FIELD OF THE DISCLOSURE

[0001] This disclosure generally relates to a curable sealant composition. More specifically, this disclosure relates to a sealant composition that includes a polysulfide having an -SH group and a capped polycarbodiimide.

BACKGROUND

[0002] Polysulfide sealants are known in the art and have been used in a variety of industries. Polysulfide sealants are a staple manufacturing of many products such as aircraft. Polysulfide sealants exhibit excellent diesel fuel resistance and excellent adhesion to aluminum over a broad range of temperatures.

[0003] Polysulfide sealants are available in one or two part compositions. Polysulfide compositions typically comprise polysulfides, curatives, and additives. Polysulfides are cured by an oxidoreduction reaction wherein lead, manganese, and/or chromate oxidizers are typically used to cure the polysulfides over a number of days. Lead, manganese, and chromate oxidizers include heavy metals which can cause regulatory and other problems. Further, polysulfide sealants cured with lead, manganese, and/or chromate oxidizers typically react slowly, causing longer curing times.

[0004] In manufacturing, longer curing times increase production times and reduce efficiencies. For example, polysulfide sealants can be particularly difficult to use in applications such as the manufacturing or repair of aircraft. In aircraft manufacturing, conventional type A and B polysulfide sealants, are usually applied over a surface or in the form of a bead for coating bolts, rivets or other structural elements in numerous joints, and often require consistent longer tack free times and shorter cure times. Further, such polysulfide sealants must be used quickly and in their entirety to prevent premature partial curing and waste. Therefore, there remains an opportunity for improvement.

SUMMARY OF THE DISCLOSURE

[0005] This disclosure provides a curable sealant composition including a polysulfide having an -SH group and a capped polycarbodiimide. The capped polycarbodiimide has the following general structure:

wherein R ¹ is a C1-C I2 alkyl, a C1-C12 cycloalkyl, a C ₆ -Ci2 aromatic, a C ₆ -Ci2 heterocyclyl, or a C6-C12 heteroaryl linking group; R ² is an alkyl, cycloalkyl, aromatic, heterocyclic, or heteroaryl end cap; R ³ is an alkyl, cycloalkyl, aromatic, heterocyclic, or heteroaryl end cap; and n is an integer from 2 to 60. A method of forming the curable sealant composition comprising and the capped polycarbodiimide is disclosed.

[0006] This disclosure also provides a cured sealant formed from the curable sealant composition and the capped polycarbodiimide as well as an article including a substrate and the cured sealant or curable sealant disposed on the substrate.

DETAILED DESCRIPTION OF THE DISCLOSURE

[0007] This disclosure provides a curable sealant composition (hereinafter described as the "composition"). The composition is curable and may be cured. After cure, the composition may be described as a curable sealant composition or simply as the cured composition. This disclosure describes an uncured composition, a partially cured composition, and a completely or fully cured composition. Accordingly, below, the terminology "composition" may describe any of the aforementioned types of compositions unless otherwise particularly stated.

[0008] The composition is not particularly limited and may be used in any industry; for example, in aeronautics, construction, for constructing and/or maintaining aircraft or spacecraft, in motor vehicles, in rail vehicles, in ships, in machines, in appliances and furniture, and, more particularly, for adhesive bonding and/or protection against corrosion of aircraft or spacecraft, motor vehicles, rail vehicles, ships, machines, appliances and furniture. In one embodiment, the composition is used as a sealant in an aircraft. In another embodiment, the composition is used as a sealant on a fuel-tank of an aircraft. In still another embodiment, the composition is used as a sealant on a fuel-tank of a vehicle such as a train, automobile, etc.

[0009] The composition includes, is, consists essentially of, or consists of, a polysulfide having an -SH group and a capped polycarbodiimide. Each of these is described in detail below. The terminology "consists essentially of describes non-limiting embodiments that are free of one or more polymers that are not, for example, polysulfides and/or capped polycarbodiimides, free of one or more monomers that are not, for example, carbodiimides, free of one or more catalyst components that are not those of this disclosure, and/or free of one or more additives known in the art and/or described below. The selection of which components to exclude from a composition "consisting essentially of the polysulfide and the capped polycarbodiimide can be made by one of skill in the art.

Polysulfide:

[0010] The composition includes a polysulfide but may include two or more polysulfides or combinations of polysulfides, any one or more of which may be described below. For example, the composition may include at least one polysulfide, at least two polysulfides, etc. In various non-limiting embodiments described herein, the terminology "polysulfide" may include two or more polysulfides.

[0011] In various embodiments, the terminology "polysulfide" typically describes (one or more) polysulfide (homo)polymer(s). However, it is contemplated that (one or more) polysulfide (co)polymer(s) may also be used, either alone or in combination with the (one or more) (homo)polymers. The polysulfide may alternatively be described as a polythioether. In the art, various species of the genus polysulfides are polythioethers. Accordingly, the polysulfide may be further defined as polythioether or two or more polythioethers. Alternatively, the composition may include a polysulfide and a polythioether.

[0012] The polysulfide has an -SH group, but otherwise is not particularly limited and may be any in the art. The polysulfide may have a single -SH group or two or more -SH groups. One or more or all of the groups may be terminal or pendant. In various embodiments, the polysulfide is described as part of a class of chemical compounds including chains of sulfur atoms. In another embodiment, the polysulfide is a polymer having at least one S-S bond in its chain and an -SH group. The polysulfide of this disclosure is typically described as an organic polysulfide, as opposed to a sulfide anion (S _a ^2" )- hi one embodiment, the polysulfide of this disclosure has the formula RS _a R(-SH)b, wherein (a) is a number of 2 or greater, each R is independently an alkyl or aryl group, each -SH group is terminal or pendant, and (b) is a number of 1 or greater.

[0013] In other embodiments, the polysulfide is further defined as including a plurality of blocks each having the formula -R ⁵ -S _x - wherein x is from 1 to 5 and R ⁵ is an alkyl group having 2 to 16 carbon atoms or an alkyl group having 16 carbon atoms that further comprises one or more ether groups, and further having a terminal thiol group having the formula -R ⁶ - SH, wherein R ⁶ is an alkyl group having 2 to 16 carbon atoms or an alkyl group having 2 to 16 carbon atoms that further comprises an ether-bond.

[0014] In still other embodiments, the polysulfide is a polythioether that has the formula -R ⁷ - [-S-(CH ₂ )2-0-[-R ⁸ -0-]m-(CH ₂ )2-S-R ⁷ -]n-. In this formula, each of R ⁷ and R ⁸ is independently a C ₂ -C ₆ n-alkylene group, a C3-C6 branched alkylene group, a C ₆ -C ₈ cycloalkylene group, a Ce-Cio alkylcycloalkylene group, or -[(-CH ₂ -) _p -X-] _q -(-CH ₂ -) _r -, or -[(-CH ₂ -) _p -X-] _q -(-CH ₂ -) _r - in which at least one CH ₂ unit is substituted with a methyl group. Moreover, m is a number from 0 to 10, e.g. 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, n is a number from 1 to 60, e.g. 5 to 55, 10 to 50, 15 to 45, 20 to 40, 25 to 35; p is a number from 2 to 6, e.g. 2, 3, 4, 5, or 6; q is a number from 1 to 5, e.g. 1, 2, 3, 4, or 5, and r is a number from 2 to 10, e.g. 2, 3, 4, 5, 6, 7, 8, 9, or 10. In various non-limiting embodiments, all values and ranges of values between the aforementioned values are hereby expressly contemplated.

[0015] In further embodiments, the polysulfide is a polythioether that has the formula:

HS-(C ₂ H ₄ -0-CH ₂ -0-C ₂ H4-(S-S) ₂ - ₈ )x-C ₂ H4-0-CH ₂ -0-C ₂ H ₄ -SH wherein x is from 1 to 200, e.g. 5 to 195, 10 to 190, 15 to 185, 20 to 180, 25 to 175, 30 to 170, 35 to 165, 40 to 160, 45 to 155, 50 to 150, 55 to 145, 60 to 140, 65 to 135, 70 to 130, 75 to 125, 80 to 120, 85 to 115, 90 to 110, 95 to 105, or 95 to 100. In various non-limiting embodiments, all values and ranges of values between the aforementioned values are hereby expressly contemplated.

