EPOXY RESIN COMPOSITIONS

Abstract

There is provided a resin composition for producing a composite part, comprising: a) from 30 to 90 wt % by weight of the composition of an epoxy resin component; and b) from 5 to 50 wt % by weight of the composition of a curative component; wherein the epoxy resin component comprises N,N,N,N-tetraglycidyl-4,4-diamino-3,3-dimethyldiphenylmethane (M-TGDDM) in an amount of at least 30 wt % by weight of the epoxy resin component; and further wherein the curative component comprises one or more of a diaminodiphenyl sulfone, a diaminobenzophenone, a fluorene diamine, a methylene bis aniline, including hybrid methylene bis anilines, or a substituted diamine toluene. There is also provided the use of N,N,N,N-tetraglycidyl-4,4-diamino-3,3-dimethyldiphenylmethane (M-TGDDM) as a compression performance improving additive in a resin composition for producing a composite part. There are also provided curable composite components, cured composite components produced therefrom and the use of such components as aircraft components.

Claims

1. A resin composition for producing a composite part, comprising: a) from 30 to 90 wt % by weight of the composition of an epoxy resin component; and b) from 5 to 50 wt % by weight of the composition of a curative component; wherein the epoxy resin component comprises N,N,N,N-tetraglycidyl-4,4-diamino-3,3-dimethyldiphenylmethane (M-TGDDM) in an amount of at least 30 wt % by weight of the epoxy resin component; and wherein the curative component comprises one or more of a diaminodiphenyl sulfone, a diaminobenzophenone, a fluorene diamine, a methylene bis aniline, or a substituted diamine toluene.

2. The composition according to claim 1, wherein the epoxy resin component comprises from to 65 wt % of said composition.

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4. The composition according to claim 2, wherein said composition comprises at from 20 to 60 least 10 wt % by weight M TGDDM.

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Description

EXAMPLES

[0056] Three batches of M-TGDDM were tested and were found to have viscosities of 2205 mPa.Math.as, 2821 mPa.Math.s and 2150 mPa.Math.s respectively at 50? C., compared to a viscosity of 3000 TO 6000 mPa.Math.s at 50? C. for commercial samples of TGDDM. This reduced viscosity is an advantage for resin transfer moulding formulations, because, for example, formulations containing the M-TGDDM will have lower viscosity at injection temperatures.

[0057] Various stoichiometric combinations of TGDDM based resins and aromatic amine curing agents were produced and cured at 180? C. for 2 hours. Differential scanning calorimetry (DSC) was performed using a TA Discovery instrument to determine, uncured Tgs, peak of cure temperatures and reaction enthalpies using a heating rate of 10? C./min, and the results are listed below in Table 1.

TABLE-US-00002 TABLE 1 Uncured Tg Peak of cure Enthalpy Formulation (? C.) (? C.) (J/g) TGDDM + 44DDS ?9 235 629 M-TGDDM + 44DDS ?12 249 573 E-TGDDM + 44DDS ?25 261 550 TGDDM + 33DDS ?10 218 663 M-TGDDM + 33DDS ?15 231 531 TGDDM + MDEA ?15 240 450 M-TGDDM + MDEA ?20 266 380

[0058] Table 1 shows that using M-TGDDM in place of TGDDM decreases reactivity as shown by the increase in peak of cure temperature when using the same curative. For example, M-TGDDM/44DDS has a peak of cure temperature 14? C. higher than TGDDM/44DDS. M-TGDDM has lower uncured Tgs than TGDDM, which is due to the lower viscosity of M-TGDDM. This lower viscosity would allow greater addition of solid components such as PES than TGDDM thereby increasing mechanical performance.

[0059] Further stoichiometric combinations of TGDDM and M-TGDDM with various curing agents were produced and cured at 180? C. for 2 hours. Dynamic mechanical analysis (DMA) was performed using a TA Q800 instrument on cured resin to determine glass transition temperatures (E) at a heating rate of 5? C./min and at a frequency of 1 Hz and using an amplitude of 30 ?m. The results are shown in Table 2.

TABLE-US-00003 TABLE 2 Dry E Tg Compression Modulus Formulation (? C.) (GPa) TGDDM + 33DDS 210 4.54 M-TGDDM + 33DDS 202 5.28 TGDDM + 44DDS 255 3.85 M-TGDDM + 44DDS 255 4.55 TGDDM + MDEA 195-200 3.00 M-TGDDM + MDEA 193 3.61 TGDDM + MDEA + MMIPA 210 3.30 M-TGDDM + MDEA + 206 4.00 MMIPA

[0060] Table 2 shows that compared to TGDDM, the compression modulus of M-TGDDM is higher when using the same curatives by around 15-20%. The Tg performance of the M-TGDDM resin is more or less the same as TGDDM.

[0061] The following formulations were produced and tested for resin and composite properties following curing for 2 hours at 180? C. The tests included neat resin compression modulus, open hole compression gross strength and filled hole compression gross strength. Neat resin compression modulus was performed using an Instron mechanical test machine on neat resin cylinders (60-70 mm in length and 12-14 mm in diameter) that were machined to parallel ends. The results are shown in Table 3.

TABLE-US-00004 Formulation 1 TGDDM 60 wt % 4,4-methylene bis (2,6-diethylaniline) (MDEA) 27 wt % 4,4-methylene bis (2-isopropyl-6-methyleneaniline) 13 wt % (MMIPA) Formulation 2 TGDDM 38 wt % E-TGDDM 21 wt % 4,4-methylene bis (2-chloroaniline) 34 wt % Diethyltoluenediamine (DETDA) 4 wt % Core shell impact modifier 3 wt % Formulation 3 M-TGDDM 60.6 wt % 4,4-methylene bis (2-chloroaniline) 32.8 wt % Diethyltoluenediamine (DETDA) 3.6 wt % Core shell impact modifier 3.0 wt %

TABLE-US-00005 TABLE 3 Neat resin compression OHC gross FHC gross Formulation modulus (GPa) strength (MPa) strength (MPa) Formulation 1 3.30 280 394/426 Formulation 2 3.67 281 404 Formulation 3 3.92 310 452

[0062] Table 3 shows that Formulation 3 containing M-TGDDM has a high neat resin compression modulus vale of 3.92. This high value translates to high OHC and FHC values in composite; whereas Formulation 1 and Formulation 2 (based on TGDDM) have similar OHC and FHC values even though the neat resin modulus values of Formulation 2 is higher than Formulation 3.

[0063] A further formulation based on a mixture of TGDDM and M-TGDDM was produced as follows:

TABLE-US-00006 Formulation 4 TGDDM 38.1 wt % M-TGDDM 20.6 wt % 4,4-methylene bis (2-chloroaniline) 34.3 wt % Diethyltoluenediamine (DETDA) 3.4 wt % Core shell impact modifier 3.6 wt %

[0064] The viscosities of Formulations 3 and 4 were measured under isothermal conditions at 110? C., using a parallel plate rheometer configuration, and both were found to have similar viscosities after 100 minutes. However, Formulation 3, containing only M-TGDD as the epoxy resin, has longer pot-life than Formulation 4, which contains both TGDDM and M-TGDDM. This allows for a longer injection window for RTM formulations.