Polyurethane adhesive for aluminum bonding and other substrates

Abstract

The present invention relates to a two-component polyurethane adhesive composition applicable to bonding corrosive substrates such as aluminum, but is not limited thereto. The adhesive comprises a prepolymer component and a curing agent. The prepolymer contains silane, and the curing agent contains an amine as a silane activator.

Description

Technical Field

[0001] The present invention relates to a polymerizable adhesive composition containing a two-component urethane adhesive composition, and a method for producing and using an adhesive obtained by polymerizing the polymerizable adhesive composition. In certain embodiments, the polymerizable adhesive composition can include a silane and / or a silane-terminated polymer and can include an activating catalyst.

Background Art

[0002] Conventional epoxy adhesives and acrylate adhesives are known for their good adhesion properties to metals, but their use is limited due to their high modulus of elasticity and low elongation. This limits their ability to effectively bond dissimilar materials. On the other hand, polyurethane adhesives have the ability to have a wide range of moduli of elasticity and high elongation. However, their use in aluminum bonding has been limited because of their insufficient corrosion resistance and insufficient adhesion after exposure to water immersion and / or salt spray. To improve adhesion to metals, silanes are commonly used. However, the addition of silanes to polyurethane adhesives has been studied for many years without success.

[0003] It has now been found that these objectives can be achieved by the compositions described below.

Summary of the Invention

Problems to be Solved by the Invention

[0004]

Means for Solving the Problems

[0005] The present invention relates to an adhesive composition that can be used to bond to metals that tend to corrode. Preferably, the adhesive composition is a polyurethane-based adhesive.

[0006] The first such adhesive composition is a two-component polyurethane adhesive composition comprising: (a) an NCO prepolymer comprising a reaction product of an isocyanate compound and a polyol, preferably comprising up to about 30% %NCO in the prepolymer, the prepolymer comprising a silane component comprising up to 15% by weight of the adhesive, the silane component comprising at least epoxy-functionalized silane, preferably up to about 10% by weight of epoxy-functionalized silane in the adhesive, and isocyanurato-functionalized silane, preferably up to about 5% by weight of isocyanurato-functionalized silane in the adhesive; and (b) a curing agent comprising a polyol, at least one of tertiary amines, blocked tertiary amines and combinations thereof, and optionally a diamine, preferably up to about 15% by weight of diamine, wherein the diamine has a number-average molecular weight of up to about 6000 daltons.

[0007] The second adhesive composition disclosed herein is also a two-component adhesive. Preferably, it is a polyurethane adhesive. The composition may include an NCO prepolymer containing the reaction product of an isocyanate compound and a polyol, preferably containing up to about 30% %NCO in the prepolymer. Preferably, the prepolymer also includes an epoxy-functionalized silane adhesion promoter having a number-average molecular weight of at least about 1000 daltons. A preferred concentration of the epoxy-functionalized silane adhesion promoter constitutes up to about 10% by weight of the adhesive. The second adhesive may also include a polyol and a curing agent containing at least one of a tertiary amine, a blocked tertiary amine, and a combination thereof. The concentration of the tertiary amine or blocked tertiary amine may constitute up to about 5% by weight of the adhesive. The curing agent may also include an optional polyetherdiamine. A preferred concentration of the optional polyetherdiamine may constitute up to about 15% by weight of the adhesive.

[0008] A third adhesive composition of this disclosure is another two-component polyurethane adhesive. The third adhesive composition comprises an NCO prepolymer containing a reaction product of an isocyanate compound and a polyol. Preferably, the %NCO in the prepolymer is up to about 30%. The prepolymer may contain a silyl-modified polymer comprising at least one of silyl-terminated polyethers, silyl-terminated isocyanates, silyl-terminated acrylates, and combinations thereof. Preferably, the concentration of the silyl-modified polymer constitutes up to about 25% by weight of the adhesive. The prepolymer may also contain an optional epoxy-functionalized silane. The concentration of the epoxy-functionalized silane may constitute up to about 10% by weight of the adhesive composition.

[0009] The third adhesive composition may further comprise a curing agent. The curing agent may comprise a polyol and an optional tin catalyst. Exemplary concentrations of the tin catalyst may be at least about 0.02% by weight and up to about 10% by weight of the adhesive.

[0010] The disclosure further includes a laminate manufactured from a first substrate, a second substrate, and one of the adhesives. Preferably, the adhesive is sandwiched between the first substrate and the second substrate. Preferably, at least one of the substrates is a corrosion-prone metal, such as aluminum, aluminum alloy, coated aluminum, or coated aluminum alloy, but not limited to these. More preferably, both the first substrate and the second substrate may contain a corrosion-prone metal, such as aluminum, aluminum alloy, coated aluminum, or coated aluminum alloy, but not limited to these.

[0011] The present invention further includes a method for manufacturing the aforementioned laminate. The method may include the step of applying one of the adhesives to one of the first substrate and the second substrate. Furthermore, the first substrate and the second substrate are pressed together, and the adhesive is placed between the first substrate and the second substrate.

[0012] The present invention makes it possible to address the aforementioned needs. In particular, the compositions according to the present invention have surprisingly shown improved adhesion to metals such as aluminum, stainless steel, carbon steel, alloys of the aforementioned metals, and coated versions of the aforementioned metals and their alloys.

[0013] These adhesives also exhibited excellent water and corrosion resistance.

[0014] Preferably, the aforementioned adhesive exhibits a Young's modulus of at least 1 MPa, preferably at least about 5 MPa. Exemplary Young's moduli may include at least about 7 MPa or at least about 10 MPa.

[0015] The embodiments of adhesives disclosed herein successfully address the limitations of conventional polyurethane adhesives used to bond corrosion-prone metals. Laminates formed with the above adhesives exhibited excellent lap shear strength and failure mode, even after 7 months of exposure to salt spray.

[0016] The above adhesive performed well in an 8-week salt spray test in the automotive industry and passed the standards. The above composition can provide new opportunities for the use of polyurethane adhesives in industries where corrosion resistance and durability in harsh environments are critical requirements. [Modes for carrying out the invention]

[0017] Before describing in detail at least one embodiment of this disclosure, it should be understood that this disclosure is not limited in its application to the structural and arrangement details of components or steps, or methodologies, described in the following description or shown in the drawings. Other embodiments of this disclosure are possible, or can be implemented or performed in various ways. It should also be understood that the expressions and terminology used herein are for illustrative purposes only and should not be considered limiting.

[0018] Unless otherwise defined herein, technical terms used in connection with this disclosure shall have meanings generally understood by those skilled in the art. Furthermore, unless contextually required, singular terms shall include plural forms, and plural terms shall include singular forms.

[0019] All patents, published patent applications, and non-patent publications referenced herein represent the level of skill of a person skilled in the art relating to this disclosure. All patents, published patent applications, and non-patent publications referenced in any part of this application are expressly incorporated herein by reference in whole to the same extent as each individual patent or publication is specifically and individually indicated as being incorporated by reference.

[0020] All articles and / or methods disclosed herein can be manufactured and performed without undue experimentation in light of this disclosure. While the articles and methods of this disclosure have been described in relation to preferred embodiments, it will be apparent to those skilled in the art that modifications can be applied to the articles and / or methods described herein, as well as to the steps or order of steps of the methods, without departing from the concepts, spirit, and scope of this disclosure. All such similar substitutions and modifications that are apparent to those skilled in the art are considered to be within the spirit, scope, and concepts of this disclosure.

[0021] When used in accordance with this disclosure, the following terms shall be understood to have the following meanings unless otherwise indicated.

[0022] The use of the word "a" or "an" when used in conjunction with the term "comprising" can mean "one", but is also consistent with the meaning of "one or more", "at least one", and "one or more than two". The use of the term "or" is used to mean "and / or" unless it is explicitly indicated that the alternatives refer to alternatives that are mutually exclusive, but the present disclosure supports definitions that refer to only the alternatives and "and / or". Throughout this application, the term "about" is used to indicate that a value includes the inherent variability of the error of the quantification device, the method used to determine the value, or the variability that exists among the test subjects.

[0023] References to "one embodiment" or "one aspect" or "one version" or "one objective" or "another embodiment" or "another aspect" or "another version" or "another objective" of the invention herein can include one or more such embodiments, aspects, versions or objectives, unless the context clearly indicates otherwise.

[0024] The term "at least one" refers to any amount of one and two or more, including, but not limited to, 1, 2, 3, 4, 5, 10, 15, 20, 30, 40, 50, 100, etc. The term "at least one" can extend up to a maximum of 100 or more than 1000, depending on the term to which it is attached.

[0025] All percentages, parts, ratios, and proportions used herein are by weight of the total composition, unless otherwise specified. All such weights for the listed components are based on the active level and thus do not include solvents or by-products that may be included in commercially available materials, unless otherwise specified.

