Cured composition having high impact strength and temperature resistance, based on an epoxy resin and a polyisocyanate

Abstract

The invention relates to a method for producing a cured composition which has at least one oxazolidinone ring and at least one isocyanurate ring and is cross-linked by the same, starting from a liquid reactive mixture which, based on the total weight thereof, contains at least one epoxy resin, at least one polyisocyanate, at least one polyol, and at least one catalyst composition. The invention further relates to the cured composition obtainable thereby.

Claims

1. A method for preparing a cured polymer composition which comprises at least one oxazolidinone ring and at least one isocyanurate ring, wherein the method comprises the steps of: (1) providing a liquid reaction mixture comprising, based on the total weight thereof: (a) 30 to 50 wt. % of at least one liquid, aromatic epoxy resin; (b) 35 to 70 wt. % of at least one liquid, aromatic polyisocyanate; (c) 4 to 20.0 wt. % of at least one polyol; and (d) 0.01 to 10.0 wt. % of a catalyst wherein all of the catalyst in the reaction mixture consist of 1-methylimidazole, 2,4-ethylmethylimidazole (EMI), 4-dimethylaminopyridine, 1,4-diazabicyclo[2.2.2]octane (DABCO), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5-diazabicyclo[3.4.0]non-5-ene (DBN) and mixtures thereof, wherein the at least one epoxy resin, based on the at least one polyisocyanate, is used in such amounts that the molar equivalent ratio of isocyanate groups to epoxide groups is between 1.4 and 10; and (2) curing the reaction mixture in order to obtain a cured polymer composition which comprises at least one oxazolidinone ring and at least one isocyanurate ring.

2. The method according to claim 1, wherein the at least one epoxy resin is a glycidyl ether.

3. The method according to claim 1, wherein the at least one epoxy resin is a bisphenol diglycidyl ether.

4. The method according to claim 1, wherein the at least one polyisocyanate is a methylene diphenyl diisocyanate (MDI).

5. The method according to claim 1, wherein the at least one polyol is selected from the group consisting of polyether polyol, polyester polyol and mixtures thereof.

6. The method according to claim 1, wherein the at least one polyol is selected from the group consisting of polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyhexamethylene glycol and mixtures thereof.

7. The method according to claim 1, wherein: (a) the reaction mixture is free of epoxy curing agents which enter into a polyaddition reaction; (b) the reaction mixture has a viscosity of <100 mPas at a temperature of 80° C.; (c) the cured polymer composition has a modulus of elasticity of more than 2500 N/mm.sup.2; and/or (d) the cured polymer composition has a glass transition temperature of more than 100.

8. The method according to claim 1, wherein: (a) the reaction mixture in step (2) is cured at a temperature of between 10° C. and 230° C. for 0.01 to 10 hours; or (b) the reaction mixture in step (2) is first cured at a temperature of between 50° C. and 130° C. for 0.1 hours to 3 hours and then at a temperature of between 110° C. and 190° C. for 0.1 hours to 3 hours.

9. The method according to claim 1, wherein the method is a transfer molding (RTM) method and the reaction mixture is a reactive injection resin.

10. The method according to claim 9, wherein step (1) comprises injecting the reactive injection resin into a die in which fibers or semi-finished fiber products are disposed.

11. The cured polymer composition of claim 1.

12. A resin composition, wherein the resin composition comprises, based on the total weight thereof: (a) 45.0 to 82.5 wt. % of at least one liquid, aromatic epoxy resin; (b) 35 to 60 wt. % of at least one liquid, aromatic polyisocyanate; (c) 1.0 to 20.0 wt. % of at least one polyol; and (d) 0.01 to 10.0 wt. % of at least one catalyst; wherein the at one epoxy resin, based on the at least one polyisocyanate, being used in such amounts that the molar equivalent ratio of isocyanate groups to epoxide groups is greater than 1.2.

13. Cured reaction products of the polymer composition according to claim 12.

14. A fiber-reinforced molded article comprising cured reaction products of the polymer composition according to claim 12.

15. The resin composition according to claim 12, wherein all of the catalyst is a tertiary amine of formula (I) NR.sub.1R.sub.2R.sub.3 and/or an imine of formula (II) N(═R.sub.4)R.sub.5, R.sub.1 to R.sub.3 and R.sub.5 are each independently selected from the group consisting of substituted or unsubstituted, linear or branched alkyl having 1 to 20 carbon atoms, substituted or unsubstituted, linear or branched alkenyl having 3 to 20 carbon atoms and substituted or unsubstituted aryl having 5 to 20 carbon atoms, or at least two of R.sub.1 to R.sub.3 form, together with the nitrogen atom to which they are bonded, a 5- to 10-membered heteroalicyclic ring or heteroaryl ring, which optionally contains one or more additional nitrogen atoms, R.sub.4 is a substituted or unsubstituted, linear or branched alkylenyl having 3 to 20 carbon atoms, or R.sub.4 and R.sub.5 form, together with the nitrogen atom to which they are bonded, a 5- to 10-membered heteroalicyclic ring or heteroaryl ring, which optionally contains additional nitrogen atoms.

16. The resin composition according to claim 15, wherein R.sub.4 and R.sub.5 form, together with the nitrogen atom to which they are bonded, a 5- to 10-membered heteroalicyclic ring or heteroaryl ring, which optionally contains additional nitrogen atoms.

