Two-component adhesive of epoxy resin/polyol pack and polyamide/aliphatic amine/tertiary amine pack
View Patent ↗An epoxy adhesive composition of an epoxy resin, an epoxy terminated liquid rubber, filler, and an amine curing package for said epoxy resin is disclosed. Advantageously, a short chain diol will be incorporated into the adhesive in order to enhance reactivity and strength build. Advantageously, a mixture of amines will be used in the curative including multifunctional aliphatic amines that improve adhesion and strength build; tertiary amines which are used to enhance adhesion and strength build, polyamides which can be used to provide flexibility; and amine-terminated rubbers (ATBN) which can improve toughness and impact resistance to the cured system. The preferred short chain diol is glycerin. Surfaces of adherends are joined with the dried residue of the epoxy adhesive composition by applying the epoxy resin composition to one or both surfaces, joining the surfaces, and applying pressure, optionally with heating.
1. In a two-component epoxy adhesive composition of an epoxy resin and an amine hardener, the improvement for enhancing reaction rate and adhesion to toughened SMC substrates, which comprises:
(a) a resin pack comprising i) an epoxy compound reacted with butadiene-(meth)acrylonitrile copolymer having at least two groups which are reactive with epoxy groups and ii) short chain aliphatic polyol accelerating agent;
(b) a curative pack comprising a polyamide, aliphatic amine, and a tertiary amine,
wherein said curative pack includes amine terminated rubber.
2. The improved epoxy adhesive composition of claim 1 , wherein said epoxy resin is one or more of polyglycidyl ethers of polyhydric polyols, polyglycidyl ethers of aliphatic and aromatic polycarboxylic acids, polyglycidyl ethers of polyphenols, epoxy resins modified with acrylate or urethane moieties, glycidylamine epoxy resins, or novolak resins.
3. The improved epoxy adhesive composition of claim 1 , wherein said polyamide is a reaction of an aliphatic polyamine with one or more polymeric unsaturated higher fatty acids being one or more of a dimerized unsaturated higher fatty acid, an unsaturated trimerized higher fatty acid, or and their associated imidazolines.
4. The improved epoxy adhesive composition of claim 1 , wherein said tertiary amines are one or more of pyridines, pyrazines, pyrimidines, purines, benzimidazoles, quinolines, imidazoles, or Mannich bases.
5. The improved epoxy adhesive composition of claim 3 , wherein the Mannich bases are one or more of tris(dimethyl)aminoethylphenol, tris(dimethyl)aminomethyphenol, dimethylaminomethylphenol, 4,4′-dihydroxy-3,5,3′, 5′-tetra(dimethylaminomethyl)-phenyl-dimethyl methane, or Mannich bases derived from a phenol having at least one tertiary amino group being one or more of dialkylamino, dihydroxyalkylamino, diarylamino, dihyroxyarylamino, piperidino, and morpholino groups, and a least one phenolic hydroxyl group.
6. The improved epoxy adhesive composition of claim 1 , wherein said imidazoles are one or more of 2-ethyl-4-methyl imidazole, methyl imidazole, imidazole, 2,4-diamino-6(2′-methylimidazolyl-(1′))ethyl-S-triazine isocyanurate, 2,4-diamino-6(2′-methylimidazolyl-(1′))ethyl-S-triazine, or 2-heptadecylimidazole.
7. The improved epoxy adhesive composition of claim 1 , wherein said curative pack includes one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, 2-methyl-1,5-pentanediamine, pentaethylenehexamine, hexamethylenediamine, trimethyl-1,6-hexanediamine, polyetherdiamine, diethylaminopropylamine, oleylamine, isophorone diamine, diethanolamine, triethanolamine, m-xylenediamine, diaminodiphenylsulfone, bis(aminopropyl)piperazine, or N-aminoethylpiperazine.
8. The epoxy adhesive composition of claim 1 , wherein said polyol is one or more of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, glycerol, dipropylene glycol, tripropylene glycol, 2-methyl-1,3-propanediol, pentaerythritol, trimethylopropane, 1,4,6-octanetriol, butanediol, pentanediol, hexanediol, dodecanediol, octanediol, chioropentanediol, glycerol monoethyl ether, diethylene glycol, 2-ethylhexanediol, 1,4-cyclohexanediol, 1,2,6-hexanetriol, 1,3,5-hexanetriol, or 1,3-bis-(2-hydroxyethoxy)propane.
9. The improved epoxy adhesive composition of claim 1 , wherein said butadiene-(meth)acrylonitrile copolymer is present in an amount of between about 5 and about 30 percent.
10. The improved epoxy adhesive composition of claim 1 , which includes one or more of phosphine, polyamine, polyamidoamine, and polyamide catalysts and curing agents; particulate and reinforcing fillers and thixotropic agents, tinctorial pigments, opacifying pigments; or fillers.
11. The improved epoxy adhesive composition of claim 1 , wherein said fillers include one or more of para-aramid, kaolin, talc, mica, clay, calcium carbonate, alkaline earth inorganic salt, metal, metal oxide, silica, hollow glass sphere, or ceramic bead.
12. The improved epoxy adhesive composition of claim 1 , wherein said short chain aliphatic polyol comprises glycerin in an amount of between about 0.5 and about 9.9 percent.