FLAME-RETARDED STYRENE-CONTAINING COMPOSITIONS

Abstract

A composition comprising: an impact modified styrene-containing polymer; at least one bromine-containing flame retardant; at least one dialkyl phosphinic acid metal salt M.sub.1.sup.n+(R.sup.1R.sup.2PO.sub.2).sub.n wherein M.sub.1 is a metal cation with valence n and R.sup.1, R.sup.2 are alkyl groups which may be the same or different; at least one anti-dripping agent, wherein the total concentration of the bromine-containing flame retardant and the dialkyl phosphinic acid metal salt is less than 28% by weight based on the sum of all components in the composition, wherein said composition is free of antimony and meets UL-94 V-1/1.6 mm or UL-94 V-0/1.6 mm test requirements.

Claims

1. A composition comprising: an impact modified styrene-containing polymer; at least one bromine-containing flame retardant; at least one dialkyl phosphinic acid metal salt M.sub.1.sup.n+(R.sup.1R.sup.2PO.sub.2).sub.n wherein M.sub.1 is a metal cation with valence n and R.sup.1, R.sup.2 are alkyl groups which may be the same or different; at least one anti-dripping agent, wherein the total concentration of the bromine-containing flame retardant and the dialkyl phosphinic acid metal salt is less than 28% by weight based on the sum of all components in the composition, wherein said composition is free of antimony and meets UL-94 V-1/1.6 mm or UL-94 V-0/1.6 mm test requirements.

2. A composition according to claim 1, wherein the impact modified styrene-containing polymer is selected from the group consisting of acrylonitrile-butadiene-styrene (ABS) and high impact polystyrene (HIPS).

3. A composition according to claim 2, wherein the styrene-containing polymer is ABS.

4. A composition according to claim 1, wherein the total concentration of the bromine-containing flame retardant and the M.sub.1.sup.n+(R.sup.1R.sup.2PO.sub.2).sub.n is from 18 to 26% by weight.

5. A composition according to claim 1, wherein the bromine concentration of the composition is from 9.5 to 15.5% by weight based on the total weight of the composition.

6. A composition according to claim 1, wherein the concentration of the dialkyl phosphinic acid metal salt M.sub.1.sup.n+(R.sup.1R.sup.2PO.sub.2).sub.n is from 3 to 9% by weight based on the total weight of the composition.

7. A composition according to claim 1, wherein M.sub.1.sup.n+(R.sup.1R.sup.2PO.sub.2).sub.n is Al((C.sub.2H.sub.5).sub.2PO.sub.2).sub.3.

8. A composition according to claim 1, further comprising one or more metal hypophosphite salts M.sub.2.sup.q+(H.sub.2PO.sub.2).sub.q, wherein M.sub.2 indicates a metal cation with valence q, wherein M.sub.1 and M.sub.2 may be the same or different.

9. A composition according to claim 8, wherein the sum of concentrations of M.sub.1.sup.n+(R.sup.1R.sup.2PO.sub.2).sub.n and M.sub.2.sup.q+(H.sub.2PO.sub.2).sub.q is from 3 to 9% by weight based on the sum of all components in the composition.

10. A composition according to claim 9, wherein M.sub.1.sup.n+(R.sup.1R.sup.2PO.sub.2).sub.n is Al((C.sub.2H.sub.5).sub.2PO.sub.2).sub.3 and M.sub.2.sup.q+(H.sub.2PO.sub.2).sub.q is selected from the group consisting of Al(H.sub.2PO.sub.2).sub.3 and Ca(H.sub.2PO.sub.2).sub.2, the composition is characterized in that the bromine concentration supplied by the flame retardant is either in the range from 9.5%[bromine]<11.5% or in the range from 11.5%[bromine]13.0%, and wherein
4.5{[Al((C.sub.2H.sub.5).sub.2PO.sub.2).sub.3]+[Al(H.sub.2PO.sub.2).sub.3]}7.5; or
4.5{[Al((C.sub.2H.sub.5).sub.2PO.sub.2).sub.3]+[Ca(H.sub.2PO.sub.2).sub.2]}7.5.