[0026] All references to singular features or limitations of the invention are, unless otherwise specified or clearly implied to the contrary by the context in which the reference is made, to be taken to include the corresponding plural features or limitations, and vice versa.

[0027] The numerical ranges used in this specification, whether specifically disclosed or not, are intended to include all numbers and subsets of numbers contained within those ranges. Further, these numerical ranges should be interpreted as providing support for claims directed to any number or subset of numbers within those ranges.

[0028] As used herein, the word "comprising" (and any form of comprising such as "comprise" and "comprises"), "having" (and any form of having such as "have" and "has"), "including" (and any form of including such as "includes" and "include"), or "containing" (and any form of containing such as "contains" and "contain") is inclusive or open-ended and does not exclude additional, unrecited elements or method steps. The terms "or combinations thereof" and "and / or combinations thereof" as used herein refer to all permutations and combinations of the recited items preceding those terms. For example, "A, B, C, or combinations thereof" includes at least one of A, B, C, AB, AC, BC, or ABC, and, where order is important in a particular context, is also intended to include BA, CA, CB, CBA, BCA, ACB, BAC, or CAB. Continuing with this example, combinations containing repetitions of one or more items or terms such as BB, AAA, AAB, BBC, AAABCCCC, CBBAAA, CABABB, etc. are explicitly included. One of ordinary skill in the art will understand, unless otherwise apparent from the context, that typically there is no limit to the number of items or terms in any combination.

[0029] For the purposes of the following detailed description, except for any example of operation, or where otherwise shown, for example, the numbers representing the amounts of components used in the specification and claims should be understood to be modified in all examples by the term “approximately.” The numerical parameters described herein and in the appended claims are approximations that may vary depending on the desired characteristics obtained when carrying out the invention.

[0030] The terms “or any combination thereof,” “and any combination thereof,” and “any combination thereof,” as used herein, refer to all permutations and combinations of the enumerated items preceding the term.

[0031] The term "approximately" refers to a range of values ​​that is 10% of the specified value. For example, the phrase "approximately 200" includes 200 ± 10%, or 180 to 220.

[0032] The term "polymerization" or "polymerizing" refers to a method of chemically reacting monomer compounds to form polymer chains. Polymer chains can be alternating, blocky, or random. There are many different types of polymerization methods to choose from, and non-exclusive examples include: polycondensation, stepwise polymerization, and free radical polymerization.

[0033] The term "polymer" refers to any large molecule, including macromolecules. The term "polymer" refers to a large molecule containing one or more types of monomer residues (repeating units) linked by covalent chemical bonds. Non-limiting examples of polymers include homopolymers, as well as non-homopolymers such as copolymers, terpolymers, tetrapolymers, and higher-order analogues.

[0034] The term "monomer" refers to a small molecule that, during polymerization, chemically bonds with one or more monomers of the same or different types to form a polymer.

[0035] In this specification, the term "copolymer" refers to a polymer prepared from two or more monomers.

[0036] The present invention relates to an adhesive that can be used to bond corrosion-prone metals. Specific embodiments may be two-component adhesives, preferably polyurethane adhesives.

[0037] In certain embodiments, the polyurethane adhesive composition may include a combination of silane and a catalyst. In certain embodiments, remarkable bonding performance to aluminum was observed.

[0038] The various embodiments disclosed herein relate to adhesive compositions, and more particularly to polyurethane adhesive compositions. More specifically, to two-component adhesive compositions. In a typical embodiment, the two-component adhesive composition comprises a prepolymer, preferably an NCO prepolymer, and a curing agent.

[0039] In the first embodiment, the two-component polyurethane adhesive composition comprises an NCO prepolymer (hereinafter referred to as "prepolymer") containing the reaction product of an isocyanate compound and a polyol. The %NCO in the prepolymer may be up to about 30% by weight. Exemplary embodiments of the %NCO in the prepolymer may include 1-20%, less than about 20%, at least about 10%, and 1-10%.

[0040] The NCO prepolymer may contain a silane component. The concentration of the silane component may be up to about 15% by weight. The silane component may include at least an epoxy-functionalized silane, preferably up to about 10% by weight, and an isocyanurato-functionalized silane, preferably up to about 5% by weight.

[0041] Suitable epoxy-functionalized silanes include 2-glycidoxyethyl-dimethylmethoxysilane; 6-glycidoxyhexyl-tributoxysilane; 3-glycidoxypropyl-trimethoxysilane; 3-glycidoxypropyl-triethoxysilane; 3-glycidoxypropyl-methyldiethoxysilane; 5-glycidoxypentyl-trimethoxysilane; 5-glycidoxypentyl-triethoxysilane, 3-glycidoxypropyl-triisopropoxysilane, and combinations thereof. Preferably, the epoxy-functionalized silane may include 3-glycidoxypropyl-trimethoxysilane.

[0042] Appropriate amounts of epoxysilane compounds include up to about 10% by weight, up to about 8% by weight, up to about 5% by weight, up to about 4% by weight, at least about 0.1% by weight, at least about 0.4% by weight, and at least about 0.6% by weight.

[0043] Non-limiting examples of isocyanurato silanes include, but are not limited to, 1,3,5-tris[3-(trimethoxysilyl)propyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione). Other examples include (isocyanatomethyl)methyldimethoxysilane, 3-isocyanatopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-isocyanatopropylmethyldimethoxysilane, 3-isocyanatopropylmethyldiethoxysilane, tris[3-(trimethoxysilyl)propyl]isocyanurate, tris[3-(triethoxysilyl)propyl]isocyanurate, isocyanatomethyltrimethoxysilane, and isocyanatomethyltriethoxysilane. The aforementioned isocyanurato compounds can be used in any combination thereof.

[0044] Appropriate amounts of isocyanurato-functionalized silane compounds include a maximum of approximately 5% by weight, a maximum of 4% by weight, less than or equal to 1.5% by weight, at least approximately 0.4% by weight, and at least approximately 0.6% by weight.

[0045] The first embodiment may also include a curing agent. The curing agent may comprise a polyol and at least one of a tertiary amine, a blocked tertiary amine, and a combination thereof. Optionally, the curing agent may comprise a diamine, preferably in an amount of up to about 15% by weight. A preferred diamine is a polyetherdiamine. The diamine may have a number-average molecular weight of up to about 6000 daltons. Optionally, the number-average molecular weight may be up to about 4000 daltons, at least about 200 daltons, and at least about 300 daltons.

[0046] With respect to NCO prepolymers, examples of compounds that can be used as isocyanate compounds include, but are not limited to, isocyanate compounds containing two or more isocyanate groups. They can be used in this disclosure as stoichiometric isocyanates, excess isocyanates, and free isocyanates. The isocyanates may be monomers or polymeric isocyanates, including aromatic, aliphatic, and alicyclic polyisocyanates.

[0047] Polyisocyanates can be diisocyanates including aliphatic, alicyclic, aromatic, and aliphatic-aromatic diisocyanates. Specific examples of aliphatic and alicyclic diisocyanates include ethylene diisocyanate, ethylidene diisocyanate, propylene diisocyanate, butylene diisocyanate, trimethylene diisocyanate, cyclopentylene-1,3-diisocyanate, cyclohexylene-1,4-diisocyanate, cyclohexylene-1,2-diisocyanate, dichlorohexamethylene diisocyanate, furfrylidene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,2,4-trimethyl-1,6-hexamethylene diisocyanate, 1,12-dodecamethylene diisocyanate, and 1-isocyanato-2-isocyanatomethylcyclopenta Examples include, but are not limited to, 1-isocyanato-3-isocyanato-methyl-3,5,5-trimethylcyclohexane (isophorone diisocyanate or IPDI), bis-(4-isocyanatocyclohexyl)-methane, 2,4'-dicyclohexylmethane diisocyanate, 1,3- or 1,4-bis-(isocyanatomethyl)-cyclohexane, bis-(4-isocyanato-3-methylcyclohexyl)-methane, α',α',α',α'-tetramethyl-1,3- and / or-1,4-xylylene diisocyanate, 1-isocyanato-1-methyl-4(3)-isocyanatomethylcyclohexane, 2,4- or 2,6-hexahydrotoluylene diisocyanate.

[0048] Aromatic and aliphatic-aromatic diisocyanates include specific examples such as 2,4- or 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,2-diphenylpropane-4,4'-diisocyanate, xylylene diisocyanate, 1,4-naphthylene diisocyanate, 1,5-naphthylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, diphenyl-4,4'-diisocyanate, azobenzene-4,4'-diisocyanate, and diphenylsulfone-4,4 Examples include, but are not limited to, '-diisocyanates, 2,4-tolylene diisocyanate, 1-chlorobenzene-2,4-diisocyanate, 4,4',4"-triisocyanatotriphenylmethane, 1,3,5-triisocyanatobenzene, 2,4,6-triisocyanatotoluene, 4,4'-dimethyldiphenylmethane-2,2',5,5-tetratetraisocyanate, and modified aromatic diisocyanates containing a carbodiimide group, urethane group, allophanate group, isocyanurate group, urea group, or biuret.

