Sulfur-containing polyureas and methods of use

Abstract

Disclosed are sulfur-containing polyurea compositions and methods of using the compositions as sealants, particularly as low specific-gravity aerospace sealants.

What is claimed is: 
     
         1 . A composition comprising:
 (a) a polyisocyanate prepolymer comprising the reaction product of reactants comprising:
 (i) a diisocyanate having a first isocyanate group and a second isocyanate group, wherein the reactivity of the first isocyanate group with a thiol group is greater than the reactivity of the second isocyanate group with the thiol group; and 
 (ii) a thiol-terminated sulfur-containing polymer; 
   wherein the molar ratio of isocyanate groups to thiol groups is from about 2.1:1, to about 2.5:1; and   (b) a polyamine selected from an aromatic polyamine, an aromatic amine-terminated polythioether adduct, and a combination thereof.   
     
     
         2 . The composition of  claim 1 , wherein the molar ratio is about 2.2:1. 
     
     
         3 . The composition of  claim 1 , wherein the polyisocyanate prepolymer is selected from an isocyanate-terminated polythioether prepolymer, an isocyanate-terminated polyformal prepolymer, and a combination thereof. 
     
     
         4 . The composition of  claim 3 , wherein the isocyanate-terminated polythioether is selected from a difunctional isocyanate-terminated polythioether of Formula (1), a multifunctional isocyanate-terminated polythioether of Formula (1′), and a combination thereof:
   Y—NH—C(O)—X—R 1 —[—S—(CH 2 ) p —O—(R 2 —O) m —(CH 2 ) 2 —S—R—] n —X—C(O)—NH—Y  (1)
 
   {Y—NH—C(O)—X—R—[—S—(CH 2 ) p —O—(R 2 —O) m —(CH 2 ) 2 —S—R—] n —S—(CH 2 )— 2 —V′—} z B  (1′)
 
 wherein:
 each R 1  independently is selected from C 2-10  alkanediyl, substituted C 2-10  alkanediyl wherein the substituent groups are selected from C 1-3  alkyl, C 1-3  alkoxy, C 6-8  cycloalkyl, C 6-10  alkylcycloalkyl, and C 5-8  heterocycloalkyl, and —[(—CHR 3 —) s —X′—] q —(—CHR 3 —) r —, wherein:
 s 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, and —NHR—, wherein R is selected from hydrogen and methyl; 
 
 each R 2  is independently selected from C 1-10  alkanediyl, C 6-8  cycloalkanediyl, C 6-14  alkylcycloalkanediyl, and —[(—CHR 3 —) s —X′—] q —(—CHR 3 —) r —, wherein s, q, r, R 3 , and X′ are as defined above;
 m is an integer from 0 to 50; 
 n is an integer from 1 to 60; 
 p is an integer from 2 to 6; and 
 each X is S; 
 
 B represents a core of a z-valent polyfunctionalizing agent B(V) z , wherein:
 z in an integer from 3 to 6; and 
 each V is a group comprising a terminal vinyl group; 
 
 each —S—(CH 2 ) 2 —V— is a moiety derived from the reaction of V with a thiol; and 
 each Y—NH—C(O)— is a group derived from the diisocyanate. 
 
 
     
     
         5 . The composition of  claim 3 , wherein the isocyanate-terminated polyformal is selected from a difunctional isocyanate-terminated polyformal of Formula (3), a multifunctional isocyanate-terminated polyformal of Formula (3′), and a combination thereof: 
       
         
           
           
               
               
           
         
         wherein:
 t is an integer selected from 1 to 50; 
 each u is independently selected from 1 and 2; 
 each R 4  is independently selected from C 2-6  alkanediyl; 
 each R 5  is independently selected from hydrogen, C 1-6  alkyl, C 7-12  phenylalkyl, substituted C 7-12  phenylalkyl, C 6-12  cycloalkylalkyl, substituted C 6-12  cycloalkylalkyl, C 3-12  cycloalkyl, substituted C 3-12  cycloalkyl, C 6-12  aryl, and substituted C 6-12  aryl; 
 each —R 6′ — is derived from a group comprising a terminal thiol group; 
 B represents a core of a z-valent polyol B(OH) z  wherein z is an integer from 3 to 6; and 
 each Y—NH—C(O)— is a moiety derived from the diisocyanate. 
 
       
     
     
         6 . The composition of  claim 5 , wherein each —R 6′ — is independently selected from a moiety of Formula (a′), Formula (b′), Formula (c′), Formula (d′), Formula (e′), Formula (f′), Formula (g′), and Formula (h′): 
       
         
           
           
               
               
           
         
         wherein:
 each R 8  is independently selected from a moiety derived from a diisocyanate and a moiety derived from an ethylenically unsaturated monoisocyanate; 
 each R 9  is independently selected from C 2-14  alkanediyl and C 2-14  heteroalkanediyl; and 
 each R 10  is independently selected from C 2-6  alkanediyl, C 2-6  heteroalkanediyl, C 6-12  arenediyl, substituted C 6-12  arenediyl, C 6-12  heteroarenediyl, substituted C 6-12  heteroarenediyl, C 3-12  cycloalkanediyl, substituted C 3-12  cycloalkanediyl, C 3-12  heterocycloalkanediyl, substituted C 3-12  heterocycloalkanediyl, C 7-18  alkanearenediyl, substituted C 7-18  heteroalkanearenediyl, C 4-18  alkanecycloalkanediyl, and substituted C 4-18  alkanecycloalkanediyl. 
 
