STABILIZERS FOR BROMINATED POLYMERIC FLAME RETARDANTS

Abstract

The invention provides a process comprising reacting an epoxy novolac resin with monohydroxy aromatic compound, optionally in the presence of a poly-functional agent for linking together the epoxy novolac chains. The polymers thus obtained are modified, solid, novolac epoxy resins which are useful as stabilizers for flame retardants such as polystyrene-block-brominated polybutadiene-block-polystyrene.

Claims

1.-42. (canceled)

43. A process comprising reacting an epoxy novolac resin with monohydroxy aromatic compound in the presence of a poly-functional agent for linking together the epoxy novolac chains, the process comprising: combining the epoxy novolac resin starting material with the monohydroxy aromatic compound and the poly-functional agent in the presence of a catalyst under heating to form a liquid reaction mixture, allowing the reaction to reach completion and recovering a polymer in a solid form.

44. The process according to claim 43, wherein the epoxy novolac resin is of Formula II, and wherein, with n, the average degree of polymerization is in the range from 0.2 to 7.0: ##STR00111##

45. The process according to claim 43, wherein the process is devoid of a solvent.

46. The process according to claim 43, wherein the monohydroxy aromatic compound is HOC.sub.6H.sub.5-mX.sub.m, where X is selected from halogen and alkyl and m is an integer from 0 to 5, inclusive.

47. The process according to claim 46, wherein the monohydroxy aromatic compound HOC.sub.6H.sub.5-mX.sub.m is a compound of Formula III: ##STR00112## wherein Hal is selected from the group of bromine and chlorine and m is an integer from 0 to 5, inclusive, and wherein the compound of Formula III is selected from the group consisting of: ##STR00113##

48. The process according to claim 43, wherein the monohydroxy aromatic compound is characterized in that the OH functionality is part of a carboxylic group attached to an aromatic ring, having the formula HOOCC.sub.6H.sub.5-mX.sub.m, wherein X is selected from halogen and alkyl and m is an integer from 0 to 5, inclusive.

49. The process according to claim 43, wherein the poly-functional agent is a bi-functional agent selected from the group consisting of HOR.sup.1OH, HOOCR.sup.2COOH, HOR.sup.3COOH, .sub.2HNR.sup.4NH.sub.2 and R.sup.4NH.sub.2, wherein each of R.sup.1, R.sup.2, R.sup.3 and R.sup.4 is independently an aromatic or aliphatic moiety.

50. The process according to claim 49, wherein the bi-functional agent is HOR.sup.1OH.

51. The process according to claim 50, wherein R.sup.1 comprises two non-fused aromatic rings, with each ring bearing one OH group, such that the bi-functional agent is of Formula IV: ##STR00114## wherein Hal is halogen and t is an integer independently indicating the number of halogen atoms attached to each benzene ring, t being 0, 1 or 2; Z indicates a bridging moiety selected from the group consisting of: a) (CX.sub.2).sub.p, wherein each X is independently H or CH.sub.3, p is 0 or 1, and b) SO.sub.2.

52. The process according to claim 51, wherein the compound of Formula IV is selected from the group consisting of: ##STR00115##

53. The process according to claim 50, wherein R.sup.1 comprises one aromatic ring, such that the bi-functional agent has the formula HOArOH, wherein Ar is an aromatic ring that is optionally halogenated.

54. The process according to claim 50, wherein R.sup.1 comprises two or more fused aromatic rings, such that the bi-functional agent has the formula HO(Ar).sub.nOH, wherein (Ar).sub.n indicates a fused aromatic system composed of two or more aromatic rings (n2).

55. The process according to claim 49, wherein the bi-functional agent is HOOCR.sup.2COOH, wherein R.sup.2 comprises one or two aromatic rings to which the COOH groups are bonded.

56. The process according to claim 49, wherein the bi-functional agent is selected from the group consisting of saturated dicarboxylic acids of HOOC(CH.sub.2).sub.nCOOH, with 0n20 and unsaturated dicarboxylic acids HOOC(CHCH).sub.m(CH.sub.2).sub.nCOOH, where m1 and n0, wherein the saturated and unsaturated dicarboxylic acids can be branched and/or interrupted by one or more heteroatom (s).

