Pitch pocket and sealant

Abstract

A one-part pourable sealant that is thermosetting, non-shrinking, and capable of quickly curing in a closed cavity to a depth of at least two inches includes a silyl-terminated polymer, a hygroscopic plasticizer present in an amount that is effective to promote rapid and deep curing, and a catalyst for promoting curing of the silyl-terminated polymer. The sealer composition is useful in a method of forming a seal around a roof penetration. The method includes dispensing the sealer composition into a pitch pocket formed around a roof penetration and allowing the sealer composition dispensed into the pitch pocket to cure by exposure to moisture in the air.

Description

wherein R² and R³ are the same or different and each represents an alkyl group containing 1 to 20 carbon atoms, an aryl group containing 6 to 20 carbon atoms, an aralkyl group containing 7 to 20 carbon atoms or a triorganosiloxy group of the formula (R⁴)₃SiO— (wherein R⁴ independently represents a hydrocarbon group containing 1 to 20 carbon atoms) and, when two or more R² and/or R³ groups are present, they may be the same or different; X represents a hydrolyzable group or a hydroxyl group and, when two or more X groups are present, they may be the same or different; a represents an integer of 0 to 2; b represents an integer of 0 to 3; and p represents an integer of 0 to 19 and, when p is 2 or more, the —[Si(R₂)_2-a (X)_aO]groups may be the same or different. In the reactive silyl group represented by the above general formula, there is at least one hydrolyzable group or hydroxyl group represented by X.

The above-mentioned alkyl group containing 1 to 20 carbon atoms includes, but is not limited to methyl, ethyl, isopropyl, butyl, t-butyl, cyclohexyl and the like.

The above-mentioned aryl group containing 6 to 20 carbon atoms includes, but is not limited to, phenyl, naphthyl and the like.

The above-mentioned aralkyl group containing 7 to 20 carbon atoms includes, but is not limited to, benzyl and the like.

The above-mentioned monovalent hydrocarbon group containing 1 to 20 carbon atoms includes, but is not limited to, methyl, ethyl, isopropyl, butyl, t-butyl, pentyl, ethynyl, 1-propenyl, vinyl, allyl, 1-methylbutyl, 2-ethylbutyl, phenyl and the like.

The above-mentioned hydrolyzable group represented by X is not limited to any particular species and includes a hydrogen atom, halogen atoms, and alkoxyl, acyloxy, ketoximate, amino, amido, acid amido, aminoxy, mercapto, alkenyloxy and the like groups. Among these, a hydrogen atom and alkoxy, acyloxy, ketoximate, amino, amido, aminoxy, mercapto and alkenyloxy groups are preferred and, from the viewpoint of mild hydrolyzability and ease of handling, alkoxyl groups are particularly preferred.

One to three hydroxyl groups and/or hydrolyzable groups each represented by X may be bound to one silicon atom. The sum total of the hydroxyl and/or hydrolyzable groups in the reactive silyl group represented by the above general formula is preferably within the range of 1 to 5.

The number of silicon atoms forming the above-mentioned reactive silyl group may be 1 or 2 or more.

In the practice of the present invention, those reactive silyl groups which are represented by the general formula shown below are preferred because of their ready availability:
—Si(R³)_3-bX_b
wherein R³, X and b are as defined above.

Methods of introducing a reactive silyl group onto a polymer, such as a polyether, or more specifically a polyoxyalkylene polymer, are well known in the art. For example, polymers having terminal hydroxyl, epoxy or isocyanate functional groups can be reacted with a compound having a reactive silyl group and a functional group capable of reacting with the hydroxyl, epoxy or isocyanate group.

As another example, silyl-terminated polyurethane polymers may be used. A suitable silyl-terminated polyurethane polymer may be prepared by reacting a hydroxyl-terminated polyether, such as a hydroxyl-terminated polyoxyalkylene, with a polyisocyanate compound, such as 4,4′-methylenebis(phenylisocyanate), to form an isocyanate-terminated polymer, which can then be reacted with an aminosilane, such as aminopropyltrimethoxysilane, to form a silyl-terminated polyurethane.

Silyl-terminated polyesters are those having the reactive silyl groups discussed above with a backbone comprising —O—CO—R⁵—CO—O—R⁶— or —R⁷—CO—O— repeat units, wherein R⁵, R⁶ and R⁷ are divalent organic groups such as straight or branched alkylene groups.

The silyl-terminated polymers used in this invention may be straight-chained or branched, and typically have a weight average molecular weight of from about 500 to 50,000 Daltons, and more preferably from about 1,000 to about 30,000 Daltons.

Suitable silyl-terminated polyethers are commercially available from Kaneka Corporation under the names KANEKA MS POLYMER™ and KANEKA SILYL™, and from Union Carbide Specialty Chemicals Division under the name SILMOD™.