[0049] Modified aromatic diisocyanates may be uretonimine-modified isocyanates, such as uretonimine-modified 4,4'-diphenylmethane diisocyanate, which can be derived from 2,4- or 2,6-tolylene diisocyanate or from 4,4'- or 2,4'-diphenylmethane diisocyanate. Suitable uretonimine-modified isocyanates include Rubinate® 1680, commercially available from Huntsman Corporation, and ISONATE® 143L Modified MDI, commercially available from The Dow Chemicals Company.

[0050] In one non-limiting embodiment, the isocyanate may be hexamethylene diisocyanate, toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), methyene bisphenyl diisocyanate (MDI), hydrogenated MDI (HMDI), or poly-MDI (having a functional value greater than 2).

[0051] The polyols in NCO prepolymers can be any polyol suitable for the production of polyurethanes. They may be polyols based on polyalkylene oxides, polyesters, or combinations thereof, which may contain bulky side chains and / or long hydrophobic chains. Polyols based on polyalkylene oxides are often called polyether polyols. Polyols can also include polyamide polyols, polycaprolactone polyols, e.g., poly-ε-caprolactone polyols, polycarbonate polyols, hydroxyl-terminated polybutadienes, e.g., fully hydrogenated hydroxyl-terminated polybutadienes and / or partially hydrogenated hydroxyl-terminated polybutadienes, polyisobutylenediols, and mixtures thereof.

[0052] Polyether polyols may include linear and / or branched polyethers having hydroxyl groups. Examples of polyether polyols include substituted and / or unsubstituted polyoxyalkylene polyols such as polyethylene glycol, polypropylene glycol, polybutylene glycol, and polytetramethylene ether glycol (PTMEG). Furthermore, homopolymers and copolymers of polyoxyalkylene polyols may also be used. In particular, copolymers of polyoxyalkylene polyols may include adducts having at least one compound selected from the group consisting of ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, 2-ethylhexanediol-1,3-glycerin, 1,2,6-hexanetriol, trimethylolpropane, trimethylolethane, tris(hydroxyphenyl)propane, triethanolamine, triisopropanolamine, ethylenediamine, and ethanolamine, and at least one compound selected from the group consisting of ethylene oxide, propylene oxide, and butylene oxide.

[0053] Polyether polyols may include polymers of propylene oxide and / or copolymers of ethylene and propylene oxide, and the oxide is present. In one non-limiting embodiment, the polyether polyol is polypropylene oxide capped with ethylene oxide.

[0054] The number-average molecular weight of polyether polyols is typically at least about 350 daltons, preferably at least about 400 daltons. If desired, polyether polyols may have a number-average molecular weight that can vary in the range of about 2,000 daltons to about 20,000 daltons, or about 3,500 daltons to about 15,000 daltons, or about 2,000 daltons to about 14,000 daltons. For example, Acclaim® 4220N polyol (commercially available from Covestro) is based on propylene oxide, has ethylene oxide at the terminus, and has a number-average molecular weight of 4,000 daltons.

[0055] The polyether polyols used in this disclosure may include one or more difunctional polyether polyols, one or more trifunctional polyether polyols, one or more tetrafunctional polyether polyols, or combinations thereof. The number-average molecular weight of a difunctional polyether polyol may vary in the range of about 2,000 to about 20,000 daltons, or about 2,000 to about 12,000 daltons. For example, Pluracol® P2010 is a polyether polyol with a number-average molecular weight of 2,000 daltons, commercially available from BASF. PPG2000, available from PPG, is another example of a suitable polyol.

[0056] Furthermore, the number-average molecular weight of trifunctional polyether polyols can vary in the range of about 80 to about 20,000 daltons or about 100 to 12,000 daltons, including Pluracol® TP-440 polyol, which is commercially available from BASF. The molecular weight of tetrafunctional polyether polyols can vary in the range of about 100 to about 20,000 daltons or about 400 to 12,000 daltons. For example, Pluracol® 355 is a polyether polyol commercially available from BASF with a number-average molecular weight of 600 daltons. In some embodiments, the polyether polyol has a molecular weight of at least 4,000 daltons. In alternative examples, the polyether polyol has a molecular weight of about 4,000 daltons or less, preferably less than about 3,000 daltons.

[0057] Polyols based on polyester (also called polyester polyols) include amorphous and liquid polyester polyols, fatty acid polyester polyols, and, for example, castor oil and vegetable oils with different molecular weights and functional values.

[0058] Polyester polyols can be formed as reaction products of one or more carboxylic acids and one or more polyols, such as diols and / or triols. Examples of carboxylic acids useful for the formation of polyester polyols include, but are not limited to, adipic acid, glutaric acid, succinic acid, malonic acid, oxalic acid, and mixtures thereof. Examples of diols useful for the formation of polyester polyols include, but are not limited to, ethylene glycol, propanediol, butanediol, neopentyldiol, pentanediol, and hexanediol, and mixtures thereof. An example of a triol considered useful for the formation of polyester polyols is trimethylolpropane.

[0059] Examples of fatty acid polyester polyols include castor oil, hydroxylation products of unsaturated or polyunsaturated natural oils, hydrogenation products of unsaturated or polyunsaturated polyhydroxyl natural oils, polyhydroxyl esters of alkylhydroxyl fatty acids, polymerized natural oils, soybean polyols, alkylhydroxylated amides of fatty acids, and cashew nut shell liquid.

[0060] In one non-limiting embodiment, a polyester polyol can be obtained from the reaction of a triol with azelaic acid. The triol may be glycerol. An example of such a polyester polyol is Emerox® 14001, derived from natural oils and commercially available from Emery Oleochemicals Company.

[0061] The number-average molecular weight of polyester polyols typically varies in the range of approximately 1,000 to 20,000 daltons, or approximately 1,300 to 10,000 daltons. Admex® 525 polyol (commercially available from Eastman Chemical Company) is a polyester polyol with a molecular weight of 1,400 and can be used.

[0062] The prepolymer may optionally contain one or more fillers. Examples of fillers include fumed silica, molecular sieves, pigments, talc, oxides, nanoclay, rubber particles, conductive particles, and any combination thereof. The amount of the optional filler may range from about 1 to 45% by weight of the adhesive composition.

[0063] The above description of polyols is equally applicable to polyols of curing agents. In one embodiment, the free polyol of the curing agent includes a polyol having a number-average molecular weight of at least about 300 daltons, more preferably at least about 2,000 daltons, even more preferably at least about 4,000 daltons, and even more preferably at least 15,000 daltons.

[0064] Examples of tertiary amines or blocked tertiary amines include amidine compounds such as diazabicyclo compounds. Non-limiting examples of diazabicyclo compounds include 1,4-diazabicyclo[2.2.2]octane, also known as triethylenediamine, 1,8-diazabicyclo[5.4.0]undeca-7-ene, 1,5-diazabicyclo(5.4.0)undeca-5-ene, and combinations thereof.

[0065] Examples of appropriate amounts of tertiary amine include a maximum of approximately 3% by weight, a maximum of approximately 2% by weight, a maximum of approximately 1% by weight, a maximum of approximately 0.5% by weight, at least approximately 0.02% by weight, and at least approximately 0.03% by weight.

[0066] Appropriate amounts of diamine include up to approximately 10% by weight, up to approximately 7% by weight, and at least approximately 0.5% by weight.

[0067] Optionally, the curing agent may comprise one or more alcohols, preferably diols and / or triols. Preferably, the diol or triol has an average number-average molecular weight of about 1000 daltons or less, more preferably less than about 500 daltons, and even more preferably less than 250 daltons. Suitable examples of diols and triols include polyethylene glycol, polypropylene glycol, polybutylene glycol, polytetramethylene ether glycol (PTMEG), and combinations thereof. Specific commercially available diols include PTMEG-650 (MW650) from Korea PTG Co., Ltd. or Pluracol TP-440 from BASF.

[0068] The curing agent may optionally contain one or more fillers. Examples of fillers include fumed silica, molecular sieves, pigments, talc, oxides, nanoclay, rubber particles, conductive particles, and any combination thereof. The amount of the optional filler in the curing agent may range from about 1 to 45% by weight of the adhesive composition.

[0069] The curing agent may also contain one or more catalysts. Examples of suitable catalysts include organometallic catalysts and amine catalysts, either separately or in combination.

