Adhesive composition for bonding dissimilar materials and laminates made therefrom

Abstract

The present invention relates to polyurethane adhesive compositions and laminates containing one of the adhesive compositions, as well as methods for making such laminates. The adhesive can be a two-component adhesive. The prepolymer can include an NCO prepolymer and one or more silane adhesion promoters. The curing component includes a second polyol. The second polyol can have a number average molecular weight of at least about 2,000 daltons, or alternatively, up to at least about 80,000 daltons, including all number average molecular weights therebetween. The curing agent can also include a monoether. The adhesive can be a low modulus or high modulus adhesive depending on the application.

Description

[Technical Field]

[0001] The present invention relates to an adhesive composition that can be used to bond dissimilar materials, a laminate formed by such bonding of dissimilar materials, and a method for producing such a laminate. [Background technology]

[0002] In 2012, the U.S. Environmental Protection Agency enacted regulations requiring all U.S. vehicles to achieve an average fuel economy of 54.5 miles per gallon by 2025. To meet this stringent standard, the automotive industry has turned to materials that can reduce vehicle weight. Commonly used lightweight materials include aluminum, composites such as SMC, and thermoplastics such as polyolefins. SMC, also known as sheet molding compound, is a high-strength composite material that typically contains primarily thermosetting resins, fillers, and fiber reinforcement. Thermosetting resins are typically based on unsaturated polyesters, vinyl esters, phenolics, or modified vinyl urethanes.

[0003] Polyurethane adhesives are becoming increasingly important in the automotive industry. These adhesives are frequently used to bond a variety of substrates, including coated metals, thermoplastics, and composites. These adhesives are often used in combination to bond coated metals to SMC, SMC to thermoplastics, and thermoplastics to coated metals.

[0004] When polyurethanes are used to bond to SMCs, many adhesives require the use of a primer or surface pretreatment (e.g., Scotch-Brite or sanding) for optimal adhesion, especially when cured at room temperature. Polyolefins can be difficult to bond to due to their low surface energy. Typically, the surface must be treated with a flame or plasma treatment followed by a primer pretreatment or other method.

[0005] Generally, industrial adhesives used to bond dissimilar materials must have good adhesion, as well as a suitable modulus and high elongation. To meet these requirements, plasticizers and tougheners are added in large amounts to polymerizable adhesive compositions. In addition, primers are used for good adhesion to some materials.

[0006] Bonding dissimilar materials presents difficult challenges for industrial adhesives. Different substrates have different coefficients of thermal expansion. When materials are heated, they expand at different rates. For example, a long aluminum profile bonded to glass will expand and contract repeatedly, potentially causing the glass to shatter due to thermal shock.

[0007] There is a need for a polymerizable adhesive composition that can provide suitable modulus, high elongation, and excellent adhesion for bonding a variety of dissimilar substrates, including coated metals, sheet molded composites (SMC), carbon fiber, and thermoplastics, without the use of plasticizers and toughening agents. Furthermore, there is a need for a polymerizable adhesive composition that does not require the use of a primer when applied to bond these materials to achieve excellent adhesion. It has now been discovered that these objectives can be achieved by the following composition: Summary of the Invention

[0008] These and other embodiments will become apparent from the disclosure that follows. The present invention relates to a two-component ("2K") adhesive composition. The composition comprises an NCO prepolymer comprising the reaction product of an isocyanate compound and a polyol. Preferably, the NCO content in the prepolymer is up to about 30%, more preferably about 1-20%, even more preferably less than about 20% to at least about 10%, or about 1-10%. The composition comprises a second component comprising a second polyol. The second polyol preferably has a number average molecular weight of at least about 2,000 daltons, more preferably at least about 4,000 daltons, even more preferably at least about 8,000 daltons, and most preferably at least about 10,000 daltons. The third component comprises a silane adhesion promoter selected from the group consisting of isocyanurate silane adhesion promoters, isocyanate silane adhesion promoters, and combinations thereof, wherein the silane adhesion promoter is present in a concentration of about 0.1-10% by weight. Optional components may include one or more catalysts, preferably tin catalysts.

[0009] Preferably, the adhesive may have a tensile strength of at least about 1 MPa, more preferably at least about 5 MPa, more preferably at least about 7 MPa, and even more preferably at least about 10 MPa, and an NCO / OH index of at least about 80-130, preferably at least about 100, more preferably at least about 110, and even more preferably about 125 or less.

[0010] For certain embodiments, for low modulus embodiments, the adhesive may have a Young's modulus of at least about 1 MPa up to about 10 MPa, preferably about 5 MPa or less. For high modulus adhesives, the adhesive may have a Young's modulus of at least about 10 MPa, preferably at least about 25 MPa, more preferably at least about 50 MPa, and even more preferably at least about 100 MPa.

[0011] With respect to tensile shear adhesion, certain embodiments may have a tensile shear adhesion of at least about 2 MPa, more preferably at least about 3 MPa, even more preferably at least about 5 MPa, and even more preferably up to 10 MPa.

[0012] The present disclosure also encompasses a laminate and a method for manufacturing the laminate. The laminate may include a first substrate, a second substrate, and the adhesive sandwiched between the first substrate and the second substrate. The thermal expansion coefficient of the first substrate differs from the thermal expansion coefficient of the second substrate by at least about 5%, preferably at least about 10%, and more preferably at least about 15%, measured in a temperature range of about -30°C to about 82°C.

[0013] A method for manufacturing a laminate includes applying the adhesive composition to at least one of a first substrate or a second substrate, and adhering the first substrate to the second substrate. The factors related to the thermal expansion coefficients of the first substrate and the second substrate can also be applied to the method for manufacturing a laminate.

[0014] Additionally, embodiments disclosed herein include an alternative two-part ("2K") adhesive composition. The alternative adhesive composition includes an NCO prepolymer comprising the reaction product of an isocyanate compound and a first polyol. The alternative two-part composition further includes a curable second component. The curable second component includes a second polyol, the second polyol preferably having a number average molecular weight of at least 15,000 daltons and including a monoether.

[0015] Preferably, the alternative two-component adhesive comprises a polyurethane and preferably has a tensile strength of at least about 1 MPa, more preferably up to at least about 5 MPa, more preferably at least about 7 MPa, and even more preferably at least about 10 MPa, and preferably has an NCO index of at least about 80 to about 150 or less, preferably at least about 85 to about 130, and more preferably about 125 or less.

[0016] With respect to certain embodiments of the alternative adhesive composition, for low modulus embodiments, the adhesive may have a Young's modulus of at least about 1 MPa up to about 10 MPa, preferably about 5 MPa or less. For high modulus adhesives, the adhesive may have a Young's modulus of at least about 10 MPa, preferably at least about 25 MPa, more preferably at least about 50 MPa, even more preferably at least about 75 MPa, and even more preferably at least about 100 MPa.

[0017] The alternative two-component adhesive may also be used to produce a laminate. The laminate may include a first substrate, a second substrate, and the alternative two-component adhesive sandwiched between the first substrate and the second substrate. Furthermore, the coefficient of thermal expansion of the first substrate differs from the coefficient of thermal expansion of the second substrate by at least about 5%, preferably at least about 10%, and more preferably at least about 15%, measured over a temperature range of about -30°C to about 82°C.

[0018] A method for producing a laminate includes producing a laminate including an alternative two-part adhesive, the method including applying the alternative two-part adhesive to either a first substrate or a second substrate and adhering the first substrate to the second substrate. The requirement that the coefficient of thermal expansion of the first substrate differs from the coefficient of thermal expansion of the second substrate by at least about 5% as discussed above also applies to this method.

