Oxazolidinone- and isocyanurate-crosslinked matrix for fiber-reinforced material

Abstract

The present 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 crosslinked thereby, starting from a liquid reaction mixture comprising: (a) at least one liquid, aromatic epoxy resin; (b) at least one liquid, aromatic polyisocyanate; and (c) a catalyst composition; relative to the at least one polyisocyanate, the at least one epoxy resin is used in amounts such that the molar equivalent ratio of epoxide groups to isocyanate groups is at least 0.4; and curing the reaction mixture to give a cured polymer composition comprising at least one oxazolidinone ring and at least one isocyanurate ring, and also to the cured compositions obtainable by these methods.

Claims

1. A method for producing a cured polymer composition comprising at least one oxazolidinone ring and at least one isocyanurate ring, the method comprising the following steps: (1) providing a liquid reaction mixture, comprising: (a) at least one liquid, aromatic epoxy resin; (b) at least one liquid, aromatic polyisocyanate; and (c) a catalyst composition, comprising an ionic compound of formula (I) ##STR00002## wherein R.sub.1 and R.sub.3 are each selected independently of one another 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; R.sub.4 and R.sub.5 are each selected independently of one another from the group consisting of hydrogen, 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, substituted or unsubstituted, linear or branched alkoxy having 1 to 20 carbon atoms, and substituted or unsubstituted aryl having 5 to 10 carbon atoms; or R.sub.1 and R.sub.5 and/or R.sub.3 and R.sub.4 or R.sub.4 and R.sub.5, together with the carbon or nitrogen atoms to which they are bound, can form a 5- or 6-membered substituted or unsubstituted cycloalkyl, cycloheteroalkyl, aryl or heteroaryl ring, wherein the cycloheteroalkyl or heteroaryl ring comprises 1 to 3 heteroatoms selected from O, N and S; R2 is hydrogen; X is an anion not including Fl.sup., Cl.sup., Br.sup. or I.sup.; and n is 1, 2 or 3; wherein the at least one epoxy resin, relative to the at least one polyisocyanate, is used in amounts so that the molar equivalent ratio of epoxide groups to isocyanate groups is in the range of 0.4 to 1; and (2) curing the reaction mixture so as to obtain a cured polymer composition comprising 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 methylene diphenyl diisocyanate (MDI).

5. The method according to claim 1, wherein the catalyst composition further comprises at least one nitrogen-containing base.

6. The method according to claim 1, wherein the catalyst composition further comprises at least one non-ionic, nitrogen containing base which comprises at least one tertiary nitrogen atom and/or an imine nitrogen atom.

7. The method according to claim 1, wherein 0.01 to 10 wt. % of the catalyst composition is employed, based on the total weight of the reaction mixture.

8. The method according to claim 1, wherein: the reaction mixture is free from epoxide curing agents which catalyze a polyaddition reaction; the reaction mixture has a viscosity of <100 mPas at a temperature of 120 C.; the cured polymer composition has a modulus of elasticity of more than 2500 N/mm.sup.2; and/or the cured polymer composition has a glass transition temperature of more than 150 C.

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

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

11. The method according to claim 10, wherein step (1) comprises injecting the injection resin into a molding tool, into which fiber prewovens/preforms have been placed.

12. A cured polymer composition, obtainable by a method according to claim 1.

13. The cured polymer composition according to claim 12, wherein the cured polymer composition is a fiber-reinforced molded part further comprising a fiber prewoven/preform therein.

14. The method according to claim 8, wherein the cured polymer composition has a modulus of elasticity of more than 3000 N/mm.sub.2.

15. The method of claim 1 wherein X is selected from dicyandiamide anion, OH.sup., HSO.sub.3, NO.sub.2, NO.sub.3, PF.sub.6, ClO.sub.4, acetate, citrate, formate, glutarate, lactate, malate, malonate, oxalate, pyruvate, tartrate, cyanocyanamide, SCN.sup. and P(OEt).sub.2O.sub.2.

