Non-chromate corrosion inhibiting polythioether sealants

Patent metadata

Field	Value
Publication number	US-10053606-B2
Application number	US-201514922316-A
Country	US
Kind code	B2
Filing date	Oct 26, 2015
Priority date	Oct 26, 2015
Publication date	Aug 21, 2018
Grant date	Aug 21, 2018

Abstract

Compositions comprising thiol-terminated polythioether prepolymers, polyepoxides and non-chromate corrosion inhibitors suitable for use in aerospace sealant applications are disclosed. Sealants prepared using the compositions adhere to a variety of aerospace substrates following exposure to aerospace fluids.

First claim

What is claimed is:

1. A composition comprising:
a thiol-terminated polythioether prepolymer;
a polyepoxide curing agent; and
a non-chromate corrosion inhibitor, wherein the non-chromate corrosion inhibitor comprises:
from 2 wt % to 6 wt % of zinc borate;
from 1 wt % to 5 wt % of 2-benzothiazolylthiobutanedioic acid;
from 35 wt % to 70 wt % of zinc orthophosphate;
from 20 wt % to 50 wt % of sodium titanate; and
from 3 wt % to 8 wt % of tricalcium phosphate,
wherein wt % is based on the total weight of the non-chromate corrosion inhibitor.

2. The composition of claim 1 , wherein the polyepoxide curing agent comprises an epoxy novolac resin, a bisphenol A/epichlorohydrin epoxy resin, or a combination thereof.

3. The composition of claim 1 , wherein the thiol-terminated polythioether prepolymer comprises a backbone having 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, a heterocyclic group, and a -[(—CHR 3 —) p -X—] q -(CHR 3 ) r — group, wherein each R 3 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, a heterocyclic group, and a -[(—CH 2 —) p -X—] q -(CH 2 ) r — group;
each X is independently selected from O, S, —NH—, and —N(—CH 3 )—;
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.

4. The composition of claim 1 , wherein the thiol-terminated polythioether prepolymer comprises a thiol-terminated polythioether prepolymer of Formula (2a), a thiol-terminated polythioether prepolymer of Formula (2b), or a combination thereof:
HS—R 1 —[-S(CH 2 ) 2 —O—(R 2 —O) m —(CH 2 ) 2 —S—R 1 —] n -SH  (2a)

{HS—R 1 —[-S—(CH 2 ) 2 —O—(R 2 —O) m —(CH 2 ) 2 —S—R 1 —] n -S—V′—} z B  (2b)

wherein:
each R 1 independently is selected from C 2-10 alkanediyl, C 6-8 cycloalkanediyl, C 6-14 alkanecycloalkanediyl, C 5-8 heterocycloalkanediyl, and -[(—CHR 3 —) p -X—] q -(—CHR 3 —) r —, wherein:
p is an integer from 2 to 6;
q is an integer from 1 to 5;
r is an integer from 2 to 10;
each R 3 is independently selected from hydrogen and methyl; and
each X is independently selected from —O—, —S—, —NH—, and —N(—CH 3 )—;

each R 2 is independently selected from C 1-10 alkanediyl, C 6-8 cycloalkanediyl, C 6-14 alkanecycloalkanediyl, and -[(—CHR 3 —) p -X—] q -(—CHR 3 —) r —, wherein p, q, r, R 3 , and X are as defined as for R 1 ;
m is an integer from 0 to 50;
n is an integer from 1 to 60; and
B represents a core of a z-valent, vinyl-terminated polyfunctionalizing agent B(—V) z wherein:
z is an integer from 3 to 6; and
each V is a group comprising a terminal vinyl group; and

each —V′— is derived from the reaction of —V with a thiol.

5. The composition of claim 1 , wherein the thiol-terminated polythioether prepolymer comprises the reaction product of reactants comprising:
(a) a dithiol of Formula (3):
HS—R 1 —SH  (3)

wherein:
R 1 is selected from C 2-6 alkanediyl, C 6-8 cycloalkanediyl, C 6-10 alkanecycloalkanediyl, C 5-8 heterocycloalkanediyl, and -[—(CHR 3 ) p —X—] q -(CHR 3 ) r —;

wherein:
each R 3 is independently selected from hydrogen and methyl;
each X is independently selected from —O—, —S—, —NH—, and —N(—CH 3 )—;
p is an integer from 2 to 6;
q is an integer from 1 to 5; and
r is an integer from 2 to 10; and

(b) a divinyl ether of Formula (4):
CH 2 ═CH—O—[-R 2 —O—] m —CH═CH 2   (4)

wherein:
each R 2 is independently selected from C 1-10 alkanediyl, C 6-8 cycloalkanediyl, C 6-14 alkanecycloalkanediyl, and -[(—CHR 3 —) p -X—] q -(—CHR 3 —) r , wherein p, q, r, R 3 , and X are as defined for R 1 ; and
m is an integer from 0 to 50.