[0016] In further embodiments, the polysulfide is a polythioether that has the formula:

H(S-C ₂ H ₄ -0-CH ₂ -0-C ₂ H ₄ -S)zH

wherein z is from 7 to 43, e.g. 10 to 40, 15 to 35, 20 to 30, or 20 to 25.

[0017] In further embodiments, the polysulfide has the formula: HS-(R-SS)t-R-SH, wherein each R is independently a C ₂ -C ₆ n-alkylene group, a C3-C6 branched alkylene group, a C ₆ -C ₈ cycloalkylene group, or a C ₆ -Cio alkylcycloalkylene group and wherein t is from 5 to 40, e.g. 10 to 35, 15 to 30, 20 to 30, or 25 to 30. In various non-limiting embodiments, all values and ranges of values between the aforementioned values are hereby expressly contemplated. [0018] In further embodiments, the polysulfide has the formula: HS-(R-SS) _q -CH ₂ CH((SS- R) _v -SH)-CH ₂ -(SS-R)r-SH, wherein each R is independently a C ₂ -C ₆ n-alkylene group, a C3-C6 branched alkylene group, a C ₆ -C ₈ cycloalkylene group, or a C ₆ -Cio alkylcycloalkylene group, wherein q+v+r is from 5 to 40, e.g. 10 to 35, 15 to 30, 20 to 30, or 25 to 30. In various non- limiting embodiments, all values and ranges of values between the aforementioned values are hereby expressly contemplated.

[0019] In further embodiments, the polysulfide is a polythioether that has the formula:

HS-R-(0-CH ₂ -CH ₂ -S-CH ₂ -CH ₂ -0-CH-CH ₂ -S-CH ₂ -0-CH ₂ -CH ₂ -S-CH ₂ -CH ₂ -)-R-SH, wherein each R is independently as described above.

[0020] In still other embodiments the polysulfide may be described as a long-chain polymer with a weight average molecular weight of 2800 to 9000 g/mol, e.g. those of Thioplast G131 or with a weight average molecular weight of 3300 to 5000 g/mol such as Thioplast G10, Thioplast G12, Thioplast Gl, Thiokol LP 32, and/or Thiokol LP 12. In various non-limiting embodiments, all values and ranges of values between the aforementioned values are hereby expressly contemplated.

[0021] Alternatively, the polysulfide may be described as a short-chain polymer with a weight average molecular weight of 100 to 3200 g/mol, e.g. from 400 to 2800 g/mol and/or from 500 to 1200 g/mol, such as, for example, Thiokol LP3, Thioplast G4, Thioplast G22 or Thioplast G44.

[0022] In other embodiments, both long-chain polymers with a weight average molecular weight of 2800 to 9000 g/mol or 3300 to 5000 g/mol and short-chain polymers with a weight average molecular weight of 400 to 2800 g/mol or from 500 to 1200 g/mol, are used, e.g. in a weight ratio of 25: 1 to 0.5: 1, from 10: 1 to 1 : 1 or from 6: 1 to 2: 1. In various non-limiting embodiments, all values and ranges of values between the aforementioned values are hereby expressly contemplated.

[0023] In still other embodiments, the polysulfide is described as a liquid polymer having a weight average molecular weight of from 100 to 7500 g/mol or from 500 to 6000 g/mol or from 1000 to 3000 g/mol. Alternatively, the polysulfide may have a weight average molecular weight of from 1,000 to 7,500, from 1,500 to 6,000, from 2,000 to 5,500, from 2,500 to 5,000, from 3,000 to 4,500, or from 3,500 to 4,000, g/mol. In various non-limiting embodiments, all values and ranges of values between the aforementioned values are hereby expressly contemplated.

[0024] In further embodiments, the polysulfide has a total sulfur content of from 1 to 50 wt %, 2 to 45 wt % or 10 to 38 wt %. In other embodiments, the polysulfide has an average functionality of -SH groups of greater than 2, greater than or equal to 2, 2, less than 2, or less than or equal to 2, e.g. from 1.5 to 2.5 or 1.9 to 2.2. In various embodiments, the average functionality is from 1.5 to 2 or 0.8 to 1.5. In other embodiments, the polysulfide has an average glass transition temperature Tg of from -80 to -30°C or -60 to -40°C, measured according to AITM 1-0003 Airbus Industry Test Method of June 1995. In various non- limiting embodiments, all values and ranges of values between the aforementioned values are hereby expressly contemplated.

[0025] The amount of the polysulfide in the composition is not particularly limited. In various embodiments, the polysulfide is present in the composition in an amount of from 1 to 99, from 1 to 95, from 10 to 95, from 1 to 80, from 1 to 30, from 5 to 30, from 5 to 80, from 60 to 80, or from 30 to 80, parts by weight per 100 parts by weight of the composition. In various non-limiting embodiments, all values and ranges of values between the aforementioned values are hereby expressly contemplated.

Capped Polycarbodiimide:

[0026] The capped polycarbodiimide may be, include, consist essentially of, or consist of, any capped polycarbodiimide having the following general structure:

R ¹ is a C1-C12 alkyl, C1-C12 cycloalkyl, a C ₆ -Ci2 aromatic, a C ₆ -Ci2 heterocyclyl, or a C6-C12 heteroaryl linking group. In a preferred embodiment, R ¹ is a C ₆ -Ci2 aromatic group.

[0027] R ² is an alkyl, cycloalkyl, aromatic, heterocyclic, or heteroaryl end cap. In some embodiments, R ² comprises a urethane group and/or a carbodiimide group. In other embodiments, R ² comprises an aromatic group.

[0028] R ³ is an alkyl, cycloalkyl, aromatic, heterocyclic, or heteroaryl end cap. In some embodiments, R ³ comprises a urethane group and/or a carbodiimide group. In other embodiments, R ³ comprises an aromatic group. [0029] And n is an integer from 2 to 60, or from 5 to 50.

[0030] In some embodiments, the capped polycarbodiimide has 0.25, or 0.1, or 0.01, wt% or less of free isocyanate groups. Alternatively in some embodiments, the capped polycarbodiimide has 0.25, or 0.1, or 0.01, wt% or less residual monomelic TDI. As is explained in the subject application, the capped polycarbodiimide is the reaction product of isocyanate. As is set forth herein, "the polycarbodiimide is made by a process such that it lacks residual isocyanate (NCO) groups, or at least has a very high percentage of -N=C=N- linkages in comparison to residual NCO groups." Free isocyanate groups are isocyanate groups, e.g. isocyanate groups detectable via infra-red spectroscopy that are free or unreacted. Such free isocyanate groups could be any isocyanate groups found on any residual unreacted isocyanate, any isocyanate groups found on the capped polycarbodiimide itself, or any isocyanate groups found on any residual reaction intermediates or bi-products formed during the synthesis of the capped isocyanate.

[0031] In many embodiments, the capped polycarbodiimide is polycarbodiimide capped. In such embodiments, the polycarbodiimide of formula (I) includes an R ² and/or R ³ comprising a carbodiimide group. Examples of such capped polycarbodiimides include structures (II) and (III) below.

[0032] In one particular embodiment, the capped polycarbodiimide has the following general structure:

wherein n is an integer from 2 to 60, or from 5 to 50.

[0033] In another particular embodiment, the capped polycarbodiimide has the following general structure:

wherein n is an integer from 2 to 60, or from 5 to 50.

[0034] In many embodiments, the capped polycarbodiimide is urethane capped. That is, the capped polycarbodiimide is a polycarbodiimide-polyurethane hybrid. In such embodiments, the polycarbodiimide of formula (I) includes an R ² and/or R ³ comprising a urethane group. Examples of such capped polycarbodiimides include structures (IV) and (XIII) below.

[0035] In still another particular embodiment, capped polycarbodiimide is a polycarbodiimide-polyurethane hybrid having the following general structure:

wherein R ⁴ is an alkyl, cycloalkyl, aromatic, heterocyclic, or heteroaryl end cap; and n is an integer from 2 to 60, or from 5 to 50.

[0036] For example, the capped polycarbodiimide is a polycarbodiimide-polyurethane hybrid having the following general structure:

(V), wherein R ⁴ is a hydrogen atom, a hydrocarbon, or any cap comprising a urethane group, a carbodiimide group, a hydroxyl group, and/or amino group; and n is an integer from 2 to 60, or from 5 to 50.

