HK1168375B - One-part moisture curable sealant and method of making the same - Google Patents

Description

One-part moisture curable sealant and method of making same

Technical Field

The present invention relates to sealants for aerospace and other applications. More particularly, the present invention relates to one-part moisture curable sealants.

Background

Sealants useful in aerospace and other applications can be classified as pre-mix refrigerant compositions (PMFs) and two-component systems. In a two-component system, the first component comprises a primary polymer, such as a polysulfide polymer, along with several additional species. The first component does not contain a curing agent, but the curing agent is in the second component. The two components are manufactured, packaged separately and mixed together immediately prior to use.

Unlike two-component systems, which require mixing of the cured paste and matrix prior to use, PMFs can be cured by external factors such as temperature. To this end, the PMF must be frozen at, for example, -40F to-80F in order to inhibit or slow down the curing reaction. When the PMF was later brought to room temperature, the cure rate increased significantly. PMF offers ready-to-use convenience without mixing and is therefore more cost and time effective than certain two-component systems. However, current PMFs have a limited shelf life and require storage at very low temperatures of-40F to-80F. Indeed, current PMFs require that the matrix components and activator be frozen immediately after mixing to slow down the curing reaction. In addition, PMFs must be stored at freezing temperatures prior to use to slow solidification. The need for refrigeration adds considerable manufacturing costs, at least in terms of additional labor and equipment. In addition, the compositions must be shipped and stored at low freezing temperatures (i.e., -40 ° F to-80 ° F), adding even more cost. In addition, PMFs have a limited shelf life as freezing the composition only slows the curing reaction.

Summary of The Invention

In accordance with one embodiment of the present invention, a one-part moisture-curable sealant composition includes a silane-terminated polythioether component, a filler, and a catalyst. The silane-terminated polythioether component, filler, and catalyst are combined and packaged in a moisture-tight, sealed container to substantially prevent curing. The composition is stable under substantially moisture-free conditions and at ambient temperatures. When the moisture-tight sealed container is unsealed and the composition is exposed to moisture, the moisture promotes curing of the composition to form a sealant.

In accordance with one embodiment of the present invention, a method of making a one-part moisture-curable sealant composition includes reacting a mercapto-terminated polythioether with a compound having a silane group to form a silane-terminated polythioether. The silane-terminated polythioether is then combined with a filler and a catalyst and isolated from moisture to prevent curing. Finally, the composition is applied to a substrate, and when applied, the composition is exposed to moisture and allowed to cure to form a sealant.

Embodiments of the present invention have the added benefit that they do not require refrigeration and low temperature storage and that they have an extended shelf life.

Detailed Description

In one exemplary embodiment of the invention, a one-part moisture-curable sealant composition includes a silane-terminated polythioether component, a filler, and a catalyst. The silane-terminated polythioether component, filler, and catalyst are combined and packaged in a moisture-tight, sealed container to substantially prevent curing. The composition is stable under substantially moisture-free conditions and at ambient temperatures. As used herein, "moisture-free" and "substantially moisture-free" mean that the composition may contain some moisture, but the amount of moisture is insufficient to cause substantial curing of the composition. When the moisture-tight sealed container is unsealed and the composition is applied to a substrate, the composition is exposed to moisture which facilitates curing of the composition to form a sealant that can be used in a number of applications including, but not limited to, aerospace and similar applications.

The silane-terminated polythioether component can be any silane-terminated polythioether that is terminated with a hydrolyzable group that is also capable of condensing. The silane-terminated polythioether component can be a single silane-terminated polythioether or a combination of silane-terminated polythioethers. The silane end groups contain hydrolyzable and condensable groups attached to the Si atom. Non-limiting examples of suitable hydrolyzable groups for attachment to the Si atom of the silane group include alkoxy groups and the like.

Silane-terminated polythioethers may be prepared, according to embodiments of the present invention, by reacting a mercapto-terminated polythioether with a compound having a silane group. Any suitable mercapto-terminated polythioether may be used. As used herein, "polythioether" refers to a polymer having a backbone that comprises S atoms and does not comprise S-S bonds, i.e., the polymer backbone has-C-S-C-bonds. Non-limiting examples of suitable silane group-bearing compounds include silane-terminated vinyl compounds, silane-terminated isocyanate compounds, and silane-terminated epoxy compounds.