6. The composition of claim 5 , wherein the reactants comprise (c) a polyfunctional compound B(—V) z , wherein,
B represents a core of a z-valent, vinyl-terminated polyfunctionalizing agent B(—V) z ,
z is an integer from 3 to 6; and
each —V is a moiety comprising a terminal vinyl group.

7. The composition of claim 1 , wherein the composition comprises:
from 30 wt % to 65 wt % of the thiol-terminated polythioether prepolymer;
from 3 wt % to 10 wt % of the polyepoxide curing agent; and
from 1 wt % to 12 wt % of the non-chromate corrosion inhibitor,
where wt % is based on the total weight of the composition.

8. The composition of claim 1 , comprising an amine catalyst.

9. The composition of claim 8 , wherein the amine catalyst comprises 1,4-diazabicyclo[2.2.2]octane, 2,4,6-tri(dimethylaminomethol)phenol, imidazole, or a combination of any of the foregoing.

10. The composition of claim 1 , wherein the composition is formulated as a sealant.

11. A cured sealant prepared from the composition of claim 10 .

12. A method of sealing a part comprising:
applying the composition of claim 10 , to at least a portion of a part; and
curing the applied composition to provide a sealed part.

13. A cured sealant prepared from the composition of claim 1 .

14. A part comprising the cured sealant of claim 13 .

15. An aerospace vehicle comprising the cured sealant of claim 13 .

16. A composition comprising:
a thiol-terminated polythioether prepolymer;
a polyepoxide curing agent; and
a non-chromate corrosion inhibitor, wherein the non-chromate corrosion inhibitor comprises:
from 0.05 wt % to 0.5 wt % of zinc borate;
from 0.05 wt % to 0.4 wt % of 2-benzothiazolylthiobutanedioic acid;
from 1 wt % to 6 wt % of zinc orthophosphate;
from 0.5 wt % to 5 wt % of sodium titanate; and
from 0.05 wt % to 0.7 wt % of tricalcium phosphate,
where wt % is based on the total weight of the composition.

17. A cured sealant prepared from the composition of claim 16 .

18. A part comprising the cured sealant of claim 17 .

19. An aerospace vehicle comprising the cured sealant of claim 17 .

20. A sealant system, comprising:
a first part comprising:
a thiol-terminated polythioether prepolymer; and
a first portion of a non-chromate corrosion inhibitor, wherein the first portion comprises:
from 1 wt % to 7 wt % of zinc orthophosphate;
from 0.5 wt % to 5 wt % of sodium titanate; and
from 0.1 wt % to 0.7 wt % of tricalcium phosphate,
wherein wt % is based on the total weight of the first part; and

a second part comprising:
a polyepoxide; and
a second portion of a non-chromate corrosion inhibitor, wherein the second portion comprises:
from 0.5 wt % to 3.5 wt % of zinc borate; and
from 0.5 wt % to 3 wt % of 2-benzothiazolylthiobutanedioic acid,
wherein wt % is based on the total weight of the second part.

21. The sealant composition of claim 20 , wherein, the first part comprises:
from 40 wt % to 80 wt % of a thiol-terminated polythioether prepolymer;
wherein wt % is based on the total weight of the first part; and
the second part comprises:
from 30 wt % to 60 wt % of a polyepoxide,
wherein wt % is based on the total weight of the second part.

22. A curable sealant composition formed by combining the first part and the second part of the sealant system of claim 20 .

23. A cured sealant prepared from the

Assignees

• Prc Desoto Int Inc

Inventors

• Virnelson Bruce
• Stott Adam
• Manion Sean
• Bertino Brian
• Srivatsan Nagarajan

Classifications

• C23F11/188

  containing phosphates · CPC title

• C08G75/04

  from mercapto compounds or metallic derivatives thereof (C08G75/0204 takes precedence) · CPC title

• C08L81/00

  Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing sulfur with or without nitrogen, oxygen or carbon only; Compositions of polysulfones; Compositions of derivatives of such polymers · CPC title

• C09K3/1012 Primary

  Sulfur-containing polymers, e.g. polysulfides · CPC title

• C08G65/326

  containing sulfur · CPC title