57. A polymer comprising chains of Formula I: ##STR00116## wherein n is 0.2n7, and wherein (i) the polymer comprises individual, nonlinked chains of Formula (I), with A being a pendant group selected from: ##STR00117## and at least one of A=CH.sub.2CHOHCH.sub.2OC.sub.6H.sub.5-mX.sub.m, wherein X is independently selected from the group consisting of halogen and alkyl and m is an integer indicating the number of halogen atoms or alkyl groups attached to the benzene ring (0m5); A=CH.sub.2CHOHCH.sub.2OAr, wherein Ar comprises at least two aromatic rings optionally substituted with alkyl or halogen; A=CH.sub.2CHOHCH.sub.2O(O)CC.sub.6H.sub.5-mX.sub.m, wherein X is independently selected from the group consisting of halogen and alkyl and m is an integer indicating the number of halogen atoms or alkyl groups attached to the benzene ring (0m5); or A=CH.sub.2CHOHCH.sub.2O(O)CAr, wherein Ar comprises at least two aromatic rings optionally substituted with alkyl or halogen; (ii) the polymer is non-linear, comprising chains of Formula I linked together by having at least one A group of a first chain and an A group of at least a second chain forming together a bridge of the formula CH.sub.2CHOHCH.sub.2-Linker-CH.sub.2CHOHCH.sub.2, where remaining A groups in said chains being pendant groups selected from: ##STR00118## and at least one of A=CH.sub.2CHOHCH.sub.2OC.sub.6H.sub.5-mX.sub.m, wherein X is independently selected from the group consisting of halogen and alkyl and m is an integer indicating the number of halogen atoms or alkyl groups attached to the benzene ring (0m5); A=CH.sub.2CHOHCH.sub.2OAr, wherein Ar comprises at least two aromatic rings optionally substituted with alkyl or halogen; A=CH.sub.2CHOHCH.sub.2O(O)CC.sub.6H.sub.5-mX.sub.m, wherein X is independently selected from the group consisting of halogen and alkyl and m is an integer indicating the number of halogen atoms or alkyl groups attached to the benzene ring (0m5); or A=CH.sub.2CHOHCH.sub.2O(O)CAr, wherein Ar comprises at least two aromatic rings optionally substituted with alkyl or halogen.

58. The polymer according to claim 57, comprising individual chains of Formula I-a: ##STR00119## wherein n is as defined in claim 57, and the pendant groups denoted by A are selected from both ##STR00120## and A=CH.sub.2CHOHCH.sub.2OC.sub.6H.sub.5-mHal.sub.m, wherein Hal is halogen, and m is an integer indicating the number of halogen atoms attached to the benzene ring, m being 0, 1, 2, 3, 4 or 5.

59. The polymer according to claim 58, wherein the pendant groups denoted by A are selected from both ##STR00121##

60. A polymer according to claim 57 of Formula I-b: ##STR00122## wherein: r and r independently indicate the number of repeat units where A is a pendant group of the formula: ##STR00123## l and l independently indicate the number of repeat units where A is a pendant group of the formula: A=CH.sub.2CHOHCH.sub.2OC.sub.6H.sub.5-mX.sub.m, wherein X is independently selected from the group consisting of halogen and alkyl and m is an integer indicating the number of halogen atoms or alkyl groups attached to the benzene ring (0m5); or of the formula A=CH.sub.2CHOHCH.sub.2OAr, wherein Ar comprises at least two aromatic rings optionally substituted with alkyl or halogen; or of the formula A=CH.sub.2CHOHCH.sub.2O(O)CC.sub.6H.sub.5-mX.sub.m, wherein X is independently selected from the group consisting of halogen and alkyl and m is an integer indicating the number of halogen atoms or alkyl groups attached to the benzene ring (0m5); or of the formula A=CH.sub.2CHOHCH.sub.2O(O)CAr, wherein Ar comprises at least two aromatic rings optionally substituted with alkyl or halogen; and k indicates the number of repeat units which are junction points through which individual chains are crosslinked, the Linker being selected from the group consisting of OR.sup.1O, O(O)CR.sup.2C(O)O, OR.sup.3C(O)O, HNR.sup.4NH and R.sup.4(N), where R.sup.1, R.sup.2, R.sup.3 and R.sup.4 comprise aromatic or aliphatic moieties; and wherein r+k+l=n+2, r+k+l=n+2, where 0.2n7.

61. The polymer according to claim 60, comprising pendent groups A of the formula: ##STR00124##

62. The polymer according to claim 60, wherein the Linker has the formula OC.sub.6H.sub.4-tHal.sub.t-(CX.sub.2).sub.pC.sub.6H.sub.4-tHal.sub.t-O, where each X is independently H or CH.sub.3, p is 0 or 1, Hal is halogen and t is an integer indicating the number of halogen atoms attached to the benzene ring.