Useful mercapto-terminated polythioethers can be made by reacting a divinyl ether or a mixture of divinyl ethers with an excess of a dithiol or a mixture of dithiols. In some exemplary embodiments, the mercapto-terminated polythioether used in the reaction to prepare the silane-terminated polythioether may be a mercapto-terminated polythioether represented by the following formula (1). The mercapto-terminated polythioethers useful for forming the present invention have a terminal mercapto functionality of at least 2.

H-[S-R₁-S-(CH₂)_p-O-(-R₂-O-)_m-(CH₂)_q-]_n-S-R₁-SH(1)

In formula 1, R₁May be selected from C₂-C₁₀N-alkylene group, C₂-C₆Branched alkylene group, C₆-C₈Cycloalkylene radical, C₆-C₁₀Alkylcycloalkylene, heterocyclic radical, - [ (-CH)₂)_p-X]_q-(CH₂)_r-a group and at least one-CH therein₂- [ (-CH) with the units replaced by methyl groups₂)_p-X]_q-(-CH₂)_r-a group. R₂May be selected from C₂-C₁₀N-alkylene group, C₂-C₆Branched alkylene group, C₆-C₈Cycloalkylene radical, C₆-C₁₄Alkylcycloalkylene, heterocyclic group and- [ (-CH)₂)_p-X]_q-(CH₂)_r-a group. X may be selected from the group consisting of O atom, S atom and-NR₃-a group. R₃May be selected from H atoms and methyl groups. In formula 1, m is an integer of 1 to 50, n is an integer of 1 to 60, p is an integer of 2 to 6, q is an integer of 1 to 5, and r is an integer of 2 to 10. In one embodiment, for example, R₁Is C₂-C₆Alkyl and R₂Is C₂-C₆An alkyl group.

In an exemplary embodiment, the mercapto-terminated polythioether component can be represented by a mercapto-terminated polythioether of formula 1, wherein R is₁Is- [ (-CH)₂)_p-X]_q-(-CH₂)_r-, p is 2, X is an O atom, q is 2, R is 2, R is₂Is ethylene, m is 2 and n is 9. In an alternative embodiment of a mercapto-terminated polythioether, m is 1, R₂Is n-butylene, R₁Not ethylene or n-propylene. In another embodiment of a mercapto-terminated polythioether, m is 1, p is 2, q is 2, R is 2, and R is₂Is an ethylene group, and X is not an O atom.

Additional non-limiting examples of suitable mercapto-terminated polythioether compounds include those disclosed in U.S.6,509,418 to Zook et al, the entire contents of which are incorporated herein by reference.

According to embodiments of the present invention, a mercapto-terminated polythioether is reacted with a compound having a silane group to produce a silane-terminated polythioether component. Of suitable compounds having silane groupsNon-limiting examples include silane-terminated vinyl compounds, silane-terminated isocyanate compounds, and silane-terminated epoxy compounds. The silane groups comprise hydrolyzable groups bonded to the Si atom. In particular, the silane group may consist of-Si (Y)_aA_b) Wherein Y is a functional group which is both hydrolysable and condensable, a and b are each 1-3 and a + b is 3. Non-limiting examples of suitable hydrolyzable and condensable groups include alkoxy groups and the like.

Non-limiting examples of suitable compounds having silane groups include the compounds represented by ZR₄Si(Y_aA_b) A compound of wherein R₄Can be any suitable organic chain, Z is a terminal functional group capable of reacting with a thiol, A is C₁-C₄Hydrocarbyl groups, a and b are each 1-3 and a + b is 3. For example, R₄May be C₁-C₃The hydrocarbon chain, Z, may be a vinyl group, an isocyanate group, an epoxy group, or the like. Non-limiting exemplary compounds having silane groups include silane-terminated vinyl compounds, silane-terminated isocyanate compounds, and silane-terminated epoxy compounds. In one embodiment, for example, the silane terminated vinyl compound is derived from CH₂＝CH-R₄-Si(Y_aA_b) And (4) showing. In an exemplary embodiment, the silane-terminated isocyanate compound is prepared from NCO-R₄-Si(Y_aA_b) And (4) showing. In an exemplary embodiment, the silane-terminated epoxy compound is prepared fromAnd (4) showing.

In the compounds having silane groups, Y may be any hydrolyzable group which can also be condensed, R₄As described above, and R₅And may be hydrogen or any suitable organic chain. For example, R₅May be any suitable hydrocarbon chain, etc. Non-limiting examples of suitable hydrolyzable groups for Y include alkoxy groups and the like. In some embodiments, for example, smaller alkoxy groups, such as methoxy or ethoxy, are used.