[0019] The present invention makes it possible to address the above needs. In particular, the compositions according to the present invention unexpectedly achieve excellent adhesion with high elongation and an appropriate Young's modulus. Some embodiments may have a desired low or high Young's modulus depending on the particular application. DETAILED DESCRIPTION OF THE INVENTION

[0020] Before describing at least one embodiment of the inventive concepts in detail with illustrative figures, experiments, results, and experimental procedures, it should be understood that the inventive concepts are not limited in their application to the details of construction and arrangement of components set forth in the following description or illustrated in the figures, experiments, and / or results. The inventive concepts may be practiced or carried out in other embodiments or in various ways. Therefore, the terms used herein should be interpreted as having the broadest possible scope and meaning, and the embodiments are illustrative and not exhaustive. It should also be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting.

[0021] Scientific and technical terms used in connection with this disclosure shall have the meanings commonly understood by those skilled in the art unless otherwise defined herein. Furthermore, unless otherwise required by context, the singular shall include the plural and the plural shall include the singular. Generally, the chemical nomenclature and techniques used herein are those well known and commonly used in the art. Reactions and purification techniques are performed according to manufacturer's specifications or methods commonly practiced in the art or methods described herein.

[0022] All patents, published patent applications, and non-patent literature mentioned in the specification are indicative of the level of skill of those skilled in the art to which this disclosure pertains. All patents, published patent applications, and non-patent literature referenced in any part of this application are expressly incorporated by reference herein in their entirety to the same extent as if each individual patent or publication were specifically and individually indicated to be incorporated by reference.

[0023] All of the compositions and / or methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the compositions and methods of this invention have been described in terms of preferred embodiments, it will be apparent to those skilled in the art that various changes can be made in the compositions and / or methods, and in the steps or sequence of steps of the methods, described herein without departing from the concept, spirit, and scope of the invention. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope, and concept of the inventive concept as defined by the appended claims. Terms used in this disclosure, unless specifically stated otherwise, shall be understood to have the following meanings:

[0024] When the word "a" or "an" is used in conjunction with the term "comprising" in the claims and / or specification, it can mean "one," but is also consistent with the meanings of "one or more," "at least one," and "one or more." The term "or" in the claims means "and / or" unless explicitly referring to alternatives only or where the alternatives are mutually exclusive; however, this disclosure also supports definitions that refer to alternatives only and "and / or." Throughout this application, the term "about" is used to indicate values ​​that include inherent error of the device, the method used to determine the value, and / or subject-to-subject variation. The term "at least one" refers to a quantity of one or more, including one, and is understood to include quantities such as, but not limited to, 2, 3, 4, 5, 10, 15, 20, 30, 40, 50, 100, etc. The term "at least one" may extend to 100 or 1000 or more, depending on the accompanying term. Furthermore, amounts of 100 / 1000 are not considered limiting, and satisfactory results may be obtained at higher limits. Furthermore, the term "at least one of X, Y, and Z" is understood to include X alone, Y alone, Z alone, and any combination of X, Y, and Z.

[0025] As used in this specification and claims, "comprising" (and all forms of "comprising", e.g., "comprise" and "comprises"), "having" (and all forms of "having", e.g., "have" and "has"), "including" (and all forms of "including", e.g., "includes" and "include"), or "containing" (and all forms of "containing", e.g., "contains" and "contain") is inclusive or open-ended and does not exclude additional, unrecited elements or method steps.

[0026] As used herein, the term "or combinations thereof" refers to all permutations and combinations of the items listed before the term. For example, "A, B, C, or combinations thereof" is intended to include at least any of the following: A, B, C, AB, AC, BC, or ABC, and, where order is important in a particular context, also includes BA, CA, CB, CBA, BCA, ACB, BAC, or CAB. Continuing with this example, combinations containing repeats of one or more items or terms are also expressly included. For example, BB, AAA, MB, BBC, AAABCCCC, CBBAAA, CABABB, etc. Those of skill in the art will understand that the number of items or terms in a combination is generally not limited unless the context clearly dictates otherwise.

[0027] The term "monomer" refers to a small molecule that chemically bonds with one or more monomers of the same or different type during polymerization to form a polymer.

[0028] The term "polymer" refers to a large molecule containing one or more types of monomer residues (repeating units) joined by covalent chemical bonds. By this definition, polymers encompass compounds that can contain very few (commonly referred to as oligomers) to very many monomer units.

[0029] Unless otherwise specified, the standards referred to in this application refer to the standards in effect as of the filing date. Examples of methods that can be used to measure properties are given below. However, these methods are equally applicable, and the claims are not limited to the following methods unless expressly stated in the claims. (1) Methods that may be required to measure number average molecular weight include, but are not limited to, gel permeation chromatography (GPC), vapor phase osmometry, membrane osmometry, and vapor pressure depression. (2) NCO%: One method for measuring NCO% is ASTM D5155. The measurement of NCO% is not necessarily limited to the above method. Unless otherwise specified, NCO% is the weight percent of free NCO in the prepolymer. (3) NCO index is the equivalent ratio of isocyanate to hydroxyl-containing polyol. (4) Viscosity: The viscosity can be measured using a TA Instruments Discovery HR-1 rheometer and a cone-plate. In the viscosity measurements of Examples 1 and 2, the diameter of the cone-plate was 40 mm. Unless otherwise specified, the temperature was 23°C and the shear rate was 0.79 (1 / s). (5) Tensile strength of adhesive: Tensile strength may be measured according to ASTM D-638. The embodiments disclosed herein are not limited to measuring tensile strength according to the above ASTM standard. (6) CTE: One test method that can be used to measure the coefficient of thermal expansion (CTE) is ASTM test method E831. The embodiments disclosed herein are not limited to measuring CTE according to the above ASTM standard. (7) Flame retardancy reported herein may be measured in accordance with UL-94. (8) Hydroxyl number: OH number can be measured according to ASTM D4274 "Test method for polyurethane raw materials: Determination of hydroxyl number of polyol". The method for measuring OH number is not limited to the above ASTM standard. Some kinds of titration methods may also be suitable. (9) Young's modulus: Any suitable method or device may be used to measure the Young's modulus discussed herein, but as an example, the LMEC-1 Young's modulus measuring device may be used.

[0030] "About X" means about ±10% of the value of X. In the context of the present invention, a range of values ​​is understood to include both end values. For example, the range "between 0% and 25%" specifically includes the values ​​0% and 25%.

[0031] A first embodiment disclosed herein includes a two-component ("2K") adhesive composition. The adhesive is preferably a polyurethane adhesive. The adhesive may include an NCO prepolymer. The NCO prepolymer may include an isocyanate compound, preferably the reaction product of a polyisocyanate compound and a polyol. Isocyanates containing two or more isocyanate groups may be used in the present disclosure as stoichiometric isocyanates, excess isocyanates, and free isocyanates. The isocyanates may be monomeric or polymeric isocyanates, including aromatic, aliphatic, and cycloaliphatic polyisocyanates.

[0032] The polyisocyanate may be a diisocyanate, including aliphatic, cycloaliphatic, aromatic, and aliphatic-aromatic diisocyanates. Specific examples of aliphatic and cycloaliphatic diisocyanates include, but are not limited to, ethylene diisocyanate, ethylidene diisocyanate, propylene diisocyanate, butylene diisocyanate, trimethylene diisocyanate, cyclopentylene-1,3-diisocyanate, cyclohexylene-1,4-diisocyanate, cyclohexylene-1,2-diisocyanate, dichlorohexa-methylene diisocyanate, furfurylidene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,2,4-trimethyl-1,6-hexamethylene diisocyanate, 1,12-dodecamethylene diisocyanate, 1-isocyanato-2-methyl-methylsilane, ... Examples include cyclopentane, 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, and the like.