[0037] In one embodiment, the capped polycarbodiimide is a polycarbodiimide-polyurethane hybrid having the following general structure:

[0038] In another embodiment, the capped polycarbodiimide is a polycarbodiimide- polyurethane hybrid having the following general structure:

z (VII).

[0039] Yet, in another embodiment, the capped polycarbodiimide is further defined as a mixture of both of structures (VI) and (VII) wherein each is independently present in a weight ratio of from 0: 100 to 100:0, respectively. In various non-limiting embodiments, all values and ranges of values between and including the aforementioned values are hereby expressly contemplated.

[0040] In the structures (VI) and (VII), each n is independently a number from 1 to 20, e.g. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20, or any range thereof. In various embodiments, n is determined based on a monol, diol, triol, or polyol used to form urethane linkages (NCO linkages) in the aforementioned structure. In various non-limiting embodiments, all values and ranges of values between and including the aforementioned values are hereby expressly contemplated.

[0041] In the structures (VI) and (VII), each Y is independently an alkoxy or polyalkoxy group having (w) oxygen atoms, wherein each w is independently at least 1. In various embodiments, each w is independently 1, 2, or 3. However, it is contemplated that each w may independently be greater than 3, e.g. 4, 5, 6, 7, or 8. The terminology "alkoxy" typically describes a group having an alkyl moiety singly bonded to an oxygen atom, which in turn is typically bonded to a hydrogen atom, e.g. alkyl-O-H. The terminology "polyalkoxy" group typically describes two or more alkoxy groups bonded together. One or more Y may be bonded to (or capped with) a hydrogen atom, e.g. if z = 0. In various non-limiting embodiments, all values and ranges of values between and including the aforementioned values are hereby expressly contemplated.

[0042] In alternative embodiments of the structures (VI) and (VII), each Y is independently derived from a tri-hydroxy functional polyol having a hydroxyl number from 1500 to 2000, from 1550 to 1950, from 1600 to 1900, from 1650 to 1850, from 1700 to 1800, from 1700 to 1750, or from 1750 to 1800, mg KOH/g. In various embodiments, each Y is independently derived from a tri-hydroxy functional polyol having a hydroxyl number from 800 to 1200, 850 to 1150, 900 to 1100, 950 to 1050, 950 to 1000, or 1000 to 1050, mg KOH/g. In other embodiments, each Y is independently derived from a tri-hydroxy functional polyol having a hydroxyl number from 200 to 400, from 250 to 350, from 250 to 300, or from 300 to 350, mg KOH/g. In other embodiments, each Y is independently derived from a tri-hydroxy functional polyol having a hydroxyl number from 20 to 400, from 30 to 390, from 40 to 380, from 50 to 370, from 60 to 360, from 70 to 350, from 80 to 340, from 90 to 330, from 100 to 320, from 110 to 310, from 120 to 300, from 130 to 290, from 140 to 280, from 150 to 270, from 160 to 260, from 170 to 250, from 180 to 240, from 190 to 230, from 200 to 220, from 200 to 210, or from 210 to 220, mg KOH/g. In other embodiments, each Y is independently derived from glycerine. In further embodiments, each Y is independently derived from propylene glycol, ethylene glycol, butylene glycol, copolymers thereof, and combinations thereof. Alternatively, each Y may be independently derived from a diol. Further, each Y may be independently derived from a monol, e.g. 1-decanol, 2-propyl-l-heptanol, or 2-ethyl- hexanol, or a combination thereof. Other, lower carbon number monols may also be used such as n-butanol, pentanol, or any alcohols having 4, 5, 6, 7, 8, 9, 10, 11, or 12, carbon atoms. Alternatively, each Y may be described as being independently derived from a polyester polymer. The monols, diols, and polyols used may be chosen from those set forth in the instant Examples below, e.g. glycerine, Pluracol 858, Pluracol GP 430, and Pluracol GP 730, and combinations thereof. In further embodiments, each Y may be described as being independently derived from a polyol that is 4, 5, 6, 7, or 8, hydroxy-functional or a combination thereof. In still other embodiments, each Y may independently be any described above. For example, if the capped polycarbodiimide has two Y groups, then they may be the same or different from each other. In one embodiment, Y is or is derived from trimethylolpropane. It is also contemplated that any isomer of any of the aforementioned compounds may also be used. In various non-limiting embodiments, all values and ranges of values between and including the aforementioned values are hereby expressly contemplated.

[0043] Moreover in the structures (VI) and (VII), z is a number from 0 to (w-1), e.g., 0, 1 or 2. Additionally, x, Y, and a total of the CnF i groups are present in a ratio of from (4 to 5):(0.5 to 1.5):(2.5 to 4.5), respectively. In various embodiments, the first value of from (4 to 5) may be further defined as from 4.1 to 4.9, from 4.2 to 4.8, from 4.3 to 4.7, from 4.4 to 4.6, from 4.4 to 4.5, or from 4.5 to 4.6, or any other range thereof. In other embodiments, the second value of from (0.5 to 1.5) may be further defined as 0.6 to 1.4, 0.7 to 1.3, 0.8 to 1.2, 0.9 to 1.1, 0.9 to 1, or 1 to 1.1, or any other range thereof. In further embodiments, the third value of from (2.5 to 4.5) may be further defined as 2.6 to 4.4, 2.7 to 4.3, 2.8 to 4.2, 2.9 to 4.1, 3 to 4, 3.1 to 3.9, 3.2 to 3.8, 3.3 to 3.7, 3.4 to 3.6, 3.4 to 3.5, or 3.5 to 3.6. In various non- limiting embodiments, all values and ranges of values between and including the aforementioned values are hereby expressly contemplated.

[0044] In one embodiment, w is 3 and z is 2. For example, the capped polycarbodiimide is a polycarbodiimide-polyurethane hybrid which may have the structure:

[0045] Alternatively, the capped polycarbodiimide is a polycarbodiimide-polyurethane hybrid which may have the structure:

[0046] However, it is contemplated that even when w is 3 and z is 2, the hybrid may have a different structure than what is set forth above, e.g. depending on Y.

[0047] In other embodiments, w is 2 and z is 1. For example, the hybrid may have the structure:

[0048] Alternatively, the capped polycarbodiimide may have the structure:

[0049] However, it is contemplated that even when w is 2 and z is 1, the hybrid may have a different structure than what is set forth above, e.g. depending on Y. [0050] In further embodiments, w is 1 and z is 0. For example, the hybrid may have the structure:

[0051] Alternatively, the hybrid may have the structure:

[0052] However, it is contemplated that even when w is 1 and z is 0, the hybrid may have a different structure than what is set forth above, e.g. depending on Y.

[0053] The capped polycarbodiimide can be utilized in the composition in any amount. In various embodiments, the capped polycarbodiimide is present in the composition in an amount of from 1 to 99, from 1 to 75, from 1 to 50, from 1 to 40, from 1 to 30, from 5 to 80, from 5 to 30, from 10 to 40, or from 10 to 30, parts by weight per 100 parts by weight of the composition. In various non-limiting embodiments, all values and ranges of values between the aforementioned values are hereby expressly contemplated.

[0054] In various embodiments, the polysulfide and the capped polycarbodiimide are present in the composition in a weight ratio of from 100: 1 to 1 : 100, from 10: 1 to 1 : 10, from 2: 1 to 1 :2, from 5: 1 to 1 :5, from 10: 1 to 100: 1, from 10: 1 to 50: 1, or from 15: 1 to 30: 1. In various non-limiting embodiments, all values and ranges of values between the aforementioned ratios are hereby expressly contemplated. Catalyst:

[0055] The composition may also include, or be free of, a catalyst. The composition may also include one or more catalysts. The catalyst is typically present in the composition to catalyze the reaction between the polysulfide and the capped polycarbodiimide. It is to be appreciated that the catalyst is typically not consumed in the reaction between the polysulfide and the capped polycarbodiimide. More specifically, the catalyst typically participates in, but is not consumed in, the reaction. The catalyst may include any suitable catalyst or mixtures of catalysts known in the art.