In an exemplary embodiment of the invention, a sealant composition comprises a silane-terminated polythioether polymer, a filler, and a catalyst. Any suitable catalyst may be used, and a single catalyst or a mixture of catalysts may be used. In one embodiment, for example, the catalyst is a tin catalyst. Non-limiting examples of suitable tin catalysts include organotins, such as dibutyltin bis (acetylacetonate) and dibutyltin dilaurate (available as MetacureT-12 from air products and Chemicals, Inc., Allentown, Pennsylvania).

In some embodiments, the silane-terminated polythioether component is present in the sealant composition in an amount from about 30 to about 80 weight percent. In one embodiment, for example, the silane-terminated polythioether component is present in the composition in an amount from about 55 to about 75 weight percent. In another embodiment, the silane-terminated polythioether component is present in the composition in an amount from about 66 to about 67 weight percent.

In some embodiments, the catalyst is present in the composition in an amount of about 0.1 to 5 wt%. In one embodiment, for example, the catalyst is present in the composition in an amount of about 0.1 to 2 weight percent. In another embodiment, the catalyst is present in the composition in an amount of about 0.9 wt%.

Non-limiting examples of suitable fillers include carbon black, calcium carbonate, silica, and polymer powders. In some embodiments, the filler is present in the composition in an amount of about 5 to 60 weight percent. In another embodiment, the filler is present in the composition in an amount of about 28 to 29 weight percent.

In some embodiments, the compositions of the present invention comprise lightweight filler particles. The term "lightweight" as used herein in relation to the above-described particles means that the particles have a specific gravity of no greater than 0.7, in some cases no greater than 0.25 or no greater than 0.1. Suitable lightweight filler particles generally fall into two categories-microspheres and amorphous particles. The microspheres tend to have a specific gravity of 0.1 to 0.7 and include, for example, polystyreneMicrospheres of olefinic foam, polyacrylate and polyolefin, and silica microspheres having a particle size of 5-100 microns and a specific gravity of 0.25: (W.R.Grace&Co.). Other examples include alumina/silica microspheres having a particle size of 5 to 300 microns and a specific gravity of 0.7: (Pluess-Stauffer International), aluminum silicate microspheres having a specific gravity of about 0.45 to about 0.7And calcium carbonate-coated polyvinylidene chloride (polyvinylidene) copolymer microspheres (DUALITE) having a specific gravity of 0.13Pierce&StevensCorp.). In some embodiments, the compositions of the present invention comprise lightweight filler particles comprising an outer surface coated with a thin coating, such as [0016 ] in U.S. patent application 12/190,826]-[0052]To which reference is made, the citation of which is incorporated herein by reference.

The composition may also contain a number of additives as desired. Non-limiting examples of suitable additives include plasticizers, pigments, surfactants, adhesion promoters, thixotropic agents, flame retardants, masking agents, and mixtures thereof. When used, additives may be present in the composition in an amount of about 0 to 60 wt%. In some exemplary embodiments, the additive is present in the composition in an amount of about 25 to 60 wt%.

In some exemplary embodiments, the composition comprises at least one plasticizer. One non-limiting example of a suitable plasticizer is HB-40 (ex Solutia, Inc., St. Louis, Missouri). HB-40 is a mixture comprising hydrogenated terphenyl, partially hydrogenated quaterphenyl and higher polyphenyls, and terphenyl. However, any suitable plasticizer may be used. In some exemplary embodiments, the plasticizer is present in the composition in an amount of about 0.1 to 40 weight percent. In an exemplary embodiment, the plasticizer is present in the composition in an amount of about 0.1 to 8 weight percent. In another embodiment, the plasticizer is present in the composition in an amount of about 3 to 4 weight percent. In embodiments in which a plasticizer is used, the plasticizer and catalyst can be placed in solution prior to combining the catalyst with the silane-terminated polythioether.

One advantage of the compositions of the present invention is that separate curing agents such as the polyolefins, polyacrylates, metal oxides and polyepoxides described in U.S.6,509,418 to Zook et al (cited above) are not necessary in order to provide curable compositions. Thus, the compositions of the present invention are, in some embodiments, substantially free of any such curing agent, or in some cases, completely free of. The term "substantially free" as used herein means that a substance, if any, is present only as an incidental impurity. In other words, the substance does not affect the properties of the composition. The term "completely free" as used herein means that no material is present at all in the composition.