[0033] Specific examples of aromatic and aliphatic-aromatic diisocyanates include, but are not limited to, 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, diphenyl sulfonate, Examples of suitable aromatic diisocyanates include benzene-4,4'-diisocyanate, 2,4-tolylene diisocyanate, 1-chlorobenzene-2,4-diisocyanate, 4,4',4"-triisocyanatotriphenylmethane, 1,3,5-triisocyanato-benzene, 2,4,6-triisocyanato-toluene, 4,4'-dimethyldiphenyl-methane-2,2',5,5-tetraisocyanate, and modified aromatic diisocyanates containing carbodiimide groups, urethane groups, allophanate groups, isocyanurate groups, urea groups or biuret.

[0034] The modified aromatic diisocyanate may be a uretonimine-modified isocyanate derived from 2,4- or 2,6-tolylene diisocyanate, or may be derived from 4,4'- or 2,4'-diphenylmethane diisocyanate, such as a uretonimine-modified 4,4'-diphenylmethane diisocyanate. Suitable uretonimine-modified isocyanates include Rubinate® 1680, available from Huntsman Corporation, and Isonate™ 143L Modified MDI, available from Dow Chemicals Company.

[0035] In one non-limiting embodiment, the isocyanate can be hexamethylene diisocyanate, toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), methylene bisphenyl diisocyanate (MDI), hydrogenated MDI (HMDI), or polyMDI (with two or more functional groups).

[0036] The stoichiometric polyol can be any polyol suitable for polyurethane production. These can be polyols based on polyalkylene oxides, polyesters, or combinations thereof, and can contain bulky side chains and / or long hydrophobic chains. Polyalkylene oxide-based polyols are commonly referred to as 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 polybutadiene and / or partially hydrogenated hydroxyl-terminated polybutadiene), polyisobutylene diols, and mixtures thereof.

[0037] Polyether polyols can 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, and polybutylene glycol. Furthermore, homopolymers and copolymers of polyoxyalkylene polyols can also be used. In particular, copolymers of polyoxyalkylene polyols can include adducts of 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 with at least one compound selected from the group consisting of ethylene oxide, propylene oxide, and butylene oxide.

[0038] In one example, the polyether polyol can include a polymer of propylene oxide and / or a copolymer of ethylene and propylene oxide. In one non-limiting embodiment, the polyether polyol is an ethylene oxide-capped polypropylene oxide.

[0039] The number average molecular weight of the polyether polyols can typically vary from about 2,000 daltons to about 20,000 daltons, or from about 3,500 daltons to about 12,000 daltons, or from about 2,000 daltons to about 12,000 daltons. For example, Acclaim® 4220N polyol, available from Covestro, is propylene oxide-based and ethylene oxide-terminated and has a number average molecular weight of 4,000 daltons.

[0040] 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 the difunctional polyether polyols may vary from about 2,000 to about 20,000 daltons, or from about 2,000 to 12,000 daltons. For example, Pluracol® P2010, available from BASF, is a polyether polyol with a number average molecular weight of 2,000 daltons. PPG 2000, available from PPG, is another example of a suitable polyol. The molecular weight of the trifunctional polyether polyols may vary from about 84 to about 20,000 daltons, or from about 100 to 12,000 daltons, including Pluracol® TP-440 polyol, available from BASF. The molecular weight of the tetrafunctional polyether polyol can vary from about 100 to about 20,000 daltons, or from about 400 to 12,000 daltons. For example, Pluracol® 355, available from BASF, is a polyether polyol 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 another example, the polyether polyol has a molecular weight of about 4,000 daltons or less, preferably less than about 3,000 daltons.

[0041] Polyester-based polyols (also called polyester polyols) can include amorphous and liquid polyester polyols, fatty acid polyester polyols such as castor oil and vegetable oils of different molecular weights and functional groups.

[0042] Polyester polyols can be formed as the reaction product of one or more carboxylic acids and one or more polyols (e.g., diols and / or triols). Carboxylic acids useful for forming polyester polyols can include, but are not limited to, adipic acid, glutaric acid, succinic acid, malonic acid, oxalic acid, and mixtures thereof. Diols useful for forming polyester polyols can include, but are not limited to, ethylene glycol, propanediol, butanediol, neopentyldiol, pentanediol, hexanediol, and mixtures thereof. Triols potentially useful for forming polyester polyols can include trimethylolpropane.

[0043] Examples of fatty acid polyester polyols may include castor oil, hydroxylated products of unsaturated or polyunsaturated natural oils, hydrogenated products of unsaturated or polyunsaturated polyhydroxyl natural oils, polyhydroxyl esters of alkyl hydroxyl fatty acids, polymerized natural oils, soybean polyols, alkyl hydroxylated amides of fatty acids, and cashew nut seed oil.

[0044] In one non-limiting embodiment, the polyester polyol can be obtained from the reaction of a triol with azelaic acid. The triol can be glycerol. An example of such a polyester polyol is Emerox® 14001, which is derived from natural oils and is commercially available from Emery Oleochemicals Company.

[0045] The number average molecular weight of polyester polyols typically varies from about 1,000 to about 20,000 daltons, or from about 1,300 to 10,000 daltons. Admex™ 525 polyol (commercially available from Eastman Chemical Company) is a 1,400 molecular weight polyester polyol that can be used.

[0046] The NCO% in the prepolymer is preferably about 30% or less, more preferably about 1-20%, even more preferably less than about 20%, and even more preferably about 10% or more or up to about 20%. In a specific example, one preferred range of NCO% is about 12-22%, in another preferred embodiment about 10%-less than 19%, and in yet another embodiment the preferred range is about 14-19%.

[0047] The second component of the adhesive composition can include a second polyol. Preferably, the second polyol has a number average molecular weight of about 2,000 daltons or greater, more preferably about 4,000 daltons or greater, even more preferably about 8,000 daltons or greater, and most preferably greater than about 10,000 daltons.

[0048] In one particular embodiment, the number average molecular weight of the second polyol of the second component is about 18,000 daltons or less. Specific embodiments of the number average molecular weight of the second polyol can be about 15,000 daltons or less, about 13,000 daltons or less, or about 12,000 daltons or less.

[0049] In another particular embodiment, the second polyol of the second component can have a number average molecular weight of at least about 15,000 daltons, preferably at least about 20,000 daltons, even more preferably at least about 50,000 daltons, and most preferably greater than about 80,000 daltons.

[0050] Suitable examples of the polyol second component include polymer-modified polyols, preferably modified polyether polyols. In a preferred embodiment, the concentration of the polymer-modified polyol is about 70% by weight or less of the second component.

[0051] In certain embodiments, the second polyol comprises at least one polymer or prepolymer comprising one or more polyether polyols with one or more organic polymer particles dispersed therein or grafted onto its backbone. The one or more organic polymer particles may be based on monovinylidene aromatic monomers and copolymers of monovinylidene aromatic monomers with conjugated dienes, acrylates, methacrylates, unsaturated nitrites, or mixtures thereof. The copolymers may be block or random copolymers. In one non-limiting embodiment of the present disclosure, the one or more organic polymer particles comprise unsaturated nitrites, copolymers of conjugated dienes and monovinylidene aromatic monomers, copolymers of unsaturated nitrites and monovinylidene aromatic monomers, or polyureas. In another non-limiting embodiment of the present disclosure, the particles most preferably comprise polystyrene-acrylonitrile copolymers. Preferably, the organic polymer particles are incorporated into the prepolymer by incorporating a polyol (preferably a triol) containing organic polymer particles and dispersing the organic polymer particles. One or more of the polyols, e.g., triols, have dispersed therein one or more organic polymers, e.g., thermoplastic polymers, rubber-modified thermoplastic polymers, or polyureas. Preferred polyols with dispersed or grafted organic polymer particles are disclosed in Zhou, U.S. Pat. No. 6,709,539, column 4, line 13 to column 6, line 18, incorporated herein by reference. Preferably, the polyol used to disperse the organic particles is one or more polyether triols described herein. Preferably, the prepolymer containing one or more organic polymer particles is present in the composition of the present invention in an amount sufficient to enhance the elastomeric properties and modulus of the composition. In this particular embodiment, the second polyol also preferably has a number average molecular weight of about 15,000 daltons, more preferably at least about 20,000 daltons, even more preferably at least about 50,000 daltons, and most preferably greater than about 80,000 daltons.