11. A composition according to claim 1, wherein the bromine-containing flame retardant has bromine content of 50% to 70% by weight and its bromine atoms are all aromatically-bound.

12. A composition according to claim 11, wherein the bromine-containing flame retardant is selected from the group consisting of: (i) Tris(2,4,6-tribromophenoxy)-s-triazine represented by the following formula: ##STR00006## and ii) brominated epoxy resins and end-capped derivatives thereof, represented by the formula: ##STR00007## wherein m indicates degree of polymerization, R.sub.1 and R.sub.2 are independently selected from the group consisting of: ##STR00008##

13. A composition according to claim 12, wherein the bromine-containing flame retardant is tris(2,4,6-tribromophenoxy)-s-triazine.

14. A composition according to claim 13, comprising from 70 to 80% by weight of ABS, from 15 to 20% by weight of tris(2,4,6-tribromophenoxy)-s-triazine, from 3 to 9% by weight of either Al((C.sub.2H.sub.5).sub.2PO.sub.2).sub.3 or a mixture consisting of Al((C.sub.2H.sub.5).sub.2PO.sub.2).sub.3 and at least one of Al(H.sub.2PO.sub.2).sub.3 and Ca(H.sub.2PO.sub.2).sub.2, and from 0.1 to 0.5% by weight of polytetrafluoroethylene, based on the total weight of the composition.

15. A composition according to claim 12, wherein the bromine-containing flame retardant is tribromophenol end-capped low-molecular weight resin represented by the following Formula (IIa) and mixtures thereof: ##STR00009## wherein m is an integer in the range between 0 and 5 with number-average molecular weight from 1300 to 2500.

16. A composition according to claim 15, comprising from 70 to 80% by weight of ABS, from 18 to 23% by weight of tribromophenol end-capped low-molecular weight epoxy resin of Formula IIa, from 3 to 9% by weight of either Al((C.sub.2H.sub.5).sub.2PO.sub.2).sub.3 or a mixture consisting of Al((C.sub.2H.sub.5).sub.2PO.sub.2).sub.3 and at least one of Al(H.sub.2PO.sub.2).sub.3 and Ca(H.sub.2PO.sub.2).sub.2 and from 0.1 to 0.5% by weight of polytetrafluoroethylene based on the total weight of the composition.

17. A composition according to claim 1, which further comprises at least one additive selected from the group consisting of aryl phosphate esters and charring agents, wherein the total concentration of the bromine-containing flame retardant, the M.sub.1.sup.n+(R.sup.1R.sup.2PO.sub.2).sub.n, the M.sub.2.sup.q+(H.sub.2PO.sub.2).sub.q, the aryl phosphate ester and the charring agent is from 18 to 26% by weight based on the sum of all components in the composition.

18. A composition according to claim 17, comprising from 60 to 80% by weight of ABS; from 14 to 20% by weight of tris(2,4,6-tribromophenoxy)-s-triazine; from 4.5 to 7.5% by weight of a mixture of {Al((C.sub.2H.sub.5).sub.2PO.sub.2).sub.3+Al(H.sub.2PO.sub.2).sub.3} or a mixture of {Al((C.sub.2H.sub.5).sub.2PO.sub.2).sub.3+Ca(H.sub.2PO.sub.2).sub.2}; from 0.5 to 3% by weight of aryl phosphate ester of hydroquinone; and from 0.1 to 0.5% by weight of polytetrafluoroethylene, based on the total weight of the composition.

19. A composition according to claim 17, comprising from 60 to 80% by weight of ABS; from 14 to 20% by weight of tris(2,4,6-tribromophenoxy)-s-triazine; from 4.5 to 7.5% by weight of a mixture of {Al((C.sub.2H.sub.5).sub.2PO.sub.2).sub.3+Al(H.sub.2PO.sub.2).sub.3} or a mixture of {Al((C.sub.2H.sub.5).sub.2PO.sub.2).sub.3+Ca(H.sub.2PO.sub.2).sub.2}, from 1 to 6% by weight of charring agent; and from 0.1 to 0.5% by weight of polytetrafluoroethylene, based on the total weight of the composition.

