WO2019014582A1

WO2019014582A1 - Silylammonium salts as latent polyurethane catalysts

Info

Publication number: WO2019014582A1
Application number: PCT/US2018/042070
Authority: WO
Inventors: Timothy DE VRIES; Sergio Grunder; Gary L. Jialanella; Matthias S. Ober; Duane R. Romer; Stefan Schmatloch
Original assignee: Dow Global Technologies Llc
Priority date: 2017-07-13
Filing date: 2018-07-13
Publication date: 2019-01-17

Abstract

Disclosed are silylammonium salts capable of acting as latent polyurethane catalysts and the methods of producing these silylammonium salts. Also disclosed are compositions including Part 1, which includes one or more polyisocyanates, and Part 2, which includes one or more compounds containing isocyanate reactive groups. The one or more silylammonium salts may disassociate so the amine is capable of catalyzing a reaction between Part 1 and Part 2 to form a two-component polyurethane adhesive.

Description

SILYLAM M ONIU M SALTS AS LATENT POLYURETHANE CATALYSTS

CLAIM OF PRIORITY

[001 ] The present application claims priority to U.S. Provisional Patent Application No. 62/532,086, filed on July 13, 2017, the contents of which is incorporated herein by reference in its entirety.

FIELD

[002] Disclosed is a silylammonium salt that is useful as a latent catalyst for forming two-part polyurethane adhesives. Further disclosed are methods of forming the silylammonium salt and bonding structures together using the latent two-part polyurethane adhesives.

BACKGROUND

[003] Polyurethanes are a well-known type of adhesive. They contain precursor materials that cure in place to form an adhesive layer. Polyurethane adhesives come in one-part and two-part types. One-part types generally exhibit a moisture cure or a heat- activated cure. Two-part types consist of a resin component that includes one or more polyisocyanate compounds, and a curative component that includes one or more polyols. When the two components mixed, the polyisocyanates and polyols react to form a cured polyurethane adhesive. A polyurethane adhesive can be formulated to cure at room temperature or upon exposure to certain conditions, an example of which is an elevated temperature. As the adhesive cures, it can form a strong adhesive bond to many types of substrates.

[004] Two-part curable compositions are used in a variety of applications such as adhesives, coatings, foams and the like. Two-part compositions are used where rapid cure is required for the application, especially where the two parts are not shelf stable when in contact with one another. "Shelf stable" means that the composition does not cure in storage. It is desirable that the adhesive composition exhibits a suitable open time and cures rapidly. The "open time" of a two-part adhesive refers to the amount of time after the two components are mixed that the adhesive remains flowable and capable of bonding to a substrate. The "latency" of catalysts used in forming the two-part adhesive refers to the amount of time during which there is a lack of activity of a catalyst, which is therefore a property of a catalyst that provides the open time. Upon activation of the catalyst, the latency may be removed or the latency period may end.

[005] Two-part adhesives can be used in a variety of applications, including in passenger vehicles. Passenger vehicles, and the construction thereof, have been affected by issues surrounding carbon footprint, carbon dioxide emissions, and legislation relating to these emissions. Lightweighting associated with new materials has become a crucial part of the strategy for achieving fuel economy targets in the designs of new models. Materials such as aluminum, magnesium, sheet molding compound, and carbon fiber composites for use in replacement of steel components are being implemented quickly on these new models of vehicles, and adhesive formulations are enabling this approach, since the new and dissimilar materials are difficult or even impossible to weld.

[006] Previously, achieving both a long open time or latency and a fast cure has been made possible by formulating an adhesive with heat-activated cure. Thermally-activated catalysts, such as phenol-blocked or acetic acid-blocked diazabicyclo[5.4.0]undec-7-ene (DBU) have been described, for example, in U.S. Publication No. 2012/0285612, and U.S. Patent Nos. 7,834, 123 and 3,769,244, all of which are incorporated by reference. However, the use of thermally activated catalysts or heat-activated curing is not necessarily appropriate in these new applications, and the catalytic activity would be too low at room temperature.

[007] Therefore, what is needed is a composition that includes a latent catalyst, and a two-part adhesive formed when employing the latent catalyst, that provides improved latency of the system to increase open time for working with the adhesive, provides for curing at ambient temperatures. There also remains a need for providing an adhesive capable of bonding to different materials, such as aluminum, magnesium, sheet molding compound, and carbon fiber composites. There also remains a need for an adhesive capable of bonding dissimilar materials together. What is also needed is a method for forming the catalyst and method for forming the adhesive capable of improving latency of the system to increase open time for working with the adhesive while maintaining ambient temperature curability.

SUMMARY [008] Disclosed is a composition comprising a Part 1 (e.g., comprising one or more polyisocyanates); a Part 2 (e.g., comprising one or more compounds containing isocyanate reactive groups); and one or more positively charged silyl-protected amine complexes, wherein the silyl group and the amine of the silyl-protected amine complex dissociate when Part 1 and Part 2 are contacted with each other, and the amine is capable of catalyzing a reaction between Part 1 and Part 2, which may be useful for forming a two- component polyurethane adhesive. The amine of the amine complex may be a tertiary amine or a secondary ketimine. The one or more silyl-protected amine complexes may be located in Part 1 or Part 2. The one or more silyl-protected amine complexes may be located in Part 1. Part 2 may comprise one or more polyols. The one or more silyl- protected amine complexes may be present in an amount of about 0.01 weight percent to about 5 weight percent based on the weight of Part 2. The one or more silyl-protected amine complexes may be present in an amount of about 0.05 weight percent to about 2 weight percent based on the weight of Part 2. The latency of the composition after contacting Part 1 and Part 2 may be about 3 minutes or greater.

[009] Disclosed is a method comprising forming a positively charged complex between an amine and a silyl group, and a counterion, to form a silylammonium salt, where the silyl group and the amine dissociate and the amine is capable of catalyzing a reaction between parts of a two-component polyurethane adhesive, where Part 1 comprises one or more polyisocyanates, and Part 2 comprises one or more compounds containing isocyanate reactive groups. The amine may be a tertiary amine or a secondary ketimine. The method may form a two-component polyurethane adhesive. The silylammonium salt may be adapted to be added to Part 1. Part 1 and the silylammonium salt may be adapted to be contacted with Part 2. The two component polyurethane adhesive may be capable of curing at ambient temperatures. The silylammonium salt may be present in an amount of about 0.01 weight percent to about 5 weight percent, based on the weight of Part 2. The silylammonium salt may be present in an amount of about 0.05 weight percent to about 2 weight percent, based on the weight of Part 2. The latency after contacting Part 1 and Part 2 may be about 3 minutes or greater

[0010] Also disclosed is the composition or method as described herein, where the positively charged complex and a counterion correspond to the formula:

R¹ , separately in each occurrence, may be a hydrocarbyl group which may contain one or more heteroatoms. R², separately in each occurrence, may be a hydrocarbylene group which may contain one or more heteroatoms. R¹ and R² may combine to form a cyclic ring. The cyclic ring may include further heteroatoms. X, separately in each occurrence, may be an alkyi group, such as a Ci-Cs alkyi group, which may be linear, branched, or cyclic, an aryl group, a Ci-Cs alkoxy group, an alkylhalide, or a heteraryl group. A^" may be any anion that forms a complex but does not interfere with the dissociation of the silyl- protected amine complexes when Part 1 and Part 2 are contacted. The amine may include an aromatic or cycloaliphatic structure having one or more rings. The nitrogetn atom of the amine group may be pendant from the aromatic or cycloaliphatic structure. The nitrogen atom may be incorporated into the one or more rings. The amine may contain an aromatic structure including aromatic ring. The amine may include a tertiary amine disposed on an alkyi group bound to the aromatic ring. The amine may contain a cyclic amidine structure. The amine may be 1 ,8-diazabicycloundec-7-ene (DBU) 1 ,5- diazabicyclo[4.3.0]non-5-ene (DBN), 1 ,4-diazabicyclo[2.2.2]octane (DABCO), pyridine, ethylene diamine, 4-methylmorpholine, or 1-methylimidazole. The silyl group and the anion A^" may be provided from a silyl acetate, silyl trifluoroacetate, silyl sulfonate, silyl halide, silyl carboxylate, silyl triflate, silyl tosylate, or methyl sulfanate. The silyl group and the anion A^" may be provided from a silyl sulfonate. The positively charged complex and counteranion may be prepared in a mole ratio of about 0:5 to about 1 :0.5 amine to silyl acetate, silyl trifluoroacetate, silyl sulfonate, silyl halide, silyl carboxylate, silyl triflate, silyl tosylate, or methyl sulfanate. For example, it may be about 1 : 1. The molar ratio may be about 0.5-2, about 0.75-1.5. For example, the molar ratio may be about 1. The silyl group may be selected from a triisobutylsilyl group, a triisopropylsilyl group, a tri-n-propyl-silyl group, or a tribenzylsilyl group. The silyl sulfonate may be triisopropylsilyl trifluoromethanesulfonate (TIPS OTf). [001 1] Disclosed is a method of forming a two-component polyurethane adhesive by contacting Part 1 and Part 2 and employing the silylammonium salt in accordance with the teachings herein; applying the adhesive to a first substrate; and contacting a second substrate with the first substrate, with the two-component polyurethane adhesive disposed between the first substrate and the second substrate. The latency after contacting Part 1 and Part 2 may be about 3 minutes or greater. The two-component polyurethane adhesive may be capable of curing at ambient temperatures. The silylammonium salt may be located in Part 1 , and the silylammonium salt may dissociate upon contacting Part 1 and Part 2, which may catalyze a reaction between Part 1 and Part 2. The method may be free of a step of heating when curing the adhesive. The first substrate and the second substrate may be dissimilar substrates. One or both of the first substrate and the second substrate may comprise glass, metal, fiber reinforced polymers, coated metal, polymers, coated polymers, thermoplastic polymers, thermoset polymers, ceramics, wood, natural products, natural fibers, paper, cardboard, or a combination thereof.