63. The polymer according to claim 62, comprising chains of the structure: ##STR00125##

64. The polymer according to claim 60, wherein the Linker is O(O)CR.sup.2C(O)O.

65. The polymer according to claim 60, having an epoxy equivalent weight in the range from 250 to 600 g/mol epoxy.

66. The polystyrene composition, composing: polystyrene; a flame retardant selected from the group consisting of bromine-containing polymers having bromine atoms bound to aliphatic carbons, and a stabilizer selected from the group consisting of the polymers of claim 57.

67. The polystyrene composition according to claim 66, wherein the bromine-containing flame retardant to be stabilized is polystyrene-block-brominated polybutadiene-block-polystyrene.

68. The method for thermally stabilizing bromine-containing polymeric flame retardants having bromine atoms bound to aliphatic carbons, the method comprising: adding to a bulk polymer said brominated flame retardant in conjunction with the polymer according to claim 57.

69. The method according to claim 68, wherein the bromine-containing flame retardant to be stabilized is polystyrene-block-brominated polybutadiene-block-polystyrene.

Description

EXAMPLES

[0091] Methods

[0092] Melting range was determined by the capillary method.

[0093] Epoxy equivalent was determined according to ASTM D 1652.

[0094] Bromine content was determined by Parr-Bomb (% Br).

[0095] Mw was measured by: An Agilent instrument model HP-1200. Three subsequent PLgel columns, 10 m, 10 m and 3 m. Calibration was done comparing to polystyrene standards.

[0096] TGA analysis was performed by a Mettler-toledo instrument model 850. 10 mg sample were heated in aluminum oxide crucible from room temperature to about 650 C. with heating rate of 10 C./min in an air atmosphere.

[0097] T.sub.g was measured by DSC (taken as midpoint). The DSC analysis was performed with a Mettler-toledo instrument model 1821E. Samples were heated in sealed aluminum crucible from 50 C. to about 150 C. at a heating rate of 20 C./min.

Example 1

[0098] ##STR00030##

[0099] Epoxy Novolac 438 (151.1 g) was melted in a glass vessel and heated to 155. The catalyst TBPB (75 mg) was added, followed by the addition of TBP (78.2 g). The temperature dropped to 120-130 C.; the mixture was re-heated to 145 C., stirred for 5-10 minutes, and then poured onto a tray and placed in an oven at 160 C. for 6 hours. The product was manually crushed with the aid of a pestle and mortar, and the powder collected was subjected to analysis.

[0100] Melting range was found to be from 41 to 67 C. DSC analysis indicated that the T.sub.g (midpoint) is 24.5 C. Bromine content of the product was 25.5 wt %. The weight average molecular weight was 2150. The epoxy equivalent was 575 g/mol epoxy.

Example 2

[0101] ##STR00031##

[0102] Epoxy Novolac 438 (93.3 g) was melted in a glass vessel and heated to 155. The catalyst TBPB (50 mg) was added, followed by the addition of TBP (62.2 g). The temperature dropped to 120-130 C.; the mixture was re-heated to 155 C., stirred for 5-10 minutes, then poured onto a tray and placed in an oven at 160 C. for 6 hours. The product was manually crushed with the aid of a pestle and mortar, and the powder collected was subjected to analysis.

[0103] Melting range was found to be from 46 to 74.2 C. DSC analysis indicates that the T.sub.g (midpoint) is 28.3. Bromine content of the product was 28.8 wt %. The weight average molecular weight was 2200. Epoxy equivalent was 500 g/mol epoxy.

Example 3

[0104] ##STR00032##

[0105] Epoxy Novolac 438 (90.6 g) was melted in a glass vessel and heated to 155. The catalyst TBPB (50 mg) was added, followed by the addition of TBP (74.1). The temperature dropped to 120-130 C.; the mixture was re-heated to 155 C., stirred for 5-10 minutes, then poured onto a tray and placed in an oven at 160 C. for 6 hours. The product was manually crushed with the aid of a pestle and mortar, and the powder collected was subjected to analysis.

[0106] Melting range was found to be from 50.7 to 74.3 C. DSC analysis indicates that the T.sub.g (midpoint) is 33.0. Bromine content of the product is 32.4 wt %. The weight average molecular weight was 2310. Epoxy equivalent was 900 g/mol epoxy.

Example 4

[0107] ##STR00033##

[0108] Epoxy Novolac 439 (111.2 g) was melted in a glass vessel and heated to 155. The catalyst TBPB (50 mg) was added, followed by the addition of TBP (59.9). The temperature dropped to 120-130 C.; the mixture was re-heated to 155 C., stirred for 5-10 minutes, then poured onto a tray and placed in an oven at 160 C. for 6 hours. The product was manually crushed with the aid of a pestle and mortar, and the powder collected was subjected to analysis.