20. A molded article comprising the composition of claim 1.

Description

EXAMPLES

[0050] Materials and Methods

[0051] Materials used for preparing the ABS or HIPS formulations are tabulated in Table 1 (FR is the abbreviation of flame retardant):

TABLE-US-00001 TABLE 1 Component (manufacturer) GENERAL DESCRIPTION FUNCTION ABS Magnum 3404 acrylonitrile-butadiene-styrene Plastic matrix (Styron) HIPS Styron 1200 High impact polystyrene Plastic matrix FR-245 Tris(2,4,6-tribromophenoxy)- Brominated FR (ICL-IP) s-triazine bromine content: 67 wt % F-3020 End-capped brominated epoxy Brominated FR (ICL-IP) resin MW = 2000, Bromine content: 56 wt % Exolit OP 1240 Aluminum diethyl phosphinate FR (Clariant) Al((C.sub.2H.sub.5).sub.2PO.sub.2).sub.3 Ca(H.sub.2PO.sub.2).sub.2 Calcium hypophosphite FR (Sigma Aldrich) Al(H.sub.2PO.sub.2).sub.3 Aluminum hypophosphite FR (Hubei Sky Lake Chemical) HDP (Example 1 phenyl phosphate ester of FR of EP 2089402; hydroquinone from ICL-IP) DC 4-7081 PDMS Charring agent, (Dow Corning) impact modifier Hostaflon 2711 PTFE (Teflon) Anti-dripping (Dyneon) agent Irganox B-225 Phenol:phosphite 3:1 based Antioxidant & (Ciba) stabilizer heat stabilizer

[0052] Preparation

[0053] Polymer and all additives were premixed and the blend was fed via Feeder no. 1 into the main port of a twin-screw co-rotating extruder ZE25 with L/D=32 (Berstorff). Operating parameters of the extruder were as follows:

[0054] Barrel temperature (from feed end to discharge end): 160 C., 180 C., 200 C., 200 C., 210 C., 220 C., 230 C., die240 C.

[0055] Screw rotation speed: 350 rpm

[0056] Feeding rate: 12 kg/hour.

[0057] The strands produced were pelletized in a pelletizer 750/3 from Accrapak Systems Ltd. The resultant pellets were dried in a circulating air oven (Heraeus Instruments) at 80 C. for 3 hours. The dried pellets were injection molded into test specimens using Allrounder 500-150 from Arburg as follows:

TABLE-US-00002 TABLE 2 PARAMETER Set values T.sub.1 (Feeding zone) 210 C. T.sub.2 215 C. T.sub.3 220 C. T.sub.4 225 C. T.sub.5 (nozzle) 230 C. Mold temperature 35 C. Injection pressure 1300 bar Holding pressure 700 bar Back pressure 50 bar Holding time 11 s Cooling time 9 s Mold closing force 500 kN Filling volume (portion) 30 ccm Injection speed 35 ccm/sec

[0058] Specimens of 1.6 mm thicknesses were prepared. The test specimens were conditioned at 23 C. for one week and then subjected to the several tests to determine their properties.

[0059] Flammability Test

[0060] A direct flame test was carried out according to the Underwriters-Laboratories standard UL 94 in a gas methane operated flammability hood, applying the vertical burn on specimens of 1.6 mm thickness.

[0061] Mechanical Test

[0062] The Notched Izod impact test was carried out according to ASTM D256-81 using Instron Ceast 9050 pendulum impact system.

Examples 1-6 (all Comparative)

ABS Flame Retarded with Either Bromine-Containing Compound, Aluminum Diethyl Phosphinate or Metal Hypophosphite

[0063] Bromine-containing flame retardants were applied to reduce the flammability of ABS without the aid of antimony trioxide. Likewise, aluminum diethyl phosphinate and metal hypophosphite salts were tested as sole flame retardants in ABS. The compositions and the results of the flammability test are tabulated in Table 3.

