FAST-CURE RESIN FORMULATIONS WITH CONSISTENT HANDLING CHARACTERISTICS

20250075028

18/898207

September 26, 2024

The present invention relates to rapid-curing resin formulations as well as fiber- reinforced composite materials comprising the same and their use in the manufacture of molded articles, particularly where the manufacturing process requires high throughput and where resin formulations having consistent handling characteristics (e.g., tack and flexibility) would be preferable across normal to elevated laminating environments (as defined by temperatures between 20° C. and 60° C.). The present invention further relates to a manufacturing process for preparing an article, particularly a molded article, from a fiber-reinforced composite material comprising a rapid-curing resin formulation.

CYTEC INDUSTRIES, INC. (PRINCETON, NJ, US)

1. A curable resin comprising: at least one thermosetting resin selected from difunctional and multifunctional epoxy resin; from about 1 wt % to about 15 wt % of a curative mixture comprising a solid substituted imidazole curative and a diamine curative; and from about 2 wt % to about 10 wt %, of at least one thermoplastic additive selected from polyvinylformal resins, polyarylethersulfone resins, and mixtures thereof, wherein the curable resin exhibits: (i) a glass transition temperature (Tg) from about 130° C. to about 200° C. when cured; (ii) a cure conversion of at least 95% when cured for a duration of no more than 10 minutes at a temperature of no more than 10° C. above the Tg of the curable resin when cured; (iii) a phase angle of between between 50° and 87°, and preferably between 70° and 85°, when heated from 20° C. to 60° C.; and (iv) a complex modulus of between about 100 Pa·s and about 10,000,000 Pa·s between 20 and 60° C.

2. The curable resin according to claim 1, wherein the curable resin exhibits an epoxy equivalent weight of at least about 150 g/mol.

3. The curable resin according to claim 1, wherein the curable resin exhibits a cure conversion of at least 95% when cured for a duration of no more than 10 minutes at a temperature between about 120° C. and about 175° C.

4. The curable resin according to claim 1, wherein the difunctional and multifunctional epoxy resins are selected from glycidyl ethers of phenol and cresol epoxy novolacs, glycidyl ethers of phenol-aldehyde adducts, aromatic epoxy resins, aliphatic triglycidyl ethers, dialiphatic triglycidyl ethers, aliphatic polyglycidyl ethers, epoxidised olefins, triglycidyl aminophenols, aromatic glycidyl amines, heterocyclic glycidyl imidines and amides, glycidyl ethers, fluorinated epoxy resins, N,N,N′,N′-tetraglycidyl diamino diphenylmethane (TGDDM), N,N,N′,N′-tetraglycidyl-m-xylenediamine, and any combination thereof.

5. The curable resin of claim 1, wherein the at least one thermosetting resin is selected from diglycidyl ether of bisphenol F (DGEBF), diglycidyl ether of bisphenol A (DGEBA), and diglycidyl ether of dihydroxy naphthalene.

6. The curable resin according to claim 1, wherein the substituted imidazole curative is selected from 6-(2-(2-methyl-1H-imidazol-1-yl)ethyl)-1,3,5-triazine-2,4-diamine, 1-((2-methyl-1H-imidazol-1-yl)methyl)naphthalen-2-ol, 3-(2-phenyl-1H-imidazol-1-yl)propanenitrile, (2-phenyl-1H-imidazole-4,5-diyl)dimethanol, bis(2-ethyl-5-methyl-1H-imidazol-4-yl)methane, 1-(cyanoethyl)-2-ethyl-4-methylimidazole, 6-[2-(2-ethyl-4-methylimidazol-1-yl)ethyl]-1,3,5-triazine-2,4-diamine, and the diamine curative is selected from 1,3-diaminobenzene, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl sulphone (4,4′ DDS), 3,3′-diaminodiphenyl sulphone (3,3′ DDS), bis(4-amino-3,5-dimethylphenyl)-1,4-diisopropylbenzene, bis(4-aminophenyl)-1,4-diisopropylbenzene, 4-chlorophenyl-N,N-dimethyl-urea, 3,4-dichlorophenyl-N,N-dimethyl-urea, 2,6-and 2,4-toluene bis dimethyl urea, and dicyandiamide.

7. A pre-preg of fiber-reinforced curable composite material, wherein said pre-preg comprises at least one layer of reinforcing fibers impregnated with a curable resin according to claim 1.

8. The pre-preg according to claim 7, wherein the pre-preg comprises reinforcing fibers in an amount of from about 20% to about 70% reinforcing fibers wherein the percentages refer to the volume percent of the fiber by total volume of the pre-preg.

9. The pre-preg according to claim 7, wherein said reinforcing fibers exhibit a tow size of at least 12,000 filaments per tow and/or said at least one layer of reinforcing fibers is a fabric which exhibits an areal weight of at least about 150 g/m2.

10. The pre-preg according to claim 7, wherein said reinforcing fibers are continuous filaments.

11. The pre-preg according to claim 7, wherein the thickness of the pre-preg is from about 150 μm to about 1500 μm.

12. A process for the production of a molded article from a plurality of pre-pregs, the process comprising: (a) disposing a pre-preg according to claim 7 into or onto a mold; (b) optionally repeating step (a) at least once to dispose one or more additional pre-pregs into or onto said mold; and (c) thermally curing the one or more pre-pregs.

13. The process according to claim 12, wherein said thermal curing is effected while the pre-pregs are compressed in a mold cavity.

14. The process according to claim 12, wherein thermal curing is conducted at a cure temperature in the range of from about 120° C. to about 175° C., and wherein the plurality of pre-pregs is held at said cure temperature for a duration of no more 10 minutes.

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edspap.20250075028