Blends of liquid epoxy and solid phenoxy resins
This invention relates to epoxy resin formulations for preforms to be used in molding processes, especially resin transfer molding processes and to methods for preparing the performs. The epoxy formulation is based on liquid or solid epoxy resins blended, with medium to high molecular weight, phenoxy resins. These formulations are highly compatible with epoxy curable injection resins, and more over are reacted in the polymeric matrix, without reducing the glass transition temperature (Tg) of the cured composite material.
1. An epoxy resin formulation consisting essentially of a blend of:
a solid phenoxy resin comprising an average molecular weight between 30000 to 65000 daltons, and
a liquid epoxy resin selected from a diglycidyl ether of biphenol, bisphenol, hydrocarbyl-substituted biphenol, hydrocarbyl-substituted bisphenol, phenol- or hydrocarbyl-substituted bisphenol-aldehyde novolac resin, unsaturated hydrocarbon-phenol or hydrocarbyl-substituted phenol resin, with a level of the solid phenoxy resin on the liquid epoxy resin in the range of from 10 to 25 weight %, and with a level of the liquid epoxy resin on the solid phenoxy resin in the range of from 75 to 90 weight %, wherein the solid phenoxy resin comprises a linear resin terminated with phenolic functions and wherein the phenoxy resins are based on advanced bis-phenol A glycidyl ether with bis-phenol A; and
a solvent,
wherein the epoxy resin formulation does not contain a curing agent and/or a curing catalyst, and wherein the solvent is water.
2. The epoxy resin formulation of claim 1 wherein the solid phenoxy resin is present in an amount between 10 and 20 weight %.
3. A film based material comprising the epoxy resin formulation of claim 1 .
4. A fiber based material comprising:
the epoxy resin formulation of claim 1 and
an infusion curable epoxy resin system comprising an epoxy resin and a curing agent and/or a curing catalyst.
5. The fiber based material of claim 4 wherein the fibers are placed in one direction per layer.
6. The fiber based material of claim 4 in contact with a curable infusion system.
7. The fiber based material of claim 6 wherein the infusion system is based on epoxy curable resins.
8. The epoxy resin formulation of claim 1 wherein the epoxy resin is a diglycidyl ether of Bisphenol A having an epoxide equivalent weight of from about 185 to about 250.
9. An epoxy resin formulation consisting of a blend of:
a solid phenoxy resin comprising an average molecular weight between 30000 to 65000 daltons,
a liquid epoxy resin selected from a diglycidyl ether of biphenol, bisphenol, hydrocarbyl-substituted biphenol, hydrocarbyl-substituted bisphenol, phenol- or hydrocarbyl-substituted bisphenol-aldehyde novolac resin, unsaturated hydrocarbon-phenol or hydrocarbyl-substituted phenol resin, with a level of the solid phenoxy resin on the liquid epoxy resin in the range of from 10 to 25 weight %, and with a level of the liquid epoxy resin on the solid phenoxy resin in the range of from 75 to 90 weight %, wherein the solid phenoxy resin comprises a linear resin terminated with phenolic functions and wherein the phenoxy resins are based on advanced bis-phenol A glycidyl ether with bis-phenol A; and
optionally a solvent.
10. The epoxy resin formulation of claim 9 wherein the solid phenoxy resin is present in an amount between 10 and 20 weight %.
11. The epoxy resin formulation of claim 9 wherein the epoxy resin is a diglycidyl ether of Bisphenol A having an epoxide equivalent weight of from about 185 to about 250.
12. The epoxy resin formulation of claim 9 wherein the solvent is water.