[0052] The second component may include one or more additional polyols. The additional polyols may be the same or different from those described above for the NCO prepolymer. The additional polyols may be polyether polyols. In one non-limiting embodiment, the polyether polyol is a polymer of propylene oxide or a copolymer of ethylene and propylene oxide. In another non-limiting embodiment, the free polyol may be a cardanol-based polyester polyol or a poly-ε-caprolactone polyol.

[0053] The adhesive composition may also include a silane adhesion promoter selected from the group consisting of isocyanurate silane adhesion promoters, isocyanate silane adhesion promoters, and combinations thereof. The concentration of the silane adhesion promoter may comprise about 0.1 to 10% by weight. Non-limiting examples of isocyanurate 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 (isocyanatemethyl)methyldimethoxysilane, 3-isocyanatepropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, 3-isocyanatepropylmethyldimethoxysilane, 3-isocyanatepropylmethyldiethoxysilane, tris[3-(trimethoxysilyl)propyl]isocyanurate, tris[3-(triethoxysilyl)propyl]isocyanurate, isocyanatemethyltrimethoxysilane, and isocyanatemethyltriethoxysilane. The above isocyanurate compounds may be used in any combination.

[0054] Optional components of the adhesive may include one or more catalysts, preferably tin catalysts. In another optional embodiment, the adhesive composition may contain less than about 1% by weight of solvent and / or water, preferably no more than the nominal amount of either solvent or water.

[0055] The adhesive composition may further comprise a fourth component selected from the group consisting of at least one of an epoxy-functional silane adhesion promoter, a polyether diamine, a monoether, and combinations thereof. The concentration of the fourth component may comprise about 20% by weight or less, preferably at least about 0.5% by weight or less.

[0056] Non-limiting examples of suitable epoxy-functional silane adhesion promoters include: 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-(2,3-epoxypropoxypropyl)methyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and combinations thereof.

[0057] Non-limiting examples of polyetheramines include polyoxyalkylene polyamine-based diamines or triamines such as Jeffamines or Baxxodur polyetheramines. Non-limiting examples of monoethers include poly(ethylene glycol-ran-propylene glycol) monobutyl ether, poly(propylene glycol) monobutyl ether, poly(ethylene-co-1,2-butylene) monool, polyester ether monool, C12 to C18 alcohols, and combinations thereof.

[0058] The adhesive composition may further include a flame retardant package. The flame retardant package may comprise up to about 25% by weight of the adhesive composition. In a specific example, for a 2K polyurethane adhesive composition, the flame retardant package may be included in the curing agent.

[0059] In general examples, the flame retardant package may include any combination of the following: non-halogenated phosphate esters, non-halogenated phosphate polyesters, halogen-containing phosphate esters, halogen-containing phosphate polyesters, and non-halogenated phosphate polyesters. More specific examples of flame retardants include (1) halogenated flame retardants, known as organohalogen flame retardants, which contain chlorine or bromine bonded to carbon, and (2) organophosphorus flame retardants, which contain phosphorus bonded to carbon.

[0060] Examples of compounds that can be used in halogen-free systems include aluminum trihydrate, magnesium hydroxide, antimony trioxide, red phosphorus, ammonium polyphosphate, zinc borate, and any combination thereof. Examples of halogen-containing flame retardants include tris(2-chloropropyl)phosphate (TCPP), (2-hydroxyethoxy)ethyl 2-hydroxypropyl 3,4,5,6-tetrabromophthalate (Saytex RB-79), and combinations thereof.

[0061] A specific example of a brominated flame retardant package can include Saytex RB-79 combined with a chlorinated phosphate flame retardant. Another specific flame retardant example is antimony trioxide (e.g., FireGard ATO) combined with a halogen source, such as decabromodiphenylethane (which may be commercially available as "Broshield 21-B"). Another example of a flame retardant package can include an organophosphorus compound added to an adhesive or chemically bonded to a polymer.

[0062] If desired, the above components can be used in any combination, including, but not limited to, combinations of compounds comprising halogenated systems with compounds included in halogen-free systems.

[0063] The adhesive compositions disclosed herein may contain less than about 10% by weight of plasticizer, preferably less than about 5% by weight, more preferably less than about 4% by weight, even more preferably less than about 2% by weight, and most preferably less than about 1% by weight. In certain embodiments, the plasticizer content may be less than about 0.5% by weight, less than about 0.1% by weight, or below the detection limit.

[0064] The adhesive composition may include a tertiary amine, including a blocked tertiary amine, and preferably the tertiary amine includes at least one of the following: 1,4-diazabicyclo[2.2.2]octane solution, DBU (diazabicycloundecene), 1,4-diazabicyclooctane, and combinations thereof.

[0065] Another component of the adhesive composition may include a chain extender comprising a polyol having at least two hydroxyl units or aromatic diamine functional groups. Suitable chain extenders include diols and triols. In one embodiment, the chain extender may be a low molecular weight compound and may be either hydroxyl- or amine-terminated. In a non-limiting embodiment, the chain extender may be a hydroxyl-terminated low molecular weight polyol having a molecular weight ranging from about 25 to about 1,000 daltons, or from about 32 to about 600 daltons. The low molecular weight chain extender may be selected from the group consisting of ethylene glycol, diethylene glycol, 1,5-pentanediol, 1,3-pentanediol, 1,3-butanediol, 1,4-butanediol, 1,2-propylene glycol, 1,3-propylene glycol, 1,6-hexylene glycol, dipropylene glycol, neopentyl glycol, 3-methylpentanediol, 1,4-cyclohexanedimethanol, and combinations thereof. Examples of suitable aromatic diamine compounds include diethyltoluenediamine, tetrapropoxyethylenediamine, methylenebis(orthoethylaniline), and combinations thereof.

[0066] The adhesive composition may also contain various fillers, rheology modifiers, colorants, and additives as needed. Some examples of typical fillers for polyurethane adhesives include talc, precipitated calcium carbonate, and combinations thereof.

[0067] For the 2K adhesives disclosed herein, the second polyol component may comprise a portion of the curing agent ("Side B"), the NCO prepolymer may comprise a portion of the Side A prepolymer, and the volume ratio of Side A prepolymer to Side B prepolymer may be from about 1:10 to about 10:1, with preferred volume ratios being about 1:1, at least about 1:1.5, at least about 1:4, and at least about 1:2.

[0068] Preferably, the adhesive has a tensile strength of at least about 1 MPa, more preferably up to at least about 5 MPa, more preferably at least about 7 MPa, even more preferably at least about 10 MPa, and an NCO / OH index of at least about 80-130, preferably at least about 100, more preferably at least about 110, even more preferably about 125 or less.

[0069] Preferably, the adhesive composition has a Young's modulus of at least about 1 MPa to greater than 100 MPa. For certain embodiments of the adhesive composition, for low modulus embodiments, the adhesive may have a Young's modulus of at least about 1 MPa to up to about 10 MPa, preferably up to about 5 MPa. For high modulus adhesives, the adhesive may have a Young's modulus of at least about 10 MPa, preferably at least about 25 MPa, more preferably at least about 50 MPa, even more preferably at least about 75 MPa, and even more preferably at least about 100 MPa.