[0109] Melting range was found to be from 53.6 to 71 C. DSC analysis indicates that the T.sub.g (midpoint) is 35.4. Bromine content of the product was 25.0 wt %. The weight average molecular weight was 6980. Epoxy equivalent was 442 g/mol epoxy.

Example 5

[0110] ##STR00034##

[0111] Epoxy Novolac 439 (100.6 g) was melted in a glass vessel and heated to 155. The catalyst TBPB (50 mg) was added, followed by the addition of TBP (67.1). The temperature dropped to 120-130 C.; the mixture was re-heated to 155 C., stirred for 5-10 minutes, then poured onto a tray and placed in an oven at 160 C. for 6 hours. The product was manually crushed with the aid of a pestle and mortar, and the powder collected was subjected to analysis.

[0112] Melting range was found to be from 57 to 85.7 C. DSC analysis indicates that the T.sub.g (midpoint) is 38.6 C. Bromine content of the product was 28.5 wt %. The weight average molecular weight was 6800. Epoxy equivalent was 592 g/mol epoxy.

Example 6

[0113] ##STR00035##

[0114] Epoxy Novolac 439 (89.0 g) was melted in a glass vessel and heated to 155. The catalyst TBPB (50 mg) was added, followed by the addition of TBP (72.8). The temperature dropped to 120-130 C.; the mixture was re-heated to 155 C., stirred for 5-10 minutes, then poured onto a tray and placed in an oven at 160 C. for 6 hours. The product was manually crushed with the aid of a pestle and mortar, and the powder collected was subjected to analysis.

[0115] Melting range was found to be from 61.5 to 91.2 C. DSC analysis indicates that the T.sub.g (midpoint) is 42.9 C. Bromine content of the product was 32.1 wt %. The weight average molecular weight was 7150. Epoxy equivalent was 771 g/mol epoxy.

Example 7

[0116] ##STR00036##

[0117] Epoxy Novolac 438 (95.7 g) was melted in a glass vessel and heated to 155. TBBA (14.4) was added, followed by the addition of the catalyst TBPB (50 mg). TBP (34.1 g) was the last added reactant. The temperature dropped to 120-130 C.; the mixture was re-heated to 155 C., stirred for 5-10 minutes, then poured onto a tray and placed in an oven at 160 C. for 6 hours. The product was manually crushed with the aid of a pestle and mortar, and the powder collected was subjected to analysis.

[0118] Melting range was found to be from 49.3 to 70 C. DSC analysis indicates that the T.sub.g (midpoint) is 32.3 C. Bromine content of the product was 22.7 wt %. The weight average molecular weight was 3410. Epoxy equivalent was 371 g/mol epoxy.

Example 8

[0119] ##STR00037##

[0120] Epoxy Novolac 438 (100.5 g) was melted in a glass vessel and heated to 155. TBBA (20.1) was added, followed by the addition of the catalyst TBPB (50 mg). TBP (29.7 g) was the last added reactant. The temperature dropped to 120-130 C.; the mixture was re-heated to 155 C., stirred for 5-10 minutes, then poured onto a tray and placed in an oven at 160 C. for 6 hours. The product was manually crushed with the aid of a pestle and mortar, and the powder collected was subjected to analysis.

[0121] Melting range was found to be from 52.5 to 81.2 C. DSC analysis indicates that the T.sub.g (midpoint) is 35.8 C. Bromine content of the product was 21.8 wt %. The weight average molecular weight was 4320. Epoxy equivalent was 382 g/mol epoxy.

Example 9

[0122] ##STR00038##

[0123] Epoxy Novolac 438 (93.9 g) was melted in a glass vessel and heated to 155. TBBA (23.5) was added, followed by the addition of the catalyst TBPB (50 mg). TBP (22.0 g) was the last added reactant. The temperature dropped to 120-130 C.; the mixture was re-heated to 155 C., stirred for 5-10 minutes, then poured onto a tray and placed in an oven at 160 C. for 6 hours. The product was manually crushed with the aid of a pestle and mortar, and the powder collected was subjected to analysis.

[0124] Melting range was found to be from 56.2 to 73.4 C. DSC analysis indicates that the T.sub.g (midpoint) is 37.1 C. Bromine content of the product was 20.9 wt %. The weight average molecular weight was 5360. Epoxy equivalent was 382 g/mol epoxy.