       
     
     
         7 . The composition of  claim 1 , wherein the diisocyanate is selected from p2,4-toluene diisocyanate, 2,6-toluene diisocyanate, isophorone diisocyanate, and a combination of any of the foregoing. 
     
     
         8 . The composition of  claim 1 , comprising a metal acetylacetonate catalyst. 
     
     
         9 . The composition of  claim 1 , wherein the thiol-terminated sulfur-containing polymer comprises a thiol-terminated polythioether. 
     
     
         10 . The composition of  claim 9 , wherein the thiol-terminated polythioether is selected from a thiol-terminated polythioether of Formula (5), a thiol-terminated polythioether of Formula (5′), and a combination thereof:
   HS—R 1 —[—S—(CH 2 ) p —O—(R 2 —O) m —(CH 2 ) 2 —S—R 1 —] n —SH  (5)
 
   {HS—R 1 —[—S—(CH 2 ) p —O—(R 2 —O) m —(CH 2 ) 2 —S—R 1 —] n —S—(CH 2 )— 2 —V′—} z B  (5′)
 
 wherein:
 each R 1  independently is selected from C 2-10  alkanediyl, substituted C 2-10  alkanediyl wherein the substituent groups are selected from C 1-3  alkyl, C 1-3  alkoxy, C 6-8  cycloalkyl, C 6-10  alkylcycloalkyl, and C 5-8  heterocycloalkyl, and —[(—CHR 3 —) s —X′—] q —(—CHR 3 —) r —, wherein:
 s 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, and —NHR—, wherein R is selected from hydrogen and methyl; 
 
 each R 2  is independently selected from C 1-10  alkanediyl, C 6-8  cycloalkanediyl, C 6-14  alkylcycloalkanediyl, and —[(—CHR 3 —) s —X′—] q —(—CHR 3 —) r —, wherein s, q, r, R 3 , and X′ are as defined above; 
 m is an integer from 0 to 50; 
 n is an integer from 1 to 60; 
 p is an integer from 2 to 6; 
 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 —S—(CH 2 ) 2 —V— is derived from the reaction of V with a thiol. 
 
 
     
     
         11 . The composition of  claim 1 , wherein the thiol-terminated sulfur-containing polymer comprises a thiol-terminated polyformal. 
     
     
         12 . The composition of  claim 11 , wherein the thiol-terminated polyformal comprises the reaction products of reactants comprising (a) and (b), wherein:
 a) comprises the reaction products of reactants comprising (i) and (ii), wherein:
 (i) comprises a sulfur-containing polyol selected from a polyol of Formula (10), a polyol of Formula (10′), and a combination thereof: 
   
       
         
           
           
               
               
           
         
         
           wherein:
 t is an integer selected from 1 to 50; 
 each u is independently selected from 1 and 2; 
 each R 4  is independently selected from C 2-6  alkanediyl; 
 each R 5  is independently selected from hydrogen, C 1-6  alkyl, C 7-12  phenylalkyl, substituted C 7-12  phenylalkyl, C 6-12  cycloalkylalkyl, substituted C 6-12  cycloalkylalkyl, C 3-12  cycloalkyl, substituted C 3-12  cycloalkyl, C 6-12  aryl, and substituted C 6-12  aryl; and 
 B represents a core of a z-valent polyol B(OH) z  wherein z in an integer from 3 to 6; and 
 
           (ii) comprises a first compound selected from a diisocyanate, thiourea, an ethylenically unsaturated monoisocyanate, and a tosylate; and 
         
         (b) comprises a mercaptoalkanol when (ii) comprises a diisocyanate; a metal hydrosulfide when (ii) comprises thiourea; a dithiol when (ii) comprises an ethylenically unsaturated monoisocyanate; and a metal hydrosulfide when (ii) comprises a tosylate. 
       
     
     
         13 . The composition of  claim 11 , wherein the thiol-terminated polyformal is selected from a thiol-terminated polyformal of Formula (9), a thiol-terminated polyformal Formula (9′), or a combination thereof: 
       
         
           
           
               
               
           
         
         wherein:
 t is an integer selected from 1 to 50; 
 each u is independently selected from 1 and 2; 
 each R 4  is independently selected from C 2-6  alkanediyl; 
 each R 5  is independently selected from hydrogen, C 1-6  alkyl, C 7-12  phenylalkyl, substituted C 7-12  phenylalkyl, C 6-12  cycloalkylalkyl, substituted C 6-12  cycloalkylalkyl, C 3-12  cycloalkyl, substituted C 3-12  cycloalkyl, C 6-12  aryl, and substituted C 6-12  aryl; and 
 each R 6  is a group comprising a terminal thiol group; and 
 B represents a core of a z-valent polyol B(OH) z  wherein z is an integer from 3 to 6. 
 