[0070] Organometallic catalysts including organotin, bismuth, zirconium, zinc, and combinations thereof. In addition to organotin catalysts, general-purpose tin catalysts may also be suitable. The amount of catalyst may range from about 0.05 to about 10% by weight.

[0071] Other optional components of the curing agent include diols (e.g., propylene-1,3-diol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,10-decanediol, and combinations thereof) and / or diethyleneamines (e.g., diethylenediamine, e.g., piperazine and diethylenetriamine).

[0072] The composition may further contain a monoether, preferably a poly(propylene glycol) monoether, and more preferably a poly(propylene glycol) monobutyl ether. It is even more preferable that the monoether constitutes a component of the curing agent. The monoether may constitute up to about 10% by weight of the adhesive composition.

[0073] A second embodiment of the adhesive composition is the same as the first embodiment except for the silane component. In the second embodiment, the silane component is an epoxy-functionalized silane adhesion promoter having a number-average molecular weight of at least about 1000 daltons. Non-limiting examples of number-average molecular weights include at least about 1200 daltons and at least about 1400 daltons. A preferred concentration of the epoxy-functionalized silane adhesion promoter constitutes a maximum of about 10% by weight of the adhesive. The second embodiment of the adhesive may omit the isocyanurato-functionalized silane compound and preferably also omit the additional epoxy-functionalized silane component.

[0074] Exemplary amounts of epoxy-functionalized silane adhesion promoter having a number-average molecular weight of at least about 1000 Daltons are up to about 10% by weight, up to about 8% by weight, up to about 4% by weight, at least about 0.5% by weight, and at least about 1% by weight.

[0075] As described above, the second embodiment of the adhesive comprises the above-mentioned components of the prepolymer and curing agent of the first embodiment, which are incorporated herein by reference in whole.

[0076] In certain embodiments of either the first or second adhesive, the curing agent may include a second polyol. The second polyol may include a polyoxyalkylene polyol having a hydroxyl value of at least about 15 mg KOH / g, preferably at least about 17 mg KOH / g, more preferably about 30 mg KOH / g or less, and even more preferably about 25 mg KOH / g or less. The number-average molecular weight of the second polyol of the curing agent may include at least about 15,000 daltons, more preferably at least about 25,000 daltons, even more preferably at least about 50,000 daltons, and even more preferably at least about 70,000 daltons.

[0077] The composition may further contain a monoether, preferably a poly(propylene glycol) monoether, and more preferably a poly(propylene glycol) monobutyl ether. It is even more preferable that the monoether constitutes a component of the curing agent.

[0078] A third adhesive composition of this disclosure is another two-component polyurethane adhesive. The third adhesive composition differs from the first and second adhesive compositions in the silane component of its prepolymer. The prepolymer of the third adhesive composition may include a silyl-modified polymer comprising at least one of a silyl-terminated polyether, a silyl-terminated isocyanate, a silyl-terminated acrylate, and a combination thereof.

[0079] Examples of silyl-modified polymers include at least one of dimethoxysily-terminated polyethers, trimethoxysily-terminated polyethers, and combinations thereof. Another example of a silyl-modified polymer is: A n -D-SiXYZ (In the formula, (a) A is a divalent linking group comprising at least one heteroatom, preferably at least one of S, N, O, P, and Si, more preferably O; (b) D is a divalent hydrocarbon residue having 1 to 12 carbon atoms, preferably 2 to 8 carbon atoms, more preferably 3 to 6 carbon atoms; (c) X, Y, and Z are each independently selected from C1-C8 alkyl, C1-C8 alkoxy, C1-C8 acyloxy, preferably C2-C5 alkyl, C2-C5 alkoxy, and C2-C5 acyloxy substituents on a Si atom, and at least one of substituents X, Y, and Z is a C1-C8 alkoxy or a C1-C8 acyloxy; (d)n is either 0 or 1) That is the case.

[0080] Other exemplary silyl-modified polymers include S203H, S303H, S227, S327, SAX220, SAX260, SAX350, SAX400, SAT010, SAX015, SAX115, SAT145, AX602, MAX923, MAX951, SAX750, SAX510, SAX520, SAX530, SAX540, SAX580, SAX590, MAX451, MAX480, MAX850; Desmoseal®, e.g., S XP2458, S XP2636, S XP2749, S XP2774, S XP2821; Gen-iosil®, e.g., STP-E10, STP-E15, STP-E30, STP-E35; Evonik Polymers include, for example, ST47, ST48, ST77, ST61, ST61LV, ST81, ST80, and TEGOPAC®, for example, Seal100, Bond150, and Bond250.

[0081] Preferably, the concentration of the silyl-modified polymer constitutes a maximum of about 25% by weight of the adhesive. Examples of suitable amounts of silyl-modified polymer include a maximum of about 20% by weight, a maximum of about 15% by weight, at least about 1% by weight, at least about 2% by weight, and at least about 5% by weight.

[0082] The prepolymer may also contain an optional epoxy-functionalized silane. The concentration of the epoxy-functionalized silane may constitute up to about 10% by weight of the adhesive composition. Exemplary amounts of the epoxy-functionalized silane may be up to about 8% by weight, up to about 5% by weight, up to about 4% by weight, at least about 0.1% by weight, at least about 0.4% by weight, and at least about 0.6% by weight.

[0083] In preferred embodiments, the number-average molecular weight of the epoxy-functionalized silane may range from over approximately 200 daltons to a maximum of approximately 2000 daltons.

[0084] The third adhesive composition may lack an isocyanurato-functionalized silane.

[0085] In the curing agent of the third embodiment of the adhesive, it is also preferable that the curing agent contains the above-mentioned tin catalyst. The amount of tin catalyst can constitute up to 10% by weight of the adhesive. Suitable amounts of tin catalyst may include up to about 8% by weight, up to about 5% by weight, up to about 2% by weight, and at least about 0.5% by weight.

[0086] As described above, the third embodiment of the adhesive comprises the above-mentioned components of the prepolymer and curing agent of the first embodiment, which are incorporated herein by reference in whole.

[0087] Applicable to any of the embodiments described above, the volume ratio of the prepolymer to the curing agent may range from about 1:10 to about 10:1. Examples of preferred ratios include about 1:1, about 1.5:1, about 1.75:1, about 2:1, about 2.5:1, and about 3:1. The volume ratio is applicable to all of the first, second, and third embodiments, as well as various alternatives, specific or concrete embodiments thereof.

[0088] A laminate can be formed using any and all of the above embodiments of any adhesive. Preferably, the laminate comprises a first substrate and a second substrate. The adhesive is sandwiched between the first substrate and the second substrate.

[0089] In one embodiment, at least one of the first and second substrates includes a corrosion-prone metal. In a further embodiment, both the first and second substrates are corrosion-prone metals. In a further embodiment, the metals may be the same or different. Examples of suitable metals include aluminum, steel, iron, the aforementioned coating embodiments of metals, and metal alloys. The substrates may be formed from any combination of the aforementioned metals, their alloys, and their coating versions.

[0090] In another embodiment, the thermal expansion coefficient of the first substrate, measured at temperatures ranging from about -30°C to a maximum of about 82°C, differs from that of the second substrate by only about 10% or less, preferably about 5% or less, and more preferably about 2% or less.

[0091] In an alternative embodiment, the thermal expansion coefficient of the first substrate, measured at temperatures ranging from about -30°C to a maximum of about 82°C, differs from that of the second substrate by more than about 5%, preferably more than about 10%, and more preferably more than about 15%.

[0092] In a further embodiment applicable to all embodiments of the laminate, the laminate may lack a sufficient amount of primer to help adhere the adhesive to either the first or second substrate.

[0093] Alternatively, the laminate may include primers on the first substrate, the second substrate, or both substrates.

[0094] In further embodiments, the laminate comprises a first substrate and a second substrate, and an adhesive sandwiched between the first and second substrates. The thermal expansion coefficient of the first substrate, measured at temperatures ranging from about -30°C to a maximum of about 82°C, differs from that of the second substrate by about 10% or less, preferably about 5% or less, and more preferably about 2% or less. The adhesive comprises a two-component adhesive composition comprising an NCO prepolymer containing a reaction product of an isocyanate compound and a polyol. Preferably, the %NCO in the prepolymer is at most about 30%, more preferably about 1-20% or about 1-10%. The adhesive further comprises a second polyol component having a number average molecular weight of preferably at least about 2000 daltons, more preferably at least about 4000 daltons, even more preferably at least about 8000 daltons, and most preferably 15000 daltons or less. The adhesive composition may also contain an isocyanurato-silane adhesion promoter at a concentration of about 0.1 to 10% by weight of the adhesive. The adhesive may also contain a fourth component comprising an epoxy-functionalized silane adhesion promoter, the concentration of which the fourth component constitutes about 20% by weight or less of the adhesive, preferably at least 0.5% by weight. The fifth component may comprise at least one of a tertiary amine, a blocked tertiary amine, and a combination thereof. An optional sixth component may be a polyetherdiamine.