Example 10

[0125] ##STR00039##

[0126] Epoxy Novolac 438 (96.7 g) was melted in a glass vessel and heated to 155. TBBA (29.0) was added, followed by the addition of the catalyst TBPB (50 mg). TBP (16.8 g) was the last added reactant. The temperature dropped to 120-130 C.; the mixture was re-heated to 155 C., stirred for 5-10 minutes, then poured onto a tray and placed in an oven at 160 C. for 6 hours. The product was manually crushed with the aid of a pestle and mortar, and the powder collected was subjected to analysis.

[0127] Melting range was found to be from 61.4 to 86.6 C. DSC analysis indicates that the T.sub.g (midpoint) is 37.2 C. The bromine content of the product was 20.4 wt %. The weight average molecular weight was 7620. Epoxy equivalent was 387 g/mol epoxy.

Example 11

[0128] ##STR00040##

[0129] Epoxy Novolac 438 (98.2 g) was melted in a glass vessel and heated to 155 C. TBBA (34.4 g) was added, followed by the addition of the catalyst TBPB (50 mg). TBP (11.1 g) was the last added reactant. The temperature dropped to 120-130 C.; the mixture was re-heated to 155 C., stirred for 5-10 minutes, then poured onto a tray and placed in an oven at 160 C. for 6 hours. The product was manually crushed with the aid of a pestle and mortar, and the powder collected was subjected to analysis.

[0130] Melting range was found to be from 63 to 96 C. DSC analysis indicates that the T.sub.g (midpoint) is 40.3 C. Bromine content of the product was 19.8 wt %. The weight average molecular weight was 11320. Epoxy equivalent was 390 g/mol epoxy.

Example 12

[0131] ##STR00041##

[0132] Epoxy Novolac 439 (116.1 g) was melted in a glass vessel and heated to 155. TBBA (17.4 g) was added, followed by the addition of the catalyst TBPB (50 mg). TBP (41.3 g) was the last added reactant. The temperature dropped to 120-130 C.; the mixture was re-heated to 155 C., stirred for 5-10 minutes, poured onto a tray and placed in an oven at 160 C. for 6 hours. The product was manually crushed with the aid of a pestle and mortar, and the powder collected was subjected to analysis.

[0133] Melting range was found to be from 60.5 to 78.9 C. DSC analysis indicates that the T.sub.g (midpoint) is 38.8 C. Bromine content of the product was 22.7 wt %. The weight average molecular weight was 215700. Epoxy equivalent was 456 g/mol epoxy.

Example 13 (Comparative)

[0134] ##STR00042##

[0135] Epoxy Novolac 438 (98.3 g) was melted in a glass vessel and heated to 155. TBBA (43.6 g) was added, followed by the addition of the catalyst TBPB (50 mg). The temperature dropped to 120-130 C.; the mixture was re-heated to 155 C., stirred for 5-10 minutes, poured onto a tray and placed in an oven at 160 C. for 6 hours. The product was manually crashed with the aid of a pestle and mortar, and the powder collected was subjected to analysis.

[0136] Melting range was found to be from 67.6 to 90.6 C. DSC analysis indicates that the T.sub.g (midpoint) 42 C. The bromine content of the product was 17.3 wt %. The weight average molecular weight was 31704. Epoxy equivalent was 373 g/mol epoxy.

[0137] In the next sets of Examples (Examples 14-16; 17-19; 20-23 and 24-25), polystyrene formulations were prepared. Polystyrene grade used was PS 124N from Styrolution Group. As a brominated polymeric flame retardant, FR-122P was used in conjunction with different stabilizers. The stability of the resulting formulations was studied for:

a change in appearance by visually inspecting molded specimens subjected to severe conditions (molded samples were press molded in a press device ex Labtech at two temperatures: 200 C. for 3 minutes and 220 C. for 5 minutes);
a chemical change utilizing the HBr release test (1 g of pellets in a test tube are heated to 230 C. and the time that elapsed until evolving HBr is detected is recorded; HBr detection is by indicator paper); and
thermogravimetric analysis (TGA), which measures the weight loss of a sample as sample temperature is increased (in air, at heating rate of 10 C./minute); the temperature at which 5% weight loss occurs was recorded.

[0138] To prepare the formulations, polystyrene (PS 124n pellets from BASF) and other ingredients were fed into a twin-screw co-rotating extruder ZE25 with L/D=32 with open vent at 7.sup.th zone. The operating parameters of the extruder were as follows:

Barrel temperatures were set at (from feed end to discharge end): T.sub.1=no heating, T.sub.2=160 C., T.sub.3=160 C., T.sub.4=160 C., T.sub.5=160 C., T.sub.6=160 C., T.sub.7 vent=160 C., T.sub.8=160 C.; T.sub.9 die=180 C.