[0056] The composition may include, or be free of, a metal oxide catalyst. The metal oxide catalyst may be treated (e.g. with sodium hydroxide) or untreated. The metal oxide catalyst may be chosen from manganese dioxide (Mn0 ₂ ), lead dioxide (Pb0 ₂ ), lead oxide (PbO), cadmium oxide (CdO), zinc oxide (ZnO), and combinations thereof. In still other embodiments, the metal catalyst may be chosen from dioxides of lead, manganese, calcium, barium, sodium and zinc, and combinations thereof. In one embodiment, the metal oxide catalyst is manganese dioxide, also known as manganese (IV) oxide. Other manganese oxides can also be used, such as manganese (II), manganese (III), manganese (V), and manganese (VII), oxides, or combinations thereof. In a further embodiment, a combination of BaO and CaO are used. PbO may also be optionally used.

[0057] The composition may include, or be free of, an amine catalyst. For example, the catalyst may be a basic amine. In other embodiments, the catalyst is an aminic catalyst. In still other embodiments, the catalyst is chosen from tertiary amines, such as 1,4- diazabicyclo[2,2,2]octane (DAB CO or TED A), l,8-diazabicyclo[5,4,0]undec-7-ene (DBU), l,5-diazabicyclo[4,3,0]non-5-ene (DBN), N,N,N',N",N"-pentamethyldiethylenetriamine (PMDETA), N-methyl-N'-(dimethylaminoethyl)piperazine, N,N-dimethylcyclohexylamine (DMCHA), N,N',N"-tris(dimethylaminopropyl)hexahydrotriazine or bis(2-

(dimethylamino)ethyl)ether (BDMAEE), guanidine and derivatives thereof, such as diphenylguanidine, tetramethylguanidine or di-o-tolylguanidine, morpholine and derivatives thereof, such as N-methylmorpholine (NMM), N-ethylmorpholine (NEM), dimorpholinodiethyl ether (DMDEE), or N-methylmorpholine oxide (NMMO), Lewis acids, such as FeCi3, AICB or SnCi ₂ , and tin salts, such as dibutyl tin dilaurate (DBTDL) or dioctyl tin dilaurate (DOTDL), and combinations thereof.

[0058] In other embodiments, the catalyst may be chosen from guanidines, bis(piperidinothiocarbonyl) tetrasulphide, and strong N bases (as would be understood in the art), and combinations thereof. In still further embodiments, the catalyst may be chosen from tertiary amines, and more particularly l,4-diazabicyclo[2,2,2]octane (DABCO or TED A) and l,8-diazabicyclo[5,4,0]undec-7-ene (DBU), and combinations thereof.

[0059] The composition may include, or be free of, an organometallic catalyst. The catalyst may be or include a tin catalyst (e.g. an organo-tin catalyst). Suitable tin catalysts include, but are not limited to, tin(II) salts of organic carboxylic acids, e.g. tin(II) acetate, tin(II) octoate, tin(II) ethylhexanoate and tin(II) laurate. In one embodiment, the catalyst is or includes dibutyltin dilaurate, which is a dialkyltin(IV) salt of an organic carboxylic acid. The catalyst can also include other dialkyltin(IV) salts of organic carboxylic acids, such as dibutyltin diacetate, dibutyltin maleate and dioctyltin diacetate. Examples of suitable but non-limiting catalysts include iron(II) chloride; zinc chloride; lead octoate; tris(dialkylaminoalkyl)-s- hexahydrotriazines including tris(N,N-dimethylaminopropyl)-s-hexahydrotriazine; tetraalkylammonium hydroxides including tetramethylammonium hydroxide; alkali metal hydroxides including sodium hydroxide and potassium hydroxide; alkali metal alkoxides including sodium methoxide and potassium isopropoxide; and alkali metal salts of long-chain fatty acids having from 10 to 20 carbon atoms and/or lateral OH groups. In other embodiments, the catalyst is chosen from dibutyltin dilaurate, dibutyltin oxide (e.g. as a liquid solution in C ₈ -Cio phthalate), dibutyltin dilaurylmercaptide, dibutyltin bis(2- ethylhexylthioglycolate), dimethyltin dilaurylmercaptide, diomethyltin dineodecanoate, dimethyltin dioleate, dimethylti n bis(2-ethylhexylthioglycoate), dioctyltin dilaurate, dibutyltin bis(2-ethylhexoate), stannous octoate, stannous oleate, dibutyltin dimaleate, dioctyltin dimaleate, dibutyitin maleate, dibutyltin mercaptopropionate, dibutyltin bis(isoodyithioglycolate), dibutyltin diacetate, dioctyltin oxide mixture, dioctyltin oxide, dibutyltin diisooctoate, dibutyltin dineodecanoate, dibutyltin carboxylate, dioctyitin carboxylate, and combinations thereof. Potassium and potassium acetate catalysts can also be used. [0060] In further embodiments, the catalyst is an amine or thiuram catalyst. In various embodiments, the thiuram catalyst has the following structure:

wherein each of R ⁹ , R ¹⁰ , R ¹¹ , and R ¹² , is any alkyl group having 1 to 20 carbon atoms, particular embodiment, the thiuram catalyst has the following structure:

[0061] The amount of the catalyst that may be used is not particularly limited and may be chosen by one of skill in the art. In various embodiments, the catalyst is present in an amount of from 0.1 to 10, from 0.5 to 10, from 1 to 10, from 0.1 to 1, from 0.5 to 1, from 1 to 5, or from 5 to 10, parts by weight per 100 parts of polysulfide. In various non-limiting embodiments, all values and ranges of values between the aforementioned values are hereby expressly contemplated.

Additives:

[0062] The composition may also include one or more additives or be free of any one or more additives, such as those described below.

[0063] For example, in various embodiments, the composition includes a UV photosensitizer. Any type known in the art may be used. For example, the UV photosensitizer may be used such that the composition may cure in the UVA, UVB, or UVC range. In still further embodiments, mixtures of photosensitizers and/or photoinitiators may be used to adjust the absorption wavelength(s) of the composition or to shift the absorption edge and/or the absorption range of the composition. Examples of suitable photosensitizers include, but are not limited to, DAROCUR® BP (Benzophenone), Quantacure BMS (4-(4- Methylphenylthio)benzophenone), DAROCUR® ITX (Isopropylthioxanthone), and combinations thereof. In various other embodiments, the photosensitizer is utilized in amounts of from 0.1 to 5, 0.5 to 4.5, 1 to 4, 1.5 to 3.5, 2 to 3, or 2.5 to 3.5, parts by weight per 100 parts by weight of the composition. In various non-limiting embodiments, all values and ranges of values between the aforementioned values are hereby expressly contemplated.

[0064] Further, fillers based on magnesium silicate hydrate such as, for example, talc, based on aluminum hydroxide such as, for example, Al(OH) ₃ , based on a feldspar, based on quartz powder and/or based on a calcium silicate and/or aluminum silicate may be used and may have a particle size from 1 to 20 micrometers. Adding one or more fillers may serve to improve the mechanical properties of the composition. In various embodiments, the fillers are chosen from calcium silicate, magnesium silicate hydrate, aluminum silicate, quartz powder and/or aluminum hydroxide such as, for example, aluminum trihydrate. Fillers based on CaC0 ₃ , T1O2, carbon black and/or BaS0 ₄ as well as fillers with a significant Fe content and/or containing additional heavy metals may be used.

[0065] Plasticizers such as, but not limited to, aliphatic oils, waxes, fatty acid salts, resins derived from alkylated phenols and esters, and combinations thereof. In other embodiments, the composition includes one or more fillers such as, but not limited to, microspheres, polystyrene foam, polyacrylates, polyolefins, silica, aluminum/silica, aluminum silicate, calcium carbonate, coated polyvinylidene, calcium silicates, fumed silica, precipitated silica, polyethylene, calcium carbonate, carbon black, calcined clay, talc, silica, silicate fillers, rutile titanium dioxide, zeolites, and combinations thereof. In still other embodiments, the composition includes one or more adhesion promoters such as, but not limited to, methylon AP-108, Duerz 16674, Bakelite BRL 3741, Resinex 468, silanes, phenolic resins, polysulfides, epoxy functional molecules, and combinations thereof. In further embodiments, the composition includes surfactants, such as those known in the art, thixotropic agents such as sepiolite and those known in the art, solvents such as organic solvents, ethyl acetate, terphenyls, hydrogenated terphenyls, toluene, and those known in the art, and/or pigments such as titanium dioxide, zinc sulfide, carbon black, organic and inorganic pigments, and those known in the art, and combinations thereof. In further embodiments, the composition includes photosensitizers and/or photo initiators, or combinations thereof. Moreover, the composition may be free of any one or more such additives.