[0070] The disclosed adhesives can be part of a laminate. Preferably, the laminate includes a first substrate and a second substrate. Preferably, any one of the adhesives disclosed herein is sandwiched between the first substrate and the second substrate. The coefficient of thermal expansion ("CTE") of the first substrate differs from the coefficient of thermal expansion of the second substrate by at least about 5%, preferably at least about 10%, and more preferably at least about 15%, measured over a temperature range of about -30°C to about 82°C.

[0071] Preferably, the laminate is formed without a sufficient amount of primer to help the adhesive adhere to one or both substrates, and more preferably without any primer at all.

[0072] The laminates disclosed herein are not limited to specific substrates, except that the two substrates have different CTEs as described above. Non-limiting examples of substrates include metals, coated metals, thermoplastics, and composites. Preferably, the composites may include carbon fiber or sheet molding compounds. Preferably, the metals may include at least one of aluminum, steel, stainless steel, galvanized steel, carbon steel, and alloys thereof. Examples of thermoplastics may include at least one of polyamides, polyolefins, and combinations thereof. Preferably, the coating of coated metals includes nickel. Preferred polyolefins include polycarbonate, polyethylene terephthalate, polybutylene terephthalate, and combinations thereof.

[0073] The present disclosure also encompasses a method for producing the laminate described herein. The method includes applying any of the adhesives disclosed herein to either a first substrate or a second substrate. The method also includes adhering the first substrate to the second substrate. The above disclosure regarding CTE also applies to the method for producing the laminate.

[0074] Optionally, the method may not include applying a primer to either the first substrate or the second substrate, preferably both the first and second substrates. Further, the method may not include mechanically pretreating either the first substrate or the second substrate, preferably not mechanically pretreating both the first and second substrates, prior to applying the adhesive.

[0075] The method of making a laminate may also include curing the adhesive at a temperature below about 140° C., preferably below about 120° C., more preferably below about 105° C., more preferably below about 100° C., even more preferably below about 90° C., and even more preferably below about 80° C. In certain embodiments, preferred curing temperatures may include below about 75° C., below about 65° C., below about 50° C., or at room temperature or below.

[0076] The adhesive compositions disclosed herein include alternative embodiments. These alternative embodiments may also be 2K polyurethane adhesive compositions. The alternative adhesive may include an NCO prepolymer comprising the reaction product of an isocyanate compound and a first polyol. The alternative adhesive composition may include a curable second component. The curable second component may include a second polyol and a monoether.

[0077] The disclosure above regarding the NCO prepolymer equally applies to the NCO prepolymer of the alternative adhesive composition, and the disclosure above regarding the second polyol equally applies to the second polyol of the curing agent of the alternative adhesive composition.

[0078] In one embodiment, the second polyol of the curing agent in an alternative adhesive embodiment comprises a polyoxyalkylene polyol having a hydroxyl number of at least about 15 mg KOH / g, preferably at least about 17 mg KOH / g, more preferably no greater than about 30 mg KOH / g, and even more preferably no greater than about 25 mg KOH / g.

[0079] The second polyol of the curing agent of the alternative adhesive composition can have a number average molecular weight of at least about 15,000 daltons, preferably at least about 20,000 daltons, even more preferably at least about 50,000 daltons, and most preferably greater than about 80,000 daltons.

[0080] In certain embodiments, the second polyol comprises at least one polymer or prepolymer comprising one or more polyether polyols with one or more organic polymer particles dispersed therein or grafted onto its backbone. The one or more organic polymer particles may be based on monovinylidene aromatic monomers and copolymers of monovinylidene aromatic monomers with conjugated dienes, acrylates, methacrylates, unsaturated nitrites, or mixtures thereof. The copolymers may be block or random copolymers. In one non-limiting embodiment of the present disclosure, the one or more organic polymer particles comprise unsaturated nitrites, copolymers of conjugated dienes and monovinylidene aromatic monomers, copolymers of unsaturated nitrites and monovinylidene aromatic monomers, or polyureas. In another non-limiting embodiment of the present disclosure, the particles most preferably comprise polystyrene-acrylonitrile copolymers. Preferably, the organic polymer particles are incorporated into the prepolymer by incorporating a polyol (preferably a triol) containing organic polymer particles and dispersing the organic polymer particles. One or more organic polymers, such as thermoplastic polymers, rubber-modified thermoplastic polymers, or polyureas, are dispersed in the polyol, e.g., one or more triols. Preferred polyols with dispersed or grafted organic polymer particles are disclosed in Zhou, U.S. Patent No. 6,709,539, column 4, line 13 to column 6, line 18, and are incorporated herein by reference. Preferably, the polyol used to disperse the organic particles is one or more polyether triols described herein.

[0081] The concentration of the second polyol in the curing agent of the alternative adhesive composition may comprise 60% by weight or less, preferably about 50% by weight or less, more preferably about 10-40% by weight, and even more preferably about 15-35% by weight, based on the weight of the curable second component.

[0082] The monoether of the curing component of the alternative adhesive composition can include a poly(propylene glycol) monoether, preferably poly(propylene glycol) monobutyl ether. The concentration of the monoether can be about 25% by weight or less, preferably about 0.5-20% by weight, more preferably about 1-15% by weight, and even more preferably about 3-12% by weight, based on the weight of the curable second component. The monoether examples above are also applicable to the alternative adhesive embodiments and are incorporated herein as if fully rewritten.

[0083] The curable second component may further comprise a third polyol having a number average molecular weight of at least about 4,000 daltons. The curing agent of the alternative adhesive composition may further comprise a diol or triol, preferably a diol primary alcohol. The alternative adhesive also preferably comprises less than about 1 wt. % plasticizer, and is preferably plasticizer-free.

[0084] Preferably, the replacement adhesive has a tensile strength of at least about 1 MPa, more preferably at least about 5 MPa, more preferably at least about 7 MPa, and even more preferably at least about 10 MPa. Preferably, the replacement adhesive has an NCO index of at least about 80 to about 150, preferably at least about 85 to about 130, and more preferably about 125 or less.

[0085] The volume ratio of the NCO prepolymer to the curable second component can be from about 1:10 to about 10:1, with preferred volume ratios being about 1:1, at least about 1.5:1, at least about 4:1, and at least about 2:1.

[0086] The alternative adhesive may have a Young's modulus of at least about 1 MPa to greater than about 100 MPa. For certain embodiments of the alternative adhesive composition, for low modulus embodiments, the adhesive may have a Young's modulus of at least about 1 MPa to up to about 10 MPa, preferably up to about 5 MPa. For high modulus adhesives, the adhesive may have a Young's modulus of at least about 10 MPa, preferably at least about 25 MPa, more preferably at least about 50 MPa, even more preferably at least about 75 MPa, and even more preferably at least about 100 MPa.

[0087] The above disclosure regarding laminates and methods of making laminates is also applicable to the alternative adhesive compositions.

[0088] All of the above embodiments can be combined with one another, in particular the various components in the composition described above can be combined with one another in particularly preferred embodiments.

[0089] Compositions according to the present disclosure and their uses may be prepared and used in accordance with the examples set forth below, which are provided to illustrate the present disclosure and are not intended to limit, for example, the preparation of the compositions and their uses.

