Epoxy resin formulations

Abstract

Formulations comprising from 10 to 80% by weight of the formulation of a halogenated epoxy resin; from 1 to 15% by weight of the formulation of an antimony based fire retardant; from 1 to 10% by weight of the formulation of an inorganic or non-polymeric organic phosphorous containing fire retardant; and from 1 to 30% by weight of the formulation of a curative system are provided. The formulations are particularly suitable for producing aircraft interior composite components having good fire retarding properties, low smoke emission, low smoke toxicity and low heat release properties. The formulations also have excellent processing and mechanical properties. Further components may be included in the compositions to improve various properties, including the fire retarding, low smoke emission, low smoke toxicity and low heat release properties and to also further improve the processing and mechanical properties, including toughness. Compositions produced from the formulations have excellent processing and mechanical properties, and may also have good surface finishes.

Claims

1. A polymeric resin formulation comprising: a. from 15 to 60% by weight of a halogenated epoxy resin; b. from 5 to 30% by weight of an organic polymeric or oligomeric phosphorous containing fire retardant; c. from 3 to 20% by weight of a curative system; d. from 1.5 to 12% by weight of an antimony based fire retardant; e. from 1.5 to 7.5% by weight of an inorganic or non-polymeric organic phosphorous containing fire retardant; f. from 6 to 25% by weight of an epoxy novolac resin; g. from 1 to 10% by weight of one ore more thermoplastic toughening agents; h. from 2 to 38% by weight of a smoke suppressant; i. from 0.05 to 1.5% by weight of a wetting agent, and j. from 5 to 35% by weight of one or more bisphenol epoxy resins in addition to the halogenated epoxy resin.

2. The formulation according to claim 1, having a cured dry Tg of at least 145° C.

3. The formulation according to claim 1, having a viscosity of no more than 10 PaS−1 at 110° C.

4. A prepreg comprising a fibrous reinforcement and the polymeric resin formulation of claim 1.

5. The prepreg as claimed in claim 4, wherein the reinforcement fibres are carbon and said prepreg having, after curing, at least one of the following properties: a) interlaminar shear strength (ILSS) of at least 50 MPa as measured by ASTM D2344; b) 0° flexural strength of at least 1100 MPa as measured by ASTM D790; c) 0° flexural modulus of at least 95 GPa as measured by ASTM D790; d) 0° tensile strength of at least 1400 MPa as measured by ASTM D3039; or e) 0° tensile modulus of at least 110 GPa as measured by ASTM D3039.

Description

EXAMPLES 1 AND 2, AND COMPARATIVE EXAMPLES 1 AND 2

(1) The formulations for Examples 1 and 2 and Comparative Examples 1 and 2 are shown in Table 1. The formulations were prepared by dissolving the phenoxy YP50P (when used) at 130° C. in the resins, followed by the dissolution of Nofia OL3001 (when used) at 100° C. The formulations were cooled to 90° C. for the addition of Exolit RP6500 and the rest of the flame retardants (when used). The curatives were added between 60 and 65° C. The mixtures were made under continuous mixing.

(2) TABLE-US-00001 TABLE 1 Formulations Comparative Comparative Raw Materials Example 1 Example 2 Example 1 Example 2 MY9512 44.0 MX153 23.0 CHS-130T 8.0 LME 11082 26.0 27.7 YD PN638 31.3 13.6 12.0 Kaneka MX965 38.6 25.0 20.0 Phenoxy YP50P 7.5 6.0 4.0 Nofia OL 3001 10.0 20.0 Exolit RP6500 5.0 8.3 8.0 6.0 Firebrake ZB 3.0 Magnifin H10 3.0 Antimony 4.0 6.0 Pentoxide Technicure ADH-J 6.5 5.1 4.9 4.3 Omicure U52M 6.0 4.7 4.5 4.0 Total 100.0 100.0 100.0 100.0

(3) The formulations of Examples 1 and 2 both had a post cured Tg of 134° C.

(4) The formulations were prepregged by the hot melt route, where the resins are coated into two films used to consolidate a carbon fibre tape

(5) Panels were formed by prepregging the formulations of Examples 1 and 2 on various fibres for FST/OSU and mechanical screening and were cured in an autoclave with 2° C./min for 45 minutes at 150° C. and 7 bar pressure. No peel plies were used on the surfaces of the laminates. Panels comprising the formulations of Comparative Examples 1 and 2 prepregged onto various fibres were cured in an autoclave with 2° C./min for 45 minutes at 130° C. and 7 bars. The FST/OSU panels and the panels for mechanical screening (apart from ILSS testing) were cured with peel plies. The results are shown in Tables 2 and 3.