[0139] Screw rotation speed: 350 rpm

[0140] Feeding rate: 10-11 kg/hour.

[0141] The strands produced were cooled in a water bath and pelletized in a pelletizer 750/3 from Accrapak Systems Ltd. The resultant pellets were dried in a circulating air oven at 80 C. for 3 hours. For the visual evaluation, the pellets were press molded in a press into cylindrical bodies with diameter of 7 cm and height of 3 mm. Experimental details and results are presented in the Working Examples below.

Examples 14-15 (Comparative) and 16 (of the Invention)

[0142] Using the general procedure described above, polystyrene formulations were prepared. The two comparative stabilizers were F-2200 and F-2016 with epoxy equivalent of 344 g/mole epoxy and 964 g/mole epoxy, respectively. Both are commercially available from ICL-IP; the former is essentially a monomer as shown above and the latter is an oligomer with Mw=1600. The illustrative stabilizer of the invention was the polymer of Formula I-a of Example 1. To evaluate the potency of these three epoxy stabilizers, the amounts of the ingredients in the polystyrene formulations were adjusted to produce polystyrene compositions having the same epoxy equivalent, that is, the stabilizers were applied on equal molar basis such that in all three formulations the epoxy equivalent was 3440 g/mol epoxy. The compositions of the polystyrene formulation prepared and the results of the HBr release test are summarized in Table 1.

TABLE-US-00003 TABLE 1 Example 14 15 16 (comparative) (comparative) (of the invention) Composition (wt %) PS 124 50 32 47.6 FR 122P 40 40 40 F-2200 10 F-2016 28 Stabilizer of 12.4 Example 1 properties HBr release time 8:30 11:15 18:00 (min; duplicate) 8:25 11:15 17:50

[0143] The results of the second stability test are shown in the photo appended as FIG. 1. The cylindrical specimens which are seen in the photo are arranged in two rows; the upper row corresponds to specimens subjected to the 3 min/200 C. test, whereas the lower row relates to the more severe, 5 min/220 C. test. The left, middle and right sample in each row corresponds to molded specimens obtained from the composition of Examples 14, 15 and 16, respectively. It is seen that the stabilizer of the invention showed better performance in these tests, maintaining lighter color of the specimens and lesser black spots formation after heating.

Examples 17 (Comparative) and 18-19 (of the Invention)

[0144] Using the general procedure described above, polystyrene formulations were prepared. This time the comparative stabilizer was epoxy cresol novolac resin (Spon 164), with epoxy equivalent of 219 g/mole epoxy. The illustrative stabilizer of the invention was the polymer of Example 11 with epoxy equivalent of 390 g/mol epoxy. In addition to the aforementioned chief epoxy stabilizers, two auxiliary stabilizers were incorporated into the polystyrene formulation tested:

[0145] (i) a sterically hindered phenolic antioxidant (Irganox 1010, chemically named Pentaerythritol Tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate); and

[0146] (ii) Organophosphite antioxidant (Ultranox 626).

[0147] The compositions of the polystyrene formulations and the results of the stability tests are summarized in Table 2.

TABLE-US-00004 TABLE 2 Example 18 19 17 (of the (of the (comparative) invention) invention) Composition (wt %) PS 124 47 47 47 FR 122P 40 40 40 Epon 164 8 Stabilizer of 8 8 Example 11 Irganox 1010 1 1 2.5 Ultranox 626 4 4 2.5 Thermal properties TGA, 5% weight 275.75 276.41 287.58 loss recorded at temperature ( C.) HBr release time 19:10 20:42 18:30 (min; duplicate) 19:43 20:02 17:50

[0148] The results of the stability tests tabulated above indicate that the stabilizer of the invention is at least as good as epoxy cresol novolac resin, despite the fact that the latter has lower epoxy equivalent, that is, more epoxide groups per unit weight available for stabilizing the flame retardant. The relative amounts of the auxiliary stabilizers may be adjusted to further improve thermal stability, that is, by using the organophosphate as the major auxiliary additive.

Examples 20-23

[0149] Using the general procedure described above, polystyrene formulations were prepared. The illustrative stabilizer of the invention was the polymer of Example 11 with epoxy equivalent of 390 g/mol epoxy. In addition to the aforementioned chief stabilizer, hydrotalcite (Hycite 713, abbreviated HTC) was used as auxiliary stabilizing additive. The compositions of the polystyrene formulations prepared and the results of the HBr release test and TGA are summarized in Table 3.