[0095] In an alternative embodiment, the laminate comprises a first substrate and a second substrate, and an adhesive sandwiched between the first and second substrates. The coefficient of thermal expansion of the first substrate, measured at temperatures ranging from about -30°C to a maximum of about 82°C, differs from that of the second substrate by more than about 15%, preferably more than about 10%, and more preferably more than about 15%. The adhesive comprises a two-component adhesive composition comprising an NCO prepolymer containing a reaction product of an isocyanate compound and a polyol. Preferably, the %NCO in the prepolymer contains at least about 30%, more preferably about 1-20% or about 1-10%. The adhesive further comprises a second polyol component having a number average molecular weight of preferably at least about 2000 daltons, more preferably at least about 4000 daltons, even more preferably at least about 8000 daltons, and most preferably 15000 daltons or less. The adhesive composition may also contain an isocyanurato-silane adhesion promoter at a concentration of about 0.1 to 10% by weight of the adhesive. The adhesive may also contain a fourth component comprising an epoxy-functionalized silane adhesion promoter, the concentration of which the fourth component constitutes about 20% by weight or less of the adhesive, preferably at least 0.5% by weight. The fifth component may comprise at least one of a tertiary amine, a blocked tertiary amine, and a combination thereof. An optional sixth component may be a polyetherdiamine.

[0096] The number-average molecular weight can be determined by, but is not limited to, gel permeation chromatography (GPC), gas phase osmosis, membrane osmosis, and vapor pressure reduction.

[0097] One technique for determining %NCO is ASTM D5155. However, the determination of %NCO is not necessarily limited to the aforementioned technique.

[0098] The NCO index is the equivalent ratio of isocyanate to polyols containing hydroxyl groups.

[0099] Viscosity: Viscosity can be measured using a TA Instruments Discovery HR-1 rheometer equipped with a cone plate. For measuring the viscosity in Examples 1 and 2, the cone plate had a diameter of 40 mm. Unless otherwise specified, the temperature was 23°C and the shear rate was 0.79 1 / s.

[0100] Tensile strength of the adhesive: The tensile strength may be determined according to ASTM D-638. The embodiments disclosed herein are not limited to determining the tensile strength according to the aforementioned ASTM standard.

[0101] One test method that may be used to determine the coefficient of thermal expansion ("CTE") is ASTM test method E831. Embodiments disclosed herein are not limited to determining the CTE according to the aforementioned ASTM standard.

[0102] The hydroxyl value (OH number) can be determined by ASTM D4274 Standard Test Methods for Testing Polyurethane Raw Materials: Determination of Hydroxyl Numbers of Polyols. The method for determining the OH number is not limited to the aforementioned ASTM standard; the type of titration method may also be appropriate.

[0103] Young's modulus: The Young's modulus discussed herein can be determined using any suitable method or instrument, but an example of an instrument that may be used to measure Young's modulus is the LMEC-1 Young's modulus instrument.

[0104] The above weight percentages are based on the total adhesive composition unless otherwise specified.

[0105] All of the above embodiments can be combined with one another. In particular, various aforementioned components in the composition and particularly preferred embodiments can be combined with one another.

[0106] The following examples will be described without limiting the present invention.

[0107] Examples Tables 1 and 2 show the formulations of samples 1-9 (controls 1-3 and examples 4-9). General procedures for preparing the prepolymer and curing agent are shown in Tables 3 and 4.

[0108] In samples 1-9 shown in Table 5 (controls 1-3 and examples 4-9), the prepolymers and curing agents prepared in Tables 1 and 2 were separately filled into side-by-side cartridges and pumped through a static mixing tube to achieve complete mixing as shown in Table 5. The mixed polymerizable adhesive composition was then applied directly from the static mixing tube to one side of the test substrate. A lap shear test was performed to measure the lap shear strength and failure mode of the adhesive bond.

[0109] Lapped shear test specimens were prepared by overlapping the last 2.5 cm of a pair of 10 × 2.5 cm specimens to obtain a 17.8 cm long specimen containing adhesive and 0.76 mm glass spacer beads between the overlaps. The specimen was placed between double-sided fixtures held at the curing temperature until solidification. The specimen was then removed from the fixtures and held for testing at approximately 20–25°C for approximately 24–72 hours. The lapped shear test was performed at a crosshead speed of 2 inches / min according to ASTM D5868. ASTM D5868 is incorporated herein by reference in its entirety. All adhesives were prepared with isocyanate indices ranging from approximately 95 to approximately 110 unless otherwise noted. Salt spray was performed in a Q-FOG cycle corrosion test chamber according to GMW14124 specifications. Adhesives were evaluated using water immersion and salt spray tests, as lack of corrosion resistance and poor adhesion after water immersion and / or salt spray are major challenges for polyurethane adhesives.

[0110] Adhesives prepared from controls 1-3 and examples 4-7 were used to bond glass-filled polypropylene (GFPP) to bare aluminum (Al-6061). Prior to bonding, the surface of the GFPP was wiped with IPA, followed by flame treatment, and the surface of the Al-6061 was polished. Lapp shear tests were performed on the cured adhesives at room temperature (RT) after 1 week or 90 days of water immersion and / or 8 weeks or 7 months of salt spraying. Both strength and fracture pattern (pass %) were evaluated. Industry standards require a minimum fracture pattern pass rate of 90%.

[0111] A brief explanation of the results shown in Table 6.

[0112] Control 1 is a high-performance, low-modulus PU adhesive formulation based on the best available knowledge, but without silane (reference / control 1). It exhibited insufficient strength when tested at RT and after one week of water immersion, and did not pass the required 90% cohesive failure mode.

[0113] Control 2 (Control 2) has only one silane, A-187 silane (epoxy functional), in the prepolymer. The silane activator, Jeffamine, is present in the curing agent. This showed good lap shear strength, but the lap shear tested by RT did not pass the required 90% cohesive failure mode. However, this showed significant improvement in the results after one week of water immersion, achieving a 95% cohesive failure mode.

[0114] Control 3 contains one silane, VPS7163 (isocyanurato silane), in the prepolymer. Jeffamine (polyetheramine) is present in the curing agent. Neither the failure mode at RT nor the failure mode after water immersion passed the required 90% cohesive failure mode.

[0115] Example 4 contained both A-187 silane and VPS7163 in the prepolymer and Jeffamine in the curing agent. This showed excellent lap shear strength and fracture mode when tested at RT and after 1 week of water immersion.

[0116] Example 5 contains both A-187 silane and VPS7163 in the prepolymer and Jeffamine + DBU (tertiary amine) in the curing agent. This showed excellent lap shear strength and fracture mode when tested at RT and after 1 week of water immersion.

[0117] Example 6 contains both A-187 silane and VPS7163 in the prepolymer, and does not contain Jeffamine in the curing agent, but contains DABCO33LV. This showed excellent lap shear strength and fracture mode when tested at RT and after 1 week of water immersion.

[0118] Example 7 contains both A-187 silane and VPS7163 in the prepolymer and Jeffamine in the curing agent. This exhibited excellent wrap shear strength and fracture mode after 90 days of water immersion and 8 weeks of salt spraying.

[0119] Adhesives prepared in Examples 5, 7, and 8 were used to bond Al-6061 to Al-6061 (bare aluminum) and to Alodine-treated Al (A-5200). Before bonding, the surface of Al-6061 was polished and the surface of A-5200 was wiped with IPA. The cured adhesives were subjected to a wrap shear test at room temperature (RT) after 1 week of water immersion and / or 8 weeks or 7 months of salt spraying.

[0120] A brief explanation of the results shown in Table 6.

[0121] Example 5 contains both A-187 silane and VPS7163 in the prepolymer and Jeffamine + DBU (tertiary amine catalyst) in the curing agent. This showed excellent lap shear strength and fracture mode for both alodine-treated and bare aluminum when tested after exposure to salt spray for 7 months (which is extremely difficult to pass). Automotive OEMs typically only require passing salt spray for 8 weeks.

[0122] Example 7 contained both A-187 silane and VPS7163 in the prepolymer and Jeffamine in the curing agent. This showed excellent lap shear strength and failure mode for both alodine-treated and bare aluminum when tested after 8 weeks of salt spray exposure. For this adhesive, only 8 weeks of salt spray exposure was tested, followed by longer exposures.

[0123] Controls 1-3 and Examples 4-7 were all low modulus adhesives. The modulus of each sample was less than 10 MPa. Example 8 was a high modulus adhesive with a modulus of at least 10 MPa. The modulus referred to herein is Young's modulus.