(6) Both the formulations of Example 1 and Example 2 prepregged on AS7 carbon fibre at 194 gsm FAW (available from Hexcel Corporation, USA) at 36% resin content (RC) pass the heat release FAR25.853 requirements and the ABD0031 smoke density requirements in flaming mode for 3 mm thick monolithic laminates, (0/90) ns lay-up (see Table 2). The formulations have better FST/OSU performance compared to Comparative Example 1 (a commercial products), which fails the heat release and smoke density requirements when prepregged onto carbon fibre AS4 at 160 gsm (available from Hexcel corporation, USA) at a lower resin content (34%). The formulations of Examples 1 and 2 also perform better than the formulation of Comparative Example 2 (a further commercial product) in heat release testing when prepregged on the same carbon fibre (AS7 at 194 gsm) and the same resin content (36%).

(7) TABLE-US-00002 TABLE 2 FST/OSU results OSU Test specification ASTM E906 NBS Ds Peak Total Max in 4 min HRR HRR (Flaming mode) Thick- (kW/ (kWmin/ Test ness m2) m2) specification System (mm) Avg Avg FAR 25.853 Comparative 3 91.8 71.3 181 Example 1 at 34% on AS4/160 gsm Comparative 3 129.9 67.9 41 Example 2 at 36% on AS7/194 gsm Example 1 3 32 21 48.4 at 36% on AS7/194 gsm Example 2 3 29 24.5 131 at 36% on AS7/194 gsm Requirements 65 65 150

(8) Example 1 and Example 2 prepregs also pass the heat release and smoke density for 1 mm and 5 mm, (0/90) ns panels (results in Table 3)

(9) TABLE-US-00003 TABLE 3 FST/OSU results for Examples 1 and 2 OSU ASTM E906 NBS Ds Peak Total Max in 4 min HRR HRR (Flaming mode) Thick- (kW/ (kWmin/ Test ness m2) m2) specification System (mm) Avg Avg FAR 25.853 Example 1 1 27.7 24.7 106.2 at 36% on AS7/194 gsm Example 2 1 42.4 27.2 88.3 at 36% on AS7/194 gsm Example 1 5 45.8 9.5 31 at 36% on AS7/194 gsm Example 2 5 37.3 14.8 50.4 at 36% on AS7/194 gsm Requirements 65 65 150

(10) Without wishing to be bound by theory, it is believed that the improved heat release performance without compromising the smoke density is due to phosphorus and halogenated flame retardants which act independently and additively. Both phosphorus and halogenated flame retardants act in the gas phase in a similar way by removing the H. and OH. radicals from flammable gases. The phosphonate oligomer (OL3001 with 10% P) and red phosphorus (43-47% in Exolit RP6500) are char-forming flame retardant primarily active in the condensed phase. Heated phosphorus will react to form a polymeric phosphoric acid creating an insulating char layer.

(11) The mechanical results for Examples 1 and 2 are presented in the Table 4 in comparison with Comparative Examples 1 and 2.

(12) TABLE-US-00004 TABLE 4 Mechanical data Flex Flex IPSS IPSM ILSS Strength Mod (MPa) (GPa) (Mpa) (Mpa) (GPa) AITM AITM Prepreg EN2563 EN2562 EN2562 1.0002 1.0002 Example 1 at 77 1285 121.5 96 3.6 36% on AS7 at 194 gsm Example 2 at 72 1336 123.7 95 4.14 36% on AS7 at 194 gsm Comparative 74 1235 111 84 3.3 Example 1 at 34% on AS7 at 160 gsm Comparative 70 1330 116.8 71 3.45 Example 2 at 36% on AS7 at 194 gsm

(13) ILSS (Inter laminar shear strength) and flexural data for Example 1 and Example 2 was comparable with Comparative Examples 1 and 2 but higher IPSS/IPSM value were observed.

EXAMPLES 3, 4 AND 5

(14) The formulations for Examples 3, 4 and 5 are shown in Table 5.