For storage and shipping, a sealant composition comprising a silane-terminated polythioether component, a filler, and a catalyst is sealed in a moisture-resistant container. The composition is stable and remains substantially uncured when sealed to moisture in a container.

To use the sealant, the moisture resistant container is opened, the composition is applied to a substrate, and the sealant composition is exposed to moisture. As shown in the non-stoichiometric reaction of step 1 below, moisture reacts with the silane-terminated polythioether component to replace hydrolyzable and condensable groups on the Si atom with hydroxide groups (hydroxidegroups). In the presence of a catalyst and moisture, the composition cures according to the non-stoichiometric reaction of step 2 below, thereby forming a sealant that can be used in many applications.

Step 1

Step 2

In some embodiments, a method of making a silane-terminated polythioether component includes reacting a mercapto-terminated polythioether with a compound having a silane group. The mercapto-terminated polythioether and the compound having a silane group are as described above. Upon reaction, the mercapto group of the mercapto-terminated polythioether reacts with a terminal functional group capable of reacting with a thiol of a compound having a silane group to form a compound consisting of (Y)_aA_b)SiR₄Z′-R′-Z′R₄Si(Y_aA_b) The silane-terminated polythioether component is shown. R' is a polythioether chain having at least one-C-S-C-bond in the main chain and in which the main chain does not contain S-S bonds, Y is a hydrolyzable and condensable functional group, A is selected from C₁-C₄The hydrocarbon functional group, Z', is a functional group resulting from the reaction between the thiol and the Z functional group (i.e., a functional group capable of reacting with the thiol, such as an isocyanate group, an epoxy group, and a vinyl group). In one embodiment, for example, the silane-terminated polythioether component is represented by the following formula (2).

(Y_aA_b)SiR₄Z′-[-S-R₁-S-(CH₂)_p-O-(-R₂-O-)_m-(CH₂)_q-]_n-S-R₁-S-Z′R₄Si(Y_aA_b)(2)

In formula 2, Z' is the reaction product of a Z functional group and a thiol functional group. For example, when Z is vinyl, Z' will be-CH₂-CH₂-, the resulting terminal functional group will be-CH₂-CH₂R₄Si(Y_aA_b). When Z is an isocyanate group, Z' will beThe resulting terminal functional group will be-NHCO-Si (Y)_aA_b). When Z is an epoxy group, Z' will beThe resulting terminal functional group will be

The resulting silane-terminated polythioether component is then combined with a filler and a catalyst in a substantially moisture-free environment to form an uncured sealant mixture. Suitable catalysts are described above. According to some embodiments, an additive is included in the composition. Suitable additives are described above and include plasticizers, pigments, surfactants, adhesion promoters, thixotropic agents, flame retardants, fillers, masking agents, and mixtures thereof. The silane-terminated polythioether, catalyst, and optional additives can be included in the composition in amounts as described above.

The composition is isolated from moisture to prevent curing. In some embodiments, the composition is sealed in a container that is substantially free of moisture. When applied to a substrate, the composition is exposed to moisture which cures the composition to form a sealant as described above.

The following examples are provided for illustration only and are not intended to limit the scope of the present invention.

Examples

Example 1: synthesis of silane-terminated polythioethers

707.69g ofP-3.1E (a mercapto-terminated polythioether from PRC-Desoto, Sylmar, Calif.) was placed in a round bottom flask. The flask contained a nitrogen inlet and outlet. The polymer was degassed at about 5mmHg for 40 minutes. Then nitrogen was introduced. While stirring, 109.88g of 3-isocyanatopropyltriethoxysilane were added. The mixture was heated at 170 ℃ and 176 ℃ F. for 24 hours. At this point, the mercaptan equivalent weight of the mixture was 30,931. An additional 7.0g of 3-isocyanatopropyltriethoxysilane were added and heating continued for 15 hours. The mixture was then degassed at 172 ℃ F. 174 ℃ F. and 10mmHg to give an amber colored polymer. At this point, the mercaptan equivalent weight of the mixture was 67,500. It has a viscosity of 99P at 3,000RPM as measured by a Brookfield CAP2000 viscometer.

