Heat curable epoxy resin composition with water as foaming agent

Patent metadata

Field	Value
Publication number	US-9475904-B2
Application number	US-201113224691-A
Country	US
Kind code	B2
Filing date	Sep 2, 2011
Priority date	Sep 3, 2010
Publication date	Oct 25, 2016
Grant date	Oct 25, 2016

Abstract

Heat-curable epoxy resin compositions and the use thereof, for example, in motor vehicle construction and sandwich panel construction, are disclosed. Exemplary heat-curable epoxy resin compositions include, in addition to epoxy resin components A1, optionally A2, a hardener component B, a carboxylic acid C and a hydroxyalkylamide or hydroxyalkylurea H, an accelerator E for activation of the conversion of components A1, A2 and B. The compositions and the structural foams produced therefrom are notable for high mechanical strength, high glass strength and good adhesion capacity on metallic and nonmetallic substrates, and it is possible at the same time to dispense with the use of toxic or inflammable blowing agents.

First claim

What is claimed is:

1. A heat-curable epoxy resin composition, comprising:
(a) at least one solid epoxy resin A1 having an average of more than one epoxide group per molecule;
(b) at least one hardener B for epoxy resins which is activated by elevated temperature;
(c) at least one carboxylic acid C;
(d) at least one hydroxyalkylamide or hydroxyalkylurea H; and
(e) optionally at least one liquid epoxy resin A2 with an average of more than one epoxide group per molecule,
wherein the heat-curable epoxy resin composition further comprises at least one accelerator E based on a urea derivative for activating a reaction of components A1, and optionally A2, with B, and
wherein a proportion of the accelerator E is selected such that an onset temperature of a reaction of the hydroxyalkylamide or hydroxyalkylurea H with the carboxylic acid C, measured by DSC, is at least 20° C. higher than an onset temperature of the reaction between the solid epoxy resin A1, optionally liquid epoxy resin A2 and hardener B.

2. The heat-curable epoxy resin composition according to claim 1 , wherein the liquid epoxy resin A2 is selected from the group consisting of diglycidyl ethers of bisphenol A, diglycidyl ethers of bisphenol F, and diglycidyl ethers of bisphenol A/F.

3. The heat-curable epoxy resin composition according to claim 1 , wherein the carboxylic acid C is selected from the group consisting of a di- or tricarboxylic acid, and an amorphous, at least difunctional polymer with carboxyl end groups and a molecular weight between about 1600 g/mol and about 5000 g/mol.

4. The heat-curable epoxy resin composition according to claim 3 , wherein the dicarboxylic acid is selected from the group consisting of succinic acid, adipic acid, sebacic acid, glutaric acid and benzenedicarboxylic acid.

5. The heat-curable epoxy resin composition according to claim 1 , wherein the hardener B is a latent hardener selected from the group consisting of dicyandiamide, guanimine, guanidine, aminoguanidine and derivatives thereof, and aromatic or aliphatic carboxylic hydrazides.

6. The heat-curable epoxy resin composition according to claim 1 , wherein the accelerator E is selected from the group consisting of a substituted urea, a phenyldimethylurea, N,N-dimethylurea, N-isobutyl-N′,N′-dimethylurea, 1,1′-(hexane-1,6-diyl)bis(3,3′-dimethylurea), and a product of a reaction of an aromatic monomeric diisocyanate, with an aliphatic amine compound.

7. The heat-curable epoxy resin composition according to claim 1 , wherein the proportion of the accelerator E is selected such that an onset temperature of a reaction between solid epoxy resin A1, liquid epoxy resin A2 and hardener B, measured by DSC, is lowered by 35-60° C.

8. The heat-curable epoxy resin composition according to claim 7 , wherein the proportion of the accelerator E is 0.3-5.0% by weight, of a total weight of the composition.

9. The heat-curable epoxy resin composition according to claim 1 , wherein the hydroxyalkylamide or hydroxyalkylurea H is a hydroxyalkylamide of the formula (VIII)

wherein X is a phenylene group or —(CH 2 ) n —, n=1-7, and R 5 and R 6 are each independently H or an alkyl group having 1 to 5 carbon atoms or —CH 2 CH 2 —OH.

10. The heat-curable epoxy resin composition according to claim 1 , wherein a reaction between the hydroxyalkylamide or hydroxyalkylurea H and the carboxylic acid C releases water which serves as a blowing agent in a foaming process.

11. A reinforcing element for the reinforcement of metallic structures, comprising a support to which the heat-curable epoxy resin composition according to claim 1 has been applied.

12. A process for bonding heat-stable substrates, comprising:
i) applying a heat-curable epoxy resin composition according to claim 1 to a surface of a heat-stable substrate S1;
ii) contacting the applied heat-curable epoxy resin composition with a surface of a further heat-stable substrate S2;
iii) heating the heat-curable epoxy resin composition to a temperature of 100-220° C.;
wherein said substrate S2 is of a same or different material as the substrate S1.

13. The heat-curable epoxy resin composition according to claim 1 , wherein the composition is suitable for use for bonding or reinforcing metal structures or reinforcing filling of cavities in motor vehicle construction or sandwich panel construction.

14. A structural foam obtained by heating the heat-curable epoxy resin composition according to claim 1 .

15. The heat-curable epoxy resin composition according to claim 1 , wherein the accelerator E is 3-(3-chloro-4-methylphenyl)-1,1-dimethylurea (chlorotoluron), p-chlorophenyl-N,N-dimethylurea (monuron), 3-phenyl-1,1-dimethylurea (fenuron), 3,4-dichlorophenyl-N,N-dimethylurea (diuron), or a product of a reaction of diphenylmethylene 4,4′-diisocyanate with dimethylamine.

16. The heat-curable epoxy resin composition according to claim 1 , wherein the proportion of the accelerator E is 1.0-3.0% by weight, of a total weight of the composition.

17. The process for bonding heat-stable substrates according to claim 12 , wherein the surface of the heat-stable substrate S1, is a metal surface, and the surface of the further heat-stable substrate S2 is a metal surface.

18. The process for bonding heat-stable substrates according to claim 12 , wherein the heat-curable epoxy resin composition is heated to a temperature of 120-200° C.

19. The process for bonding heat-stable substrates according to claim 12 , wherein the heat-curable epoxy resin composition is heated to a temperature of between 160 and 190° C.

20. The heat-curable epoxy resin composition according to claim 1 , wherein the heat-curable epoxy resin composition is free of a toxic or inflammable blowing agent.

Assignees

• FINTER JüRGEN
• Jendoubi Elyes
• Sika Tech Ag

Inventors

• FINTER JüRGEN
• Jendoubi Elyes

Classifications

• C08J2363/00

  Characterised by the use of epoxy resins; Derivatives of epoxy resins · CPC title

• C08G59/42

  Polycarboxylic acids; Anhydrides, halides or low molecular weight esters thereof · CPC title

• C08G59/44

  Amides · CPC title

• C08G59/4246

  polymers with carboxylic terminal groups · CPC title

• C08G59/46

  together with other curing agents · CPC title