The one-part moisture curable, pourable sealer compositions of this invention preferably contain a silanol condensation cayalyst for promoting fast reaction among the reactive silyl groups contained in the silyl-terminated polymers. Examples of silanol condensation catalysts include, but are not limited to, titanate esters such as tetrabutyl titanate and tetrapropyl titanate; organotin compounds such as dibutyltin dilaurate, dibutyltin maleate, dibutyltin diacetate, stannous octylate, stannous napthenate, reaction products from dibutyltin oxide and phthalate esters, and dibutyltin diacetylacetonate; organoaluminum compounds such as aluminum trisacetylacetonate, aluminum tris(ethylacetoacetate) and diisopropocyaluminum ethyl acetoacetate; reaction products from bismuth salts and organic carboxylic acids, such as bismuth tris(2-ethylhexonate) and bismuth tris(neodecanoate); chelate compounds such as zirconium tetraacetylacetonate and titanium tetraacetylactonate; organolead compounds such as lead octylate; organovanadium compounds; amine compounds such as butylamine, octylamine, dibutylamine, monoethanolamine, diethanolamine, triethanolamine, diethylenetriamine, triethylenetetramine, oleylamine, cyclohexylamine, benzylamine, diethylaminopropylamine, xylylenediamine, triethylenediamine, guanidine, diphenylguanidine, 2,4,6-tris(dimethylaminomethyl)phenol, morpholine, N-methylmorpholine, 2-ethyl-4-methylimidazole and 1,8-diazabicyclo (5.4.0)undecene-7 (DBU); salts of said amine compounds with carboxylic or other acids; low-molecular-weight polyamide resins derived from excess polyamines and polybasics acids; and reaction products from excess polyamines and epoxy compounds. These may be used individually or in combination.

Among the silanol condensation catalysts mentioned above, organometallic compounds are preferred. The silanol condensation catalyst may be used in an amount of from about 0.01 to about 20 parts by weight per 100 parts by weight of the silyl-terminated polymer, with a more preferred addition level being from about 0.1 to about 10 parts by weight per 100 parts by weight of the silyl-terminated polymer.

In the curable compositions of the present invention, there may further be added, when necessary, various additives such as dehydrating agents, compatibilizers, tackifiers, physical property modifiers, storage stability improving agents, fillers, antioxidants, adhesion promoters, ultraviolet absorbers, metal deactivators, antiozonants, light stabilizers, amine type radical chain inhibitors, phosphorus-containing peroxide decomposers, lubricants, pigments, foaming agents, flame retardants and antistatic agents, each in an adequate amount.

The fillers mentioned above include, but are not limited to, wood meal, walnut shell flour, rice hull flour, pulp, cotton chips, mica, graphite, diatomaceous earth, china clay, kaoline, clay, talc, fumed silica, precipitated silica, silicic anhydride, quartz powder, glass beads, calcium carbonate, magnesium carbonate, titanium oxide, carbon black, glass balloons, aluminum powder, zinc powder, asbestos, glass fiber and carbon fiber. The above fillers may be used individually or in combination.

The hygroscopic plasticizer can be selected from compounds that serve a plasticizing function and which, when added to the one-part moisture curable, pourable sealer composition, allow moisture to be imbibed into the material. Most plasticizers are hydrophobic and do not exhibit the desired hygroscopic properties. Examples of suitable hygroscopic plasticizers that may be used in the one-part moisture curable, pourable sealer compositions of this invention include polyether polyols such as hydroxyl-terminated polypropylene oxide plasticizers. A suitable commercially availabe polypropylene oxide hygroscopic plasticizer is UNCON® LB 285 (UCON® LB 285 is polyoxyalkylene glycol made from n-butanol and propylene oxide), available from Union Carbide. The hygroscopic plasticizer is present in an amount that is effective to promote rapid and deep curing of the one-part moisture curable pourable sealer compositions of this invention upon exposure to ambient moisture. A suitable amount is from about 5 to about 50 parts by weight, and more preferably from about 10 to about 30 parts by weight, per 100 parts by weight of the silyl-terminated polymer.

The moisture curable compositions of this invention are particularly useful as sealants, especially as a sealer composition for forming a seal around a roof penetration. When used as a sealer for sealing a roof penetration, the composition is dispensed into a pitchpan formed around a roof member. A pitchpan is any type of continuous wall or curb formed around a roof penetration through a waterproof membrane covering a roof substrate, and into which a sealer composition is dispensed to provide a water-impermeable barrier. While not being bound to any particular theory, it is believed that the hygroscopic plasticizer allows moisture to be imbibed into the sealer composition, whereby rapid, deep curing of the composition occurs.