[0012] Disclosed is a two-component polyurethane adhesive formed using the composition and methods described herein. Also disclosed is an article formed by bonding a first substrate and a second substrate together by a composition or method as disclosed herein. The two-component polyurethane adhesive may be curable at ambient temperatures. The adhesive composition adheres strongly to many substrates. The adhesive may bond to glass, metal, fiber reinforced polymers, coated metal, polymers, coated polymers, thermoplastic polymers, thermoset polymers, ceramics, wood, natural products, natural fibers, paper, cardboard, or a combination thereof. The substrates bonded together may be different substrates. The adhesive composition exhibits good latency. The adhesive composition exhibits relatively long open times.

DETAILED DESCRIPTION

[0013] The explanations and illustrations presented herein are intended to acquaint others skilled in the art with the invention, its principles, and its practical application. Accordingly, the specific embodiments of the present invention as set forth are not intended as being exhaustive or limiting of the invention. The scope of the invention should, therefore, be determined not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. The disclosures of all articles and references, including patent applications and publications, are incorporated by reference for all purposes. Other combinations are also possible as will be gleaned from the following claims, which are also hereby incorporated by reference into this written description.

[0014] Disclosed is a composition comprising a) Part 1 comprising one or more polyisocyanates; b) Part 2 comprising one or more compounds containing isocyanate reactive groups; c) one or more positively charged silyl-protected amine complexes, wherein the amine of the silyl-protected amine complex may be a tertiary amine or a secondary ketimine; wherein the silyl group and the amine of the silyl-protected amine complex dissociate when Part 1 and Part 2 are contacted with each other, and the amine is capable of catalyzing a reaction between Part 1 and Part 2 useful for forming a two- component polyurethane adhesive. Also disclosed herein is a method comprising: forming a positively charged complex between an amine and a silyl group, and a counterion to form a silylammonium salt; wherein the silyl group and the amine dissociate and the amine is capable of catalyzing a reaction between parts of a two-component polyurethane adhesive, where Part 1 comprises one or more polyisocyanates and Part 2 comprises one or more compounds containing isocyanate reactive groups.

[0015] The teachings herein also include a method comprising forming a two- component polyurethane adhesive by contacting Part 1 and Part 2 and employing the silylammonium salt formed in accordance with the methods described herein, wherein the silylammonium salt is located in Part 1 or Part 2; applying the adhesive to a first substrate; and contacting a second substrate with the first substrate, with the two-component polyurethane adhesive disposed between the first substrate and the second substrate. The teachings further contemplate an article comprising a first substrate and a second substrate bonded together by the composition disclosed herein or a composition formed by the method disclosed herein, wherein the composition is disposed between the first substrate and the second substrate.

[0016] One or more as used herein means that at least one, or more than one, of the recited components may be used as disclosed. Nominal as used with respect to functionality means the theoretical functionality, generally this can be calculated from the stoichiometry of the ingredients used. Generally, the actual functionality is different due to imperfections in raw materials, incomplete conversion of the reactants and formation of by-products. Durability in this context means that the composition once cured remains sufficiently strong to perform its designed function, in the embodiment wherein the cured composition is an adhesive, the adhesive holds substrates together for the life or most of the life of the structure containing the cured composition. As an indicator of this durability, the curable composition (e.g. adhesive) may exhibit excellent results during accelerated aging. This may mean that after a set of substrates bonded with the adhesive is exposed to heat aging, the failure mode in Quick Knife adhesion or Lap Shear testing is cohesive, meaning the adhesive breaks before the bond of the adhesive to the substrate breaks. The adhesive may exhibit elongation when fully cured. Elongation may be about 50% or greater, about 60% or greater; or about 100% or greater. Elongation may be about 200% or less, about 180% or less, or about 160% or less. The adhesive may exhibit a high modulus of elasticity when tested at 1 mm thickness and 6 mm in length. The modulus of elasticity may be about 2 MPa or more, about 10 MPa or more, or about 20 MPa or more. The modulus may be about 300 MPa or less, about 150 MPa or less, or about 60 MPa or less. Isocyanate content means the weight percent of isocyanate groups in the designated component, such as prepolymer. The isocyanate content can be measured by analytical techniques known to one skilled in the art, for example by potentiometric titration with an active hydrogen containing compound, such as dibutyl amine. Typically, the residual content of a component can be calculated from the ingredients utilized to prepare the component or composition. Alternatively, it can be determined utilizing known analytical techniques. Residue with respect to an ingredient used to prepare the adduct as disclosed herein means that a portion of the ingredient, such as a cyclic amidine and/or an isocyanate (which may be a cyclic isocyanate), remains in the compound after inclusion as a result of the methods disclosed herein. Heteroatom means nitrogen, oxygen, sulfur and phosphorus, more preferred heteroatoms include nitrogen and oxygen. Hydrocarbyl as used herein refers to a group containing one or more carbon atom backbones and hydrogen atoms, which may optionally contain one or more heteroatoms. Where the hydrocarbyl group contains heteroatoms, the heteroatoms may form one or more functional groups well known to one skilled in the art. Hydrocarbyl groups may contain cycloaliphatic, aliphatic, aromatic or any combination of such segments. The aliphatic segments can be straight or branched. The aliphatic and cycloaliphatic segments may include one or more double and/or triple bonds. Included in hydrocarbyl groups are alkyl, alkenyl, alkynyl, aryl, cycloalkyl, cycloalkenyl, alkaryl and aralkyl groups. Cycloaliphatic groups may contain both cyclic portions and noncyclic portions. Hydrocarbylene means a hydrocarbyl group or any of the described subsets having more than one valence, such as alkylene, alkenylene, alkynylene, arylene, cycloalkylene, cycloalkenylene, alkarylene and aralkylene. As used herein percent by weight or parts by weight refer to, or are based on, the weight or the curable compositions unless otherwise specified. Based on the weight of or total weight the composition means the weight of both the polyol and the isocyanate component unless stated otherwise.

[0017] The term isocyanate-reactive compound as used herein includes any organic compound having nominally at least two isocyanate-reactive moieties. An isocyanate reactive moiety can be an active hydrogen containing moiety, which refers to a moiety containing a hydrogen atom which, because of its position in the molecule, displays significant activity according to the Zerewitinoff test described by Wohler in the Journal of the American Chemical Society, Vol. 49, p. 3181 (1927). Illustrative of such isocyanate reactive moieties, such as active hydrogen moieties, are— COOH,— OH,— NH2,— NH— ,— CONH2,— SH, and— CONH— . Active hydrogen containing compounds, isocyanate reactive moiety containing compounds, may include polyols, polyamines, polymercaptans and polyacids. The isocyanate reactive compound may be a polyol, or may be a polyether polyol. The at least two isocyanate-reactive moieties (e.g., the active hydrogen moieties) may be the same or different.

[0018] Part 1 of the composition contains one or more polyisocyanates. The polyisocyanates that may be utilized include any polyisocyanates that react with compounds containing isocyanate reactive groups to undergo curing, which impart significant cohesive strength to the cured composition and which enhance bonding to substrates. The polyisocyanates can be monomeric, oligomeric or prepolymers prepared from polyisocyanates reacted with compounds containing isocyanate reactive groups to prepare prepolymers having isocyanate groups. The polyisocyanates may be a mixture of isocyanate functional prepolymers and unreacted compounds having more than one, two or more, isocyanate groups. Such mixture may be formed as a result of reacting an equivalents excess of polyisocyanates with compounds containing more than one isocyanate reactive groups.

[0019] The prepolymer may be a reaction product of one or more polyisocyanates and one or more isocyanate reactive compounds. The prepolymer may be a reaction product of one or more aromatic diisocyanates having a molecular weight of up to 350 with i) at least one 700 to 3000 molecular weight homopolymer of poly(propylene oxide) having a nominal hydroxyl functionality of 2 to 4, or ii) a mixture of i) with up to 3 parts by weight, per part by weight of i), of a 2000 to 8000 molecular weight polyether polyol which is a copolymer of 70 to 99 weight percent propylene oxide and 1 to 30 weight percent ethylene oxide and has a nominal hydroxyl functionality of 2 to 4. The poly(propylene oxide) used to make the prepolymer may have a molecular weight of 800 to 2000 or from 800 to 1500, and has and may have a nominal functionality of 2 to 3. A copolymer of 70 to 99 weight percent propylene oxide and 1 to 30 weight percent ethylene oxide used to make the prepolymer may have a molecular weight of 3000 to 5500 and a nominal functionality of 2 to 3.

[0020] The reaction of polyisocyanate and polyol(s) produces prepolymer molecules having a polyether segment that is capped with the polyisocyanate, so the molecules have terminal isocyanate groups. Each prepolymer molecule contains a polyether segment that corresponds to the structure, after removal of hydroxyl groups, of a polyol used in the prepolymer-forming reaction. If a mixture of polyols is used to make the prepolymer, a mixture of prepolymer molecules is formed.

[0021] The isocyanate-terminated prepolymer has an isocyanate equivalent weight of about 700 to about 3500, about 700 to about 3000 or about 1000 to about 3000. The equivalent weight may be calculated by adding the weight of the polyol(s) used to prepare the prepolymer and the weight of polyisocyanate(s) consumed in reaction with the polyol(s), and dividing by the number of moles of isocyanate groups in the resulting prepolymer. The polyisocyanate used to make the prepolymer can be any of the low equivalent weight polyisocyanate compounds mentioned below, or a mixture of two or more of these. The prepolymer has at least 2, 2 to 4, or 2 to 3, isocyanate groups per molecule. The isocyanate groups of the prepolymer may be aromatic, aliphatic (including alicyclic), or a mixture of aromatic and aliphatic isocyanate groups. The isocyanate groups on the prepolymer molecules may be aromatic. The low equivalent weight polyisocyanate compound(s) in some embodiments have an isocyanate equivalent weight of 80 to 250, 80 to 200, or 80 to 180. If a mixture of polyisocyanate compounds is present, the mixture may have, for example, an average of 2 to 4 or 2.3 to 3.5 isocyanate groups per molecule.