[0090] Example Example 1: Materials and Methods material The following ingredients were combined: 1. Sample 1 Agent A: Isocyanate silane adhesion promoter in prepolymer [Table 1]

[0091] The procedure used to prepare Agent A is as follows: 1. Charge the polyol into a reactor and heat to 90°C. 2. When the temperature reaches 80°C, fill with talc under low shear rate stirring conditions until wet. 3. Add the fumed silica under low shear rate stirring conditions until wetted. 4. Mix under vacuum for 60 minutes and heat until the temperature reaches 93°C. 5. Measure the moisture content until the moisture content is less than 400 ppm. 6. Cool to 83°C. 7. Fill with Rubinate M and molecular sieves. 8. Reapply vacuum and mix for 2.0 hours. 9. Fill with Rubinate 9310 and reapply vacuum for 1 hour. 10. Cool the batch to 70°C. 11. Charge silane and mix for 10 minutes. 12. Degas for 30 minutes. 13. Measure the viscosity and isocyanate % (NCO%). NCO% = 16.5%, 0.79 1 / s, 30256 cP.

[0092] Sample 2 Intermediate [Table 2]

[0093] procedure: 1. Charge TP-440 and Acclaim 4220N into a reactor and heat to 93°C. 2. Apply vacuum for 60 minutes and check moisture content until moisture content is less than 300 ppm. 3. Charge the reactor with Mondur MLQ and Rubinate 9310 and hold under vacuum for 2 hours. 4. Cool the batch.

[0094] Sample 3 [Table 3]

[0095] The procedure used to form Part B is as follows: 1. Charge the polyol to the reactor and heat to 93°C and hold at that temperature. At 2.93°C, charge talc, fumed silica and mix at low shear until wetted. 3. Mix under vacuum and high shear rate for 60 minutes. 4. Check moisture until moisture content is below 300 ppm. 5. Reduce the temperature to 65-70°C. 6. Add 1,4-butanediol. 7. Add piperazine and Jeffamine D-400 and mix at 65-70°C for 30 minutes. 8. Add sieve, catalyst and colorant and mix at 65-70°C for 60 minutes. 9. Degas at 65-70°C for 30 minutes. 10. Measure viscosity at a shear rate of 0.79 1 / s: 32023 cP.

[0096] The test results for Samples 1 and 3 are summarized in Tables 1-3 and 1-4 below. [Table 4]

[0097] [Table 5]

[0098] Sample 4 Agent B: Hardener containing flame retardant [Table 6]

[0099] Manufacturing procedure for sample 4 1. Charge the polyol and intermediate into the reactor, heat to 93°C and hold the temperature. At 2.93°C, add the talc, fumed silica, and ammonium polyphosphate and mix at low shear until wetted. 3. Apply vacuum for 60 minutes and check until moisture reaches a level below 300 ppm. 4. Reduce the temperature to 65-70°C. 5. Add BDO. 6. Add 1,8-diaminonaphthalene, Jeffamine D-400, and Exolite OP560 and mix at 65-70°C for 30 minutes. 7. Add sieve and catalyst and mix at 65-70°C for 60 minutes. 8. Degas at 65-70°C for 30 minutes. 9. Measure viscosity and adjust if necessary. 10. Filter the batch. [Table 7]

[0100] Adhesive embodiments formed from Samples 1 and 4 were tested for flame retardant performance. Adhesives formed from Samples 1 and 4 passed the UL-94 V0 test at a 0.25 mm adhesive gap and the UL-94 V1 test at a 0.75 mm adhesive gap. Control 1 failed both flame retardant performance tests. The results are summarized in Tables 1-8. [Table 8] The designation t1 indicates the time when the sample started to burn, and t2 indicates the time when the sample stopped burning. In the case of V0, the sample did not burn. In the case of V1, the sample started to burn after 10 seconds and the burning was extinguished after 48 seconds. On the other hand, Control 1 failed V0 because it continued to burn for more than 10 seconds after the start of combustion. Similarly, Control 1 failed the test because it continued to burn for more than 60 seconds.

[0101] Example 2 Sample 5 Agent A Prepolymer [Table 9]

[0102] procedure: 1. Charge the polyol into a reactor and heat to 90°C. 2. When the temperature reaches 80°C, charge the talc and mix at low shear until all is wetted. 3. Charge the polyol into the reactor and heat to 90°C. 4. Charge the polyol into the reactor and heat to 90°C. 5. Once the temperature reaches 80°C, charge in the talc and mix at low shear until all is wetted. 6. Mix under vacuum at high shear for 60 minutes and heat until the temperature reaches 93°C. 7. Measure the moisture content until it is less than 400 PPM. Cool to 8.83°C. 9. Fill approximately 2 / 3 of the Rubinate 9720 with molecular sieves. 10. Slowly add the silica under low shear and continue mixing until wetted. 11. Reapply vacuum and mix at 83°C for 2 hours. 12. Fill with the remaining Rubinate 9720. 13. Reapply vacuum for 60 minutes. 14. Cool the reactor to 70°C. 15. Add Silane-187 and VPS 7163. 16. Degas for 30 minutes. 17.Measure viscosity and NCO%. a. The target NCO% was 17%. 18. Filter the batch.

[0103] result: Measurement characteristics Moisture content <400ppm NCO% 16.8% Viscosity 0.791 / s:27897cP

[0104] Sample 6 Intermediate [Table 10]

[0105] procedure: 1. Fill with Pluracol TP-440 and Acclaim 4220N and heat to 83°C. 2. Apply vacuum for 60 minutes and check until moisture content is less than 300 ppm. 3. Fill with Mondur MLQ and Rubinate 9310 and maintain under vacuum at 83°C for 2 hours. 4. Cool the batch.

[0106] Sample 7 (hardener using glass beads and PEP 550) [Table 11]

[0107] procedure: 1. Fill with polyol and Sample 6 intermediate. Apply vacuum and heat to 94°C. At 2.94°C, talc, fumed silica, and ammonium polyphosphate are packed under low shear rate. 3. Mix under vacuum at high shear for 60 minutes and check until moisture content is less than 300 PPM. 4. Reduce the temperature to 65-70°C. 5. Add BDO. 6. Add 1,8-diaminonaphthalene, PEP 550, Jeffamine D-400, and liquid phosphoric acid and mix at 65-70°C for 30 minutes. 7. Add the sieve and catalyst and mix at 65-70°C for 60 minutes. 8. Degas at 65-70°C for 30 minutes. 9.Measure the viscosity. a. The viscosity was 27230 cP at a shear rate of 0.79 1 / s. 10. Filter the batch.

[0108] Sample 8 Hardener (without Jeffamine D-400) [Table 12]

[0109] procedure: 1. Fill the intermediate of polyol and sample 6. 2. Apply vacuum and heat to 94°C. 3. At 94°C, talc, fumed silica, and ammonium polyphosphate are packed under low shear rate. 4. Mix under vacuum at high shear for 60 minutes and check moisture until moisture content is less than 300 PPM. 5. Reduce the temperature to 65-70°C. 6. Add BDO. 7. Add 1,8-diaminonaphthalene, PEP 550, and liquid phosphoric acid and mix at 65-70°C for 30 minutes. 8. Add the sieve and catalyst and mix at 65-70°C for 60 minutes. 9. Degas at 65-70°C for 30 minutes. 10.Measure the viscosity. a. The viscosity was 15,000 cP at a shear rate of 0.79 1 / s. 11. Filter the batch. The results of Sample 5 / Sample 7 (NCO index 124, volume ratio 1:1) and Sample 5 / Sample 8 (NCO index 121, volume ratio 1:1) were compared.

[0110] Example 3 Tables 3-11 and 3-12 show the formulations for Samples 11 to 14. The basic procedures for preparing the prepolymer and curing agent are shown in Tables 3-13 and 3-14.

[0111] For Samples 11-14 shown in Table 3-15, the prepolymer and curing agent prepared in Tables 3-11 and 3-12 were loaded into separate cartridges and injected through a static mix tube to achieve the complete mix shown in Table 3-15. The mixed polymerizable adhesive composition was then applied directly from the static mix tube to one side of the test substrate.