16. A method for transfer molding (RTM) method, comprising: providing an open mold; providing a fiber component comprising a plurality of fibers formed in a shape; disposing the fiber component into the open mold; closing the mold; providing a liquid reaction mixture, comprising: at least one liquid, aromatic epoxy resin; at least one liquid, aromatic polyisocyanate; and a catalyst composition comprising an ionic compound of Formula (I) ##STR00003## wherein R.sub.1 and R.sub.3 are each selected independently of one another 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; R.sub.4 and R.sub.5 are each selected independently of one another from the group consisting of hydrogen, 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, substituted or unsubstituted, linear or branched alkoxy having 1 to 20 carbon atoms, and substituted or unsubstituted aryl having 5 to 10 carbon atoms; or R.sub.1 and R.sub.5 and/or R.sub.3 and R.sub.4 or R.sub.4 and R.sub.5, together with the carbon or nitrogen atoms to which they are bound, can form a 5- or 6-membered substituted or unsubstituted cycloalkyl, cycloheteroalkyl, aryl or heteroaryl ring, wherein the cycloheteroalkyl or heteroaryl ring comprises 1 to 3 heteroatoms selected from O, N and S; R.sub.2 is hydrogen; X is an anion; and n is 1, 2 or 3; wherein the at least one epoxy resin, relative to the at least one polyisocyanate, is used in amounts so that the molar equivalent ratio of epoxide groups to isocyanate groups is in the range of 0.4 to 1; loading the liquid reaction mixture into the mold having the fiber component disposed therein; and curing the reaction mixture so as to obtain a fiber reinforced part comprising the fiber component disposed in a cured polymer composition comprising at least one oxazolidinone ring and at least one isocyanurate ring.

17. The method of claim 16 wherein the catalyst composition comprising at least one nitrogen-containing base comprises at least one non-ionic, nitrogen containing base which comprises at least one tertiary nitrogen atom and/or an imine nitrogen atom.

18. The method of claim 1 wherein the liquid reaction mixture is free of solvent.

Description

EXAMPLES

(1) DER331 (Dow Chemical, liquid epoxy resin made of epichlorohydrin and bisphenol A) and a catalyst composition were mixed for 30 seconds at 2000 rpm under vacuum in a high-speed mixer. After this mixture cooled to room temperature, methylene diphenyl diisocyanate (MDI) was added and likewise incorporated by mixing for 30 seconds at 2000 rpm under vacuum by way of the high-speed mixer. The reaction mixture was loaded into an upright mold and gelled at room temperature. Thereafter, the mixture was cured in two stages (1 hour at 90 C., and 1 hour at 150 C.). After cooling, the test specimens required for the mechanical tests are milled from the panel thus obtained.

(2) TABLE-US-00001 TABLE 1 Components of the reaction mixtures Composition E1 E2 E3 E4 E5 E6 E7 E8 E9 V1 Components Initial weight in parts by weight Catalyst 1 1 1 1 1 1 1 1 0.2 1 composition DER 331 50 50 60 40 50 50 50 50 50 30 MDI 50 50 40 60 50 50 50 50 50 70 E: according to the invention; V: comparative experiment E1: catalyst = imidazolium + 2,4-EMI E2: catalyst = 1-methylimidazole E3: catalyst = 1-methylimidazole E4: catalyst = 1-methylimidazole E5: catalyst = 2-phenyl-2-imidazoline E6: catalyst = N,N-dimethylbenzylamine E7: catalyst = 2-ethyl-4-methylimidazole E8: catalyst = 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) E9: catalyst = 1,4-diazabicyclo[2.2.2]octane (DABCO) V1: catalyst = 1-methylimidazole

(3) TABLE-US-00002 TABLE 2 Physical properties E1 E2 E3 E4 E5 E6 E7 E8 E9 V1 Tensile test EMod in MPa 3303 3210 3250 4140 4601 3489 4234 still 1B dog tacky bone after EN-ISO Max. stress 53.1 29.3 75.4 11.1 29.4 38.8 19 34.5 51.2 curing 527/2.3 in MPa Elongation at 1.65 0.92 2.67 0.25 0.64 0.88 0.5 0.99 1.23 rupture in % Stress 53.1 29.3 74.8 11.1 29.4 38.8 19 34.5 51 fracture in Mpa 3-point Emod in MPa 3745 3737 2904 3995 4323 2945 3038 2338 3850 bending test DIN EN- F max in 133 143 157 150 170 21.8 32.8 23 119 ISO 178 MPa % 3 4.1 7.5 3.9 4.3 0.7 1 0.95 3 compression K1c in MPa .Math. vm 0.67 0.58 0.92 0.61 0.52 0.55 0.57 0.65 ISO 13586 DMTA TG G 163 182 165 133_180_240 98 112 210 160 70 139 Tg tan delta 203 213 178 215_265 183 188 235 207 117 150