EPOXY SYSTEM

Abstract

The invention is directed to a curable composition, which comprises an epoxy resin mixture, wherein the epoxy resin mixture comprises a) an epoxy resin; b) diethyl methyl benzene diamine (DETDA) as hardener; c) at least one compound selected from the group consisting of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) as catalyst.

Claims

1. A curable composition, which comprises an epoxy resin mixture, wherein the epoxy resin mixture comprises a) an epoxy resin; b) diethyl methyl benzene diamine (DETDA) as hardener; c) at least one compound selected from the group consisting of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) as catalyst.

2. The curable composition according to claim 1, wherein the epoxy resin according to a) comprises at least one epoxy resin selected from the group consisting of diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, diglycidyl ether of hydrogenated bisphenol A, and diglycidyl ether of hydrogenated bisphenol F.

3. The curable composition according to claim 1, wherein the catalyst according to c) is present in an amount of from 0.1 to 20% by weight relative to the amount of the epoxy resin.

4. The curable composition according to claim 1, wherein the hardener according to b) is present in an amount of from 1 to 35% by weight relative to the amount of the epoxy resin.

5. The curable composition according to claim 1, wherein the epoxy resin mixture comprises d) at least one further diamine, selected from the group consisting of cycloaliphatic diamines, meta-xylenediamine (MXDA) and meta-para-xylenediamine (MPXDA).

6. The curable composition according to claim 1, comprising reinforcing fibers embedded in the curable composition, wherein the reinforcing fibers are selected from the group consisting of glass fiber, carbon fiber, nylon fiber and aramid fiber.

7. The curable composition according to claim 6, wherein the reinforcing fibers are present in an amount of from 10 to 80% by volume relative to the total volume of the curable composition.

8. A process for preparing a curable composition, comprising mixing of a) an epoxy resin; b) diethyl methyl benzene diamine (DETDA); c) at least one compound selected from the group consisting of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and 1,5-diazabicyclo[4.3.0]non-5-ene (DBN).

9. A curable composition obtained or obtainable by the process of claim 8.

10. A process for the preparation of a cured epoxy resin mixture, which comprises curing a curable composition according to claim 1.

11. A cured epoxy resin which is obtained or obtainable by a process according to claim 10.

12. A process for the preparation of composite elements, which comprises i) providing reinforcing fibers; ii) impregnating the reinforcing fibers according to i) with a curable composition comprising an epoxy resin mixture, wherein the epoxy resin mixture comprises a) an epoxy resin; b) diethyl methyl benzene diamine (DETDA) as hardener; c) at least one compound selected from the group consisting of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) as catalyst; in order to obtain reinforcing fibers impregnated with the curable composition; iii) applying the reinforcing fibers impregnated with the curable composition according to ii) to a surface of a support element obtaining a support element having reinforcing fibers impregnated with the curable composition on its surface; iv) curing the curable composition; v) optionally removing the support element.

13. The process according to claim 12, wherein the support element according to iii) has a diameter, a longitudinal extension vertically to the diameter and an outer surface parallel to the longitudinal extension and wherein applying the reinforcing fibers in iii) is done by winding the reinforcing fibers impregnated with the curable composition around the support element's outer surface.

14. A composite element which is obtained or obtainable by a process according to claim 12.

15. A method for transporting or storing liquid media, wherein the pipes, tubes or vessels comprise the composite element prepared according to the process of claim 12.

16. A process for the preparation of a cured epoxy resin mixture, which comprises curing a curable composition according to claim 9.

17. A method for transporting or storing liquid media, wherein the pipes, tubes or vessels comprise the composite element prepared according to the process of claim 14.

Description

EXAMPLES

Chemicals

[0196] Epilox A19-03: diglycidyl ether of bisphenol A having a viscosity at 25 C. in the range of from 10000 to 14000 mPa s determined according to DIN 53 015 and an EEW in the range of from 182 to 192 g/eq determined according to DIN 16 945 [0197] DETDA: diethyl methyl benzene diamine [0198] MCDA: methyl cyclohexyl diamine [0199] IPDA: isophorondiamine [0200] DBU: 1,8-diazabicyclo[5.4.0]undec-7-ene [0201] TMG: tetramethylguanidine [0202] EMIM-DCA: 1-ethyl-3-methyl-imidazolium dicyanamide [0203] DABCO: 1,4-diazabicyclo[2.2.2]octane [0204] Dicykan: 4,4-diaminodicyclohexylmethane

Reference Example 1Characterisation of Resin Properties

[0205] The individual components were mixed in the ratios indicated in table 1.

[0206] The following parameters were determined on a rheometer (Anton Parr): [0207] initial viscosity at 45 C. (start) [0208] time until a doubling of the initial viscosity at 45 C. is reached [0209] time until the maximum modulus of loss G at 145 C. is reached.

[0210] The following parameters were determined by differential scanning calorimetry (DSC) (TA instruments DSC Q 2000): [0211] Onset' temperature [0212] Enthalpy [0213] Glass transition temperature Tg after 5 h at 145 C.