[0124] Example 8 is a high modulus adhesive with an elastic modulus of approximately 500 MPa. Example 8 contains both A-187 silane and VPS7163 in the prepolymer and Jeffamine + DBU in the curing agent. It exhibited excellent lap shear strength and fracture mode against alodine aluminum when tested after one week of water immersion. Salt spray testing was not performed. This demonstrates that this concept, developed based on low modulus, is also applicable to conventional high modulus PU adhesives.

[0125] The data above demonstrates that the combination of A-187 and VPS using a tertiary amine catalyst and / or Jeffamine achieves remarkably good results in water immersion and salt spraying.

[0126] Example 9. Glass-filled polypropylene (GFPP) was bonded to bare aluminum (Al-6061) using the adhesive prepared in Example 9. Before bonding, the surface of the GFPP was wiped with IPA and subsequently flame-treated, and the surface of the Al-6061 was polished. Lapping shear tests were performed on the cured adhesive at room temperature (RT) and after 1 week of water immersion. Example 9 has a special silane in the prepolymer, VPS4721, which is a high molecular weight epoxy functional silane. It has Jeffamine in the curing agent. It showed excellent lapping shear strength and failure mode when tested at RT and after 1 week of water immersion.

[0127] The SMP (silane-modified polymer) contained in the prepolymer was evaluated for improved adhesion to aluminum. Tables 9 and 10 show the formulations of Examples 10 and 11. Tables 3 and 4 show the general procedures for manufacturing the prepolymer and curing agent.

[0128] In Examples 10-11 shown in Table 11, the prepolymers and curing agents prepared in Tables 9 and 10 were separately filled into side-by-side cartridges and pumped through a static mixing tube to achieve the complete mixing shown in Table 11. The adhesives prepared in Examples 10 and 11 were used to bond Al-6061 to Al-6061 (bare aluminum) and to alodine-treated Al to alodine-treated Al (A-5200). The cured adhesives were subjected to wrap shear tests at room temperature (RT) and after 2 weeks of water immersion.

[0129] A brief explanation of the results shown in Table 12.

[0130] Example 10 contains both A-187 silane and SAX220SMP in the prepolymer and DABCO33LV in the curing agent. This showed excellent lap shear strength and fracture mode for both alodine aluminum and bare aluminum when tested at RT and after 2 weeks of water immersion. Therefore, the combination of A-187 and SMP is a good candidate for improving the aluminum bonding performance of PU adhesives.

[0131] Example 11 contains only SAX220SMP in the prepolymer and Tib kat417 (tin catalyst) in the curing agent. This showed excellent lap shear strength and fracture mode for both alodine aluminum and bare aluminum when tested at RT. This is another good candidate for aluminum bonding.

[0132] In the following examples, the term CH is used to indicate cohesive failure, and AD is used to indicate interfacial failure. In some cases, preferred embodiments have at least about 90%, more preferably at least about 95%, and most preferably about 100% CH.

[0133] [Table 1]

[0134] [Table 2]

[0135] [Table 3]

[0136] [Table 4]

[0137] [Table 5]

[0138] Table 6

[0139] Table 7

[0140] Table 8

[0141] Table 9

[0142] Table 10

[0143] Table 11

[0144] Table 12

[0145] Table 13

[0146] Table 14

[0147] In Table 13, control 4 lacks monoethers, high molecular weight polyols (number-average molecular weight exceeding 10,000 daltons), and silanes. Alodine Al was used as the substrate for both the first and second substrates to form the laminate.

[0148] The wrap shear bond was tested at room temperature and after one week of water immersion. The control showed sufficient wrap shear bond and appropriate type of fracture when tested at room temperature, and the results were as follows: (1) After immersion in water for one week, control 4 showed low strength and poor adhesion (interfacial fracture). (2) Both Example 21 and Example 22 showed good strength and good failure mode when tested with RT and 1 week of water immersion.

[0149] While the present invention has been described in detail with reference to certain preferred embodiments, it should be understood that this disclosure is not limited to those exact embodiments. Rather, in consideration of this disclosure, many modifications and variations will be presented to those skilled in the art without departing from the scope and spirit of the invention.

[0150] manner In addition to the subject matter in the summary, detailed description, and claims of the invention, this disclosure includes the embodiments enumerated herein.

[0151] The first embodiment is a two-component polyurethane adhesive composition. The composition comprises an NCO prepolymer containing a reaction product of an isocyanate compound and a polyol. Preferably, the %NCO in the prepolymer is up to about 30%, more preferably about 1 to 20%, even more preferably less than 20% to at least 10%, or about 1 to 10%. The prepolymer may also contain a silane component, the silane component comprising at least an epoxy-functionalized silane, preferably up to about 10% by weight, more preferably up to about 8% by weight, even more preferably up to about 5% by weight, even more preferably up to about 4% by weight, similarly preferably at least about 0.1% by weight, more preferably at least about 0.4% by weight, and even more preferably at least about 0.6% by weight. The silane component may also include isocyanurato-functionalized silanes, preferably up to about 5% by weight, more preferably up to about 4% by weight, even more preferably up to about 1.5% by weight or less, even more preferably at least about 0.4% by weight, and even more preferably at least at least about 0.6% by weight.

[0152] The adhesive of the first embodiment may also comprise a polyol and a curing agent comprising at least one of a tertiary amine, a blocked tertiary amine, and a combination thereof. A preferred concentration of the tertiary amine may constitute up to about 3% by weight of the adhesive, more preferably up to about 2% by weight, even more preferably up to about 1% by weight or less, even more preferably up to 0.5% by weight or less, even more preferably at least about 0.02% by weight, and most preferably at least at least about 0.03% by weight. Optionally, the curing agent may comprise a diamine, preferably up to about 15% by weight of the adhesive, more preferably up to about 10% by weight, even more preferably up to about 7% by weight, and even more preferably at least about 0.5% by weight. Preferably, the number-average molecular weight of the diamine may comprise up to about 6000 daltons, more preferably up to about 4000 daltons, even more preferably at least about 200 daltons, and even more preferably at least about 300 daltons.

[0153] A second embodiment comprises a two-component polyurethane adhesive composition. The composition comprises an NCO prepolymer containing a reaction product of an isocyanate compound and a polyol. Preferably, the %NCO in the prepolymer is up to about 30%, more preferably about 1 to 20%, even more preferably less than 20% to at least 10%, or about 1 to 10%. The prepolymer may contain an epoxy-functionalized silane adhesion promoter having a number-average molecular weight of at least about 1000 daltons, preferably at least about 1200 daltons, and more preferably at least about 1400 daltons. Preferably, the concentration of the epoxy-functionalized silane adhesion promoter constitutes up to about 10% by weight of the adhesive, more preferably up to about 8% by weight, even more preferably up to about 4% by weight, even more preferably at least about 0.5% by weight, and most preferably at least about 1% by weight.

[0154] The adhesive of the second embodiment may also comprise a polyol and a curing agent comprising at least one of a tertiary amine, a blocked tertiary amine, and a combination thereof. The concentration of the tertiary amine may constitute up to about 5% by weight of the adhesive, more preferably up to about 4% by weight, even more preferably up to about 2% by weight, even more preferably up to about 1% by weight, and most preferably at least at about 0.02% by weight. The curing agent may also optionally comprise a diamine, preferably a polyetherdiamine. A preferred concentration of the diamine, for example, a polyetherdiamine, may constitute up to about 15% by weight of the adhesive, more preferably up to about 11% by weight, even more preferably up to 7% by weight, and even more preferably at least at about 0.5% by weight.

[0155] In a third embodiment, the adhesive of the second embodiment may lack the second silane-containing compound in the prepolymer, preferably in the composition.

[0156] A fourth embodiment is applicable to either the second or third embodiment, wherein the curing agent further comprises the second polyol. Preferably, the second polyol comprises a polyoxyalkylene polyol having a hydroxyl value of at least about 15 mg KOH / g, preferably at least about 17 mg KOH / g, more preferably about 30 mg KOH / g or less, and even more preferably about 25 mg KOH / g or less, and more preferably the number average molecular weight of the second polyol comprises at least about 15,000 daltons, more preferably at least about 25,000 daltons, even more preferably at least about 50,000 daltons, and even more preferably at least about 70,000 daltons.

[0157] A fifth embodiment is a two-component polyurethane adhesive composition according to any one of embodiment 2 or 3, wherein the curing agent comprises a second polyol, and the number-average molecular weight of the second polyol in the curing agent is at least about 300 daltons, more preferably at least about 2,000 daltons, even more preferably at least about 4,000 daltons, and even more preferably at least 15,000 daltons.

