# US 12,760,209 B2 · Sandwich structures including hybrid adhesives and methods thereof

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- Number: US 12,760,209 B2
- Document ID: US12760209B2
- Status: Granted
- Kind: B2
- Application number: 18/793,471
- Filed: 2024-08-02
- Published: 2026-02-05
- Granted: 2026-10-13
- Earliest claimed: 2024-08-02
- Assignees: The Boeing Company
- Applicants: The Boeing Company
- Inventors: Andrew Paul Nowak; Michael Jared Ventuleth; Ashley Marie Dustin; Phuong Bui; Ashley C. Tracey; Kay Youngdahl Blohowiak; Derek Borjun Huang; William Bruce Hopkins Grace; Mohamed Azdamou; Zachary Cole Hern
- Web page: https://patentgrep.com/patent/US12760209B2

## CPC

- C09J 163/00: Adhesives based on epoxy resins; Adhesives based on derivatives of epoxy resins
- B32B 3/12: characterised by a layer of regularly- arranged cells, e.g. a honeycomb structure
- B32B 7/12: using interposed adhesives or interposed materials with bonding properties
- B32B 15/043: {of metal (B32B15/01 takes precedence)}
- B32B 15/08: of synthetic resin
- B32B 15/18: comprising iron or steel {(B32B15/011, B32B15/012 and B32B15/013 take precedence)}
- B32B 15/20: comprising aluminium or copper {(B32B15/016 and B32B15/017 take precedence)}
- B32B 27/08: of synthetic resin
- B64C 7/02: Nacelles
- C08G 59/3227: {Compounds containing acyclic nitrogen atoms}
- C08G 59/504: {containing an atom other than nitrogen belonging to the amine group, carbon and hydrogen}
- B32B 2250/40: Symmetrical or sandwich layers, e.g. ABA, ABCBA, ABCCBA
- B32B 2307/202: Conductive
- B32B 2605/18: Aircraft
- 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)
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B64C: AEROPLANES; HELICOPTERS
- C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS

## Abstract

An adhesive formulation includes an epoxy-functional monomer or epoxy-functional polymer and an amino-phthalonitrile monomer or amino-phthalonitrile polymer. The adhesive formulation can include 4,4′-methylenebis(n,n-diglycidylaniline), bisphenol a diglycidyl ether, bisphenol f diglycidyl ether, n,n-diglycidyl-4-glycidyloxyaniline, 1,4-butanediol diglycidyl ether, trimethylolpropane triglycidyl ether, poly[(phenyl glycidyl ether)-co-dicyclo-pentadiene], or a combination thereof. The adhesive formulation may include a difunctional amine monomer, solvents, and one or more additives. A method of making an epoxy-phthalonitrile copolymer and a sandwich panel composition is disclosed. The sandwich panel can be a component of an aerospace structural application, such as a nacelle.

## Claims

### Claim 1

An adhesive formulation, comprising:
an epoxy-functional monomer or epoxy-functional polymer;
an amino-phthalonitrile monomer or amino-phthalonitrile polymer, wherein the amino-phthalonitrile monomer or amino-phthalonitrile polymer contains a single phthalonitrile functional group; and
one or more additives.

### Claim 2 (depends on 1)

The adhesive formulation of claim 1, wherein the epoxy-functional monomer or epoxy-functional polymer comprises two or more glycidyl functional groups.

### Claim 3 (depends on 2)

The adhesive formulation of claim 2, wherein the epoxy-functional monomer or epoxy-functional polymer comprises 4,4′-methylenebis(N,N-diglycidylaniline), bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, N,N-diglycidyl-4-glycidyloxyaniline, 1,4-butanediol diglycidyl ether, trimethylolpropane triglycidyl ether, poly[(phenyl glycidyl ether)-co-dicyclo-pentadiene], or a combination thereof.

### Claim 4 (depends on 1)

The adhesive formulation of claim 1, further comprising a difunctional amine monomer.

### Claim 5 (depends on 4)

The adhesive formulation of claim 4, wherein the difunctional amine monomer comprises 4,4′-diaminodiphenyl sulfone, 3,3′-diaminodiphenyl sulfone, p-phenylene diamine, 4,4′-diaminobenzophenone, 1,3-cyclohexanebis(methylamine), or a combination thereof.