       
     
     
         14 . The composition of  claim 13 , wherein each R 6  is independently a thiol-terminated group selected from a group of Formula (a), Formula (b), Formula (c), Formula (d), Formula (e), Formula (f), Formula (g), and Formula (h): 
       
         
           
           
               
               
           
         
         wherein:
 each R 8  is independently selected from a moiety derived from a diisocyanate and a moiety derived from an ethylenically unsaturated monoisocyanate; 
 each R 9  is independently selected from C 2-14  alkanediyl and C 2-14  heteroalkanediyl; and 
 each R 10  is independently selected from C 2-6  alkanediyl, C 2-6  heteroalkanediyl, C 6-12  arenediyl, substituted C 6-12  arenediyl, C 6-12  heteroarenediyl, substituted C 6-12  heteroarenediyl, C 3-12  cycloalkanediyl, substituted C 3-12  cycloalkanediyl, C 3-12  heterocycloalkanediyl, substituted C 3-12  heterocycloalkanediyl, C 7-18  alkanearenediyl, substituted C 7-18  heteroalkanearenediyl, C 4-18  alkanecycloalkanediyl, and substituted C 4-18  alkanecycloalkanediyl. 
 
       
     
     
         15 . The composition of  claim 1 , wherein the polyamine comprises an aromatic polyamine. 
     
     
         16 . The composition of  claim 1 , wherein the amine-terminated polythioether adduct is selected from an adduct of Formula (13), an adduct of Formula (13′), and a combination thereof:
   Y—NH—CH 2 —CH(OH)—R 16 —S—R 15 —S—R 16 —CH(OH)—CH 2 —NH—Y  (13)
 
   {Y—NH—CH 2 —CH(OH)—R 16 —S—R 15 —S—R 16 —CH(OH)—CH 2 —V′—} z B  (13′)
 
 wherein:
 each R 15  is independently selected from C 2-10  alkanediyl, C 2-10  oxyalkanediyl, C 6-8  cycloalkanediyl, C 6-10  alkylcycloalkanediyl, and —[—(CHR 3 ) s —X′—] q —(CHR 3 ) r —; wherein
 each R 3  is independently selected from hydrogen and methyl; 
 each X′ is independently selected from O, S, and —NR— wherein R is selected from hydrogen and methyl; 
 s is an integer from 2 to 6; 
 q is an integer from 1 to 5; and 
 r is an integer from 2 to 10; 
 
 each R 16  is independently selected from C 3-20  alkanediyl and C 3-20  oxyalkanediyl; 
 B represents the core of a z-valent polyfunctionalizing agent B(V) z , wherein:
 z is an integer from 3 to 6; and 
 each V comprises a group that is reactive with an epoxy group; 
 
 each —CH(OH)—CH 2 —V′— comprises a moiety resulting from the reaction of V with an epoxy group; and 
 each Y—NH— is derived from an aromatic polyamine. 
 
 
     
     
         17 . The composition of  claim 1 , wherein the amine-terminated polythioether adduct comprises the reaction products of reactants comprising:
 (a) an epoxy-terminated polythioether selected from an epoxy-terminated polythioether of Formula (15), an epoxy-terminated polythioether of Formula (15′), and a combination thereof:   
       
         
           
           
               
               
           
         
         wherein:
 each R 15  is independently selected from C 2-10  alkanediyl, C 2-10  oxyalkanediyl, C 6-8  cycloalkanediyl, C 6-10  alkylcycloalkanediyl, and —[—(CHR 3 ) s —X′—] q —(CHR 3 ) r —; wherein
 each R 3  is independently selected from hydrogen and methyl; 
 each X′ is independently selected from O, S, and —NR— wherein R is selected from hydrogen and methyl; 
 s is an integer from 2 to 6; 
 q is an integer from 1 to 5; and 
 r is an integer from 2 to 10; 
 
 each R 16  is independently selected from C 3-20  alkanediyl and C 3-20  oxyalkanediyl; 
 B represents the core of a z-valent polyfunctionalizing agent B(V) z , wherein:
 z is an integer from 3 to 6; and 
 V is a group comprising a terminal group that is reactive with an epoxy group; and 
 
 —CH(OH)—CH 2 —V′— comprises a moiety resulting from the reaction of V with an epoxy group; and 
 
         (b) an aromatic polyamine. 
       
     
     
         18 . A sealant comprising the composition of  claim 1 , wherein the specific gravity of the sealant is from about 0.5 to about 1.1. 
     
     
         19 . A sealed aperture sealed with a sealant comprising the composition of  claim 1 .