[0158] The sixth embodiment is applicable to any one of embodiments 2 to 5, wherein the adhesive composition further comprises a monoether, preferably poly(propylene glycol) monoether, more preferably poly(propylene glycol) monobutyl ether, and even more preferably the monoether constitutes a component of the curing agent.

[0159] A seventh embodiment is applicable to any one of the preceding embodiments, wherein the adhesive composition further comprises at least one of diols, triols, and combinations thereof, preferably the diol being a primary diol, and similarly preferably the diol or triol having a number average molecular weight of about 1000 daltons or less, more preferably less than about 500 daltons, and even more preferably less than about 250 daltons. In a preferred embodiment, the diol or triol is a component of the curing agent.

[0160] An eighth embodiment further comprises a high molecular weight polyol in the curing agent, wherein the number average molecular weight of the high molecular weight polyol is at least 1000 daltons, preferably at least about 4000 daltons, according to any one of the preceding embodiments.

[0161] The ninth aspect comprises a two-component polyurethane adhesive composition. The composition comprises an NCO prepolymer containing a reaction product of an isocyanate compound and a polyol. Preferably, the %NCO in the prepolymer is up to about 30%, more preferably about 1 to 20%, and even more preferably less than 20% to at least 10% or about 1 to 10%. The prepolymer may also comprise a silyl-modified polymer containing at least one of silyl-terminated polyethers, silyl-terminated isocyanates, silyl-terminated acrylates, and combinations thereof. Preferably, the concentration of the silyl-modified polymer constitutes a maximum of about 25% by weight of the adhesive, more preferably a maximum of about 20% by weight, even more preferably a maximum of about 15% by weight, even more preferably at least 1% by weight, even more preferably at least 2% by weight, and most preferably at least 5% by weight, and optionally, the epoxy-functionalized silane constitutes a maximum of about 10% by weight of the adhesive, more preferably a maximum of about 8% by weight, even more preferably a maximum of about 5% by weight, even more preferably at least 4% by weight, similarly preferably at least 0.1% by weight, more preferably at least 0.4% by weight, and even more preferably at least 0.6% by weight.

[0162] The adhesive composition of the ninth embodiment may also include a curing agent comprising a polyol and an optional tin catalyst. The preferred concentration of the tin catalyst may constitute up to about 10% by weight, more preferably about 5% by weight, even more preferably up to about 2% by weight, and even more preferably at least about 0.5% by weight of the adhesive composition.

[0163] In the tenth embodiment, the NCO prepolymer of the ninth embodiment may further comprise an epoxy-functionalized silane adhesion promoter having a number-average molecular weight greater than about 200 daltons, preferably up to about 2000 daltons.

[0164] In the eleventh embodiment, the epoxy-functionalized silane adhesion promoter comprises at least one of 2-glycidoxyethyl-dimethylmethoxysilane; 6-glycidoxyhexyl-tributoxysilane; 3-glycidoxypropyl-trimethoxysilane; 3-glycidoxypropyl-triethoxysilane; 3-glycidoxypropyl-methyldiethoxysilane; 5-glycidoxypentyl-trimethoxysilane; 5-glycidoxypentyl-triethoxysilane, 3-glycidoxypropyl-triisopropoxysilane, and combinations thereof, preferably the epoxy-functionalized silane adhesion promoter comprises 3-glycidoxypropyl-trimethoxysilane, as described in any one of embodiments 9 or 10.

[0165] In a twelfth aspect, the two-component polyurethane adhesive composition according to any one of aspects 9 to 11, wherein the silyl-modified polymer comprises at least one of a dimethoxysily-terminated polyether, a trimethoxysily-terminated polyether, and a combination thereof.

[0166] In the 13th embodiment, the silyl-modified polymer is A n -D-SiXYZ terminal group (wherein, aA is a divalent linking group comprising at least one heteroatom, preferably at least one of S, N, O, P, and Si, more preferably O; bD is a divalent hydrocarbon residue having 1 to 12 carbon atoms, preferably 2 to 8 carbon atoms, more preferably 3 to 6 carbon atoms; cX, Y, and Z are each independently selected from C1-C8 alkyl, C1-C8 alkoxy, C1-C8 acyloxy, preferably C2-C5 alkyl, C2-C5 alkoxy, and C2-C5 acyloxy substituents on a Si atom, and at least one of substituents X, Y, and Z is a C1-C8 alkoxy or a C1-C8 acyloxy; (dn is 0 or 1) A two-component polyurethane adhesive composition according to any one of embodiments 9 to 11, including the following:

[0167] A two-component adhesive according to any one of embodiments 9 to 13, wherein the volume ratio of the prepolymer to the curing agent is at least about 1:1 to a maximum of about 10:1, preferably at least about 1.5:1.

[0168] Embodiment 15 includes a laminate having a first substrate and a second substrate and an adhesive described in any one of the preceding embodiments, wherein the adhesive is disposed between the first substrate and the second substrate.

[0169] In embodiment 16, at least one of the first or second substrate of the laminate described in embodiment 15, or at least one of the substrates, contains a corrosion-prone metal, preferably the corrosion-prone substrate contains one of aluminum, an aluminum alloy, coated aluminum, or a coated aluminum alloy.

[0170] Embodiment 17 applies to either Embodiment 15 or 16, wherein the thermal expansion coefficient of the first substrate, measured at temperatures ranging from about -30°C to a maximum of about 82°C, differs from that of the second substrate by only about 10% or less, preferably about 5% or less, and more preferably about 2% or less.

[0171] Embodiment 18 applies to any one of embodiments 15 to 17, wherein the laminate lacks a sufficient amount of primer to help the adhesive adhere to either the first substrate or the second substrate.

[0172] One particular embodiment includes a laminate comprising a first substrate and a second substrate, and an adhesive sandwiched between the first and second substrates. The coefficient of thermal expansion of the first substrate, measured at temperatures ranging from about -30°C to a maximum of about 82°C, differs from that of the second substrate by more than about 5%, preferably more than about 10%, and more preferably more than about 15%. The adhesive comprises a two-component adhesive composition comprising an NCO prepolymer containing a reaction product of an isocyanate compound and a polyol. Preferably, the %NCO in the prepolymer is at most at least about 30%, more preferably about 1-20% or about 1-10%. The adhesive further comprises a second polyol component having a number average molecular weight of preferably at least about 2000 daltons, more preferably at least about 4000 daltons, even more preferably at least about 8000 daltons, and most preferably 15000 daltons or less. The adhesive composition may also contain an isocyanurato-silane adhesion promoter at a concentration of about 0.1 to 10% by weight of the adhesive. The adhesive may also contain a fourth component comprising an epoxy-functionalized silane adhesion promoter, the concentration of which the fourth component constitutes about 20% by weight or less of the adhesive, preferably at least 0.5% by weight. The fifth component may comprise at least one of a tertiary amine, a blocked tertiary amine, and a combination thereof. An optional sixth component may be a polyetherdiamine.

Claims

1. a. An NCO prepolymer comprising a reaction product of an isocyanate compound and a polyol, preferably comprising a maximum of about 30%, more preferably about 1 to 20%, even more preferably less than 20% to at least 10%, or about 1 to 10%, wherein the prepolymer comprises a silane component, the silane component comprising at least epoxy-functionalized silane, preferably up to about 10% by weight, more preferably up to about 8% by weight, even more preferably up to about 5% by weight, even more preferably up to about 4% by weight, similarly preferably at least about 0.1% by weight, more preferably at least about 0.4% by weight, even more preferably at least about 0.6% by weight, and isocyanurato-functionalized silane, preferably up to about 5% by weight, more preferably up to about 4% by weight, even more preferably about 1.5% by weight or less, even more preferably at least about 0.4% by weight, and even more preferably at least about 0.6% by weight; b. A curing agent comprising a polyol and at least one of tertiary amines, blocked tertiary amines, and combinations thereof, preferably in an amount of at least about 3% by weight, more preferably at least about 2% by weight, even more preferably about 1% by weight or less, even more preferably 0.5% by weight or less, even more preferably at least about 0.02% by weight, most preferably at least about 0.03% by weight, and optionally a diamine, preferably in an amount of at least about 15% by weight, more preferably at least about 10% by weight, even more preferably at least about 7% by weight, and even more preferably at least about 0.5% by weight, wherein the number average molecular weight of the diamine may be at most about 6000 daltons, more preferably at most about 4000 daltons, even more preferably at least about 200 daltons, and even more preferably at least about 300 daltons. A two-component polyurethane adhesive composition containing the following:

2. a. An NCO prepolymer comprising a reaction product of an isocyanate compound and a polyol, preferably comprising a maximum of about 30%, more preferably about 1 to 20%, even more preferably less than 20% to at least 10%, or about 1 to 10%, wherein the prepolymer comprises an epoxy-functionalized silane adhesion promoter having a number average molecular weight of at least about 1000 daltons, preferably at least about 1200 daltons, more preferably at least about 1400 daltons, wherein the concentration of the epoxy-functionalized silane adhesion promoter constitutes a maximum of about 10% by weight, more preferably a maximum of about 8% by weight, even more preferably a maximum of about 4% by weight, even more preferably at least about 0.5% by weight, and most preferably at least about 1% by weight of the adhesive; b. A curing agent comprising a polyol and at least one of tertiary amines, blocked tertiary amines, and combinations thereof, preferably comprising a concentration of up to about 5% by weight, more preferably up to about 4% by weight, even more preferably up to about 2% by weight, even more preferably up to about 1% by weight (up to 0.5% by weight in a particular embodiment), most preferably at least at about 0.02% by weight, and an optional polyetherdiamine, preferably a polyetherdiamine having a concentration of up to about 15% by weight, more preferably up to about 11% by weight, even more preferably up to 7% by weight, and even more preferably at least at about 0.5% by weight. A two-component polyurethane adhesive composition containing the following:

3. The two-component polyurethane adhesive composition according to claim 2, wherein the prepolymer lacks a second silane-containing compound.