[0066] Further, fillers based on magnesium silicate hydrate such as, for example, talc, based on aluminum hydroxide such as, for example, Al(OH) ₃ , based on a feldspar, based on quartz powder and/or based on a calcium silicate and/or aluminum silicate may be used and may have a particle size from 1 to 20 micrometers. Adding one or more fillers may serve to improve the mechanical properties of the composition. In various embodiments, the fillers are chosen from calcium silicate, magnesium silicate hydrate, aluminum silicate, quartz powder and/or aluminum hydroxide such as, for example, aluminum trihydrate. Fillers based on CaCCb, Ti0 ₂ , carbon black and/or BaS0 ₄ as well as fillers with a significant Fe content and/or containing additional heavy metals may be used.

[0067] Plasticizers such as, but not limited to, aliphatic oils, waxes, fatty acid salts, resins derived from alkylated phenols and esters, and combinations thereof. In other embodiments, the composition includes one or more fillers such as, but not limited to, microspheres, polystyrene foam, polyacrylates, polyolefins, silica, aluminum/silica, aluminum silicate, calcium carbonate, coated polyvinylidene, calcium silicates, fumed silica, precipitated silica, polyethylene, calcium carbonate, carbon black, calcined clay, talc, silica, silicate fillers, rutile titanium dioxide, zeolites, and combinations thereof. In still other embodiments, the composition includes one or more adhesion promoters such as, but not limited to, methylon AP-108, Duerz 16674, Bakelite BRL 3741, Resinex 468, silanes, phenolic resins, polysulfides, epoxy functional molecules, and combinations thereof. In further embodiments, the composition includes surfactants, such as those known in the art, thixotropic agents such as sepiolite and those known in the art, solvents such as organic solvents, ethyl acetate, terphenyls, hydrogenated terphenyls, toluene, and those known in the art, and/or pigments such as titanium dioxide, zinc sulfide, carbon black, organic and inorganic pigments, and those known in the art, and combinations thereof. In further embodiments, the composition includes photosensitizers and/or photo initiators, or combinations thereof. Moreover, the composition may be free of any one or more such additives.

[0068] In still other embodiments, the composition may include or be free of one or more of calcium carbonate, butanone, toluene, titanium dioxide, Ethanethiol, 2,2,-thiobis-l reaction products with reduced 1,1 '-[methyl enebis(oxy)]bis [2-chloroethane]-sodium sulfide (Na2 (Sx)-l,2,3-trichloropropane polymer, ethyl acetate, hydrogenated Terphenyls, Zeolites, quarter- and higher, partially hydrogenated Polyphenyls, Talc, carbon black, magnesium carbonate, 1,3-diphenylguanidine, bis(piperidinothiocarbonyl) tetrasulphide, photoinitiators, photosensitizers such as benzophenone, isopropyl thioxanthone, aluminum silicate, phenolic resins, Sepiolite, NaAl-based zeolite, phosphorous acid esters, monomelic isocyanates, e.g. based on MDI, pyrogenic silica, and/or combinations thereof.

[0069] Lightweight fillers, in particular those based on polyurethane including their copolymers, polyamide wax and/or polyolefin wax may also be used. Lightweight fillers may also be used to reduce the density of the composition and/or sealant. Alternatively or additionally, hollow filing bodies may also be used.

[0070] Thixotropy agents, in particular based on feldspar, silicic acid/silica, sepiolite and/or bentonite may be used to adjust rheological properties, in particular for thixotropic behavior, of the composition.

[0071] Plasticizers, in particular based on an adipate, a benzoate, a citrate, a phthalate, an ester of a polyethylene glycol, and/or a terphenyl may be used, for example, to increase the flexibility of the composition and/or sealant.

[0072] Adhesion promoters, in particular those based on a phenolic resin, a resol and/or a silane/silanol/siloxane, e.g. mercaptopropyltrimethoxysilane, mercaptopropyltriethoxysilane, glycidoxypropyltrimethoxysilane, glycidoxypropyltriethoxysilane, methacryloxymethyl trimethoxysilane and/or (methacryloxymethyl)methyldimethoxysilane and/or a bis-silylsilane may be used to improve the adhesion of the composition and/or sealant to a substrate.

[0073] Anti-aging agents may also be used such as sterically hindered phenols, phenyl eneamine and/or hindered amine light stabilizers such as 4,6-bis(dodecylthiomethyl)-o- cresol, ethylene-bis(oxyethylene)bis(3-(5-tert-butyl-4-hydroxy-m-tol yl)propionate-, thiodiethylene-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)prop ionate], pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate) and/or phenylene amines such as, for example, N-isopropyl-N'-phenyl-p-phenylenediamine. Anti-aging agents may be used to scavenge the free radicals formed due to aging processes involving the composition and may contribute to delaying and/or preventing aging such as yellowing or embrittlement of the composition and/or sealant.

[0074] Water scavengers, e.g. those based on an organofunctional alkoxysilane, based on a zeolite such as an alkali aluminum zeolite and/or based on a monofunctional isocyanate may also be used. [0075] Flame retardants, in particular those based on phosphate esters, based on ammonium polyphosphate, based on melamine, based on aluminum hydroxide and/or based on magnesium hydroxide may also be used to improve the fire prevention behavior of the composition and/or sealant such as, for example, to delay the onset of burning of the sealant, to spontaneously terminate the burning process and/or to reduce the formation of smoke.

[0076] Isocyanates may also be used. If used, the isocyanate is not particularly limited and may be any known in the art. The isocyanate may be alternatively described as an isocyanate component that itself includes two or more individual isocyanates.

[0077] If used, the isocyanate may be, include, consist essentially of, or consist of, any isocyanate known in the art, e.g. aliphatic isocyanates, aromatic isocyanates, polymeric isocyanates, or combinations thereof. The isocyanate may be, include, consist essentially of, or consist of, more than one different isocyanate, e.g., polymeric diphenylmethane diisocyanate and 4,4' -diphenylmethane diisocyanate. In various embodiments, the isocyanate is chosen from diphenylmethane diisocyanates (MDIs), polymeric diphenylmethane diisocyanates (pMDIs), toluene diisocyanates (TDIs), hexam ethylene diisocyanates (HDIs), isophorone diisocyanates ( PDIs), and combinations thereof. The isocyanate may be an isocyanate pre-polymer. The isocyanate pre-polymer may be a reaction product of an isocyanate and a polysulfide, polythioether, polyol and/or a polyamine. Alternatively, the isocyanate may be a prepolymer that is the reaction product of an isocyanate and the polysulfide. The isocyanate used in the pre-polymer can be any isocyanate as described above. The polyol used to form the pre-polymer may be any polyol having a number average molecular weight of 400 g/mol or greater. For example, polyetherols, polyesterols, and combinations thereof can be used.

[0078] Vulcanization promoters may also be used such as diphenylguanidine, thiuram, and/or sulfur (e.g. sulfur paste).

[0079] In various embodiments, at least one organic solvent, in particular based on an ester and/or an ether such as, for example, ethyl acetate and/or monopropylene glycol monomethyl ether can be used.

[0080] The one or more additives may be present in an amount of from 0 to 40, 0.1 to 10, from 0.1 to 5, or from 0.1 to 2, parts by weight per 100 parts by weight of the composition. In other embodiments, the one or more additives may be present in an amount of from 0.01 to 5, from 0.1 to 5, or from 0.1 to 2, parts by weight per 100 parts by weight of the composition. In still other embodiments, the one or more additives may be present in an amount of from 0.01 to 40, from 0.2 to 1, from 10 to 40, from 1 to 10, or from 5 to 10, parts by weight per 100 parts by weight of the composition. In various non-limiting embodiments, all values and ranges of values between the aforementioned values are hereby expressly contemplated.