[0112] Tensile shear tests were conducted to measure the tensile shear strength and failure mode of the adhesive bond. Tensile shear test specimens were prepared by overlapping the last 2.5 cm of a pair of 10 x 2.5 cm specimens to obtain a 17.8 cm long specimen with a 0.76 mm glass spacer bead between the adhesive and the overlap. The specimens were placed between a double-sided fixture held at the cure temperature until cured. The specimens were then removed from the fixture and held at about 20-25°C for about 24-72 hours before testing. Tensile shear tests were conducted in accordance with ASTM D5868 at a crosshead speed of 2 inches per minute. ASTM D5868 is incorporated herein by reference in its entirety. Unless otherwise noted, all adhesives were prepared with an isocyanate index ranging from about 95 to about 105.

[0113] Samples 11-14 were evaluated using room temperature and heat cures. Controls 12 and 13 are commercially available 2K polyurethane adhesives. The controls contained no epoxy-functional silane, no isocyanurate silane, no polyol with a number-average molecular weight of at least 15,000 daltons, and no monoether. Control 12 performed well during the heat cure, but did not pass the required 90% adhesive failure mode during the room temperature cure when tested at 82°C and after one week of water immersion. For comparison, Sample 11 (containing the monoether) exhibited excellent tensile shear strength and failure mode under both cure conditions.

[0114] Sample 12 is a low modulus adhesive containing Alamol PB14 and Hyperlite E-855 as curing agents (a monoether and a second polyol with a number average molecular weight of at least 15,000 daltons). Sample 12 has an NCO index of 103 and contains 13% MDI in the organic phase. As used herein, "organic phase" refers to all organic materials, excluding inorganic materials, in the adhesive composition. Control 13 served as the reference sample for this test. It has an NCO index of 112 and contains 25% MDI in the organic phase. Both room temperature cure and heat cure were evaluated. Control 13 performed very well under heat cure conditions, but showed poor strength and poor failure mode under room temperature cure. Sample 12 exhibited excellent tensile shear strength and failure mode under both cure conditions.

[0115] Adhesives prepared from Samples 12–14 were used to bond low surface energy substrates, glass-filled polypropylene (GFPP) to thermoplastic olefin (TPO), and PP to bare aluminum. Prior to bonding, the GFPP and TPO surfaces were wiped with IPA and flame-treated, while the aluminum-6061 surface was polished. Lap-shear tests of the cured adhesives were performed at room temperature (RT) and after 1 week of water immersion. Samples 12–14 (containing Alamol PB14 and Hyperlite E-855 curing agents) exhibited low NCO indexes (Sample 12: 103, Sample 13: 100, Sample 14: 104) and low %MDI in the organic phase (Sample 12: 13%, Sample 13: 17%, Sample 14: 12%). The results in Tables 3–18 indicate that both adhesives exhibited high lap-shear strength and excellent adhesion to the test substrates. [Table 13] [Table 14] [Table 15] [Table 16] [Table 17] [Table 18] [Table 19]

[0116] While the invention has been described in detail with reference to certain preferred embodiments, it should be understood that the disclosure is not limited to those precise embodiments. Rather, numerous modifications and variations will occur to those skilled in the art in light of the present disclosure without departing from the scope and spirit of the invention.

[0117] Aspects In addition to the summary, detailed description, and some embodiments in the claims, the present disclosure may include further aspects such as those listed below. The first aspect is a. An NCO prepolymer comprising a reaction product of an isocyanate compound and a polyol, preferably having an NCO content of about 30% or less, more preferably about 1 to 20%, and even more preferably less than 20% to at least 10%, or about 1 to 10%; b. a second component comprising a second polyol, preferably having a number average molecular weight of at least about 2,000 daltons, more preferably at least about 4,000 daltons, even more preferably at least about 8,000 daltons, and most preferably greater than 10,000 daltons; c. a silane adhesion promoter selected from the group including isocyanurate silane adhesion promoters (non-limiting examples of isocyanurate silanes include 1,3,5-tris[3-(trimethoxysilyl)propyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione), isocyanate silane adhesion promoters, and combinations thereof, at a concentration of about 0.1 to 10% by weight; and d. one or more optional catalysts, preferably tin catalysts; a two-component adhesive composition comprising: The properties of the adhesive are: (i) a tensile strength of the adhesive that is preferably at least about 1 MPa, more preferably at least about 5 MPa, even more preferably at least about 7 MPa, and even more preferably at least about 10 MPa; (ii) a Young's modulus of at least about 1 MPa; (iii) an NCO / OH index of at least about 80 to 130, preferably at least about 100, more preferably at least about 110, and even more preferably about 125 or less; (iv) and combinations thereof; may include one or more of:

[0118] In a second embodiment, the adhesive of embodiment 1 further comprises a fourth component selected from the group of at least one of an epoxy-functional silane adhesion promoter, a polyether diamine, a monoether, and combinations thereof, wherein the concentration of the fourth component is less than or equal to about 20 wt.%, preferably at least about 0.5 wt.%, and preferably the fourth component comprises at least one of an epoxy-functional silane adhesion promoter, a monoether, and combinations thereof.

[0119] In a third embodiment, the adhesive of any one of embodiments 1 or 2, wherein the second polyol of the second component comprises a polymer-modified polyol, preferably a modified polyether polyol, and the concentration of the polymer-modified polyol is less than or equal to about 70% by weight of the second component.

[0120] In a fourth embodiment, the adhesive of any one of embodiments 1-3 includes a flame retardant package, the flame retardant package comprising no more than about 25% by weight of the adhesive composition.

[0121] In a fifth aspect, in the adhesive composition of any one of aspects 1-4, the composition comprises less than about 10 wt. % plasticizer, preferably less than about 5 wt. %, more preferably less than about 4 wt. %, even more preferably less than about 2 wt. %, and most preferably less than about 1 wt. %.

[0122] In a sixth aspect, the adhesive composition of any one of aspects 1-5 includes a tertiary amine, and preferably the tertiary amine includes at least one of 1,4-diazabicyclo[2.2.2]octane solution, DBU (diazabicycloundecene), 1,4-diazabicyclooctane, and combinations thereof.

[0123] In a seventh embodiment, the adhesive composition of any one of embodiments 1-6 includes a chain extender comprising a polyol having at least two functional groups, preferably having an NCO% of the adhesive of about 30% or less, more preferably about 25% or less, even more preferably about 20% or less by weight, and most preferably at least about 10% by weight.

[0124] In an eighth embodiment, a laminate including a first substrate, a second substrate, and the adhesive of any one of embodiments 1 to 7 is sandwiched between the first substrate and the second substrate, and the thermal expansion coefficient of the first substrate differs from the thermal expansion coefficient of the second substrate by at least about 5%, preferably at least about 10%, and more preferably at least about 15%, measured in a temperature range of about −30° C. to about 82° C.

[0125] In a ninth embodiment, the laminate of embodiment 8 does not include a primer in an amount sufficient to assist the adhesive in adhering to either the first substrate or the second substrate.

[0126] In a tenth aspect, the laminate of any of aspects 8 or 9, wherein the first substrate comprises one of a metal, a coated metal, a thermoplastic, a composite; preferably the composite comprises carbon fiber, a sheet molding compound; preferably the metal may comprise at least one of aluminum, steel, stainless steel, galvanized steel, carbon steel, and alloys thereof; preferably the thermoplastic comprises at least one of a polyamide, a polyolefin, and combinations thereof; preferably the coating of the coated metal comprises nickel; and preferably the polyolefin comprises polycarbonate, polyethylene terephthalate, polybutylene terephthalate, and combinations thereof.