[0022] All or a portion of the low equivalent weight polyisocyanate compound may have aromatic isocyanate groups. Among the useful aromatic polyisocyanate compounds m-phenylene diisocyanate, toluene-2,4-diisocyanate, toluene-2,6-di-isocyanate, naphtha- ylene-1 ,5-diisocyanate, methoxyphenyl-2,4-diisocyanate, diphenyl-methane-4,4'-diiso- cyanate, diphenylmethane-2,4'-diisocyanate, 4,4'-bi-phenylene diisocyanate, 3,3'-dimeth- oxy-4,4'-biphenyl diisocyanate, 3,3'-dimethyl-4-4'-biphenyl diisocyanate, 3,3'-dimethyl- diphenyl methane-4,4'-diisocyanate, 4,4',4"-triphenyl methane triisocyanate, polymethylene polyphenylisocyanate (PMDI), toluene-2,4,6-triisocyanate and 4,4'- dimethyl-diphenylmethane-2,2',5,5'-tetraisocyanate. Modified aromatic polyisocyanates that contain urethane, urea, biuret, carbodiimide, uretoneimine, allophonate or other groups formed by reaction of isocyanate groups are also useful. The aromatic polyisocyanate may be MDI or PMDI (or a mixture thereof that is commonly referred to as "polymeric MDI"), and so-called "liquid MDI" products that are mixtures of MDI and MDI derivatives that have biuret, carbodiimide, uretoneimine and/or allophonate linkages. All or a portion of the low equivalent weight polyisocyanate compounds may be one or more aliphatic polyisocyanates. Examples of these include cyclohexane diisocyanate, 1 ,3- and/or 1 ,4-bis(isocyanatomethyl)cyclohexane, 1-methyl-cyclohexane-2,4-diisocyanate, 1- methyl-cyclohexane-2,6-diisocyanate, methylene dicyclohexane diisocyanate, isophor- one diisocyanate and hexamethylene diisocyanate.

[0023] At least some of the polyisocyanate groups present in the polyisocyanate component may be aromatic isocyanate groups. If a mixture of aromatic and aliphatic isocyanate groups are present, about 50% or more by number or about 75% or more by number, are aromatic isocyanate groups. 80 to 98% by number of the isocyanate groups may be aromatic, and 2 to 20% by number may be aliphatic. All of the isocyanate groups of the prepolymer may be aromatic, and the isocyanate groups of the polyisocyanate compound(s) having an isocyanate equivalent weight of up to 350 may be a mixture of 80 to 95% aromatic isocyanate groups and 5 to 20% aliphatic isocyanate groups.

[0024] The isocyanate functional prepolymers are the reaction product of one or more polyisocyanates and one or more isocyanate reactive compounds wherein an excess of poly-isocyanate is present on an equivalents basis. The isocyanate reactive compounds comprise one or more polyols. Exemplary polyols include those disclosed in Wu, U.S. Pat. No. 6,512,033 at column 4, line 10 to line 64, incorporated herein by reference, for example, polyether polyols, polyester polyols, poly(alkylene carbonate) polyols, hydroxyl containing polythioethers and mixtures thereof. The polyols may be polyether polyols containing one or more alkylene oxide units in the backbone of the polyol. The isocyanate reactive may be a mixture of one or more polyether diols and/or one or more polyether triols. Exemplary alkylene oxide units include ethylene oxide, propylene oxide, butylene oxide and mixtures thereof. The alkylene oxides can contain straight or branched chain alkylene units. The polyol may contain propylene oxide units, ethylene oxide units or mixtures thereof. Mixtures of alkylene oxide can be arranged randomly or in blocks. In some preferred embodiments, the polyol comprises propylene oxide chains with ethylene oxide chains capping the polyol. The ethylene oxide capped polypropylene oxides are hydrophobic, and may contain less than about 20 mole percent of ethylene oxide or less than 10 mole percent of ethylene oxide in the backbone. The isocyanate-reactive compound may have a functionality of about 1.8 or greater, about 1.9 or greater, or about 1.95 or greater. The isocyanate-reactive compound may have a functionality of about 4.0 or less, about 3.5 or less, or preferably about 3.0 or less. The equivalent weight of the isocyanate-reactive compound may be about 200 or greater, about 500 or greater, or about 1 ,000 or greater. The equivalent weight of the isocyanate-reactive compound may be about 5,000 or less, about 3,000 or less, or about 2,500 or less. The compositions may further comprise one or more prepolymers containing one or more polyether polyols having dispersed therein or grafted to the backbone one or more organic based polymer particles. Exemplary organic based polymer particles may be based on thermoplastic polymers such as monovinylidene aromatic based polymers and copolymers of monovinylidene aromatic monomers with conjugated dienes, acrylates, methacrylates, unsaturated nitriles or mixtures thereof. The copolymers can be block or random copolymers. The particles may comprise copolymers of unsaturated nitrites, conjugated dienes and a monovinylidene aromatic monomer, a copolymer of an unsaturated nitrile and a monovinylidene aromatic monomer or a polyurea. The particles may comprise a polyurea or polystyrene-acrylonitrile copolymer. The particles may comprise polystyrene- acrylonitrile copolymers. The organic polymer particles are commonly available and well- known to those skilled in the art. The organic polymer particles may have a particle size which is large enough to improve the impact properties and elastomeric properties of the finally cured adhesive, but not so large so as to reduce the ultimate strength of the adhesive after cure. The particle size may be about 10 microns or greater or about the particle size is about 20 microns or greater. The particle size may be about 50 microns or less or about 40 microns or less. The polyols may contain about 20 percent by weight or greater of organic polymer particles, about 30 percent by weight or greater or about 35 percent by weight or greater. The polyols may contain about 60 percent by weight or less of organic polymer particles, about 50 percent by weight or less or about 45 percent by weight or less. The exemplary polyols containing organic polymer particles are disclosed in Zhou, U.S. Pat. No. 6,709,539 at column 4, line 13 to column 6, line 18, incorporated herein by reference. The polyols containing the organic particles may comprise one or more polyether triols. The prepolymers containing organic based polymer particles may be present is sufficient amount to enhance the elastomeric nature and the modulus of the compositions. Such prepolymers may be present in the composition in an amount of about 5 percent by weight or less. Such prepolymers may be present in the composition in an amount of greater than 0 if present or about 0.1 percent by weight or greater. [0025] The isocyanate reactive compounds are present in an amount sufficient to react with most of the isocyanate groups of the isocyanates leaving enough isocyanate groups to correspond with the desired isocyanate content of the prepolymer. Preferably, the compounds containing isocyanate reactive groups are present in an amount of about 50 percent by weight or greater based on the prepolymer, more preferably about 65 percent by weight or greater and most preferably about 80 percent by weight or greater. Preferably, the compounds containing isocyanate reactive groups are present in an amount of about 90 percent by weight or less based on the prepolymer and most preferably about 85 percent by weight or less.

[0026] A prepolymer may be prepared by combining one or more compounds containing two or more isocyanate reactive functional groups, such as polyols or polyol mixtures, with an amount of low equivalent weight polyisocyanate compound(s) significantly greater than needed to simply cap the isocyanate reactive functional groups, for example polyol(s). After reaction, this produces a mixture of the prepolymer and unreacted low equivalent weight polyisocyanate compounds. If desired, an additional amount of polyisocyanate compound(s) can then be blended into this mixture. The one or more compounds containing two or more isocyanate reactive functional groups, polyol(s), may be combined and reacted with an excess of one or more aromatic polyisocyanates to produce a mixture of prepolymer and unreacted starting polyisocyanate compounds, and this mixture then is combined with one or more aliphatic polyisocyanates. The prepolymer may be made in a reaction of the polyol(s) with MDI, PMDI, a polymeric MDI, a derivative of any one or more of these that contains biuret, carbodiimide, uretoneimine and/or allophonate, or a mixture of any two or more of these, to produce a mixture of prepolymer and unreacted starting polyisocyanates, and the mixture is then combined with one or more aliphatic polyisocyanates, especially an aliphatic polyisocyanate based on hexamethylene diisocyanate.

[0027] Part 1 , the polyisocyanate component, may contain up to 70% by weight of one or more particulate inorganic fillers as described before. Part 1 , the polyisocyanate component, may contain about 10% by weight or more, about 20% by weight or more of one or more such fillers, and may contain, for example, 20 to 50% or 30 to 40% by weight thereof. The filler amounts are based on the weight of Part 1 , the polyisocyanate component. The filler may exclude carbon particles.

[0028] Part 1 , the polyisocyanate component, may also contain one or more other additional ingredients, such as those described above with respect to the Part 2. Part 1 , the polyisocyanate component, may contain about 0.5% by weight or less, about 0.1 %, by weight or less of organic compounds having a boiling temperature of 80°C or less, about 0.1 % by weight or less, or about 0.05% by weight or less, of water and/or other chemical blowing agents that produce a gas under the conditions of the curing reaction. Part 1 , the polyisocyanate component, may contain plasticizers in an amount of about 0% by weight or greater, about 20% by weight or greater, or about 25% by weight or greater as described with respect to Part 2. The plasticizers may be present in an amount of about 50% by weight or less, about 40% by weight or less, or about 35% by weight or less. Part 1 , the isocyanate component, may be devoid of a plasticizer.

[0029] The viscosity of the isocyanate functional prepolymers may be about 200 Pa.s or less, about 150 Pa.s or less or about 120 Pa.s or less. The viscosity of the isocyanate functional prepolymers may be about 50 Pa.s or greater. The viscosity of the compositions can be adjusted with fillers. Below about 50 Pa.s a composition prepared from the isocyanate functional polymers may exhibit poor high speed tensile strength. Above about 150 Pa.s the isocyanate functional components, prepolymer, may be unstable and hard to pump. "Viscosity" as used herein is measured by the Brookfield Viscometer, Model DV- E with a RV spindle #5 at a speed of 5 revolutions per second and at a temperature of 23° C.