(15) TABLE-US-00005 TABLE 5 Examples 3, 4 and 5 Raw Example Example Example Materials 3 4 5 LME 11082 23.7 23.3 21.9 Kaneka MX965 18.3 LY3581 13.5 12.0 SCT 150 17.0 16.7 14.0 Phenoxy YP50P 3.7 5.7 3.0 Nofia OL 3001 9.2 8.0 Exolit RP6500 7.3 7.2 6.0 Firebrake ZB 3.0 9.5 12.0 Magnifin H10 3.0 9.5 12.0 Antimony Pentoxide 5.0 4.9 4.0 DICY 6.5 6.4 5.0 Dyhard UR 505 2.0 Polyfox 159 0.1 0.1 0.1 Omicure U52M 3.2 3.2 Total 100.0 100.0 100.0

(16) Examples 3, 4 and 5 were mixed in a similar way to Examples 1 and 2, where the resins were firstly melted at 100° C., then phenoxy was added and melted under mixing at 130° C. The mixture was cooled to 100° C. for the dissolution of Nofia OL3001 (where used). The flame retardants were added at 90° C. and the curatives between 60 and 65° C. The mixtures were made under continuous mixing.

(17) The formulations of examples 3, 4 and 5 had post cure Tgs of 140° C., 160° C. and 163° C. respectively. All 3 resins were found to be suitable for hot load/hot unload press curing at 140° C. for 15 minutes.

(18) The formulations were prepregged by the hot melt route, where the resins are coated into two films used to consolidate a UD Toray T620 60 E carbon fibre tape, a UD carbon tape and a glass fabric.

(19) The OSU and smoke density results for 1, 3 and 5 mm, (0/90) ns panels cured in an autoclave (cure cycle: 2° C. per minute to 150° C. for 45 minutes at 7 bar) are presented in Table 6. Example 3 prepreg at 36% resin content on carbon UD passes heat release, smoke density and vertical burn 12 secs and 60 secs tests. On glass fabric the formulation of Example 3 passes heat release, smoke density and vertical burn tests for 1 mm thick panels.

(20) The vertical burn results are presented in Tables 7 and 8.

(21) TABLE-US-00006 TABLE 6 FST/OSU Results NBS (DS. Max, OSU (PHR OSU (THR 4 min) Flaming Thickness (kW/m.sup.2)) (2 min. kWmin/m.sup.2)) Mode ABD0031 Material Batch (mm) ASTM E906 ASTM E906 (ATS 1000.001) Example 3 at 36% 3002 1 41 27 59 on 300/Toray T620 Example 3 at 36% 3002 3 34 16 42 on 300/T620 Example 3 at 36% 3002 5 33 4 12 on 300/UD carbon Example 3 at 37% 3003 1 32 27 71 on 7781 glass FAR 25.853/ABD0031 Requirements 65 kW/m.sup.2 65 kWmin/m.sup.2 150 Ds Max in 4 mins

(22) TABLE-US-00007 TABLE 7 Vertical burn test 12 secs and 60 secs for Example 3 on UD carbon, specification FAR 25.853 (a) Amdt 20, App. F Pt I(a) Thickness After flame Burn length Drip time Test (mm) secs Avg (mm) Avg (mm) Avg VB 12 secs 3 0 0 0 VB 60 secs 3 0 21 0 VB 12 secs 1 0 15 0 VB 60 secs 1 8.1 41 0 VB 12 secs 5 0 0 0 VB 60 secs 5 0 10 0 VB 12 sec 15 203 5 Requirements VB 60 secs 15 152 3 requirements

(23) TABLE-US-00008 TABLE 8 Vertical burn data 12 secs and 60 secs Example 3 on glass fibre, FAR 25.853 (a) Amdt 20, App. F Pt I(a) Thickness after flame Burn length Drip time Test (mm) secs Avg (mm) Avg (mm) Avg VB 12 secs 1 4.9 17 0 VB 60 secs 1 2.4 76 0 VB 12 sec 15 203 5 Requirements VB 60 secs 15 152 3 requirements

(24) FST, vertical burn at 12 seconds and 60 seconds data for Examples 4 and 5 is presented in Table 9. The prepregs were made on glass fibre by hot melt impregnation at 40% resin content. The formulations pass vertical burn requirements for 1 mm, 3 mm and 5 mm panels.