### Claim 6 (depends on 1)

The adhesive formulation of claim 1, wherein the amino-phthalonitrile monomer or amino-phthalonitrile polymer contains at least one primary amine functional group.

### Claim 7 (depends on 1)

The adhesive formulation of claim 1, further comprising a solvent comprising dimethyl sulfoxide, N,N-dimethylformamide, 1-methyl-2-pyrrolidinone, 2-phenoxyethanol, acetone, 2-butanone, 2-pentanone, 4-methyl-2-pentanone, n-butyl acetate, toluene, xylene, benzene, or a combination thereof.

### Claim 8 (depends on 1)

The adhesive formulation of claim 1, wherein the one or more additives are selected from a group consisting of a filler, a dispersant, a rheology modifier, a catalyst, a cure promoter, a surfactant, a pigment, and any combination thereof.

### Claim 9

A method of making an epoxy-phthalonitrile copolymer, comprising:
combining an epoxy-functional monomer and an amino-phthalonitrile functional monomer, wherein the amino-phthalonitrile functional monomer contains a single phthalonitrile functional group;
heating the epoxy-functional monomer and the amino-phthalonitrile functional monomer to a first melting temperature to form a solution;
mixing the solution until it is homogenous; and
heating the solution at a second temperature to cure the epoxy-phthalonitrile copolymer.

### Claim 10 (depends on 9)

The method of making an epoxy-phthalonitrile copolymer of claim 9, wherein the second temperature is less than or equal to 350° F., and the second temperature is sustained for less than or equal to 5 hours.

### Claim 11

A sandwich panel composition, comprising:
a honeycomb core;
a first facesheet panel affixed to a first outer edge of the honeycomb core;
a second facesheet panel affixed to a second outer edge of the honeycomb core;
a first phthalonitrile-epoxy adhesive layer between the first facesheet panel and the first outer edge of the honeycomb core, wherein the first phthalonitrile-epoxy adhesive layer comprises an amino-phthalonitrile monomer or amino-phthalonitrile polymer containing a single phthalonitrile functional group; and
a second phthalonitrile-epoxy adhesive layer between the second facesheet panel and the second outer edge of the honeycomb core, wherein the second phthalonitrile-epoxy adhesive layer comprises an amino-phthalonitrile monomer or amino-phthalonitrile polymer containing a single phthalonitrile functional group.

### Claim 12 (depends on 11)

The sandwich panel composition of claim 11, wherein the first facesheet or the second facesheet comprises a polymer matrix.

### Claim 13 (depends on 12)

The sandwich panel composition of claim 12, wherein the polymer matrix comprises a material selected from the group consisting of epoxy, polyaramid, phenolic, bismaleimide, polyimide, phthalonitrile, polyether ether ketone (PEEK), polyetherketoneketone (PEKK), polyester, benzoxazine, and a combination thereof.

### Claim 14 (depends on 11)

The sandwich panel composition of claim 11, wherein the first facesheet or the second facesheet comprises a metal or metal alloy.

### Claim 15 (depends on 14)

The sandwich panel composition of claim 14, wherein the first facesheet or the second facesheet comprises aluminum, titanium, stainless steel, or a combination thereof.

### Claim 16 (depends on 11)

The sandwich panel composition of claim 11, wherein the honeycomb core comprises an electrically conductive material.

### Claim 17 (depends on 11)

The sandwich panel composition of claim 11, wherein the honeycomb core comprises a metal, or a polymer matrix.

### Claim 18 (depends on 11)

The sandwich panel composition of claim 11, wherein the honeycomb core comprises a material selected from the group consisting of aluminum, titanium, stainless steel, aramid, polyaramid, and any combination thereof.

### Claim 19 (depends on 11)

The sandwich panel composition of claim 11, wherein the sandwich panel is a component of an aerospace structural application.

### Claim 20 (depends on 19)

The sandwich panel composition of claim 19, wherein the sandwich panel is a component of a nacelle.