Blends of liquid epoxy and solid phenoxy resins

Abstract

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.

Claims

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.

Description

EXAMPLES

Example 1

(1) Blend of EP 834 (EPIKOTE Resin 834) and phenoxy resin PKHH (Ex InChem), the epoxy resin is placed in a reactor under nitrogen and heated until 100 C. and further to 160 C. under agitation, when reached the pellets of PKHH are gradually added. After 180-240 minutes the PKHH resin is completely dissolved into the epoxy resin. The table 1 below reports the ratio tried, the viscosities and the Tg.

(2) For two blends we have measured the adhesive properties.

(3) TABLE-US-00001 TABLE 1 Visco @ Visco @ Visco @ Loop tack E 834 PKHH 100 C. 120 C. 140 C. Tg, C. @ room temp A 75 25 7500 B 80 20 26750 7250 18 C 85 15 10050 2750 8 2.980/3.303 D 90 10 2850 900 3 9.703/9.270 Visco measured with Brookfield and with Spindle 27, Tg measured by DSC condition see test method section. Loop tack test in N/inch.sup.2. The films based on 1C and 1D were stored for more than 12 months on release paper at 23 C. without any changes in performance.

Example 2

(4) The phenoxy resin-liquid epoxy resin blend as prepared according to 1D has been tested with a conventional infusion curable epoxy resin system RIMR135 (epoxy part) and RIMH137 (hardener part) (ex. Momentive Specialty Chemicals Inc.). In the Table 2 below the Tg is reported after a cure cycle of 5 hours at 80 C.

(5) TABLE-US-00002 TABLE 2 Weight % of 1D Tg midpoint value, in C. 0.0 84.10 0.5 81.05 5.0 81.34 10.0 79.01

Example 3

(6) A fiber reinforcement is impregnated with the phenoxy resin-liquid epoxy resin of example 1D and cured with the infusion epoxy curable of Example 2.

(7) The ratio organic matrix over the glass fiber is 40/60 on volume or 30/70 on weight.

(8) For a glass fiber material of 800-1000 gram/m.sup.2 the phenoxy resin-liquid epoxy resin of Example 1 is applied in proportion of 20-40 gram/m.sup.2. No negative impact on mechanical properties has been observed.