TABLE-US-00003 TABLE 3 Example Example 5 Example 1 Example 2 Example 3 Example 4 Reference Example 6 reference reference reference reference WO 2015/170130 reference Composition ABS (wt %) 75.7 71.6 66.8 75.6 64.3 75.6 FR-245 (wt %) 23.9 32.8 (bromine wt %, (16) (22) calculated) F-3020 28.0 (bromine wt %, (16) calculated) Al((C.sub.2H.sub.5).sub.2PO.sub.2).sub.3 24.0 (wt %) Al(H.sub.2PO.sub.2).sub.3 (wt %) 35 Ca(H.sub.2PO.sub.2).sub.2 (wt %) 24.0 PTFE (wt %) 0.2 0.2 0.2 0.2 0.3 0.2 Irganox B-225 0.2 0.2 0.2 0.2 0.2 (wt %) Flammability test UL 94 1.6 mm NR NR V-0 NR NR NR

[0064] The results indicate that an amount of 16 wt % bromine in the composition, supplied by either FR-245 or F-3020, is insufficient when antimony trioxide is absent, seeing that UL-94 rating has not been achieved (Examples 1 and 2). To obtain UL-94 V-0/1.6 mm rating when FR-245 is used solely in ABS, it is necessary to increase the amount of bromine to about 22 wt %, namely, unacceptably high loading level of the flame retardant is needed (33%; Example 3).

[0065] As to aluminum diethyl phosphinate and metal hypophosphite salts, they are clearly inefficient in ABS when used alone (Examples 4, 5 and 6). None of them is able to reduce the flammability of ABS to attain UL-94 rating even at loading levels of about 25% by weight.

Examples 7-11 (of the Invention)

Antimony-Free ABS Flame Retarded with Bromine-Containing Compound (12 wt % Added Bromine Concentration) and Al((C.SUB.2.H.SUB.5.).SUB.2.PO.SUB.2.).SUB.3

[0066] As shown in this set of examples, a combination of a bromine-containing flame retardant and aluminum diethyl phosphinate is able to achieve UL 94 V-0/1.6 mm rated ABS composition even in the absence of antimony trioxide. The amount of the brominated flame retardant incorporated into the composition was adjusted to supply 12% by weight bromine concentration in the compositiona customary bromine concentration in many commercial antimony-containing ABS formulations.

TABLE-US-00004 TABLE 4 Example Example Example Example Example 7 8 9 10 11 composition ABS (wt %) 75.7 72.2 75.7 75.7 75.7 FR-245 (wt %) 17.9 (12) 17.9 (12) 17.9 (12) 17.9 (12) (bromine wt %, calculated) F-3020 21.4 (12) (bromine wt %, calculated) Al((C.sub.2H.sub.5).sub.2PO.sub.2).sub.3 (wt %) 6.0 6.0 3.0 3.0 2.5 Al(H.sub.2PO.sub.2).sub.3 (wt %) 3.0 Ca(H.sub.2PO.sub.2).sub.2 (wt %) 3.0 2.5 HDP (wt %) 1.0 PTFE (wt %) 0.2 0.2 0.2 0.2 0.2 Irganox B-225 (wt %) 0.2 0.2 0.2 0.2 0.2 flammability test UL 94 1.6 mm rating V-0 V-0 V-0 V-0 V-0 Mechanical test Notched IZOD, J/m 69.1 ND 76.18 88.52 94.55

[0067] It is seen that an addition of a fairly small amount of Al((C.sub.2H.sub.5).sub.2PO.sub.2).sub.3 enables good flame retardancy to be reached despite the absence of antimony (Example 7 and 8). Furthermore, impact strength is increased on replacing a portion of Al(C.sub.2H.sub.5).sub.2PO.sub.2).sub.3 with Al(H.sub.2PO.sub.2).sub.3 or Ca(H.sub.2PO.sub.2).sub.2 while keeping the total concentration of these additives within a reasonable (6% by weight) threshold (Example 9 and 10). The impact properties can be further improved with the aid of a very small amount of phenyl phosphate ester of hydroquinone, maintaining good flammability without exceeding the 6% by weight limit: [Al((C.sub.2H.sub.5).sub.2PO.sub.2).sub.3]+[Ca(H.sub.2PO.sub.2).sub.2]+[HDP]6% (Example 11).