[0030] Part 1 , polyisocyanate component, may contain one or more polyisocyanate compounds. The polyisocyanate preferably is a mixture of one or more isocyanate- terminated prepolymers having at least 2 isocyanate groups per molecule and an isocyanate equivalent weight of 700 to 3500, and one or more low equivalent weight polyisocyanate compounds that have an isocyanate equivalent weight of up to 350 and 2 to 4 isocyanate groups per molecule. When such a mixture is present, the prepolymer may constitute 20 to 65 percent of the weight of the polyisocyanate component. In some embodiments, the prepolymer constitutes 20 to 60 percent, 20 to 50 percent or 25 to 35 percent of the weight of the polyisocyanate component. The low equivalent weight polyisocyanate, when such a mixture is present, may constitute 20 to 50 weight percent of weight of the polyisocyanate component. The isocyanate content of the prepolymers may be about 1 percent by weight or greater, about 6 percent by weight or greater, about 8 percent by weight or greater or about 10 percent by weight or greater. The isocyanate content in the isocyanate functional prepolymers may be about 35 percent by weight or less, about 30 percent by weight or less, about 25 percent by weight or less or about 15 percent by weight or less. [0031] Part 2 comprises one or more compounds containing isocyanate reactive groups. Any one or more compounds containing isocyanate reactive groups which provide the desired final properties may be utilized in the composition. The one or more compounds containing isocyanate reactive groups can be one or more chain extenders, crosslinking agents, polyols or polyamines. Polyols as described hereinbefore can be utilized as the one or more compounds containing isocyanate reactive groups. The polyols or polyamines can be prepolymers as described herein-before prepared utilizing excess equivalents of active hydrogen functional groups such that the resulting prepolymers contain active hydrogen functional groups, for example hydroxyl and or amino groups. The one or more compounds containing isocyanate reactive groups may comprise one or more low molecular weight compounds having two or more isocyanate reactive groups and a hydrocarbon backbone wherein the backbone may further comprise one or more heteroatoms. It is advantageous to use such low molecular weight compounds in two-part compositions. Such low molecular weight compounds may be compounds known in the art as chain extenders, difunctional compounds, or crosslinkers, having, on average, greater than two active hydrogen groups per compound. The molecular weight of the low molecular weight compound may be about 250 or less, about 120 or less or about 100 or less. The low molecular weight compound may comprise one or more multifunctional alcohols, multifunctional alkanol amines, one or more adducts of multifunctional alcohol and an alkylene oxide, one or more adducts of a multifunctional alkanol amine and an alkylene oxide or a mixture thereof. The low molecular weight compound are used in a sufficient amount to obtain the desired G-Modulus (E-Modulus). In two-part compositions, the low molecular compound may be located Part 2. The low molecular weight compound may present in Part 2 in an amount of about 2 percent by weight or greater, more preferably about 3.0 percent by weight or greater and most preferably about 4.0 percent by weight or greater. The low molecular weight compound may be present in the composition in an amount of about 12 percent by weight or less, about 10 percent by weight or less or about 8 percent by weight or less.

[0032] Part 2 may further comprise polyoxyalkylene polyamine having 2 or greater amines per polyamine. The polyoxyalkylene polyamine may have 2 to 4 amines per polyamine or 2 to 3 amines per polyamine. The polyoxyalkylene polyamine may have a weight average molecular weight of about 200 or greater or about 400 or greater. The polyoxyalkylene polyamine may have a weight average molecular weight of about 5,000 or less or about 3,000 or less. Exemplary polyoxyalkylene polyamines are JEFFAMINE™ D-T-403 polypropylene oxide triamine having a molecular weight of about 400 and JEFFAMINE™ D-400 polypropylene oxide diamine having a molecular weight of about 400. The polyoxyalkylene polyamines may be present in a sufficient amount to prevent the composition from sagging once mixed and applied. The polyoxyalkylene polyamine may be present in Part 2 in an amount of about 0.2 percent by weight or greater, about 0.3 percent by weight or greater or about 0.5 percent by weight or greater. The polyoxyalkylene polyamine may be present in the Part 2 in an amount of about 6 percent by weight or less, about 5 percent by weight or less or about 4 percent by weight or less.

[0033] The one or more compounds containing isocyanate reactive groups may be one or more polyether polyols. Each such polyether polyol may have a hydroxyl equivalent weight of 400 to 2000. The hydroxyl equivalent weight of each polyol may be at least 500, at least 800 or at least 1000, and may be up to 1800, up to 1500 or up to 1200. Each such polyether polyol may have a nominal hydroxyl functionality of 2 to 4. By "nominal functionality" of a polyether polyol, or compounds containing isocyanate reactive groups, it is meant the average number of oxyalkylatable hydrogen atoms on the initiator compound that is alkoxylated to form the polyether polyol. The actual functionalities of the polyether polyol(s) may be somewhat lower than the nominal functionality, due to side- reactions that occur during the alkoxylation process. In the case of a mixture of polyether polyols, the number average nominal functionality may be 2 to 3.5 or 2.5 to 3.5. The polyether polyol(s) may be selected from homopolymers of propylene oxide and copolymers of 70 to 99% by weight propylene oxide and 1 to 30% by weight ethylene oxide. Such a copolymer of propylene oxide and ethylene oxide may be utilized if a single polyether polyol is present. If two or more polyether polyols are present, at least one is such may be a copolymer of propylene oxide and ethylene oxide. In the case of a copolymer, the propylene oxide and ethylene oxide may be randomly copolymerized, block copolymerized, or both. About 50% or more of the hydroxyl groups of the polyether polyol or mixture of polyether polyols may be primary hydroxyl, with the remainder being secondary hydroxyl groups. 70% or more of the hydroxyl groups in the polyether polyol or mixture thereof may be primary hydroxyl.

[0034] The polyether polyol(s) (ingredient a)) may constitute about 35 weight percent or greater of Part 2. The polyether polyol(s) may constitute about 40 weight percent or greater or about 50 weight percent or greater of Part, may constitute about 80 weight percent or less, about 65 weight percent or less or about 55 weight percent or less. [0035] Part 2 may comprise one or more aliphatic diol chain extenders. The aliphatic diol chain extender(s) may each have a hydroxyl equivalent weight of about 200 or less, about 100 or less, about 75 or less or about 60 or less, and about two aliphatic hydroxyl groups per molecule. Examples of these are monoethylene glycol, di-ethylene glycol, triethylene glycol, 1 ,2-propane diol, 1 ,3-propane diol, 2,3-dimethyl-1 ,3-propanediol, dipropylene glycol, tripropylene glycol, 1 ,4-butanediol, 1 ,6-hexanediol and other linear or branched alkylene diols having up to about 20 carbon atoms. The aliphatic diol chain extender may be monoethylene glycol, 1 ,4-butanediol or a mixture thereof. The chain extender may be present in an amount of about 0.1 percent by weight or greater of Part 2, about 1.0 percent by weight or greater, about 2.0 percent by weight or greater, about 3 percent by weight or greater or about 4 percent by weight or greater. The chain extender may be present in an amount of about 25 percent by weight or less of Part 2, about 10 percent by weight or less, about 9 percent by weight or less, about 8 percent by weight or less, about 7 percent by weight or less or about 6 percent by weight or less. The aliphatic diol chain extender or mixture thereof may be present in an amount of 2.5 to 6 equivalents per equivalent of the polyols of Part 2.

[0036] Part 2, polyol component, may contain one or more latent room temperature organometallic catalysts. A latent room temperature organometallic catalysts is a catalyst that functions to catalyze the reaction of the nucleophiles (polyols, polyamines) present in the polyol component with the isocyanates present in the isocyanate component. The latent organometallic catalyst may show delayed action. The latent room temperature catalysts may exhibit accelerated catalytic activity when exposed to temperatures at a temperature of 40 °C or greater. Any latent room temperature organometallic catalysts which provides good open time, acceptable initial lap shear strengths and which maintains an acceptable level of reactivity after partial curing and storage may be utilized. Exemplary classes of latent room temperature organometallic catalysts contain tin, zinc or bismuth. Exemplary latent room temperature organometallic catalysts include zinc alkanoates, bismuth alkanoates, dialkyltin alkanoates, dialkyl tin mercaptides, dialkyl tin bis(alkylmercaptoacetates), dialkyltin thioglycol-ates or mixtures thereof. Exemplary latent room temperature organometallic catalysts include zinc neoalkanoates, bismuth neoalkanoates, dialkyltin neoalkanoates, dialkyl tin mercaptides, dialkyl tin bis(alkylmercapto acetates), dialkyltin thioglycolates or mixtures thereof. The latent room temperature organometallic catalysts may be dialkyl tin mercaptides, dialkyl tin bis(alkylmercapto-acetates), dialkyltin thioglycolates or mixtures thereof. The latent room temperature organometallic catalysts may be dialkyltin thioglycolates or mixtures thereof. The alkyl groups on the latent room temperature organometallic catalysts may be any alkyl groups of about 1 or more carbon atoms or 4 or greater carbon atoms. The alkyl groups on the latent room temperature organometallic catalysts may be any alkyl groups of about 20 or less carbon atoms or 12 or less carbon atoms. Exemplary alkyls groups include methyl, butyl, octyl and dodecyl groups. The latent room temperature organometallic catalysts may be present in an amount sufficient to provide good open time, acceptable initial lap shear strengths and which maintains an acceptable level of reactivity after partial curing and storage. The latent room temperature organometallic catalysts may be present in an amount of about 0.005 percent by weight or greater based on the weight of Part 2, about 0.01 percent by weight or greater, about 0.020 percent by weight or greater, or about 0.030 percent by weight or greater. The latent room temperature organometallic catalysts may be present in an amount of about 1.0 percent by weight or less based on the weight of the Part 2, about 0.080 percent by weight or less, about 0.070 percent by weight or less or about 0.050 percent by weight or less. These amounts are based on active catalyst, and ignore the mass of solvents or other materials as may be present in a commercially available catalyst product.