Example 2: synthesis of silane-terminated polythioethers

736.69g ofP-3.1E was placed in a round bottom flask. The flask contained a nitrogen inlet and outlet. The polymer was degassed at 170 ° F and about 5mmHg for 1 hour. Then nitrogen was introduced. While stirring, 70.56g of vinyltrimethoxysilane was added. Heating was continued for additional 1/2 hours. 10.284g portions of the free radical initiator Vazo-67(2, 2' -azobis (2-methylbutyronitrile) from E.I. duPontde Nemour company) were added at 2 hour intervals while the temperature was maintained at 168-172 ℃ F. at this time, the mercaptan equivalent weight of the mixture was 25,670. an additional 5.0g of vinyltrimethoxysilane was added, followed by 4.343g portions of Vazo-67 at 2 hour intervals, heating was continued at 168-172 ℃ F. the mixture was then allowed to stand at 172-174 ℃ F. and 10mmHgDegassed to give an amber polymer. At this point, the mercaptan equivalent weight of the mixture was 32,644 and its viscosity was 44P at 3,000 RPM.

Example 3: synthesis of silane-terminated polythioethers

715.70g ofP-3.1E was placed in a round bottom flask. The flask contained a nitrogen inlet and outlet. The polymer was degassed at 160 ℃ F. at 170 ℃ F. and about 5mmHg for 1/2 hours. Then nitrogen was introduced. While stirring, 88.01g of vinyltriethoxysilane was added. Heating was continued for another 40 minutes. 10.299g portions of Vazo-67 were added at 2 hour intervals while maintaining the temperature at 168 ℃ F. and 172 ℃ F. At this point, the mercaptan equivalent weight of the mixture was 24,178. A further 7.0g of vinyltriethoxysilane were added, followed by 4.335g portions of Vazo-67 at 2-hour intervals. Heating was continued at 168-. The mixture was then degassed at 168-172 ℃ F. and 10mmHg to give an amber colored polymer. At this point, the mercaptan equivalent weight of the mixture was 40,225 and its viscosity was 34P at 3,000 RPM.

Example 4: sealant composition

Silane-terminated polythioether Compounds were made as in example 1, i.e., the silane group on the silane-terminated polythioether was-Si (OCH)₂CH₃)₃A group. 15g of carbon black was placed in a 300 ℃ F. oven for 5 days. 35g of the silane-terminated polythioether was then mixed with the carbon black until the carbon black was substantially wetted. 2.0gHB-40 and 0.5g MetacureT-12 were then combined with the silane-terminated polythioether/carbon black mixture until all ingredients were thoroughly mixed. The composition is then packaged in a moisture-tight sealed container.

Example 5: sealant composition

Silane-terminated polythioether Compounds were made as in example 2, i.e., the silane group on the silane-terminated polythioether was-Si (OCH)₃)₃A group. 15g of carbon black was placed in a 300 ℃ F. oven for 5 days. 35g of the silane-terminated polythioether was then mixed with the carbon black until the carbon black was substantially wetted. 2.0gHB-40 and 0.5g MetacureT-12 were then combined with the silane-terminated polythioether/carbon black mixture until all ingredients were thoroughly mixed. The composition is then packaged in a moisture-tight sealed container.

The compositions of examples 4 and 5 were allowed to sit in a moisture-tight sealed container at ambient conditions for approximately 1 month. After 1 month of storage, the container was opened and allowed to stand at ambient conditions, thereby allowing the composition to cure. Hardness measurements were made periodically with a Rex durometer. The percent volume swell and percent weight loss of the cured samples were determined according to SAEAS5127/1, section 7.4. The results are shown in tables 1-4, which report cure time, percent weight loss, and volume swell for each sample. In particular, table 1 reports hardness data for the sealant composition samples prepared according to example 4, table 2 reports hardness data for the sealant composition samples prepared according to example 5, table 3 reports volume swell and percent weight loss for the sealant composition samples prepared according to example 4, and table 4 reports volume swell and percent weight loss for the sealant composition samples prepared according to example 5.