TABLE-US-00001 TABLE 1 Parts Hardener Diamine Parts Parts per (amine (amine per Aminic per experiment resin weight 1) parts 2) weight curing catalyst weight 1 Epilox 100 DETDA 24 0 100% 0 (comparative) A19-03 2 Epilox 100 DETDA 24 0 100% DBU 2 A19-03 3 Epilox 100 DETDA 19.8 MCDA 3.2 100% DBU 2 A19-03 4 Epilox 100 DETDA 20 IPDA 4 100% DBU 2 A19-03 5 Epilox 100 DETDA 9.1 IPDA 8.6 75% TMG 1.3 (comparative) A19-03 6 Epilox 100 DETDA 8 MCDA 6 70% EMIM- 1.0 (comparative) A19-03 DCA 7 Epilox 100 DETDA 8 MCDA 9.5 75% DABCO 1.5 (comparative) A19-03 8 Epilox 100 DETDA 9.7 MCDA 10 100% DBU 1.3 A19-03 9 Epilox 100 DETDA 7.3 MCDA 7.7 75% DBU 2 A19-03 10 Epilox 100 DETDA 15.6 Dicykan 10.4 100% 0 (comparative) A19-03 initial viscosity Time until start t.sub.open max. modulus Onset Tg after 5 h [mPa*s] [min] of loss at temperature Enthalpy at 145 C. Experiment no. at 45 C. at 45 C. 145 C. [min] [ C.] [J/g] [ C.] 1 (comparative) 640 >300 164 121 240 160 2 653 107 93 85.6 248 161 3 606 53 73 77.4 306 157 4 670 43 76 59 105 160 5 (comparative) 580 31 61* 54.1 386 124 6 (comparative) 620 33 24 59/123 166 152 7 (comparative) 530 11 102 63 310 116 8 400 28 38 59 324 156 9 543 31 46 56 242 118 10 (comparative) 659 29 76 50 279 163 not present Aminic curingpercentage of epoxy groups contained in the resin, which can react with the amino groups of all amines present in the curable composition, i.e. the amino groups of amine 1 and amine 2. xxxnot determined *determined at 120 C. instead of 145 C.

Example 1Preparation and Characterisation of Glass Fiber Laminates

[0214] The individual components were mixed in the ratios as indicated in table 2 in order to obtain epoxy resin mixtures. Afterwards, glass fibers were impregnated with the epoxy resin mixtures in fiber direction 0/90 resulting in laminates with a fiber volume content of about 40%. Curing was done as indicated in Table 2. The fiber-matrix-adhesion of the cured composite elements (plates) was determined in dry state by interlaminar shear strength (ILSS) experiment according to ASTM D2344. Therein, the force necessary for delamination is determined both in warp and in weft direction. 50% of the test specimen was stored for 14 days in water having a temperature of 95 C. Afterwards, these test specimen were measured in warp and in weft direction in wet stage. The results are indicated in table 2.

TABLE-US-00002 TABLE 2 Parts Hardener Parts Diamine Parts Parts per (diamine per (diamine per per Curing Aminic plate resin weight a) weight b) weight catalyst weight conditions curing 2 Epilox 100 DETDA 24 0 DBU 2 2 h 80 C. + 100% A19-03 5 h 145 C. 3 Epilox 100 DETDA 19.8 MCDA 3.2 DBU 2 2 h 80 C. + 100% A19-03 5 h 145 C. 4 Epilox 100 DETDA 20 IPDA 4 DBU 2 2 h 80 C. + 100% A19-03 5 h 145 C. 5 Epilox 100 DETDA 9.1 IPDA 8.6 TMG 1.3 2 h 80 C. + 75% (comparative) A19-03 5 h 125 C. 6 Epilox 100 DETDA 8 MCDA 6 EMIM- 1.0 5 h 145 C. 70% (comparative) A19-03 DCA 7 Epilox 100 DETDA 8 MCDA 9.5 DABCO 1.5 2 h 80 C. + 75% (comparative) A19-03 5 h 145 C. 8 Epilox 100 DETDA 9.7 MCDA 10 DBU 1.3 2 h 80 C. + 100% A19-03 5 h 145 C. 9 Epilox 100 DETDA 7.3 MCDA 7.7 DBU 2 2 h 80 C. + 75% A19-03 5 h 145 C. 10 Epilox 100 DETDA 15.6 Dicykan 10.4 0 2 h 80 C. + 100% (comparative) A19-03 5 h 145 C. ILSS dry warp Mean ILSS dry weft ILSS wet warp ILSS wet weft value Mean value Mean value Mean value plate Tg [ C.] [N/mm.sup.2] [N/mm.sup.2] [N/mm.sup.2] [N/mm.sup.2] 2 141 54.59 51.40 44.90 41.19 3 163 54.38 50.52 42.20 41.30 4 157 54.50 54.26 46.79 40.55 5 (comparative) 128 54.68 49.34 33.78 29.68 6 (comparative) 157 44.26 40.21 40.83 36.03 7 (comparative) 121 49.65 45.88 42.22 36.35 8 161 58.31 51.21 51.28 46.26 9 120 58.67 52.80 50.53 46.01 10 (comparative) 165 51.54 40.70 42.88 36.91 not present Aminic curingpercentage of epoxy groups contained in the resin, which can react with the amino groups of all amines present in the curable composition, i.e. the amino groups of amine 1 and amine 2.

[0215] As apparent from the results shown in Tables 1 and 2, DETDA offered a very suitable t.sub.open (>300 min) but required much time for curing. Mixing of DETDA with other cycloaliphatic amines reduced the curing time but also reduced t.sub.open, i.e. the time left for processing. The addition of catalysts also accelerated the curing, wherein only the combination of DETDA with DBU still gave suitable t.sub.open values in the range of from 28 to 107 minutes. The ILSS measurements in dry state resulted in comparable results at least for the combinations of DETDA with DBU and of DETDA with TMG; already the combinations of DETDA with EMIM-DCA and of DETDA with DABCO gave poorer results. However, it was surprisingly found that only the combination of DETDA with DBU still resulted in good ILSS values after storage in hot water, i.e. only the laminates with DETDA and DBU showed a good resistance to hot water treatment, meaning that the ILSS in warp direction was above 50 N/mm.sup.2 and in weft direction was above 40 N/mm.sup.2.