Examples 12-14

Antimony-Free ABS Flame Retarded with Bromine-Containing Compound (10-11% Added Bromine Concentration) and Al((C.SUB.2.H.SUB.5.).SUB.2.PO.SUB.2.).SUB.3

[0068] ABS formulations that are UL-94 V-0/1.6 mm rated down to 10% bromine loading level are available in the market owing to the presence of the powerful synergist antimony trioxide at a concentration of about 4% by weight. In this set of examples, we investigated the ability of {Al((C.sub.2H.sub.5).sub.2PO.sub.2).sub.3+Al(H.sub.2PO.sub.2).sub.3} or {Al((C.sub.2H.sub.5).sub.2PO.sub.2).sub.3+Ca(H.sub.2PO.sub.2).sub.2} combinations to help reaching good flammability in ABS when the loading level of bromine is less than 12% by weight and when the formulation is completely devoid of antimony trioxide.

[0069] The ABS formulations prepared and the results of the tests are tabulated in Table 5.

TABLE-US-00005 TABLE 5 Example Example Example 12 13 14 composition ABS (wt %) 77.2 78.7 75.7 FR-245 (wt %) 16.4 (11) 14.9 (10) 14.9 (10) (bromine wt %, calculated) Al((C.sub.2H.sub.5).sub.2PO.sub.2).sub.3 (wt %) 3.0 3.0 3.0 Al(H.sub.2PO.sub.2).sub.3 (wt %) 3.0 3.0 Ca(H.sub.2PO.sub.2).sub.2 (wt %) 3.0 PDMS (wt %) 3.0 PTFE (wt %) 0.2 0.2 0.2 Irganox B-225 (wt %) 0.2 0.2 0.2 Flammability test UL 94 1.6 mm rating V-0 V-1 V-0 Mechanical test Notched IZOD, J/m 75.03 108.2 109.35

[0070] It is seen that {Al((C.sub.2H.sub.5).sub.2PO.sub.2).sub.3+Al(H.sub.2PO.sub.2).sub.3} and {Al((C.sub.2H.sub.5).sub.2PO.sub.2)).sub.3+Ca(H.sub.2PO.sub.2).sub.2} mixtures meet the challenge successfully, compensating effectively for the complete removal on antimony from 10-11% loaded-bromine ABS formulations. These mixtures can be added at 6% by weight to enable antimony-free ABS formulations to attain at least UL-94 V-1/1.6 mm rating (Examples 12 and 13, respectively). With the addition of polydimethylsiloxane, UL-94 V-0/1.6 mm ABS formulation can be produced with enhanced impact strength (Example 14).

Example 15

HIPS Flame-Retarded with a Combination Consisting of Bromine-Containing Compound and Al((C.SUB.2.H.SUB.5.).SUB.2.PO.SUB.2.).SUB.3

[0071] HIPS can also be flame retarded effectively with bromine-containing compound {Tris(2,4,6-tribromophenoxy)-s-triazine, FR-245)} in the absence of antimony trioxide but with added Al((C.sub.2H.sub.5).sub.2PO.sub.2).sub.3.

TABLE-US-00006 TABLE 5 Example 15 composition HIPS (wt %) 75.7 FR-245 (wt %) 17.9 (12) (bromine wt %, calculated) Al((C.sub.2H.sub.5).sub.2PO.sub.2).sub.3 6.0 PTFE (wt %) 0.2 Irganox B-225 (wt %) 0.2 Flammability test UL 94 1.6 mm V-1