TABLE 1 hardness

Time of day	Example 4
		31 hours	Watch stem
48 hours	2A
		3 days	3A
4 days	10A
		7 days	25A
9 days	32A
		11 days	37A
13 days	45A
		17 days	51A
72 days	77A

TABLE 2 hardness

Time of day	Example 5
		23 hours	Watch stem
48 hours	6A
		3 days	18A
4 days	35A
		7 days	50A
9 days	60A
		11 days	63A
13 days	65A
		17 days	68A
72 days	78A

TABLE 3 percent volume swell and weight loss for example 4

Sample number	Average volume swelling	Percent average weight loss
			1	9.18％	4.53％
2	8.26％	4.44％
			3	8.94％	3.99％
4	8.54％	4.49％
			Average	8.73％	4.36％

TABLE 4 percent volume swell and weight loss for example 5

Sample number	Average volume swelling	Percent average weight loss
			1	10.93％	4.06％
2	10.72％	4.31％
			3	10.95％	4.31％
4	10.65％	4.32％
			Average	10.81％	4.25％

The results shown in tables 1-4 demonstrate that sealant compositions prepared according to examples 4 and 5 do not cure to a meaningful degree as long as they are moisture-isolated. Surprisingly, when free of moisture, the composition remains uncured even under ambient conditions, thereby eliminating the need to store and transport the composition at-40 ° F or-80 ° F. The results also demonstrate an unexpectedly long shelf life of the composition when sealed to moisture. In addition, the volume swell and weight loss results indicate that the sealant composition is suitable for use as a fuel tank sealant.

The present invention has been described with reference to exemplary embodiments and aspects, but is not limited to these embodiments and aspects. Those skilled in the art will appreciate that other modifications and applications may be made without meaningfully departing from the spirit and scope of the present invention. For example, although the compositions are described as useful as fuel tank sealants, they may also be useful in other applications. In addition, while certain exemplary polythioether components and compounds having silane groups are listed as being suitable for a particular reaction, other suitable polythioethers and compounds having silane groups can be used. Thus, the foregoing description should not be read as limited to the exact embodiments and aspects described, but rather should be read consistent with and as support for the following claims, which are intended to have their fullest and fairest scope.

Throughout this document, the use of the word "about" in connection with a numerical range modifies both the upper and lower values given and also reflects the marginal areas of variation relating to measurement, significant figures, and interchangeability, all as would be understood by one of ordinary skill in the art.

Claims (9)

1. A composition for forming a sealant, the composition comprising:

from 30 wt% to 80 wt% of a silane-terminated polythioether component, wherein the silane-terminated polythioether comprises the reaction product comprising:

(a)P-3.1E; and

(b) of the formula Z-R₄-Si(Y_aA_b) The compound of (a) is represented by,

wherein:

y is a hydrolyzable and condensable functional group;

a is selected from C₁-C₄A hydrocarbon functional group;

z is a functional group selected from the group consisting of isocyanate, epoxy and vinyl;

R₄is C₁-C₃A hydrocarbon chain;

a and b are each an integer of 0 to 3 and the sum of a and b is 3;

0.1 wt% to 5 wt% of a catalyst; and

5 to 60 weight percent of filler.

2. A composition for forming a sealant, comprising: silane-terminated polythioethers having the structure

Wherein:

y is a hydrolyzable and condensable functional group;

a is selected from C₁-C₄A hydrocarbon functional group;

z' between a thiol and a functional group chosen from isocyanate, epoxy and vinyl

A functional group resulting from the reaction;

R₄is C₁-C₃A hydrocarbon chain;

a and b are each an integer of 0 to 3 and the sum of a and b is 3;

0.1 wt% to 5 wt% of a catalyst; and

5 to 60 weight percent of filler.

3. The composition of claim 1, wherein Y is alkoxy.

4. The composition of claim 3 wherein Y is methoxy or ethoxy.

5. The composition of claim 1, wherein the catalyst comprises a tin catalyst.

6. The composition of claim 1, wherein the composition is substantially free of any polyolefin, polyacrylate, metal oxide, and polyepoxide curing agents.

7. A sealant formed from the composition of claim 1.

8. An aerospace vehicle comprising a gap at least partially sealed with the sealant of claim 7.

9. A method of making the sealant composition of claim 1, the method comprising:

make itP-3.1E is reacted with a compound represented by the formula Z-R4-Si (YaAb) to form a silane-terminated polythioether,

wherein:

y is a hydrolyzable and condensable functional group;

a is selected from C₁-C₄A hydrocarbon functional group;

z is a functional group selected from the group consisting of isocyanate, epoxy and vinyl;

R₄is C₁-C₃A hydrocarbon chain;

a and b are each an integer of 0 to 3 and the sum of a and b is 3;

combining 30 wt% to 80 wt% of the silane-terminated polythioether with 0.1 wt% to 5 wt% of a catalyst and 5 wt% to 60 wt% of a filler to form a composition; and

isolating the composition from moisture, wherein the composition remains uncured at ambient temperature when sealed to moisture.