# US 10,369,767 B2 · Blocking/deblocking resin systems for use as a “co-cure-ply” in the fabrication of large-scale composite structure

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- Number: US 10,369,767 B2
- Document ID: US10369767B2
- Status: Granted
- Kind: B2
- Application number: 15/274,147
- Filed: 2016-09-23
- Published: 2017-03-23
- Granted: 2019-08-06
- Earliest claimed: 2015-09-23
- Assignees: United States of America as represented by the Administrator of NASA
- Applicants: U.S.A. as represented by the Administrator of the National Aeronautics and Space Administration
- Inventors: Frank L. Palmieri; John W. Connell; Christopher J. Wohl, Jr.
- Web page: https://patentgrep.com/patent/US10369767B2

## CPC

- B29C 70/0035: {comprising two or more matrix materials}
- B29C 65/02: by heating, with or without pressure
- B29C 65/4835: {Heat curing adhesives}
- B29C 65/5014: {being fibre-reinforced (B29C65/5028 takes precedence)}
- B29C 65/5057: {positioned between the surfaces to be joined (B29C65/5035 takes precedence)}
- B29C 66/0242: {Heating, or preheating, e.g. drying (B29C66/3464 takes precedence)}
- B29C 66/1122: {Single lap to lap joints, i.e. overlap joints (B29C66/45, B29C66/472, B29C66/52272 take precedence)}
- B29C 66/43: {Joining a relatively small portion of the surface of said articles (B29C66/45 takes precedence)}
- B29C 66/71: {characterised by the composition of the plastics material of the parts to be joined (welding bar compositions B29C65/125)}
- B29C 66/721: {Fibre-reinforced materials (B29C66/729 takes precedence)}
- B29C 66/73752: {the to-be-joined areas of both parts to be joined being uncured}
- B29C 66/73754: {the to-be-joined areas of both parts to be joined being partially cured}
- B29C 66/73941: {characterised by the materials of both parts being thermosets}
- B29C 66/91445: {by steps}
- B29C 66/919: {characterised by specific temperature, heat or thermal flux values or ranges (specific electrical resistance values B29C66/81262)}
- B29C 66/91921: {in explicit relation to another temperature, e.g. to the softening temperature or softening point, to the thermal degradation temperature or to the ambient temperature}
- B29C 70/30: Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core
- B32B 7/12: using interposed adhesives or interposed materials with bonding properties
- B32B 27/34: comprising polyamides
- C09J 5/06: involving heating of the applied adhesive
- B29C 65/14: using wave energy {, i.e. electromagnetic radiation,} or particle radiation {(using mechanical waves B29C65/06; using ultrasonic waves B29C65/08; pressing means transparent to electromagnetic radiation B29C66/81267)}
- B29C 66/81455: {being a fluid inflatable bag or bladder, a diaphragm or a vacuum bag for applying isostatic pressure (inflatable element positioned between the joining tool and a backing-up part B29C66/82421)}
- B32B 2305/74: Partially cured
- B32B 2305/77: Uncured, e.g. green
- B32B 2309/02: Temperature
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- C09J: ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES (preparation of glue or gelatine C09H)

## 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.

## Claims

### Claim 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.

### Claim 2 (depends on 1)

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.

### Claim 3 (depends on 1)

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.

### Claim 4 (depends on 1)

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

### Claim 5 (depends on 1)

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

### Claim 6 (depends on 1)

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

### Claim 7 (depends on 1)

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

### Claim 8 (depends on 1)

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

### Claim 9 (depends on 8)

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

### Claim 10 (depends on 1)

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

### Claim 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.

### Claim 12 (depends on 11)

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.

### Claim 13 (depends on 11)

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

### Claim 14 (depends on 11)

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

### Claim 15 (depends on 1)

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

### Claim 16 (depends on 11)

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

### Claim 17 (depends on 11)

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

### Claim 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.

### Claim 19 (depends on 18)

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

### Claim 20 (depends on 18)

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