Sealant System:

[0081] This disclosure provides single component sealant systems, e.g. one part systems. Of course, this disclosure also provides two part sealant systems. In one embodiment, this system includes a first component including, consisting essentially of, or consisting of, the polysulfide, and a second component including, consisting essentially of, or consisting of, the capped polycarbodiimide and optionally one or more additives (including catalysts). In another embodiment, this system includes a first component including, consisting essentially of, or consisting of, the polysulfide and one or more optional additives, and a second component including, consisting essentially of, or consisting of, the capped polycarbodiimide. The terminology "consisting essentially of describes that the first and/or second component is free of other polymers, monomers, catalysts, etc. In various embodiments, the first component and the second component are utilized in an amount of 1 : 1, 2: 1, 3 : 1, 4: 1, 5: 1, 6: 1, 7: 1, 8: 1, 9: 1, 10: 1, 11 : 1, 12: 1, 13 : 1, 14: 1, 15: 1, 16: 1, 17: 1, 18: 1, 19: 1, or 20: 1, or vice versa, or any combinations thereof. In various non-limiting embodiments, all values and ranges of values between the aforementioned values are hereby expressly contemplated. The first component may be alternatively described as "Part A" as first introduced above. The second component may be alternatively described as "Part B" also introduced above. For example, the polysulfide and the capped polycarbodiimide are present in the composition in a weight ratio of from 16: 1 to 2: 1, referred as Part A to Part B ratio for the two part sealant system.

[0082] This disclosure also provides a dual-cure sealant system. In one embodiment, this system includes a first component including, consisting essentially of, or consisting of, the polysulfide and the capped polycarbodiimide, and a second component including, consisting essentially of, or consisting of, the catalyst, e.g. the metal oxide catalyst. In another embodiment, this system includes a first component including, consisting essentially of, or consisting of, the polysulfide and a first portion of the capped polycarbodiimide, and a second component including, consisting essentially of, or consisting of, the catalyst and a second portion of the capped polycarbodiimide. In still other embodiments, the system includes a first component including, consisting essentially of, or consisting of, the polysulfide and a second component including, consisting essentially of, or consisting of, the catalyst and the capped polycarbodiimide. Moreover, one or more additives or any other components described above may be present in one or both components. The terminology "consisting essentially of describes that the first and/or second component is free of other polymers, monomers, catalysts, etc. In various embodiments, the first component and the second component are utilized in an amount of 1 : 1, 2: 1, 3 : 1, 4: 1, 5: 1, 6: 1, 7: 1, 8: 1, 9: 1, or 10: 1, or vice versa. In various non-limiting embodiments, all values and ranges of values between the aforementioned values are hereby expressly contemplated.

Sealant:

[0083] The disclosure also provides a sealant, which may be described as the result of the composition after cure. The sealant may be referred to as an isothiourea. Alternatively, the sealant may be described as a partially cured composition.

[0084] The sealant may be described as the polymerization product of the polysulfide and the capped polycarbodiimide. This typically forms an isothiourea. Alternatively, the sealant may include, consist essentially of, or consist of, such a polymerization product. The terminology "consist essentially of describes embodiments that are free of polymers or co-polymers, of any known in the art, that are not the sealant itself, i.e., the polymerization product of the polysulfide and capped polycarbodiimide. It is believed that the polymerization reaction generally progresses as follows:

[0085] In various embodiments, the reaction can occur at an equivalent ratio of from 10: 1 to 1 : 10, from 10: 1 to 1 : 1 (SH to carbodiimide).

[0086] In various embodiments, the composition cures to have a viscosity of greater than 500, 1,000, 1,500, 2,000, 2,500, or 3,000 cps in 45, 40, 35, 30, 25, 20, 15, 10, or 5 minutes. Typically, a maximum viscosity in 15, 10, or 5 minutes is greater than 1000 cps as measured using a viscometer such as a Brookfield DV-II + Pro with an appropriate spindle such as a #RV7 spindle. The maximum viscosities in these times may be 10,000, 50,000, 100,000, 500,000, 1,000,000, 1,500,000, etc. up to about 350,000,000, cps, measured in the same way. In various non-limiting embodiments, all values and ranges of values between the aforementioned values are hereby expressly contemplated.

[0087] In various embodiments, the composition cures to a tack-free time of from 0.05 to 5 minutes after the start of cure according to DIN 65262-1. In other embodiments, the composition cures to a tack-free time of less than 120, 115, 110, 105, 100, 95, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 10, or 5, minutes, after the start of cure according to DIN 65262-1. In other embodiments, the sealant has a complete curing time or the time until reaching a Shore hardness of 30, determined according to ISO 7619 or ASTM D2240, from 1 to 960 min, of from 5 to 300 min, of from 10 to 60 min. In additional embodiments, one or more portions of the sealant composition, e.g. the first and second components, may have a density, determined according to ISO 2781, of from 0.9 to 1.6 g/cm ³ or from 1.2 to 1.5 g/cm ³ . In various non-limiting embodiments, all values and ranges of values between the aforementioned values are hereby expressly contemplated.

[0088] In other embodiments, the sealant has a Shore A hardness, determined according to ISO 7619 and measured 2 weeks after cure in storage in air at 23°C and 50% relative atmospheric humidity, of from 20 to 80, of from 30 to 60, or of from 40 to 55. In additional embodiments, the sealant has a Shore A hardness of at least 10 within 30 to 180 minutes of curing. In further embodiments, the sealant has an elongation at break, determined according to ISO 37 and measured 2 weeks after cure during storage in air at 23°C and 50% relative atmospheric humidity, of from 100 to 1000%, of from 200% to 800%, or from 300% to 600%). In various non-limiting embodiments, all values and ranges of values between the aforementioned values are hereby expressly contemplated.

[0089] In other embodiments, the sealant has an elongation, determined according to ISO 37 and measured after 168 hours in storage in a fuel at 60°C, using the jet Al type of fuel, is of from 25 to 800%, of from 200 to 600%, or of from 300 to 500%. In other embodiments, the sealant has an elongation at break of the sealants according to the invention, determined according to ISO 37 and measured after 300 hours in storage in fuel at 100°C, using the jet Al type of fuel is preferably of from 100 to 700%, especially preferably of from 200 to 600%, or 400 to 500%). In even further embodiments, the sealant has an elongation at break, determined according to ISO 37 and measured after 1000 hours in storage in water at 35°C, of from 100 to 700%, e.g. from 200 to 500% or 250 to 350%. In various non-limiting embodiments, all values and ranges of values between the aforementioned values are hereby expressly contemplated.

[0090] In other embodiments, the sealant has a peel resistance on aluminum alloy 2024 T3, determined according to DIN 65262-1, of from 60 to 350 N/25 mm, e.g. from 100 to 250 N/25 mm or 160 to 200 N/25 mm. Alternatively, the sealant has a peel resistance on enamels, such as, for example, on base enamels including solvent such as, for example, epoxy base enamel 37035 A from Akzo Nobel Aerospace Coatings, on water-based base enamels such as, for example, those based on epoxy such as Seevenax 313-01 and Seevenax 313-02 from Mankiewicz, on cover enamels such as, for example, water-based top coats based on epoxies such as Seevenax 313-01 from Mankiewicz, on finish F 70-A from Mapaero and/or on solvent-containing top coats based on polyurethanes such as Aerodur 21-100 from Akzo Nobel and Alexit 406-22 from Mankiewicz, determined according to DIN 65262-1, of from 50 to 350 N/25 mm, e.g. from 10 to 300 N/25 mm or from 170 to 210 N/25 mm. In various embodiments, the peel resistance is determined on substrates of aluminum or aluminum alloys, of titanium or titanium alloys, of stainless steels, of composite materials such as, for example, carbon fiber-reinforced plastic CFP and/or on enamel substrates that have been enameled, for example, with at least one solvent-containing or water-based base coat and/or top coat, in particular based on epoxy, polyester or polyurethane enamel. In various non- limiting embodiments, all values and ranges of values between the aforementioned values are hereby expressly contemplated.