[0037] Part 2 component may contain compounds having primary and/or secondary amino groups. Exemplary compounds having primary and/or secondary amino groups include polyoxyalkylene polyamines having 2 or greater amines per poly-amine, 2 to 4 amines per polyamine, or 2 to 3 amines per polyamine. The polyoxyalkylene poly-amines may have a weight average molecular weight of about 200 or greater or about 400 or greater. The polyoxyalkylene polyamine may have a weight average molecular weight of about 5,000 or less or about 3,000 or less. Exemplary polyoxyalkylene polyamines are JEFFAMINE™ D-T-403 polypropylene oxide triamine having a molecular weight of about 400 and JEFFAMINE™ D-400 polypropylene oxide diamine having a molecular weight of about 400. The compounds having primary and/or secondary amino groups are present in a sufficient amount to prevent the composition from sagging once mixed and applied. The compounds having primary and/or secondary amino groups may be present in Part 2 in an amount of about 0.2 percent by weight or greater, about 0.3 percent by weight or greater or about 0.5 percent by weight or greater. The compounds having primary and/or secondary amino groups may be present in Part 2 in an amount of about 6 percent by weight or less, about 4 percent by weight or less or about 2 percent by weight or less. [0038] Part 2 may further include one or more optional components. Part 2 may contain at least one particulate filler; however, if a filler is present, it constitutes no more than about 80 weight percent of the total weight of Part 2. The filler may constitute about 25 weight percent or greater of Part 2, or about 30 weight percent or greater. The filler may constitute about 80 weight percent or less of Part 2, about 60 weight percent or less or about 50 weight percent or less. The particulate filler is in the form of particles having a size of about 50 nm to about 100 μηι. The fillers may have a particle size (d50) of about 250 nm or greater, about 500 nm or greater or about 1 μηι or greater. The fillers may have a particle size (d50) of about 50 μηι or less, about 25 μηι or less or about 10 μηι or less. Particles sizes are conveniently measured using dynamic light scattering methods, or laser diffraction methods for particles having a size below about 100 nm. The particulate filler is a solid material at room temperature, is not soluble in the other ingredients of the polyol component or in the polyisocyanate component or any ingredient thereof. The filler is a material that does not melt, volatilize or degrade under the conditions of the curing reaction between the isocyanate reactive and isocyanate functional components. The filler may be, for example, an inorganic filler such as glass, silica, boron oxide, boron nitride, titanium oxide, titanium nitride, fly ash, calcium carbonate, various alumina- silicates including clays such as wollastonite and kaolin, metal particles such as iron, titanium, aluminum, copper, brass, bronze and the like; thermoset polymer particles such as polyurethane, cured particles of an epoxy, phenol-formaldehyde, or cresol- formaldehyde resin, crosslinked polystyrene and the like; thermoplastics such as polystyrene, styrene-acrylonitrile copolymers, polyimide, polyamide-imide, polyether ketone, polyether-ether ketone, polyethyleneimine, poly(p-phenylene sulfide), polyoxymethylene, polycarbonate and the like; and various types of carbon such as activated carbon, graphite, carbon black and the like. In some embodiments, the particulate filler excludes carbon particles. The particles in some embodiments have an aspect ratio of about 5 or less, about 2 or less, or about 1.5 or less. Some or all of the filler particles can be grafted onto one or more of the polyether polyol(s) that Part 2.

[0039] Another optional ingredient is one or more dispersing aids, which wet the surface of the filler particles and help them disperse into theisocyamnate reactive component, such as polyether polyol(s). These may also have the effect of reducing viscosity. Among these are, for example, various dispersing agents sold by BYK Chemie under the BYK, DISPERBYK and ANTI-TERRA-U tradenames, such as alkylammonium salt of a low-molecular-weight polycarboxylic acid polymer and salts of unsaturated polyamine amides and low-molecular acidic polyesters, and fluorinated surfactants such as FC-4430, FC-4432 and FC-4434 from 3M Corporation. Such dispersing aids may constitute, for example, up to 2 weight percent, preferably up to 1 weight percent, of Part 2.

[0040] Another useful optional ingredient of Part 2 is a desiccant such as fumed silica, hydrophobically modified fumed silica, silica gel, aerogel, various zeolites and molecular sieves, and the like. One or more desiccants may constitute about 1 percent by weight or greater based on the weight of Part 2 and about 5 weight percent or less, or about 4 weight percent or less of Part 2, and may be absent from the polyol component.

[0041] The Part 2 may further include one or more additional isocyanate-reactive compounds, different from those previously described, and which do not contain amine hydrogen atoms. If any such additional isocyanate-reactive compound(s) are present, they may constitute no more than 10 percent, no more than 5 percent or no more than 2 percent of the weight of the polyol component. Examples of such additional isocyanate- reactive compounds include, for example, one or more polyester polyols; one or more polyether polyols containing at least 50 weight percent polymerized ethylene oxide; one or more polyether polyols having a hydroxyl equivalent weight of 100 to 499; and one or more hydroxy-functional crosslinkers having three or more isocyanate-reactive groups per molecule and a hydroxyl equivalent weight of up to 499.

[0042] The composition may be non-cellular, and for that reason, Part 2 may contain about 0.5% by weight or less, about 0.1 %, by weight or less of organic compounds having a boiling temperature of 80°C or below, and about 0.1 % by weight or less, or about 0.05% by weight or less, of water and/or other chemical blowing agents that produce a gas under the conditions of the curing reaction.

[0043] Part 2 may contain about 10 weight percent or less, about 5 weight percent or less, or about 1 weight percent or less, of a plasticizer such as a phthalate, terephthalate, mellitate, sebacate, maleate or other ester plasticizer, a sulfonamide plasticizer, a phosphate ester plasticizer, or a polyether di(carboxylate) plasticizer. Such a plasticizer may be absent from the polyol component.

[0044] The present teachings contemplate a composition including a complex that dissociates to catalyze a reaction between the parts, Part 1 (e.g., the polyisocyanate part) and Part 2 (e.g., the isocyanate reactive part or the polyol part), of a two-component polyurethane adhesive. Any complex that dissociates and catalyzes the reaction, which facilitates the desired cure properties may be used in the disclosed compositions. The complex may be a silylammonium salt. The complex may be one or more positively charged silyl-protected amine complexes. The amine of the silyl-protected amine complexes may be a tertiary amine or a secondary ketimine. The amine may include an aromatic or cycloaliphatic structure, having one or more rings. The nitrogen atom of the amine group may be pendant from the aromatic or cycloaliphatic structure. The nitrogen atom may be incorporated into the one or more rings. The amine may contain an aromatic structure including an aromatic ring. The amine may include a tertiary amine. The tertiary amine may be disposed on an alkyl group bound to the aromatic ring. The silyl-protected amine complexes may contain one or more tertiary amines and/or one or more secondary ketimines. The amines may contain one or more heteroatoms other than nitrogen, for example oxygen or oxygen containing functional groups. The amine may contain a cyclic amidine structure. Exemplary silyl-protected amine complexes correspond to the formula:

wherein R¹ , separately in each occurrence, is a hydrocarbyl group which may contain one or more heteroatoms;

R², separately in each occurrence, is a hydrocarbylene group which may contain one or more heteroatoms;

R¹ and R² combine to form a cyclic ring, and wherein the cyclic ring may include further heteroatoms;

X, separately in each occurrence, is an alkyl group, such as a Ci-Cs alkyl group, which may be linear, branched, or cyclic, an aryl group, a Ci-Ce alkoxy group, an alkylhalide, or a heteraryl group; and

A^" is any anion that forms a complex but does not interfere with the dissociation of the silyl-protected amine complexes when Part 1 and Part 2 are contacted.

[0045] The amine of the positively charged silyl-protected complex may include any amine group that is a tertiary amine group or a secondary ketimine group, that, when disassociated, can catalyze the reaction of isocyanate groups with isocyanate reactive groups at ambient temperature. Exemplary amines include 1 ,8-diazabicycloundec-7-ene (DBU), 1 ,5-Diazabicyclo[4.3.0]non-5-ene (DBN), tris1 ,3,5-(2(N,N-dimethyl amino) ethyl) benzene, 1 ,4-diazabicyclo[2.2.2]octane (DABCO), pyridine, ethylene diamine, 4- methylmorpholine, and 1-methylimidazole.

[0046] The silyl group of the complex may be any silyl group capable of providing the desired latency. The latency of the reaction between Part 1 and Part 2 to form a polyurethane adhesive may depend on the steric hindrance of the silyl group of the complex. The silyl group may provide sufficient stability to the complex that it does not dissociate too rapidly and blocks the amine enough that the alcohol of Part 2, the polyol component, does not react with the amine too quickly. The silyl group and the anion A^" may be provided from a silyl acetate, silyl trifluoroacetate, silyl sulfonate, silyl halide, silyl carboxylate, silyl triflate, silyl tosylate, or methyl sulfanate. The silyl group may be selected from a triisobutylsilyl group, a triisopropylsilyl group, a tri-n-propyl-silyl group, or a tribenzylsilyl group. The silyl group and the anion A^" may be provided from a silyl sulfonate. For example, the silyl sulfonate may be triisopropylsilyl trifluoromethanesulfonate (TIPS OTf).

[0047] The one or more silyl-protected amine complexes may be selected from:

DBU-TIPS OTf DBN-TIPS OTf

1 2

[0048] The silylammonium salt or the positively charged silyl-protected amine complex may be added to Part 1 or Part 2 of the composition. The silylammonium salt or the positively charged silyl-protected amine complex may be added to Part 1 , since the salt or complex may be isocyanate stable and reactive toward a polyol. Therefore, when Part 1 is mixed with Part 2, the positively charged silyl-protected amine complex may dissociate so that the amine can act to catalyze the reaction. The dissociation may occur slowly so that the reaction takes place with a desired latency upon exposure to Part 2. For example, the latency may be about 5 minutes or more, about about 8 minutes or more, or about 10 minutes or more. The latency of the composition after contacting the Parts 1 and 2 may be about 1 hour or less, about 30 minutes or less, or about 20 minutes or less. The latency may be tuned by the selection of the silyl group within the silyl-protected amine complex, where the greater the steric hindrance, the longer the latency. The dissociation may take place at ambient temperature. The reaction may take place in the absence of a heating step.

[0049] Part 1 , polyisocyanate component, and Part 2, polyol component, may be formulated such that when equal volumes of the components are provided, the isocyanate index may be 1.0 to 1.8, 1.1 to 1.8, or 1.15 to 1.65. "Isocyanate index" is the ratio of the number of isocyanate groups in the polyisocyanate component to the number of isocyanate-reactive groups in the polyol component. The isocyanate index, at a 1 : 1 volume ratio, may be 1.15 to 1.65.