(25) TABLE-US-00009 TABLE 9 Vertical burn results at 12 and 60 seconds for Examples 4 and 5. VB 12 secs FAR 25.853 (a) VB 60 secs FAR 25.853 (a) Amdt 20, App. F Pt I(a) App. F Pt I(a) Amdt 20, After After Specimen flame Burn Drip flame Burn Drip Prepreg thickness time distance time time distance time description (mm) (secs) (mm) I(secs) (secs) (mm) I(secs) Example 4 at 1 8.5 50 0 0.3 49 0 40% on 300 3 0 3 0 10.6 29 0 glass fabric 5 0 3 0 14.9 14 0 Example 5 at 1 1.6 14 0 1.2 52 0 40% on 300 3 0 2.9 0 6.2 27.8 0 glass fabric 5 0 2.3 0 0 16.2 0 Requirement 15 203 5 15 152 3

(26) FST smoke density results for Examples 4 and 5 prepregged as above is shown in Table 10. The formulation of Example 4 at 40% resin content on glass passes the NBS smoke density test in flaming mode Ds Max 150 (FAR 25.853 target) and Ds Max 200 (ABD0031 target) for 1 mm, 3 mm and 5 mm panels. The formulation of Example 5 at 40% resin content passes Ds Max 200

(27) TABLE-US-00010 TABLE 10 Smoke density - Examples 4 and 5 NBS Ds Max in 4 min (Flaming mode) Specimen Avg FAR 25.853 thickness PtV//ABD0031 Prepreg (mm) (ATS 1000.001) Example 4 at 40% on 300 glass 1 111.18 3 84.08 5 54.93 Example 5 at 40% on 300 glass 1 96.51 3 184.26 5 167.18 Requirements ABD 0031 Iss F 150 Requirements FAR 25.853 Pt V 200

(28) OSU heat release data for Examples 4 and 5 is shown in Table 11 below. The formulations at 40% resin content on glass pass the FAR 25.853 Pt. IV peak heat release 65 kW/m.sup.2 and total heat release 65 kWmin/m.sup.2 requirements.

(29) TABLE-US-00011 TABLE 11 OSU heat release - Examples 4 and 5 Specimen thickness PHR THR Designation (mm) Avg Avg Example 4 at 40% on 300 glass 1 45.8 30.6 3 56.6 2.16 5 41.7 1.1 Example 5 at 40% on 300 glass 1 31.7 18.13 3 19.9 1.83 5 30.7 0.13 Requirements FAR 25.853 Pt IV 65 65

EXAMPLE 6

(30) The formulation of Example 6 is shown in Table 12

(31) TABLE-US-00012 TABLE 12 Formulation Raw Material % wt LME 11082 20.19% Araldite GY281 6.16% SCT150 14.45% Phenoxy YP50P 3.11% Polyfox 159 0.59% Exolit RP 6500 6.22% Nofia OL 3001 7.02% Antimony Pentoxide 4.24% Firebrake ZB 12.41% Magnifin H10 12.41% D50 EP 10.99% Dyhard UR505 2.22% Total 100%

(32) The formulation of Example 6 was prepared in a similar manner to the formulations of Examples 1 to 5. The formulation had a post cure Tg of 156° C. and a viscosity of 6.7 Pas.sup.−1 at 110° C. The resin was suitable for hot load/hot unload press curing at 140° C. for 15 minutes.

(33) Panels were prepared by prepregging the formulation of Example 6 on 24 k standard modulus carbon fibre (Tenax STS40) at 39.5% resin content at a FAW of 300 gsm. The panels were cured in an autoclave with 2° C./minute ramp to 150° C. for 45 minutes at 7 bar.

(34) Mechanical data for the panels of Example 6 is given in Table 13.

(35) TABLE-US-00013 TABLE 13 Mechanical data Example 6 Test Method Mean Min ILSS (MPa) EN2563 91 83 Flexural strength (MPa) EN2562 1705 1646 Flexural modulus (GPa) 118 116 0° Tensile Strength (MPa) EN2561 1818 1729 0° Tensile Modulus (GPa) 129 122 0° Compression Strength (MPa) EN2580B 1550 1489 0° Compression Modulus (GPa) 109 107

(36) The results in Table 13 clearly show that the panels of Example 6 had excellent mechanical properties.

