Epoxy resin system containing polyethylene tetraamines for resin transfer molding processes

Patent metadata

Field	Value
Publication number	US-9688807-B2
Application number	US-201314422021-A
Country	US
Kind code	B2
Filing date	Nov 11, 2013
Priority date	Nov 13, 2012
Publication date	Jun 27, 2017
Grant date	Jun 27, 2017

Abstract

A two-component curable epoxy resin system is disclosed. The resin system includes an epoxy resin component containing at least 80% by weight of a polyglycidyl ether of a polyphenol. The system also includes a hardener mixture containing mainly polyethylene tetraamines. The system includes one or more of i) alkali metal salts, ii) carboxylic acid-, carboxylic anhydride- or carboxylic acid ester-substituted phenol compounds, iii) an amino as a catalyst. The system has beneficial curing characteristics that make it useful for producing fiber-reinforced composites in a resin transfer molding process.

First claim

The invention claimed is:

1. A process for forming a fiber-reinforced epoxy composite, comprising;
a) mixing an epoxy resin component with an amine hardener by impingement mixing and transferring the resulting reactive mixture into a mold that contains reinforcing fibers, and
b) curing the reactive mixture in the mold at temperature of 100 to 120° C. to form a fiber-reinforced composite in which the reinforcing fibers are embedded in a polymeric matrix formed by curing the reactive mixture, and
c) demolding the fiber-reinforced composite, wherein;
1) the epoxy resin component contains one or more epoxy resins, wherein at least 80% by weight of the epoxy resin is one or more polyglycidyl ethers of a polyphenol that has an epoxy equivalent weight of up to about 250;
2) the amine hardener is a polyethylene tetraamine mixture containing at least 95% by weight polyethylene tetraamines, the mixture containing at least 40% by weight linear triethylene tetraamine,
3) in step a) the epoxy resin component and the amine hardener are mixed in proportions which, prior to reaction, provide 0.8 to 1.25 epoxy equivalents per equivalent of amine hydrogens; and
4) at least one catalyst selected from the group consisting of i) from 0.01 to 0.05 moles of an alkali metal salt per mole of the amine hardener, ii) from 0.025 to 0.25 moles of an carboxylic acid-, carboxylic anhydride- or carboxylic acid ester-substituted phenol compound per mole of the amine hardener, iii) from 0.025 to 0.25 moles of an amino acid per mole of the amine hardener is provided in the amine hardener, wherein the reactive mixture exhibits a gel time of at least 30 seconds and a demold time of no greater than 350 seconds measured at 100° C.

2. The process of claim 1 , wherein the catalyst is lithium bromide.

3. The process of claim 1 , wherein the catalyst is one or more of salicylic acid, methyl salicylate, ethyl salicylate, 4-hydroxybenzoic acid, methyl 4-hydroxybenzoate, ethyl 4-hydroxybenzoate, 4-hydroxyisophthalic acid, methyl 4-hydroxyisophthalate, and ethyl 4-hydroxyisophthalate.

4. The process of claim 3 , wherein the catalyst is L-proline.

5. The process of claim 1 , wherein the demold time is 300 seconds or less.

6. The process of claim 1 , wherein the demold time is 240 seconds or less.

7. The process of claim 1 , wherein the cured epoxy resin phase has a glass transition temperature of at least 110° C. at the time of demold.

8. The process of claim 1 , which is a resin transfer molding process.

9. The process of claim 1 , wherein the polyethylene ttramine mixture contains no more than 0.3% by weight aminoethylethanolamine.

10. The process of claim 1 , wherein the reactive mixture contains an internal mold release agent.

11. A cured fiber-reinforced composite made by the process of claim 1 .

Assignees

• Dow Global Technologies Llc

Inventors

• Grunder Sergio
• Koeniger Rainer
• Morley Timothy A
• Jelic Nebjosa
• Reimers Martin
• Cate Peter

Classifications

• C08G59/502

  Polyalkylene polyamines · CPC title

• C08G59/683

  Phenolates · CPC title

• C08G59/685

  Carboxylates · CPC title

• C08L2205/16

  Fibres; Fibrils · CPC title

• C08G59/02 Primary

  Polycondensates containing more than one epoxy group per molecule · CPC title