Claims

1. A one-part, moisture curable, pourable sealer composition, comprising:

a silyl-terminated polymer, a hygroscopic plasticizer present in an amount that is effective to promote rapid and deep curing, and a catalyst for promoting curing of the silyl-terminated polymer.

2. The composition of claim 1, wherein the silyl-terminated polymer is selected from the group consisting of silylated polyurethanes, silylated polyethers, and silylated polyesters.

3. The composition of claim 2, wherein the silylated polymer is an alpha, omega-telechelic silyl-terminated polymer.

4. The composition of claim 1, wherein the silyl-terminated polymer is an oxyalkylene polymer having at least one reactive silyl group at each end of the polymer molecule.

5. The composition of claim 4, wherein the silyl-terminated polymer has a backbone selected from the group consisting of polypropylene oxide, polyethylene oxide, and copolyethylene oxide/polypropylene oxide.

6. A one-part, moisture curable, pourable sealer composition, comprising:

a silyl-terminated polymer, a hygroscopic plasticizer present in an amount that is effective to promote rapid and deep curing, and a catalyst for promoting curing of the silyl-terminated polymer, wherein the silyl-terminated polymer is a silyl-terminated polyurethane.

7. The composition of claim 6, wherein the silyl-terminated polyurethane is the reaction product of an isocyanate-terminated polymer with an aminosilane, and wherein the isocyanate-terminated polymer is the reaction product of a hydroxyl-terminated polyether with a polyisocyanate compound.

8. The composition of claim 7, wherein the hydroxyl-terminated polyether is a hydroxyl-terminated polyoxyalkylene.

9. The composition of claim 1, wherein the silyl-terminated polymer has a weight average molecular weight of from about 500 to 50,000 Daltons.

10. The A one-part, moisture-curable, pourable sealer composition of claim 1 , comprising:

a silyl-terminated polymer, a hygroscopic plasticizer present in an amount that is effective to promote rapid and deep curing, and a catalyst for promoting curing of the silyl-terminated polymer, wherein the hygroscopic plasticizer is a polyether polyol.

11. The composition of claim 10, wherein the polyether polyol is a hydroxyl-terminated polypropylene oxide.

12. The composition of claim 10, wherein the hygroscopic plasticizer is present in the one-part moisture curable pourable sealer composition in an amount of from about 5 to about 50 parts by weight per 100 parts by weight of the silyl-terminated polymer.

13. A method of forming a seal around a roof penetration, comprising:

dispensing a one-part moisture curable, pourable sealer composition into a pitch pocket formed around the roof penetration, said one-part moisture curable pourable sealer composition containing a silyl-terminated polymer and a hygroscopic plasticizer present in an amount that is effective to promote rapid and deep curing.

14. The method of claim 13, wherein the silyl-terminated polymer is selected from the group consisting of silylated polyurethanes, silylated polyethers, and silylated polyesters.

15. The method of claim 14, wherein the silylated polymer is an alpha, omega-telechelic silyl-terminated polymer.

16. The method of claim 13, wherein the silyl-terminated polymer is an oxyalkylene polymer having at least one reactive silyl group at each end of the polymer molecule.

17. The method of claim 16, wherein the silyl-terminated polymer has a backbone selected from the group consisting of polypropylene oxide, polyethylene oxide, and copolyethylene oxide/polypropylene oxide.

18. A method of forming a seal around a roof penetration, comprising:

dispensing a one-part moisture curable, pourable sealer composition into a pitch pocket formed around the roof penetration, said one-part moisture curable pourable sealer composition containing a silyl-terminated polymer and a hygroscopic plasticizer present in an amount that is effective to promote rapid and deep curing, wherein the silyl-terminated polymer is a silyl-terminated polyurethane.

19. The method of claim 13, wherein the hygroscopic plasticizer is a polyether polyol.

20. The method of claim 19, wherein the polyether polyol is a hydroxyl-terminated polypropylene oxide.

21. A method of forming a seal around a roof penetration, comprising:

dispensing a one-part moisture curable, pourable sealer composition into a pitch pocket formed around the roof penetration, said one-part moisture curable pourable sealer composition containing a silyl-terminated polymer.

22. The method of claim 21, wherein the silyl-terminated polymer is selected from the group consisting of silylated polyurethanes, silylated polyethers, and silylated polyesters.

23. The method of claim 22, wherein the silylated polymer is an alpha, omega-telechelic silyl-terminated polymer.

24. The method of claim 21, wherein the silyl-terminated polymer is an oxyalkylene polymer having at least one reactive silyl group at each end of the polymer molecule.

25. The method of claim 24, wherein the silyl-terminated polymer has a backbone selected from the group consisting of polypropylene oxide, polyethylene oxide, and copolyethylene oxide/polypropylene oxide.