(37) Heat release data for the panels of Example 6 at various thicknesses is shown in Table 14.

(38) TABLE-US-00014 TABLE 14 Heat release data (OSU) OSU Heat release Avg Thickness THR PHR (mm) (kWmin/m.sup.2) (kW/m.sup.2) Example 6 1 2 12 3 7 39 5 0 14 FAR 25.853 Pt IV 65 65

(39) Vertical burn data for the panels of Example 6 at various thicknesses is shown in Table 15.

(40) TABLE-US-00015 TABLE 15 Vertical burn data (FST) VB 12 secs Avg VB 60 secs Avg After Burn Drip After Burn Drip Actual Thickness Flame length time Flame length time RC % (mm) (sec) (mm) (sec) (sec) (mm) (sec) Example 6 39.5 0.63 3 30 0 0 41 0 1 3 7 0 0 31 0 3 0 3 0 9 22 0 5 0 2 0 0 9 0 FAR 25.853 Pt.I 15 203 5 15 153 3

(41) Smoke density data for the panels of Example 6 at various thicknesses is shown in Table 16.

(42) TABLE-US-00016 TABLE 16 Smoke density data (FST) NBS Smoke Density Thickness (DsMax in 4 mins) (mm) in Flaming Mode Example 6 1 40 3 54 5 69 FAR 25.853 Pt V 200

(43) The results in Tables 14, 15 and 16 show that the formulation of Example 6 provides panels having excellent heat release, vertical burn and smoke density properties, in all cases easily passing industry standard tests whilst also providing excellent mechanical properties (see Table 13). The formulation also provided excellent post cure Tg and had useful curing characteristics.

EXAMPLE 7

(44) The formulation of Example 7 is shown in Table 17.

(45) The formulation of Example 7 was prepared in a similar manner to the formulations of Examples 1 to 6.

(46) TABLE-US-00017 TABLE 17 Formulation Raw Material % Wt LME 11082 20.2 Araldite GY281 10.2 SCT150 14.5 BYK 9010 0.5 Exolit RP 6500 6.2 Nofia OL 3001 7.0 Antimony Pentoxide 4.2 Firebrake ZB 12.0 Magnifin H10 12.0 D50 EP 11.0 Dyhard UR505 2.2 Total 100.0

(47) The formulation had a post cure Tg of 154° C. and a viscosity of 1.3 Pas.sup.−1 at 110° C. The resin had high tack and good flow properties, and was suitable for hot load/hot unload press curing at 140° C. for 15 minutes.

(48) Panels were prepared by prepregging the formulation of Example 7 on 24 k standard modulus carbon fibre (Tenax STS40) at 38.4% resin content at a FAW of 300 gsm. The panels were cured in an autoclave with 2° C./minute ramp to 150° C. for 45 minutes at 7 bar and tested in the same manner as the panela of example 6.

(49) Mechanical data for the panels of Example 7 is given in Table 18.

(50) TABLE-US-00018 TABLE 18 Mechanical data Example 7 Test Mean Min ILSS (MPa) 84.7 73 Flexural Strength (MPa) 1602 1510 Flexural Modulus (GPa) 120 118

(51) The results in Table 18 clearly show that the panels of Example 7 had excellent mechanical properties.

(52) Heat release data for the panels of Example 7 at various thicknesses is shown in Table 19.

(53) TABLE-US-00019 TABLE 19 Heat release data (OSU) OSU Heat release data for 1955-1 OSU Heat release Avg Thick THR PHR (mm) (kWmin/m.sup.2) (kW/m.sup.2) Example 7 1 45.5 42.9 3 20.8 29.5 5 22.6 50.5 FAR 25.853 Pt IV 65 65

(54) Smoke density data for the panels of Example 7 at various thicknesses is shown in Table 20.

(55) TABLE-US-00020 TABLE 20 Smoke density data (FST) Thick Ds Max in 4 mins (mm) Flaming mode Avg Example 7 1 109.2 3 142.7 5 108.9 FAR 25.853 Pt V 200

(56) The results in Tables 19 and 20 show that the formulation of Example 7 provides panels having excellent heat release and smoke density properties, in all cases easily passing industry standard tests whilst also providing excellent mechanical properties (see Table 18). The formulation also provided excellent post cure Tg and had useful curing characteristics, plus useful viscosity and tack.