[0050] Disclosed is a process for bonding two substrates. Part 1 and Part 2 are mixed to form the mixed adhesive. The ratio of these materials is generally sufficient to provide an isocyanate index of 1.0 to 1.8, 1.1 to 1.8 or 1.15 to 1.65. The mixed adhesive is formed into an adhesive layer between and in contact with the two substrates. An adhesion promoter may be applied to one or both of the substrates prior to contacting the substrate(s) with the adhesive. The adhesive layer is then cured between and in contact with the two substrates to form a layer of cured adhesive bonded to each of the two substrates.

[0051] The methods used to mix Part 1 with Part 2 to form the adhesive layer and cure the adhesive are, broadly speaking, not critical and a variety of apparatus can be used to perform these steps. Thus, the parts can be mixed and applied to the substrates manually, in various types of batch apparatus, and/or using various sorts of automated metering, mixing and dispensing equipment.

[0052] The parts often will react spontaneously upon mixing at room temperature (about 22°C) and cure without the need to heat the adhesive to a greater temperature. Curing may be effected by simply mixing the components at a temperature of, for example, 0 to 50°C, 15 °C to 50 °C, 0 °C to 35°C, 15 °C to 35 °C, or 20 °C to 35 °C and allowing the components to react at that temperature. At about room temperature, the two-part adhesive may exhibit an open time of about 3 minutes or greater, about 5 minutes or greater, about 8 minutes or greater, about 9 minutes or greater or 10 to 15 minutes, measured as described in the following examples. [0053] Heating can be applied to the adhesive to obtain a more rapid cure. Heat sources may include hot air, induction, hot press, infrared, or an oven, for example. The heat may allow for shorter cycle times. The two parts can be heated separately and then mixed and cured, with or without further applied heat. Alternatively, the polyol and isocyanate components can be mixed at a lower temperature, such as 0 to 35°C and then heated to a higher cure temperature. The substrate can be heated before applying the adhesive if desired. If an elevated temperature is used in the curing step, such a temperature may be, for example, about 36 °C or greater, or about 50 °C or greater. Such a temperature may be, for example, about 150°C or less, or about 130°C or less.

[0054] A layer of the two-component polyurethane adhesive may be formed at a bondline between two substrates to form an assembly. The adhesive layer may then at least partially cured at the bondline by applying infrared radiation to the assembly. Infrared radiation may be applied, for example, until the temperature of the adhesive layer reaches about 80°C or greater, or about 90°C or greater, or about 150°C or less, or about 130°C or less. The assembly so heated may be maintained under infrared radiation until the adhesive layer has been exposed to such temperatures for a period of 5 seconds or more to effect the partial or complete cure. For example, the infrared radiation may be continued until the temperature of adhesive layer is 80 to 150°C, preferably 90 to 130°C, for 5 to 60 seconds, 5 to 45 seconds, for 10 to 30 seconds or for 10 to 20 seconds, at which time the exposure to infrared radiation is discontinued.

[0055] If only a partial cure is performed by applying infrared radiation, the partial curing can be either or both of two types. In one type of partial curing, the entire adhesive layer is cured, but only partially. Such partial curing preferably is at least to the gel point, at which a three-dimensional polymeric network is formed in the adhesive layer by the curing of the components. In another type of partial curing, only one or more predetermined, localized portions of the adhesive layer at the bondline are cured. This produces an adhesive layer having at least partially cured portions and portions that have undergone little or no cure. The predetermined, localized portions of the adhesive layer may constitute, for example, 5 to 80%, 5 to 50% or 5 to 25% of the total area of the adhesive layer. Subsequent to the partial curing step, the uncured or only partially cured portions of the adhesive layer then are cured further to form a fully-cured adhesive. The subsequent step of completing the cure can be done at approximately room temperature (such as from 15 to 35°C) or an elevated temperature such as greater than 35°C to 80°C. [0056] A two-step curing process as just described is useful in a variety of manufacturing, building and construction, and in-field assembly and repair applications. By performing only a partial cure by applying infrared radiation, a rapid bonding of the adhesive to the substrate can be obtained in a very short time, often a matter of 10 seconds to 2 minutes. The bonded parts can be handled after 1 hour or less from partial cure, after about 10 minutes or less after partial cure, about 3 minutes or less after partial cure or about 1 minute or less after partial cure. This initial bond is often robust enough that the assembly can withstand further handling. Further handing may include, for example, transporting the assembly to a downstream work station, and further manufacturing steps which might include joining the assembly to one or more other components, various shaping and/or machining steps, the application of a coating, and the like. The completion of the cure can take place during and/or after such additional handling steps. Often, the adhesive will fully cure without exposing it to elevated temperature, infrared radiation or other energy source, due at least in part to the catalytic action of the positively charged silyl-protected amine complexes. The silyl-protected amine complexes may dissociate to produce an active catalyst that promotes the cure, even if any subsequent curing steps are performed without additional applied energy.

[0057] The substrates are not limited. They may be a metal, a metal alloy, an organic polymer, a lignocellulosic material such as wood, cardboard or paper, a ceramic material, various types of composites, or other materials. Carbon fiber reinforced plastic is a substrate of particular interest. The substrates in some embodiments are vehicular parts or vehicular sub-assemblies that are adhered together with a cured adhesive composition disclosed. The substrates may be are individual plies that are glued together using the adhesive to form a multilayer laminate. The substrates may be building members.

[0058] Other components commonly used in curable compositions may be used in the compositions disclosed. Such materials are well known to those skilled in the art and may include ultraviolet stabilizers and antioxidants and the like. The compositions may also contain durability stabilizers known in the art. Among preferred durability stabilizers are alkyl substituted phenols, phosphites, sebacates and cinnamates. A preferred class of durability stabilizers includes organophosphites. The organophosphites are preferably present in a sufficient amount to enhance the durability of bond of the adhesive composition to the substrate surface. Such phosphites are disclosed in Hsieh et al. US 7,416,599 column 10, line 47 to Column 1 1 line 25, incorporated herein by reference. Among preferred organophosphites are poly(dipropyleneglycol) phenyl phosphite (avail- able from Dover Chemical Corporation under the trademark and designation DOVER- PHOS 12), tetrakis isodecyl 4,4'isopropylidene diphosphite (available from Dover Chemical Corporation under the trademark and designation DOVERPHOS 675), and phenyl diisodecyl phosphite (available from Dover Chemical Corporation under the trademark and designation DOVERPHOS 7). Preferably, the organophosphite may be present in the composition in an amount of about 0.1 percent by weight or greater or about 0.2 percent by weight or greater based on the weight of the composition. The organophosphite may be present in the composition in an amount of about 1.0 percent by weight or less or about 0.5 percent by weight or less based on the weight of the composition.

[0059] The composition may be formulated by blending the components together using means well known in the art. Generally, the components are blended in a suitable mixer. Such blending is preferably conducted in an inert atmosphere in the absence of oxygen and atmospheric moisture to prevent premature reaction

[0060] The compositions disclosed may be formulated to provide an open time of about 5 minutes or greater, about 8 minutes or greater, or about 10 minutes or greater. The two part adhesive compositions may be formulated to provide an open time of about 1 hour or less, about 30 minutes or less, or about 20 minutes or less. "Open time" is understood to mean the time after application of the composition to a first substrate until it starts to become a high viscous paste and is not subject to deformation during assembly to conform to the shape of the second substrate and to adhere to it. Open time may be measured by rheology reactivity wherein the rheology reactivity is about 500 seconds or greater or about 600 seconds or greater. The "latency" of catalysts used in forming the two-part adhesive refers to the amount of time during which there is a lack of activity of a catalyst, which is therefore a property of a catalyst that provides the open time. Upon activation of the catalyst, the latency may be removed or the latency period may end. The latency of the two-part adhesive composition may be about 5 minutes or greater, about 8 minutes or greater, or about 10 minutes or greater. The latency of the composition after contacting the Parts 1 and 2 may be about 1 hour or less, about 30 minutes or less, or about 20 minutes or less.

[0061] The compositions disclosed may exhibit a lap shear strength after 1 hour room temperature cure of greater than 0.6 MPa, about 0.8 MPa or greater or about 1 MPa or greater. The compositions may exhibit a low loss in Lap shear strength after storage of one month, for example less than 42 percent reduction is lap shear strength or about 40 percent or less loss in lap shear strength. [0062] Molecular weights as described herein are number average molecular weights which may be determined by Gel Permeation Chromatography (also referred to as GPC). For polyurethane prepolymers, it is also possible to calculate approximate number average molecular weight from the equivalent ratio of the isocyanate compounds and of the polyol compounds with which they are reacted as known to the persons skilled in the art.

[0063] The compositions disclosed may comprise any one or more of the features described in this specification in any combination, including the preferences and examples listed in this specification, and includes the following features: the one or more silyl- protected amine complexes are located in Part 1 or Part 2; the one or more silyl-protected amine complexes are located in Part 1 ; Part 2 comprises one or more polyols; the one or more silyl-protected tertiary complexes are present in an amount of about 0.01 weight percent to about 5 weight percent based on the weight of Part 2; the one or more silyl- protected amine complexes are present in an amount of about 0.05 weight percent to about 2 weight percent based on the weight of Part 2; latency of the composition after contacting Part 1 and Part 2 is about 3 minutes or greater; the positively charged complex and a counterion correspond to the formula:

where R¹ , separately in each occurrence, is a hydrocarbyl group which may contain one or more heteroatoms; R², separately in each occurrence, is a hydrocarbylene group which may contain one or more heteroatoms; R¹ and R² combine to form a cyclic ring, and wherein the cyclic ring may include further heteroatoms; X, separately in each occurrence, is an alkyl group, such as a Ci-Cs alkyl group, which may be linear, branched, or cyclic, an aryl group, a Ci-Cs alkoxy group, an alkylhalide, or a heteraryl group; A^" is any anion that forms a complex but does not interfere with the dissociation of the silyl-protected amine complexes when Part 1 and Part 2 are contacted; the amine includes an aromatic or cycloaliphatic structure, having one or more rings, wherein the nitrogen atom of the amine group is pendant from the aromatic or cycloaliphatic structure, or the nitrogen atom is incorporated into the one or more rings; the amine contains an aromatic structure including an aromatic ring; the amine includes a tertiary amine is disposed on an alkyl group bound to the aromatic ring; the amine contains a cyclic amidine structure; the amine is 1 ,8-diazabicycloundec-7-ene (DBU), 1 ,5-diazabicyclo[4.3.0]non-5-ene (DBN), 1 ,4- diazabicyclo[2.2.2]octane (DABCO), pyridine, ethylene diamine, 4-methylmorpholine, or 1-methylimidazole; the silyl group and the anion A^" are provided from a silyl acetate, silyl trifluoroacetate, silyl sulfonate, silyl halide, silyl carboxylate, silyl triflate, silyl tosylate, or methyl sulfanate; the silyl group and the anion A^" are provided from a silyl sulfonate; the one or more silyl-protected amine complexes are prepared in a mole ratio of about 0:5 to about 1 :0.5 amine to silyl acetate, silyl trifluoroacetate, silyl sulfonate, silyl halide, silyl carboxylate, silyl triflate, silyl tosylate, or methyl sulfanate; the silyl group is selected from a triisobutylsilyl group, a triisopropylsilyl group, a tri-n-propyl-silyl group, or a tribenzylsilyl group; the silyl sulfonate is triisopropylsilyl trifluoromethanesulfonate (TIPS OTf); the one or more silyl-protected amine complexes are selected from:

DBU-TIPS OTf DBN-TIPS OTf

1 2

. The teachings also contemplate a two-component polyurethane adhesive formed using the composition as described herein, where the two-component polyurethane adhesive is curable at ambient temperatures.

[0064] The methods disclosed may further comprise any one or more of the features described in this specification in any combination, including the preferences and examples listed in this specification, and includes the following features: contacting an amine (e.g., a tertiary amine or a secondary ketimine) with a source of a silyl group, such as a silyl acetate, silyl trifluoroacetate, silyl sulfonate, silyl halide, silyl carboxylate, silyl triflate, silyl tosylate, or methyl sulfanate under conditions such that a positively charged complex between the amine and the silyl group and a counterion forms a silylammonium salt; conditions may include any combination of a temperature of about -20 °C to about 50 °C for about 1 minute to about 30 minutes using nonprotic solvents, no solvent, plasticizers or chloroform; the method forms a two-component polyurethane adhesive; the silylammonium salt is adapted to be added to Part 1 ; Part 1 and the silylammonium salt is adapted to be contacted with Part 2; the two-component polyurethane adhesive is capable of curing at ambient temperatures; the silylammonium salt is present in an amount of about 0.01 weight percent to about 5 weight percent based on the weight of Part 2; the silylammonium salt is present in an amount of about 0.05 weight percent to about 2 weight percent based on the weight of Part 2; latency of the composition after contacting Part 1 and Part 2 is about 3 minutes or greater; the positively charged complex and the counterion correspond to the formula:

R¹ , separately in each occurrence, is a hydrocarbyl group which may contain one or more heteroatoms; R², separately in each occurrence, is a hydrocarbylene group which may contain one or more heteroatoms; R¹ and R² combine to form a cyclic ring, and wherein the cyclic ring may include further heteroatoms; X, separately in each occurrence, is an alkyl group, such as a Ci-Cs alkyl group, which may be linear, branched, or cyclic, an aryl group, a Ci-Cs alkoxy group, an alkylhalide, or a heteraryl group; wherein A^" is any anion that forms a complex but does not interfere with the dissociation of the silylammonium salt when Part 1 and Part 2 are contacted; the tertiary amine includes an aromatic or cycloaliphatic structure, having one or more rings, wherein the nitrogen atom of the amine group is pendant from the aromatic or cycloaliphatic structure, or the nitrogen atom is incorporated into the one or more rings; the amine contains an aromatic structure including an aromatic ring; the amine includes a tertiary amine that is disposed on an alkyl group bound to the aromatic ring; the amine contains a cyclic amidine structure; the amine is 1 ,8-diazabicycloundec-7-ene (DBU) 1 ,5-diazabicyclo[4.3.0]non-5-ene (DBN), 1 ,4- diazabicyclo[2.2.2]octane (DABCO), pyridine, ethylene diamine, 4-methylmorpholine, and 1-methylimidazole; the silyl group and the anion A^" are provided from a silyl acetate, silyl trifluoroacetate, silyl sulfonate, silyl halide, silyl carboxylate, silyl triflate, silyl tosylate, or methyl sulfanate; the silyl group and the anion A^" are provided from a silyl sulfonate; the silylammonium salt is prepared in a mole ratio of about 0:5 to about 1 :0.5 amine to silyl acetate, silyl trifluoroacetate, silyl sulfonate, silyl halide, silyl carboxylate, silyl triflate, silyl tosylate, or methyl sulfanate; the silyl group is selected from a triisobutylsilyl group, a triisopropylsilyl group, a tri-n-propyl-silyl group, or a tnbenzylsilyl group; the silyl sulfonate is triisopropylsilyl trifluoromethanesulfonate (TIPS OTf); the silylammonium salt is selected from:

DBU-TIPS OTf DBN-TIPS OTf

2 ; latency of the two-component polyurethane adhesive after contacting Part 1 and Part 2 is about 3 minutes or greater; the two-component polyurethane adhesive is capable of curing at ambient temperatures; the silylammonium salt is located in Part 1 and the silylammonium salt dissociates upon contacting Part 1 and Part 2 and catalyzes a reaction between Part 1 and Part 2; the method is free of a step of heating when curing the adhesive; the first substrate and the second substrate comprise dissimilar substrates; one or both of the first substrate and the second substrate comprise glass, metal, fiber reinforced polymers, coated metal, polymers, coated polymers, thermoplastic polymers, thermoset polymers, ceramics, wood, natural products, natural fibers, paper, cardboard, or a combination thereof.

ILLUSTRATIVE EMBODIMENTS

[0065] The following examples are provided to illustrate the disclosed compositions, but are not intended to limit the scope thereof. All parts and percentages are by weight unless otherwise indicated.

[0066] Ingredients [0067] Polyol A is a glycerin initiated ethylene oxide based propoxylated triol with an average molecular weight of 1800 g/mol and an OH number of approximately 35 KOH/g.

[0068] The Prepolymer is made by combining Polyol A (17.74 parts), a nominally difunctional poly(propylene oxide) having a molecular weight of about 2000 and a hydroxyl equivalent weight of about 1000 (12.09 parts), the "liquid MDI" product (27.5 parts), and a plasticizer (18.07 parts) and heating the resulting mixture to a constant isocyanate content, to form a plasticized prepolymer. The plasticized prepolymer is then blended with a pure MDI product containing mostly the 4, 4'-isomer and having an isocyanate equivalent weight of about 125 (5.08 parts) and carbon black (19 parts).

[0069] The Aliphatic Polyisocyanate is a commercially available product based on hexamethylene diisocyanate, having an isocyanate equivalent weight of 193 (Desmodur™ N3400 from Bayer Material Sciences).

[0070] Catalyst A is a solid 1 ,8-diazabicycloundec-7-ene (DBU) based solid amine catalyst with a phenolic counterion.

[0071] Catalyst B is a tin-based dioctyltinmercaptide catalyst.

[0072] 1-(triisopropylsilyl)-2,3,4,6,7,8,9, 10-octahydropyrimido[1 ,2-a]azepin-1-ium trifluoromethanesulfonate (DBU-TIPS OTf).

[0073] The Polymeric MDI is a commercially available polymeric MDI product having an isocyanate functionality of about 2.2 and a viscosity of about 40 mPas.

[0074] 1 ,4-butane diol.

[0075] Hydrophobically modified polydimethylsiloxane coated fumed silica.

[0076] Calcined china clay (55% Si02, 45% AI203) with an average particle size of approximately 2 μηι (90% > 10 μηι), a BET surface area of 8.5 m2/g and a pH of 6.0-6.5.

[0077] Carbon black filler.

[0078] Part 1 (Isocyanate) Preparation Process

[0079] The following ingredients are combined, blended and stored in air moisture proof containers useful in two-part manual dispensing guns.

- Isocyanate Component

Prepolymer 52.4 53.5 52.4

Polymeric MDI 22.5 22.5 22.5

Carbon black 19 19 19

Aliphatic polyisocyanate 5 5 5

Catalyst A 0.1 1

DBU-TIPS 0.1 1

[0080] Part 2 (Polyol) Preparation Process

[0081] The following ingredients are combined, blended and stored in air moisture proof containers useful in two-part manual dispensing guns.

Table 2 - Polyol Component

[0082] Silylammonium Salt Preparation Process

[0083] To 3.7 mL 1 ,8-Diazabicyclo[5.4.0]undec-7-ene (d = 1.018 g/mL, 152.24 g/mol, 25 mmol) in 50 mL chloroform in a glovebox, 5.0 mL Triisopropylsilyl trifluoromethanesulfonate (d = 1.14 g/mL, 306.42 g/mL, 19 mmol) is added slowly with stirring, the solution turning slightly yellow. After about 3 hours, hexanes (-50 mL) are added slowly until cloudiness persists. 1 mL chloroform is then added back to dissolve. Stirring is stopped and the mixture is left open for 3 days to allow chloroform to evaporate, resulting in an oil separating out. This oil is removed and again left open until solvent evaporates, recovering 6.7 g product (79% yield). [0084] Testing

[0085] Open time is evaluated for each of the examples by manually dispensing the corresponding polyol and polyisocyanate components in a 1 : 1 by weight ratio, using Kroger TS 400 double cartridge application gun with a mounted static mixer unit, at an application pressure of at least 6 bar (606 kPa) a 30 to 50 cm bead having an 8 to 10 mm diameter onto a polyethylene film, and compressing the bead periodically with a wooden spatula until the adhesive no longer sticks to the wooden surface. The measured time is defined as open time of the adhesive.

[0086] The reactivity of the adhesive is measured by rheology in oscillating mode with a parallel plate 20 mm diameter, 1 mm plate distance set-up. The measurements are done at 10 Hz with a constant deformation of 0.062%. The complex viscosity is plotted against the time and the time at which the slope of viscosity is changed more than 30° is considered to be the reactivity.