TABLE-US-00005 TABLE 3 Example 20 21 22 23 Composition (wt %) PS 124 40 40 38 34 FR 122P 50 50 50 50 Stabilizer of 10 8 10 10 Example 11 HTC 0 2 2 6 Thermal properties TGA, 5% weight loss 258.91 268.63 279.73 ND recorded at temperature ( C.) HBr release time 7:31 9:17 11:32 17:45 (min; duplicate) 7:20 9:20 11:37 16:20

[0150] The benefit gained by the addition of HTC is apparent. Referring also to the photo shown in FIG. 2, the samples of Examples 20-23 were subjected to the 5 min/220 C. stability test and photos were taken (top left photo: sample of Example 20; top right photo: sample Example 21; bottom left photo: sample of Example 22; bottom right photo: sample of Example 23). The increased stabilizing effect achieved with the aid of a mixture of the polymer of the invention and hydrotalcite is evidenced by the enhanced whiteness of the mixed formulations.

Examples 24 (Comparative) and 25 (of the Invention)

[0151] Using the general procedure described above, polystyrene formulations were prepared. This time the comparative stabilizer was the polymer of Example 13, epoxy equivalent of 373 g/mol epoxy. The illustrative stabilizer of the invention was the polymer of Example 11 with epoxy equivalent of 390 g/mol epoxy. The compositions of the polystyrene formulations prepared and the results of the HBr release test are summarized in Table 4.

TABLE-US-00006 TABLE 4 Example 24 25 (comparative) (of the invention) Composition (wt %) PS 124 50 50 FR 122P 40 40 Stabilizer of 10 Example 13 Stabilizer of Example 11 10 properties HBr release time 9:55 11:00 (min; duplicate) 10:29 11:40;10:40

[0152] The HBr release test indicates the superiority of the polymer of the invention, with TBP pendant groups, over structurally similar polymer devoid of such pendant groups. The same observation could be made on the basis of the results of the 3 min/200 C. and 5 min/220 C. tests, presented by the photos in FIG. 3 (top left photo: sample of Example 25 following the 3 min/200 C. test; top right photo: sample of Example 24 following the 3 min/200 C. test; bottom left photo: sample of Example 25, following the 5 min/220 C. test; bottom right photo: sample of Example 24 following the 5 min/220 C. test).

Examples 26-27 (of the Invention) and 28-29 (Comparative)

[0153] Polymers of the invention and two commercial grades of cresol novolac epoxy resins were tested to determine their color properties (according to the APHA and Gardner tests, both as w/v solution in dioxane). The results are tabulated in Table 5.

TABLE-US-00007 TABLE 5 Gardner Example polymer APHA test test 26 Polymer of Example 1 164 0.7 27 Polymer of Example 11 94 0.4 28 Eponresin 164 700 4.0 ex. Momentive (Hexion) 29 AralditeECN 1280 ex. Huntsman 591 3.6

Examples 30-60

[0154] ##STR00043##

[0155] Additional examples were prepared as follows: Epoxy Novolac 438 was melted in a glass vessel and heated to 120-155 C. A bi-functional compound was added, followed by the addition of the catalyst (50 mg TBPB). End-capping molecule (that is, the monohydroxy aromatic compound) was the last added reactant. The temperature dropped to 120-130 C.; the mixture was re-heated to 150-180 C., stirred for 5-10 minutes, then poured onto a tray and placed in an oven at 150-160 C. for 5-6 hours. The solid product obtained was manually crushed with the aid of a pestle and mortar, and the powder collected was subjected to analysis. The various linkers and end-capping molecules applied, their amounts, as well as analytical results, are given in the tables below. Each table is associated with a specific sub-class of linkers.

TABLE-US-00008 TABLE 6 the bi-functional molecule is HO-R.sup.1-OH, comprising two non-fused or fused aromatic rings, each ring bearing one functional group (OH) enabling crosslinking: Epoxy Novolac Monohydroxy Melting 438 aromatic range EEW Ex amount, g linker molecule amount, g amount, g C. (g/mol-egv) 30 109.5 g [00044] [00045] 61.6-82 358 38.3 g 3.5 g 31 100 g [00046] [00047] 57.2-84.4 367 32.85 g 6.73 g 32 100 g [00048] [00049] 64.1-90 403 32.85 g 16.7 g 33 100 g [00050] [00051] 58.7-76.4 365 32.85 g 4.16 g 34 100 g [00052] [00053] 59.9-80.7 377 32.85 g 6.51 g 35 100 g [00054] [00055] 57.8-81.2 354 32.85 g 2,4,6- trimethylphenol 4.64 g 36 100 g [00056] [00057] ND ND 32.85 g 4.92 g 37 100 g Not used [00058] ND ND 35.0 g 38 100 g [00059] [00060] 59.8-76.1 365 (Bisphenol A, 16.2 g) 11.3 g 39 109.5 g [00061] [00062] 55.4-87.7 308 (Bisphenol A, 16.2 g) 3.5 g 40 100 g [00063] [00064] 45.9-74.3 279 (4,4-bisphenol 11.9 g) 11.3 g 41 100 g [00065] [00066] 46.4-70.2 325 Bisphenol-F, 12.1 g 11.3 g 42 100 g [00067] [00068] ND ND (TBBS, 34.2 g) 11.3 g 43 100 g [00069] [00070] 56-73 337 (2,7-dihydroxy 11.3 g naphthalene, 9,67 g)