4. The two-component polyurethane adhesive composition according to claim 2 or 3, wherein the curing agent further comprises a second polyol, preferably the second polyol comprising a polyoxyalkylene polyol having a hydroxyl value of at least about 15 mg KOH / g, preferably at least about 17 mg KOH / g, more preferably about 30 mg KOH / g or less, and even more preferably about 25 mg KOH / g or less, and further preferably the number average molecular weight of the second polyol comprising at least about 15,000 daltons, more preferably at least about 25,000 daltons, even more preferably at least about 50,000 daltons, and even more preferably at least about 70,000 daltons.

5. The two-component polyurethane adhesive composition according to claim 2 or 3, wherein the number-average molecular weight of the second polyol in the curing agent is at least about 300 daltons, more preferably at least about 2,000 daltons, even more preferably at least about 4,000 daltons, and even more preferably at least 10,000 daltons.

6. A two-component polyurethane adhesive composition according to any one of claims 2 to 5, further comprising a monoether, preferably a poly(propylene glycol) monoether, more preferably a poly(propylene glycol) monobutyl ether, and even more preferably the monoether constituting a component of the curing agent.

7. A two-component polyurethane adhesive composition according to any one of claims 2 to 6, further comprising at least one of a diol, a triol, and a combination thereof, preferably the diol comprising a primary diol, and similarly preferably the diol or triol having a number average molecular weight of about 1,000 daltons or less, more preferably less than about 500 daltons, and even more preferably less than 250 daltons.

8. The two-component polyurethane adhesive composition according to any one of claims 4 to 7, further comprising a third polyol in the curing agent, wherein the number average molecular weight of the third polyol is at least 1,000 daltons.

9. A two-component polyurethane adhesive composition according to any one of claims 4 to 8, wherein the number average molecular weight of the second polyol is at least 50,000 daltons.

10. a. An NCO prepolymer comprising a reaction product of an isocyanate compound and a polyol, preferably comprising a maximum of about 30%, more preferably about 1 to 20%, even more preferably less than 20% to at least 10%, or about 1 to 10%, wherein the prepolymer comprises a silyl-modified polymer comprising at least one of silyl-terminated polyethers, silyl-terminated isocyanates, silyl-terminated acrylates, and combinations thereof, preferably the concentration of the silyl-modified polymer being a maximum of about 25% by weight, more preferably a maximum of about 20% by weight, of the adhesive. More preferably, the prepolymer comprises up to about 15% by weight, even more preferably at least about 1% by weight, even more preferably at least about 2% by weight, and most preferably at least about 5% by weight, and optionally, the prepolymer comprises epoxy-functionalized silane, preferably up to about 10% by weight, more preferably up to about 8% by weight, even more preferably up to about 5% by weight, even more preferably up to about 4% by weight, similarly preferably at least about 0.1% by weight, more preferably at least about 0.4% by weight, and even more preferably at least about 0.6% by weight; b. A curing agent comprising a polyol and an optional tin catalyst in a concentration of up to about 10% by weight of the adhesive, more preferably up to about 5% by weight, even more preferably up to about 2% by weight, and even more preferably at least about 0.02% by weight. A two-component polyurethane adhesive composition containing the following:

11. The two-component polyurethane adhesive composition according to claim 10, wherein the NCO prepolymer further comprises the epoxy-functionalized silane adhesion promoter having a number average molecular weight of more than about 200 daltons, preferably up to about 2000 daltons.

12. The epoxy-functionalized silane adhesion promoter comprises 2-glycidoxyethyl-dimethylmethoxysilane; 6-glycidoxyhexyl-tributoxysilane; 3-glycidoxypropyl-trimethoxysilane; 3-glycidoxypropyl-triethoxysilane; 3-glycidoxypropyl-methyldiethoxysilane; 5-glycidoxypentyl-trimethoxysilane; 5-glycidoxypentyl-triethoxysilane, 3-glycidoxypropyl-triisopropoxysilane, and at least one of these combinations, preferably comprising 3-glycidoxypropyl-trimethoxysilane, according to claim 10 or 11.

13. The two-component polyurethane adhesive composition according to any one of claims 10 to 12, wherein the silyl-modified polymer comprises at least one of a dimethoxysilly-terminated polyether, a trimethoxysilly-terminated polyether, and a combination thereof.

14. The silyl-modified polymer is A ｎ -D-SiXYZ terminal group (wherein, a. A is a divalent linking group comprising at least one heteroatom, preferably at least one of S, N, O, P, and Si, more preferably O; b. D is a divalent hydrocarbon residue having 1 to 12 carbon atoms, preferably 2 to 8 carbon atoms, more preferably 3 to 6 carbon atoms; c. X, Y, and Z are each independently C １ to C ８ alkyl, C1 to C ８ alkoxy, C １ to C ８ acyloxy, preferably C ２ to C ５ alkyl, C ２ to C ５ alkoxy, and C ２ to C ５ acyloxy, and are substituents on the Si atom, independently selected therefrom, and at least one of the substituents X, Y, and Z is C １ to C ８ alkoxy or C １ to C ８ acyloxy; d. n is either 0 or 1. A two-component polyurethane adhesive composition according to any one of claims 10 to 12, comprising:

15. A two-component polyurethane adhesive composition according to any one of claims 10 to 14, wherein the volume ratio of the prepolymer to the curing agent is at least about 1:1 to a maximum of about 10:1, preferably at least about 1.5:

1.

16. A laminate comprising a first substrate and a second substrate, wherein one or both of the first substrate and the second substrate contain aluminum, and an adhesive according to any one of claims 1 to 15 is sandwiched between the first substrate and the second substrate.

17. A laminate comprising a first substrate and a second substrate, and an adhesive according to any one of claims 1 to 15 sandwiched between the first substrate and the second substrate, wherein the thermal expansion coefficient of the first substrate differs from that of the second substrate by more than about 5%, preferably more than about 10%, and more preferably more than about 15%, when measured at a temperature in the range of about -30°C to a maximum of about 82°C. A laminate lacking a sufficient amount of primer to help adhere an adhesive to either the first substrate or the second substrate.

18. The laminate according to claim 16 or 17, wherein at least one of the first substrate and the second substrate comprises a metal known to oxidize, preferably a metal or an alloy of the metal, more preferably aluminum and / or an aluminum alloy.

19. A laminate comprising a first substrate and a second substrate, and an adhesive sandwiched between the first substrate and the second substrate, wherein the thermal expansion coefficient of the first substrate differs from that of the second substrate by more than 5%, preferably more than 10%, and more preferably more than 15%, when measured at temperatures in the range of about -30°C to a maximum of about 82°C, and the adhesive is, i. An NCO prepolymer comprising a reaction product of an isocyanate compound and a polyol, preferably comprising a prepolymer in which %NCO is at most about 30%, more preferably about 1-20% or about 1-10%, ii. A second polyol component having a number average molecular weight of preferably at least about 1000 daltons, more preferably at least about 4000 daltons, even more preferably at least about 8000 daltons, and most preferably 15000 daltons or less. iii. An isocyanurato silane adhesion promoter in a concentration of approximately 0.1 to 10% by weight of the adhesive, iv. A fourth component comprising an epoxy-functionalized silane adhesion promoter, wherein the concentration of the fourth component constitutes about 10% by weight or less of the adhesive, preferably at least 0.5% by weight, v. A fifth component comprising at least one of a tertiary amine, a blocked tertiary amine, and a combination thereof, vi. Optionally, the sixth component of polyetherdiamine and A laminate comprising a two-component adhesive composition containing the following:

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