Blocking/deblocking resin systems for use as a “co-cure-ply” in the fabrication of large-scale composite structure

Patent metadata

Field	Value
Publication number	US-10369767-B2
Application number	US-201615274147-A
Country	US
Kind code	B2
Filing date	Sep 23, 2016
Priority date	Sep 23, 2015
Publication date	Aug 6, 2019
Grant date	Aug 6, 2019

Abstract

A method for bonding composite structures which includes providing a first and second composite substrate and coupling a co-cure prepreg tape having chemically protected polymerizable functional groups onto a surface of both the first and second composite substrates. The first and second composite substrates are then cured to the co-cure prepreg tape at a first temperature to form a co-cure prepreg tape portion where the first and second composite substrates are fully cured and the co-cure prepreg tape is partially cured. The co-cure prepreg tape portion of the first composite substrate is then coupled to the co-cure prepreg tape portion of the second composite substrate and a deprotection initiator is applied to facilitate deprotection of the chemically protected polymerizable functional groups and cure the co-cure prepreg tape portion of the first and second composite substrates to form a single covalently bonded composite structure.

First claim

What is claimed is:

1. A method for bonding composite substrates comprising:
providing a first composite substrate and a second composite substrate wherein both the first composite substrate and the second composite substrate are uncured or partially cured and comprise one or more reinforcement fibers and a first curable resin;
coupling a co-cure prepreg tape onto a faying surface of both the first and second composite substrates wherein the co-cure prepreg tape comprises a second curable resin having one or more chemically protected polymerizable functional groups;
curing the first and second composite substrates to the co-cure prepreg tape at a first temperature to form a co-cure prepreg tape portion wherein the first and second composite substrates are fully cured and the co-cure prepreg tape is partially cured;
coupling the co-cure prepreg tape portion of the first composite substrate to the co-cure prepreg tape portion of the second composite substrate;
applying a second temperature to facilitate deprotection with water and a hydrolysis catalyst of the chemically protected polymerizable functional groups to give unprotected polymerizable functional groups and cure the co-cure prepreg tape portion of the first composite substrate to the co-cure prepreg tape portion of the second composite substrate to form a single covalently bonded composite structure.

2. The method of claim 1 , further comprising
applying a reflow temperature to the co-cure prepreg tape coupled to the first and second composite substrates before curing at the first temperature.

3. The method of claim 1 , wherein:
the first temperature is from about 75° C. to about 250° C. and the second temperature is from about 75° C. to about 250° C.

4. The method of claim 1 , wherein:
the first curable resin comprises an epoxide and an amine.

5. The method of claim 1 , wherein:
the second curable resin comprises an epoxide and a chemically protected polymerizable amine.

6. The method of claim 1 , wherein:
the one or more chemically protected polymerizable functional groups is an aldimine.

7. The method of claim 1 , wherein:
the one or more chemically protected polymerizable functional groups is an ketimine.

8. The method of claim 1 , wherein:
the unprotected polymerizable functional groups are an amine.

9. The method of claim 8 , wherein:
the amine is 4,6-diethyl-2-methylbenzene-1,3-diamine.

10. The method of claim 1 , wherein:
the hydrolysis catalyst is selected from the group consisting of acidic alumina, imidazole, and combinations thereof.

11. A method for bonding composite substrates comprising:
providing a co-cure prepreg layer cured to a surface of both a first composite substrate and a second composite substrate wherein the co-cure prepreg layer comprises a chemically protected polymerizable functional group;
coupling a portion of the co-cure prepreg layer cured to the first composite substrate to a portion of the co-cure prepreg layer cured to the second composite substrate;
applying a deprotection initiator to deprotect the protected polymerizable functional group of the co-cure prepreg layers and to couple the co-cure prepreg layers of the first and second composite substrates, to form a single covalently bonded composite structure.

12. The method of claim 11 , wherein:
the deprotection initiator comprises a heat source, a chemical reagent, a light source, a mechanical force, or a combination thereof.

13. The method of claim 11 , wherein:
the first and second composite substrates comprise a curable resin material having an amine and an epoxide.

14. The method of claim 11 , wherein:
the first and second composite substrates comprise one or more reinforcement fibers.

15. The method of claim 1 , wherein:
the chemically protected polymerizable functional groups is an aldimine.

16. The method of claim 11 , wherein:
the chemically protected polymerizable functional groups is an ketimine.

17. The method of claim 11 , wherein:
the single covalently bonded composite structure comprises a crosslinked amine-cured epoxy polymer network.

18. A co-curable composite structure comprising:
a first and a second uncured or partially cured composite substrate comprising a first curable resin wherein the first curable resin comprises a first epoxide and an amine;
a first co-cure prepreg layer coupled to a surface of the first uncured or partially cured composite substrate and a second co-cure prepreg layer coupled to a surface of the second uncured or partially cured composite substrate wherein the first and the second co-cure prepreg layers comprises a second curable resin having a second epoxide and a chemically protected amine;
wherein the first and the second uncured or partially cured composite substrate and the first and the second co-cure prepreg layers are cured together at a first temperature until the amines of the first and the second uncured or partially cured composite substrate are functionally fully cured; wherein the first co-cure prepreg layer of the first composite substrate is coupled to the second co-cure prepreg layer of the second composite substrate to form the co-curable composite structure; and
wherein the chemically protected amine of the first and the second co-cure prepreg layers are partially cured and remains latent until an additional deprotection and co-cure step.

19. The co-curable composite structure of claim 18 , wherein:
the chemically protected amine is an aldimine.

20. The co-curable composite structure of claim 18 , wherein:
the chemically protected amine is a ketimine.

Assignees

• Nasa

Inventors

• Palmieri Frank L
• Connell John W
• Wohl Jr Christopher J

Classifications

• B32B2305/74

  Partially cured · CPC title

• B29C66/721

  Fibre-reinforced materials (B29C66/729 takes precedence) · CPC title

• B29C66/1122

  Single lap to lap joints, i.e. overlap joints (B29C66/45, B29C66/472, B29C66/52272 take precedence) · CPC title

• B29C66/71

  characterised by the composition of the plastics material of the parts to be joined (welding bar compositions B29C65/125) · CPC title

• B29C66/73754

  the to-be-joined areas of both parts to be joined being partially cured · CPC title