17. The resin composition according to claim 12, further comprising (e) one or more of solvent, a modified resin, toughener, filler, softener, reactive diluent, nonreactive diluent, coupling agent, adhesion promoter, wetting agent, release agents flame retardant, thixotropic agent, rheological auxiliary, ageing inhibitor, corrosion inhibitor, stabilizer and dye.

18. The resin composition according to claim 12, wherein all of the catalyst in the resin composition consists of a mixture of 2,4-ethylmethylimidazole (EMI) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU).

Description

EXAMPLES

(1) According to the weight specifications in the following tables, Table 1 and Table 2, a diglycidyl ether of bisphenol A (DEGBA; epoxy equivalent of 187 g/mol), a catalyst composition (EMI: 2-ethyl-4-methylimidazole; DBU: diazabicycloundecene) and optionally a polypropylene glycol (Mw 2000 g/mol) were mixed in a speed mixer for 30 s at 2000 rpm in a vacuum. After cooling this mixture to room temperature, a mixture of methylene diphenyl diisocyanate (MDI) and polymers thereof (PMDI), with an NCO equivalent weight of 129 g/mol, was added and likewise mixed using a speed mixer for 30 s at 2000 rpm in a vacuum. The reaction mixture was poured into PTFE molds in order to produce standard-compliant test pieces for determining mechanical data. The resin mixture was first gelled in the mold for 8 min at 100° C. The test pieces were then removed from the mold and post-cured for 30 min at 130° C. and then for 30 min at 180° C. The mechanical characteristics were determined accordingly: stress test according to EN-ISO 527; three-point bending test according to EN-ISO 178; fracture toughness according to IOS 13586; Tg by means of DMTA.

(2) Using the mechanical properties of the tests indicated in Tables 1 and 2, it can be seen that the examples using a polyol and an excess of isocyanate groups of at least 1.2 have a balanced property profile in which the modulus of elasticity, the K1c value and the glass transition temperature are all at the desired level.

(3) TABLE-US-00001 TABLE 1 ε- TG Fmax/ Fmax/ TG tan NCO/EP DEGBA MDI Polyol EMI24 DBU Modulus of elasticity/MPa MPa % K1c G″ d 1 1.20 54.0 44.8 1.4 2484 138.5 6.64 158 203 2 1.41 50.0 48.6 1.4 3083 136 4.34 0.66 166 183 3 1.73 45.0 53.6 1.4 3268 81.2 2.39 0.58 176 190 4 2.12 40.0 58.6 1.4 3315 64.6 1.87 0.58 193 235 5 1.41 49.5 48.1 1.0 1.4 2978 74.5 2.11 0.52 162 185 6 2.01 40.9 56.7 1.0 1.4 3233 100.1 2.90 0.66 170 201 7 1.20 52.5 43.6 2.5 1.4 2814 93.1 3.19 0.84 168 198 8 1.30 50.0 44.7 3.3 1.3 2671 56.2 1.99 0.86 172 9 0.69 63.4 30.2 5.0 1.4 FOAMS STRONGLY 215 10 1.13 52.5 41.1 5.0 1.4 FOAMS STRONGLY 162 198 11 1.20 50.5 42.3 5.0 1.4 2424 190.6 3.66 1.53 157 12 1.41 47.5 46.1 5.0 1.4 2532 84.1 3.66 1.1 164 186 13 1.57 45.0 48.6 5.0 1.4 2674 75.2 2.84 0.85 172 205 14 0.68 62.9 29.7 5.0 1.0 1.4 FOAMS STRONGLY 189 15 1.00 54.9 37.8 5.0 1.0 1.4 FOAMS STRONGLY 179 16 1.13 52.0 40.6 5.0 1.0 1.4 2652 129.6 5.98 0.92 159 177 17 1.20 50.5 42.3 5.0 1.0 1.4 2532 103.3 4.60 1.88 157 202 18 1.67 43.0 49.6 5.0 1.0 1.4 3043 80.6 2.56 0.82 165 274

(4) TABLE-US-00002 TABLE 2 ε- TG Fmax/ Fmax/ TG tan NCO/EP DEGBA MDI Polyol EMI24 DBU Modulus of elasticity/MPa MPa % K1c G″ d 19 1.00 52.5 36.1 10.0 1.4 FOAMS STRONGLY 154 168 20 1.20 48.0 39.8 10.0 1.4 2152 92.1 4.50 1.58 157 212 21 1.40 45.0 43.6 10.0 1.4 2264 73.1 3.29 1.54 162 173 22 2.00 37.2 51.4 10.0 1.4 2203 61.4 2.88 0.9 171 202 23 3.00 28.5 58.9 10.0 0.9 1.2 2181 73.6 3.29 0.7 172 227 24 4.00 23.2 64.1 10.0 0.9 1.2 2309 57.4 2.38 0.7 175 220 25 1.40 44.5 43.1 10.0 1.0 1.4 2544 78.0 3.37 1.27 156 176 26 1.51 42.8 44.7 10.0 1.0 1.4 2580 93.5 3.81 1.02 161 191 27 1.67 40.7 46.9 10.0 1.0 1.4 2672 95.9 3.68 1.03 164 248 28 1.77 39.5 48.1 10.0 1.0 1.4 2697 101.5 4.08 0.97 163 146 29 2.00 36.8 50.8 10.0 1.0 1.4 2398 104.0 4.92 0.89 165 182