TABLE-US-00009 TABLE 7 the polyfunctional compound is HOR.sup.1OH, HOOCR.sup.2COOH or HOR.sup.3COOH, consisting of one aromatic ring bearing at least two functional groups (OH, COOH) enabling crosslinking: Monohydroxy Epoxy Novolac Linker molecule aromatic Melting EEW Ex 438 amount, g amount, g amount, g range C. (g/mol-eqv) 44 100 g [00071] [00072] DSC 28.6 ND Hydroquinone 7.04 g TBP, 11.3 g 45 100 g [00073] [00074] DSC 28.6 ND Tetrabromo- TBP, 11.3 g Hydroquinone, 27.2 g 46 100 g [00075] [00076] 39.3-49.6 263 4.45 g 11.3 g 47 100 g [00077] [00078] 46.3-70.3 280 5.86 g 11.3 g 48 100 g [00079] [00080] 39.4-57.3 293 5.9 g 11.3 g 49 100 g [00081] [00082] ND ND 4.36 g 11.3 g 50 100 g [00083] [00084] ND ND 10.03 g 11.3 g 51 100 g [00085] [00086] 40-60 284 5.0 g 11.3 g 52 100 g [00087] [00088] 39.2-57.5 283 5.0 11.3 g

TABLE-US-00010 TABLE 8 the bi-functional compound is .sub.2HNR.sup.4NH.sub.2, consisting of one or two aromatic rings bearing NH.sub.2 groups enabling crosslinking: Epoxy Novolac Monohydroxy Melting 438 Linker molecule aromatic range EEW Ex amount, g amount, g amount, g C. (g/mol-eqv) 53 100 g [00089] [00090] ND ND 2.12 g 11.3 g 54 100 g [00091] [00092] ND ND 4.0 g 25.0 g 55 100 g [00093] [00094] ND ND 5.0 g 25.0 g 56 100 g [00095] [00096] ND ND 4.0 g 25 g 57 100 g [00097] [00098] ND ND 5.0 g 25 g 58 100 g [00099] [00100] 44.6-67.8 327 10. g 15.0 g 59 100 g [00101] [00102] 36.3-47.7 272 6.8 g 11.3 g 60 100 g [00103] [00104] ND ND 3.0 g 20.0 g

TABLE-US-00011 TABLE 9 the bi-functional compound is HOOC(CHCH)m(CH2)nCOOH; that is, an aliphatic chain (optionally interrupted with heteroatom(s)) bearing two COOH groups or the bi-functional agent is mono amine: Epoxy Novolac Monohydroxy Melting 438 Linker molecule aromatic range EEW Ex amount, g amount, g amount, g C. (g/mol-eqv) 58 100 g [00105] [00106] 44.6-67.8 327 10. g 15.0 g 59 100 g [00107] [00108] 36.3-47.7 327 6.8 g 11.3 g 58 100 g [00109] [00110] ND ND 3.0 g 20.0 g

Examples 61-63

[0156] Using the general procedure described above, polystyrene formulations were prepared. Stabilizers of the invention that were tested are the polymer of Example 11 (390 g/mol epoxy); the polymer of Example 48 (293 g/mol epoxy) and the polymer of Example 58, (327 g/mol epoxy). The compositions of the polystyrene formulations prepared and the results of the HBr release test are summarized in Table 10.

TABLE-US-00012 TABLE 10 Example 61* 62 63 composition PS 124 50 50 50 FR 122P 40 40 40 Stabilizer of 10 Example 11 Stabilizer of 10 Example 48 Stabilizer of 10 Example 58 properties HBr release time 12:46 13:50 15:00 (min:sec; average 0.25 0:26 0:36 sd) *(the results of Example 61 are different from Example 25 because a different lot of FR 122P has been used this time)