[0087] In each case, multiple test specimens are prepared. Duplicate samples are evaluated for lap shear strength after one hour curing at 23°C and 50% relative humidity (RT cure) and separately after a 180 second IR cure. In the 180 second IR cure, the test specimen is placed in IR curing equipment and exposed to an IR source for 180 seconds such that the temperature of the adhesive increases, reaching 100-1 10°C for the final 10- 20 seconds of the heating process. Lap shear strength is measured on the samples according to DIN EN 527 using a Zwick 1435 testing device equipped with a FHM 8606.00.00 or 8606.04.00 mounting device, beginning 5 to 10 seconds after the IR heating step is completed. E-coat substrates are Cathoguard 500 e-coated steel panels 100x25x0.8mm. E-coated substrates are cleaned with heptane. The flash off time of the solvent after cleaning prior to adhesive application is 5 minutes. Composite fiber reinforced plastic (CFRP) substrates with a dimension of 100x45x2.2 mm. CFRP substrates are ground manually, using a 320 grinding pad on wet CFRP panels until homogeneous optical appearance is achieved or used without cleaning or mechanical pretreatment. Panels are successively dried 8 hours at 80°C. Adhesive bond dimensions of 10x25x1.5 mm are used for the lap shear specimens. Lap shear specimens are tested after 1 hour curing time at 23°C/50 percent relative humidity or respectively after described heat accelerated curing process.

[0088] For heat accelerated curing, the assembled CFRP- CFRP lap shear specimens are placed after assembly in IR curing equipment. Lap shear specimens are built up with a bond height of 1.5 mm and an overlap area of 45 x 10 mm. The CFRP substrate, exposed to the IR source is heated during a 120 second curing process in such a way, that 100 - 1 10°C adhesive temperature is reached for a time period of 10 - 20 seconds.

[0089] The polyol side and the isocyanate side are utilized in a 1 to 1 ratio. Reactivity is measured by rheology. 1 hour and 2 hour lap shear strengths are measured with e- coated steel substrates with 15 x 25 x 1.5 mm adhesion dimension. Lab shear heat cure experiments are run with a 180 s heating cycle and Dow CFK substrates with adhesion dimensions 45 x 15 x 1.5 mm. The results are compiled in Table 3.

[0090] Example 1 , which uses a silylammonium salt (DBU-TI PS OTf ) as a precatalyst exhibits a tack free time of 10.5 minutes, which is longer than the tack free time of Comparative Examples 1 and 2. Comparative Examples 1 and 2 employ a DBU catalyst with a phenolic counterion, with the catalyst in the polyol component in Comparative Example 1 and in the isocyanate component in Comparative Example 2. The lap shear strengths in all three examples are within a workable range, yet Example 1 illustrates a longer tack free time, and therefore the latency exhibited is longer.

Table 3 - Results

[0091] In summary, the above examples show that the silylammonium salt catalyst is able to offer a long open time (10.5 minutes) but also exhibits a good heat cure property (2.34 MPa after IR).

[0092] Parts by weight as used herein refers to 100 parts by weight of the composition specifically referred to. Any numerical values recited in the above application include all values from the lower value to the upper value in increments of one unit provided that there is a separation of at least 2 units between any lower value and any higher value. These are only examples of what is specifically intended and all possible combinations of numerical values between the lowest value, and the highest value enumerated are to be considered to be expressly stated in this application in a similar manner. Unless otherwise stated, all ranges include both endpoints and all numbers between the endpoints. The use of "about" or "approximately" in connection with a range applies to both ends of the range. Thus, "about 20 to 30" is intended to cover "about 20 to about 30", inclusive of at least the specified endpoints. The term "consisting essentially of" to describe a combination shall include the elements, ingredients, components or steps identified, and such other elements ingredients, components or steps that do not materially affect the basic and novel characteristics of the combination. The use of the terms "comprising" or "including" to describe combinations of elements, ingredients, components or steps herein also contemplates embodiments that consist essentially of the elements, ingredients, components or steps. Plural elements, ingredients, components or steps can be provided by a single integrated element, ingredient, component or step. Alternatively, a single integrated element, ingredient, component or step might be divided into separate plural elements, ingredients, components or steps. The disclosure of "a" or "one" to describe an element, ingredient, component or step is not intended to foreclose additional elements, ingredients, components or steps.

Claims

CLAIMS What is claimed is:

Claim 1. A composition comprising:

a. Part 1 comprising one or more polyisocyanates;

b. Part 2 comprising one or more compounds containing isocyanate reactive groups;

c. one or more positively charged silyl-protected amine complexes;

wherein the amine of the silyl-protected amine complex is a tertiary amine or a secondary ketimine;

wherein the silyl group and the amine of the silyl-protected amine complex dissociate when Part 1 and Part 2 are contacted with each other, and the amine is capable of catalyzing a reaction between Part 1 and Part 2 useful for forming a two-component polyurethane adhesive.

Claim 2. The composition of claim 1 , wherein the one or more silyl-protected amine complexes are located in Part 1 or Part 2.

Claim 3. The composition of any of the preceding claims, wherein the one or more silyl-protected amine complexes are present in an amount of about 0.01 weight percent to about 5 weight percent based on the weight of Part 2; and preferably about 0.05 weight percent to about 2 weight percent based on the weight of Part 2.

Claim 4. The composition of any of the preceding claims, wherein the positively

charged complex and a counterion correspond to the formula:

wherein R², separately in each occurrence, is a hydrocarbylene group which may contain one or more heteroatoms;

wherein R¹ and R² combine to form a cyclic ring, and wherein the cyclic ring may include further heteroatoms;

wherein X, separately in each occurrence, is an alkyi group, such as a Ci-Cs alkyi group, which may be linear, branched, or cyclic, an aryl group, a Ci-Cs alkoxy group, an alkylhalide, or a heteraryl group; and

wherein A^" is any anion that forms a complex but does not interfere with the dissociation of the silyl-protected amine complexes when Part 1 and Part 2 are contacted.

Claim 5. The composition of any of the preceding claims, wherein the amine includes an aromatic or cycloaliphatic structure, having one or more rings, wherein the nitrogen atom of the amine group is pendant from the aromatic or cycloaliphatic structure, or the nitrogen atom is incorporated into the one or more rings.

Claim 6. The composition of any of the preceding claims, wherein the amine contains an aromatic structure including an aromatic ring and includes a tertiary amine, and wherein the tertiary amine is disposed on an alkyi group bound to the aromatic ring.

Claim 7. The composition of any of the preceding claims, wherein the amine contains a cyclic amidine structure.

Claim 8. The composition of any of the preceding claims, wherein the amine is 1 ,8- diazabicycloundec-7-ene (DBU), 1 ,5-diazabicyclo[4.3.0]non-5-ene (DBN), 1 ,4- diazabicyclo[2.2.2]octane (DABCO), pyridine, ethylene diamine, 4- methylmorpholine, or 1-methylimidazole.

Claim 9. The composition of any of claims 4 through 8, wherein the silyl group and the anion A^" are provided from a silyl acetate, silyl trifluoroacetate, silyl sulfonate, silyl halide, silyl carboxylate, silyl triflate, silyl tosylate, or methyl sultanate; preferably silyl sulfonate.

Claim 10. The composition of any one of claims 4 through 9, wherein the one or more silyl-protected amine complexes are prepared in a mole ratio of about 0:5 to about 1 :0.5 amine to silyl acetate, silyl trifluoroacetate, silyl sulfonate, silyl halide, silyl carboxylate, silyl triflate, silyl tosylate, or methyl sulfanate.

Claim 11. The composition of any one of claims 4 through 10, wherein the silyl group is selected from a triisobutylsilyl group, a triisopropylsilyl group, a tri-n-propyl-silyl group, or a tribenzylsilyl group.

Claim 12. The composition of any one of claims 4 through 1 1 , wherein the silyl

sulfonate is triisopropylsilyl trifluoromethanesulfonate (TIPS OTf).

Claim 13. The composition of any of the preceding claims, wherein the one or more silyl-protected amine complexes are selected from:

DBU-TIPS OTf DBN-TIPS OTf

1 2

Claim 14. A two-component polyurethane adhesive formed using the composition of any of the preceding claims, wherein the two-component polyurethane adhesive is curable at ambient temperatures.

Claim 15. A method of forming the two-component polyurethane adhesive of claim 14 comprising:

contacting an amine with a silyl acetate, silyl trifluoroacetate, silyl sulfonate, silyl halide, silyl carboxylate, silyl triflate, silyl tosylate, or methyl sulfanate, under conditions such that a positively charged complex between the amine and a silyl group and a counterion forms a silylammonium salt; wherein the amine is a tertiary amine or a secondary ketimine; and

contacting Part 1 of the two-component polyurethane adhesive, which includes one or more polyisocyanates, and Part 2 of the two-component polyurethane adhesive, which includes one or more compounds containing isocyanate reactive groups;

wherein the silylammonium salt dissociates upon contacting Part 1 and Part 2 and catalyzes a reaction between Part 1 and Part 2.

Claim 16. The method of claim 15, wherein the silylammonium salt is added to Part 1 , and wherein Part 1 and the silylammonium salt is contacted with Part 2.

Claim 17. The method of claim 15 or 16, wherein latency after contacting Part 1 and Part 2 is about 3 minutes or greater.

Claim 18. A method comprising:

a. forming a two-component polyurethane adhesive by contacting Part 1 and Part 2 and employing the silylammonium salt formed in accordance with the method of any of claims 15 through 17, wherein the silylammonium salt is located in Part 1 or Part 2;

b. applying the adhesive to a first substrate; and

c. contacting a second substrate with the first substrate, with the two- component polyurethane adhesive disposed between the first substrate and the second substrate which are optionally dissimilar substrates.

Claim 19. The method of any one of claims 15 through 18, wherein the method is free of a step of heating when curing the adhesive.

Claim 20. An article comprising:

a. a first substrate and a second substrate bonded together by a composition according to any one of claims 1 to 14 or a composition formed by the method of any of claims 15 to 19, wherein the composition is disposed between the first substrate and the second substrate, which are optionally dissimilar substrates.