Moisture-curable fuel-resistant sealant systems

Patent metadata

Field	Value
Publication number	US-9951252-B2
Application number	US-201514822123-A
Country	US
Kind code	B2
Filing date	Aug 10, 2015
Priority date	Aug 10, 2015
Publication date	Apr 24, 2018
Grant date	Apr 24, 2018

Abstract

Sealant systems that are pre-applied to a part to be sealed include a layer of an uncured moisture-curable sealant and a frangible barrier coating applied over the uncured moisture-curable sealant. During assembly, the barrier coating breaks to expose the moisture-curable sealant to moisture to initiate the curing reaction. The moisture-curable sealant systems are suitable for aerospace applications and include sulfur-containing prepolymers. Various curing chemistries can be used.

First claim

What is claimed is:

1. A sealant system comprising:
an uncured moisture-curable sealant composition comprising:
a vinyl ether-terminated sulfur-containing prepolymer; and
a blocked benzoic acid catalyst; and

a frangible barrier coating overlying the uncured moisture-curable sealant composition.

2. The sealant system of claim 1 , wherein the blocked benzoic acid catalyst comprises benzoyl chloride.

3. The sealant system of claim 1 , wherein the vinyl ether-terminated sulfur-containing prepolymer comprises a vinyl ether-terminated polythioether prepolymer.

4. The sealant system of claim 3 , wherein the vinyl ether-terminated polythioether prepolymer comprises a backbone comprising the structure of Formula (1):
—R 1 —[—S—(CH 2 ) 2 —O—(—R 2 —O—) m —(CH 2 ) 2 —S—R 1 ] n —  (1)

wherein,
each R 1 is independently selected from a C 2-10 n-alkanediyl group, a C 3-6 branched alkanediyl group, a C 6-8 cycloalkanediyl group, a C 6-10 alkanecycloalkanediyl group, C 6-8 heterocycloalkanediyl, and a —[(—CHR—) p —X—] q —(CHR) r — group, wherein each R is selected from hydrogen and methyl;
each R 2 is independently selected from a C 2-10 n-alkanediyl group, a C 3-6 branched alkanediyl group, a C 6-8 cycloalkanediyl group, a C 6-14 alkanecycloalkanediyl group, C 6-8 heterocycloalkanediyl, and a —[(—CH 2 —) p —X—] q —(CH 2 ) r — group;
each X is independently selected from O, S, and —NR—, wherein R is selected from hydrogen and methyl;
m ranges from 0 to 50;
n is an integer ranging from 1 to 60;
p is an integer ranging from 2 to 6;
q is an integer ranging from 1 to 5; and
r is an integer ranging from 2 to 10.

5. The sealant system of claim 4 , wherein,
R 1 is —(CH 2 ) 2 —O—(CH 2 ) 2 —O—(CH 2 ) 2 —;
R 2 is —(CH 2 ) 2 —;
m is 2; and
z is 3.

6. The sealant system of claim 1 , wherein the uncured moisture curable sealant composition is formulated as a sealant.

7. A coated part, comprising the sealant system of claim 1 applied to at least a portion of a part.

8. The coated part of claim 7 , wherein;
the part is a fastener comprising a shank; and
the sealant coating overlies at least a portion of the fastener.

9. A method of providing a coated part, comprising:
applying a moisture-curable sealant composition to at least a portion of a surface of a part, wherein the moisture-curable sealant composition comprises:
a vinyl ether-terminated sulfur-containing prepolymer; and
a blocked benzoic acid catalyst; and
applying a frangible barrier coating over the moisture-curable sealant composition, wherein the frangible barrier coating is configured to expose the moisture-curable sealant composition to atmospheric moisture during assembly.

10. The sealant system of claim 1 , wherein the uncured moisture-curable sealant composition comprises a latent source of water.

11. The sealant system of claim 10 , wherein the latent source of water comprises encapsulated water, sequestered water, or a combination thereof.

12. The sealant system of claim 10 , wherein the latent source of water comprises water incorporated into a core/shell encapsulant, water incorporated into a matrix encapsulant, water incorporated into a hydrogel, or a combination of any of the foregoing.

13. The sealant system of claim 1 , wherein the uncured moisture-curable sealant comprises an acyl halide.

14. The sealant system of claim 1 , wherein the vinyl ether-terminated sulfur-containing prepolymer comprises a polythioether, a polysulfide, a sulfur-containing polyformal, or a combination of any of the foregoing.

15. The sealant system of claim 1 , wherein the frangible barrier coating comprises a UV-curable coating.

16. A method of sealing a part, comprising assembling the coated part of claim 7 to cause the frangible barrier coating to fracture, thereby exposing the uncured moisture-curable sealant composition to atmospheric moisture, and curing the moisture-curable sealant composition.

17. The method of claim 16 , wherein,
the uncured moisture-curable sealant composition comprises a latent source of water; and
assembling the coated part causes water to be released from the latent source of water.

18. The method of claim 17 , wherein the latent source of water comprises water incorporated into a core/shell encapsulant, water incorporated into a matrix encapsulant, water incorporated into a hydrogel, or a combination of any of the foregoing.

19. An aerospace vehicle comprising a part sealed with the sealant system of claim 1 .

20. A part sealed with the sealant system of claim 1 .

Assignees

• Prc Desoto Int Inc

Inventors

• Virnelson Bruce
• Lin Renhe

Classifications

• C09D181/02

  Polythioethers; Polythioether-ethers · CPC title

• B05D7/54

  No clear coat specified · CPC title

• F16B47/003

  using adhesives for attaching purposes (using adhesives for connecting constructional elements F16B11/006) · CPC title

• B64G1/00

  Cosmonautic vehicles · CPC title

• C09D181/04 Primary

  Polysulfides · CPC title