comparative composition are prepared, respectively, and their properties are then compared, from which the superior effects of the alloy composition of the polyamide resin and of the polyester resin of the present invention are described in detail.

(2) Initially, each component used in the examples and the comparative examples of the present invention are classified and explained below, and they are indicated with reference symbols. Polyamide-66 thermoplastic {trade name: Technyl 23A, manufactured by Rhodia}. Polyester: polyethylene terephthalate resin {trade name: Eslon PET-2211, manufactured by Woongjin Chemical}. Red phosphorus: masterbatch FR4260 Glass fibers Epoxy resin of BADGE type {epoxy-equivalent weight: 3000 g/eq}, manufactured by Kukdo Chemical, Co., Ltd. Impact modifier: Lotader 3210

(3) The components chosen above are mixed uniformly in a super-mixer according to each mixing ratio of the examples and of the comparative examples. A twin-screw extruder (inside diameter of 30 mm, L/D=30) is used. The temperatures of the cylinder inside the extruder are set at about 280° C., taking into account the melting point of the resin used, and the gas inside the screws is spent at a screw spin speed of 250 to 300 rpm and a vacuum pump pressure of 50 to 70 cmHg. The components are mixed thoroughly inside the cylinder of the extruder and the extrudate formed is immersed in a bath of cold water and pelletized to a prescribed size using a pelletizer.

(4) An injection machine (German, Engel) with a closing force of 80 tonnes and an injection volume of 189.44 cc (6.4 oz) is used to prepare the sample for various property tests. After the preparation of the sample of the composition by molding under the molding temperature conditions of the general range, taking into account the melting point of the resin used, a molding temperature of 80° C., an injection pressure of 50 to 80 bar, an injection speed of 40 to 60 mm/sec, an injection time of 3 seconds and a cooling time of 15 seconds.

(5) The overall properties are reported in Table 1 below:

(6) TABLE-US-00001 TABLE 1 Component Comparative (weight %) Example 1 Example 1 Example 2 Polyamide 47.7 48.2 45.2 Polyester 20.0 20.0 20.0 Glass fibers 25.0 25.0 25.0 Fire retardant 6.6 6.6 6.6 Epoxy resin 0.5 — — Impact modifier — — 3.0 Tensile strength 1671 1656 1579 ASTM D-638 (kgf/cm.sup.2) Elongation at break 2.9 2.5 2.7 ASTM D-638 (%) Modulus of rupture 2397 2266 2162 Flexural modulus 82990 84250 79940 ASTMD790 (kgf/cm.sup.2) IZOD impact 7.25 6.9 6.96 ASTMD256 (kgf/cm/cm) GWIT, 775° C., 2 mm Fails Passes Passes UL 94 0.8 mm V-1 V-1 V-0 CTI IEC 112(V) 600

(7) In the GWIT test, the capacity to not form a flame following the application of a glowing wire is measured according to standard IEC 60695-2-13 on specimens with a thickness of 1.0 mm, at a temperature of 750° C. The standard envisages that when the sample successfully passes the test at 750° C., 25° C. are added to this temperature, and the sample is consequently classified with a GWIT of 775° C. It is noted that the composition successfully passes the test when there is no ignition during the application of the glowing wire. It is noted that the composition fails the test when there is ignition during the application of the glowing wire, i.e. production of flames with a duration of more than seconds. The test is successfully passed when the three different specimens successfully confirm the same temperature.

(8) Another comparative example was performed similar to Example 1, but without fire retardant or glass fibers. It is not possible to obtain an extruded rod because the polyamide and the polyester are so incompatible. No granules could be obtained.

(9) It is thus observed that the absence of an agent for compatibilizing between the polyamide and the polyester, such as the epoxy resin, better fire retardancy properties are obtained, especially the GWIT, when compared with a known composition of the prior art, while at the same time notably maintaining the mechanical properties; and this being achieved using a relatively small amount of fire retardants in the formulation.

(10) A composition similar to that of Example 1, but comprising another fire-retardant system, namely a compound F1 in which R.sup.1=R.sup.2=ethyl, M=aluminum and Z=3; and a compound F2: melamine polyphosphate (the weight ratio of compounds F1 and F2 is, respectively, 3:2) was produced and tested. Mechanical properties equivalent to or even greater than those of the composition of Example 1 are observed, while at the same time having a category V0 in test UL94 at 0.8 mm and which passes the GWIT test, 775° C., 2 mm.