[0091] In additional embodiments, the sealant has a tensile strength, determined according to ISO 37 and measured after 2 weeks after UV irradiation with storage in air at 23°C and 50% relative atmospheric humidity, of from 0.5 to 3.5 MPa, e.g. from 1 to 3 MPa or 1.8 to 2.7 MPa. In other embodiments, the sealant has a tensile strength, determined according to ISO 37 and measured after 168 hours at 60°C in storage in fuel of jet Al type, is of from 0.5 to 3 MPa, e.g. of from 1 to 2.5 or 1.5 to 2 MPa. In further embodiments, the sealant has a tensile strength, determined according to ISO 37 and measured after 300 hours at 100°C in storage in fuel of jet Al type, of from 0.5 to 3 MPa, e.g. from 1 to 2 or 0.8 to 1.1 MPa. In further embodiments, the sealant has a tensile strength, determined according to ISO 37 and measured after 1000 hours at 35°C in storage in water, of from 0.5 to 3 MPa, e.g. of from 1 to 2 MPa or 1.5 to 1.7 MPa. In various non-limiting embodiments, all values and ranges of values between the aforementioned values are hereby expressly contemplated.

[0092] In still other embodiments, the sealant exhibits no cracks or other defects that occur in determination of low temperature flexibility due to bending at an angle of 30 degrees at a temperature of -55°C, a tensile strength of from 0.5 to 2.8 MPa after 168 hours of storage in a fuel at a temperature of 60°C, after 300 hours of storage in a fuel at a temperature of 100°C, and after 1000 hours of storage in water at a temperature of 35°C, an elongation at break of from 100 to 800% after 168 hours of storage in fuel at a temperature of 60°C, after 300 hours of storage in a fuel at a temperature of 100°C, and after 1000 hours of storage in water at a temperature of 35°C and/or a density of from 1.00 to 1.45 g/cm ³ . In still other embodiments, the sealant has the following properties after complete curing: a tensile strength of from 0.5 to 3 MPa, an elongation at break of from 100 to 900% and/or a peel resistance of from 50 to 300 N/25 mm. In various non-limiting embodiments, all values and ranges of values between the aforementioned values are hereby expressly contemplated.

Article:

[0093] This disclosure also provides an article that includes a substrate and the composition and/or (cured or partially cured) sealant disposed thereon. The article may be one used in the aviation industry, but may also be used wherever a rapid and complete curing and especially a very rapid surface curing with a relatively long sealant processing time are necessary and/or advantageous. For example, the article may be a tank or area to be sealed. In various embodiments, the composition and/or sealant may be used for plastering as in gas stations and chemical installations, for example, for connecting structural elements placed on top of one another such as sheet metal, films and other substrates, for filling cavities and intermediate spaces, for coating metallic materials in particular and composites such as, for example, carbon fiber reinforced or glass fiber reinforced plastics, for aerodynamic smoothing and compaction as well as for preventing corrosion in locations where the anticorrosion layers of the metallic elements have been damaged or removed, for example, in the area of boreholes. A load-bearing function may also be fulfilled, for example, during shipping. In various embodiments, the article is used in the shipping industry such as, for example, in automotive engineering, in the construction of rail vehicles, in shipbuilding, in the airplane construction industry or in the spacecraft construction industry, in machine and equipment construction, in the building industry or for the production of furniture. In one embodiment, the article is an aircraft fuel tank. In another embodiment, the article is further defined as a construction article, aircraft/aerospace article, motor or rail vehicle, ship, machine, glass insulation, and/or furniture. In still another embodiment, the article is further defined as glass insulation.

Methods:

[0094] This disclosure also provides a method of forming the curable sealant composition wherein the method includes the steps of providing the polysulfide, the capped polycarbodiimide, and optionally the catalyst and combining the polysulfide, the capped polycarbodiimide, and optionally the catalyst to form the curable composition. The polysulfide and the capped polycarbodiimide are just as described above.

[0095] In some embodiments, the method utilizes the capped polycarbodiimide of formula (II) which is described above and has the following general structure:

wherein n is an integer from 2 to 60.

[0096] In such embodiments, this method may further comprise the steps of preparing the capped polycarbodiimide via:

1) combining a diisocyanate, a moisture scavenger, a monoisocyanate, and a catalyst to form a reaction mixture; and

2) heating the reaction mixture to a temperature and for a time sufficient to form the capped polycarbodiimide;

wherein the capped polycarbodiimide has 0.25 wt% or less of free isocyanate groups, the capped polycarbodiimide is a liquid at 25°C, and/or the combining and heating are conducted in the absence of a solvent. In a typical embodiment, the temperature is from 30°C to 200°C. In many embodiments, the capped polycarbodiimide is formed and reacted with the polysulfide, the capped polycarbodiimide having 0.1, or 0.25, wt% or less free isocyanate groups.

[0097] From a chemical reaction standpoint, the capped polycarbodiimide of formula (II) may be prepared according to the reaction described in Scheme 1 below:

[0098] In one such embodiment, the diisocyanate is selected from 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, and combinations thereof, and the monoisocyanate is an aromatic monoisocyanate. For example, from a chemical reaction standpoint, the capped polycarbodiimide of formula (III) shown above may be prepared according to the reaction described in Scheme 2 below:

MPPO Catalyst

[0099] In the reaction described in Schemes 1 and 2, the polycarbodiimide is prepared in a process that includes combining a diisocyanate, an oxygen scavenger, a monoisocyanate, and a carbodiimidization catalyst to form a reaction mixture. The reaction mixture is then heated to a temperature and for a time sufficient to form the polycarbodiimide.

[00100] In the reaction described in Schemes 1 and 2, the process produces a polycarbodiimide having 0.25 wt. % or less, or 0.1 wt. % or less, of free isocyanate groups. Further, steps of combining and heating may be conducted in the absence of a solvent.

[00101] In the reaction described in Schemes 1 and 2, the oxygen scavenger may be any type of oxygen scavenger known to those skilled in the art. For example, in any of the embodiments herein, the oxygen scavenger may be triphenyl phosphite. Further, any type of carbodiimidization catalyst known to those skilled in the art for producing a polycarbodiimide may be utilized. Generally, the carbodiimidization catalyst is selected from the group of tertiary amides, basic metal compounds, carboxylic acid metal salts and/or non-basic organo- metallic compounds. In certain embodiments, the carbodiimidization catalyst comprises a phosphorus compound. Specific examples of phosphorus compounds suitable for the purposes of the carbodiimidization catalyst include phospholene oxides. Suitable, non limiting examples of phospholene oxides include phospholene oxides such as 3 -methyl- 1- phenyl-2-phospholene oxide (MPPO), l-phenyl-2-phospholen-l-oxide, 3-methyl-l-2- phospholen-l-oxide, l-ethyl-2-phospholen-l-oxide, 3-methyl-l-phenyl-2-phospholen-l-oxide, 3-phospholene isomers thereof, and 3 -methyl- 1 -ethyl -2-phospholene oxide (MEPO).

[00102] In various embodiments, the capped polycarbodiimide of formula (II) is described and formed in accordance with WO 2015/127038, which is incorporated herein in its entirety. [00103] In still other embodiments, the method utilizes the capped polycarbodiimide of formula (IV) which is described above and has the following general structure:

wherein R ⁴ is an alkyl, cycloalkyl, aromatic, heterocyclic, or heteroaryl end cap and n is an integer from 2 to 60.

[00104] In various embodiments, the capped polycarbodiimide of formula (IV) is described and formed in accordance with WO 2016/126606, which is incorporated herein in its entirety.

[00105] This disclosure further provides a method of forming the cured sealant wherein the method includes the steps of providing the polysulfide and the capped polycarbodiimide, and combining the polysulfide and the capped polycarbodiimide such that the polysulfide polymerizes with the capped polycarbodiimide in the presence of optionally the catalyst to form the cured sealant.

[00106] In the method of forming the cured sealant the capped polycarbodiimide is just as described above. Further, the capped polycarbodiimide is prepared just as described above. For example, in one embodiment, the step of preparing the capped polycarbodiimide includes the steps of:

combining a diisocyanate, a moisture scavenger, a monoisocyanate, and a catalyst to form a reaction mixture; and

heating the reaction mixture to a temperature of from 30 to 200 °C and for a time sufficient to form the capped polycarbodiimide;

wherein:

the capped polycarbodiimide has 0.25 wt% or less of free isocyanate groups;

the capped polycarbodiimide is a liquid at 25°C; and the combining and heating are conducted in the absence of a solvent. [00107] Even further, this disclosure provides a method of forming the article wherein the method includes the steps of providing the polysulfide, the capped polycarbodiimide, and optionally the catalyst and applying the polysulfide, the capped polycarbodiimide, and optionally the catalyst onto the substrate such that the polysulfide polymerizes with the capped polycarbodiimide in the presence of optionally the catalyst and forms the cured sealant disposed on the substrate.

[00108] This method also provides a method of cure-on-demand triggered by UV irradiation wherein one or more catalysts are used to adjust processing time and cure time; surface cure time and bulk cure time. In various embodiments, the sealant is triggered by UV irradiation. Moreover, a developed sealant may be capable of curing in darkness with a time lag and also capable of continuing to cure after a UV source is removed. This disclosure also provides a method to achieve cure-on-demand for thicknesses significantly larger that traditional cure- on-demand systems. For example, the system and method of this disclosure could cure up to more than 10mm of thickness.

[00109] In the aforementioned methods, each step of providing may be any known in the art. Similarly, any step of combining may be any known in the art such that any one or more of the aforementioned components may be combined in any order and as a whole or in parts. Moreover, the step of applying may be further defined as dipping, pouring, spraying, brushing, or any other method of application known in the art.

[00110] Any one or more of the aforementioned additives may be utilized and combined with any one or more of the aforementioned components in any one or more steps of the method. Similarly, heat and/or UV light may also be used as part of the method. For example, one or more components of the method may be heated to a temperature of from 10 to 100, 20 to 90, or 20 to 80, °C, to cure the components. Similarly, UV light at wavelengths of from 310 to 380, from 280 to 310, or from 270 to 310, nm, may be used to cure the components.

[00111] In various embodiments, the article, the curable composition, and/or the composition after curing have one or more of the following:

an Elongation Before Jet Fuel Test of from 150 to 1500, 200 to 1450, 250 to 1400, 300 to 1350, 350 to 1300, 400 to 1250, 450 to 1200, 500 to 1150, 550 to 1100, 600 to 1050, 650 to 1000, 700 to 950, 750 to 900, 800 to 850, 100 to 500, 150 to 450, 200 to 400, 250 to 350, 300 to 350, 160 to 290, 170 to 300, 165 to 295, 170 to 290, 175 to 285, 180 to 280, 185 to 275, 190 to 270, 195 to 265, 200 to 260, 205 to 255, 210 to 250, 215 to 245, 220 to 240, 225 to 235, or 225 to 230, % as determined using ASTM D 412. In other embodiments, the curable composition, and/or the composition after curing has an Elongation Before Jet Fuel Test of from 200 to 500, 250 to 450, 300 to 400, or 350 to 400, % as determined using ASTM D 412. an Elongation After Jet Fuel Test of from 150 to 1500, 200 to 1450, 250 to 1400, 300 to 1350, 350 to 1300, 400 to 1250, 450 to 1200, 500 to 1150, 550 to 1100, 600 to 1050, 650 to 1000, 700 to 950, 750 to 900, 800 to 850, 100 to 500, 150 to 450, 200 to 400, 250 to 350, 300 to 350, 160 to 290, 170 to 300, 165 to 295, 170 to 290, 175 to 285, 180 to 280, 185 to 275, 190 to 270, 195 to 265, 200 to 260, 205 to 255, 210 to 250, 215 to 245, 220 to 240, 225 to 235, or 225 to 230, % as determined using ASTM D 412. In other embodiments, the curable composition, and/or the composition after curing has an Elongation After Jet Fuel Test of from 300 to 500, 350 to 450, or 400 to 450, % as determined using ASTM D 412.

a Strength Before Jet Fuel Test of from 150 to 1500, 200 to 1450, 250 to 1400, 300 to 1350, 350 to 1300, 400 to 1250, 450 to 1200, 500 to 1150, 550 to 1100, 600 to 1050, 650 to 1000, 700 to 950, 750 to 900, 800 to 850, 100 to 500, 150 to 450, 200 to 400, 250 to 350, 300 to 350, 160 to 290, 170 to 300, 165 to 295, 170 to 290, 175 to 285, 180 to 280, 185 to 275, 190 to 270, 195 to 265, 200 to 260, 205 to 255, 210 to 250, 215 to 245, 220 to 240, 225 to 235, 225 to 230, 200 to 400, 250 to 350, 300 to 350, 250 to 300, 255 to 295, 260 to 290, 265 to 285, 270 to 280, or 275 to 280, psi as determined using ASTM D 412. In other embodiments, the curable composition, and/or the composition after curing has a Strength Before Jet Fuel Test of from 200 to 1000, 250 to 950, 300 to 900, 350 to 850, 400 to 800, 450 to 750, 500 to 700, 550 to 650, or 600 to 650, % as determined using ASTM D 412.

a Strength After Jet Fuel Test of 150 to 1500, 200 to 1450, 250 to 1400, 300 to 1350, 350 to 1300, 400 to 1250, 450 to 1200, 500 to 1150, 550 to 1100, 600 to 1050, 650 to 1000, 700 to 950, 750 to 900, 800 to 850, 100 to 500, 150 to 450, 200 to 400, 250 to 350, 300 to 350, 160 to 290, 170 to 300, 165 to 295, 170 to 290, 175 to 285, 180 to 280, 185 to 275, 190 to 270, 195 to 265, 200 to 260, 205 to 255, 210 to 250, 215 to 245, 220 to 240, 225 to 235, 225 to 230, 200 to 400, 250 to 350, 300 to 350, 250 to 300, 255 to 295, 260 to 290, 265 to 285, 270 to 280, or 275 to 280, psi as determined using ASTM D 412. In other embodiments, the curable composition, and/or the composition after curing has a Strength After Jet Fuel Test of from 150 to 800, 200 to 750, 250 to 700, 300 to 650, 350 to 600, 400 to 550, or 450 to 500, % as determined using ASTM D 412.

[00112] In addition, all values and range of values between and including all those described above and also those described in the Examples below are hereby expressly contemplated herein in various non-limiting embodiments.

[00113] All combinations of the aforementioned embodiments throughout the entire disclosure are hereby expressly contemplated in one or more non-limiting embodiments even if such a disclosure is not described verbatim in a single paragraph or section above. In other words, an expressly contemplated embodiment may include any one or more elements described above selected and combined from any portion of the disclosure.

[00114] One or more of the values described above may vary by ± 5%, ± 10%, ± 15%, ± 20%), ± 25%o, etc. so long as the variance remains within the scope of the disclosure. Unexpected results may be obtained from each member of a Markush group independent from all other members. Each member may be relied upon individually and or in combination and provides adequate support for specific embodiments within the scope of the appended claims. The subject matter of all combinations of independent and dependent claims, both singly and multiply dependent, is herein expressly contemplated. The disclosure is illustrative including words of description rather than of limitation. Many modifications and variations of the present disclosure are possible in light of the above teachings, and the disclosure may be practiced otherwise than as specifically described herein.

[00115] It is also to be understood that any ranges and subranges relied upon in describing various embodiments of the present disclosure independently and collectively fall within the scope of the appended claims, and are understood to describe and contemplate all ranges including whole and/or fractional values therein, even if such values are not expressly written herein. One of skill in the art readily recognizes that the enumerated ranges and subranges sufficiently describe and enable various embodiments of the present disclosure, and such ranges and subranges may be further delineated into relevant halves, thirds, quarters, fifths, and so on. As just one example, a range "of from 0.1 to 0.9" may be further delineated into a lower third, i.e. from 0.1 to 0.3, a middle third, i.e. from 0.4 to 0.6, and an upper third, i.e. from 0.7 to 0.9, which individually and collectively are within the scope of the appended claims, and may be relied upon individually and/or collectively and provide adequate support for specific embodiments within the scope of the appended claims. In addition, with respect to the language which defines or modifies a range, such as "at least," "greater than," "less than," "no more than," and the like, it is to be understood that such language includes subranges and/or an upper or lower limit. As another example, a range of "at least 10" inherently includes a subrange of from at least 10 to 35, a subrange of from at least 10 to 25, a subrange of from 25 to 35, and so on, and each subrange may be relied upon individually and/or collectively and provides adequate support for specific embodiments within the scope of the appended claims. Finally, an individual number within a disclosed range may be relied upon and provides adequate support for specific embodiments within the scope of the appended claims. For example, a range "of from 1 to 9" includes various individual integers, such as 3, as well as individual numbers including a decimal point (or fraction), such as 4.1, which may be relied upon and provide adequate support for specific embodiments within the scope of the appended claims.