[0127] An eleventh aspect is a method for producing a laminate, comprising the steps of: a. applying the adhesive of any one of aspects 1-8 to either a first substrate or a second substrate; b. adhering a first substrate to a second substrate, The coefficient of thermal expansion of the first substrate differs from the coefficient of thermal expansion of the second substrate by at least about 5% as measured over a temperature range of about -30°C to about 82°C.

[0128] A twelfth embodiment includes the method of embodiment 11, wherein the method does not include applying a primer to either the first substrate or the second substrate, preferably to both the first substrate and the second substrate.

[0129] In a thirteenth aspect, any of aspects 11 or 12 does not include the step of mechanically pretreating either the first substrate or the second substrate, preferably both the first substrate and the second substrate, prior to applying the adhesive.

[0130] A fourteenth aspect is applicable to any one of aspects 11 to 13, and further comprises curing the adhesive at a temperature less than about 140°C, preferably less than about 120°C, even more preferably less than about 105°C, more preferably less than about 100°C, even more preferably less than about 90°C, and even more preferably less than about 80°C.

[0131] A fifteenth embodiment is applicable to the two-component adhesive of any one of Embodiments 1 to 8, wherein the second polyol component comprises an NCO prepolymer comprising a curing agent portion (Part B) and Part A, and the volume ratio of Part A to Part B is from about 1:10 to about 10:1, and preferred volume ratios can be about 1:1, at least about 1.5:1, at least about 4:1, and at least about 1:2.

[0132] Another aspect disclosed herein is a. an NCO prepolymer comprising the reaction product of an isocyanate compound and a first polyol; b. a curable second component comprising (i) a second polyol, and (ii) a monoether; The adhesive properties may include one or more of the following: (i) a tensile strength of the adhesive that is preferably at least about 1 MPa, more preferably at least about 5 MPa, even more preferably at least about 7 MPa, and even more preferably at least about 10 MPa; (ii) a Young's modulus preferably of at least about 1 MPa; (iii) an NCO / OH index of preferably at least about 80 to 130, more preferably at least about 100, even more preferably at least about 110, and even more preferably about 125 or less; and (iv) combinations thereof.

[0133] A seventeenth embodiment is applicable to the adhesive of embodiment 16, wherein the second polyol comprises a polyoxyalkylene polyol having a hydroxyl number of at least about 15 mg KOH / g, preferably at least about 17 mg KOH / g, more preferably no greater than about 30 mg KOH / g, and even more preferably no greater than about 25 mg KOH / g; and / or the monoether comprises a poly(propylene glycol) monoether, preferably poly(propylene glycol) monobutyl ether.

[0134] In an eighteenth embodiment, in the adhesive of any one of embodiments 16 or 17, the concentration of the monoether comprises about 25% or less by weight, preferably about 0.5-20% by weight, more preferably about 1-15% by weight, and even more preferably about 3-12% by weight, based on the curable second component.

[0135] Example 19 is applicable to any one of the preceding Examples 16-18, wherein the concentration of the second polyol comprises 60% or less, preferably about 50% or less, more preferably about 10-40% by weight, and even more preferably about 15-35% by weight, based on the weight of the curable second component.

[0136] In Example 20, the two-component adhesive of any one of the preceding Examples 16-19, wherein the curable second component further comprises a third polyol having a number average molecular weight of at least about 4000 Daltons.

[0137] Example 21 is applicable to the two-component adhesive composition of any one of the preceding Examples 16 to 20. In Example 21, the curable second component further comprises a diol or triol, preferably a diol primary alcohol.

[0138] For Example 22, the two-component adhesive composition of any one of the preceding Examples 16-21 includes less than 1 wt. % of a plasticizer, and preferably includes no plasticizer.

[0139] In Example 23, in the two-component adhesive of any one of Examples 16-22, the volume ratio of the NCO prepolymer to the curable second component is from about 1:10 to about 10:1, with preferred volume ratios including about 1:1, at least about 1.5:1, at least about 4:1, and at least about 1:2.

[0140] A twenty-fourth embodiment involves a laminate comprising a first substrate and a second substrate, and the adhesive of any one of the preceding embodiments 16-23 sandwiched between the first and second substrates, wherein the coefficient of thermal expansion of the first substrate differs from the coefficient of thermal expansion of the second substrate by at least about 5%, preferably at least about 10%, and more preferably at least about 15%, measured over a temperature range of about −30° C. to about 82° C.

[0141] A twenty-fifth embodiment applies to the laminate of embodiment 24, wherein the laminate does not include a primer in an amount sufficient to assist adhesion of the adhesive to either the first substrate or the second substrate.

[0142] Example 26 relates to any of Examples 24 and 25, wherein the first substrate comprises one of a metal, a coated metal, a thermoplastic, or a composite; preferably the composite comprises carbon fiber, a sheet molding compound; preferably the metal may comprise at least one of aluminum, steel, stainless steel, galvanized steel, carbon steel, and alloys thereof; preferably the thermoplastic comprises at least one of polyamide, polyolefin, and combinations thereof; preferably the coating of the coated metal comprises nickel; and preferably the polyolefin may comprise polycarbonate, polyethylene terephthalate, polybutylene terephthalate, and combinations thereof.

[0143] A twenty-seventh aspect includes a method of manufacturing a laminate, the method including the steps of: a. applying the adhesive of any one of the preceding embodiments 16-23 to one of a first substrate and a second substrate; b. Adhering a first substrate to a second substrate, wherein the coefficient of thermal expansion of the first substrate differs from the coefficient of thermal expansion of the second substrate by at least about 5%.

[0144] In a twenty-eighth embodiment, the method of embodiment 27 does not include applying a primer to either the first substrate or the second substrate, preferably to both the first substrate and the second substrate.

[0145] In Example 29, the method of either Example 27 or Example 28 does not include the step of mechanically pretreating either the first substrate or the second substrate, preferably both the first substrate and the second substrate, prior to applying the adhesive.

[0146] Example 30 is applicable to any one of Examples 27 to 29, wherein the method further includes curing the adhesive at a temperature less than about 140°C, preferably less than 120°C, even more preferably less than about 105°C, more preferably less than about 100°C, even more preferably less than about 90°C, and even more preferably less than about 80°C.

[0147] Example 31 is applicable to any one of Examples 16 to 23, wherein the number average molecular weight of the second polyol is at least about 10,000 daltons, preferably at least about 20,000 daltons, more preferably at least about 35,000 daltons, even more preferably at least about 50,000 daltons, and most preferably at least about 80,000 daltons.

Claims

1. 1. A two-component adhesive composition comprising: a. an NCO prepolymer comprising the reaction product of an isocyanate compound and a polyol, preferably having an NCO % in the prepolymer of about 30% or less, more preferably about 1-20%, and even more preferably less than 20% to at least 10% or about 1-10%; b. a second component comprising a second polyol, preferably having a number average molecular weight of at least about 2,000 daltons, more preferably at least about 4,000 daltons, even more preferably at least about 8,000 daltons, and most preferably greater than 10,000 daltons; c. a silane adhesion promoter selected from the group consisting of an isocyanurate silane adhesion promoter, an isocyanate silane adhesion promoter, and combinations thereof, in a concentration of about 0.1 to 10 wt. %; and d. Optionally, one or more catalysts, preferably tin catalysts; and (i) a tensile strength of the adhesive of preferably at least about 1 MPa, more preferably at least about 5 MPa, even more preferably at least about 7 MPa, and even more preferably at least about 10 MPa; (ii) a Young's modulus preferably of at least about 1 MPa to about 100 MPa; (iii) an NCO / OH Index of preferably at least about 80 to about 130, preferably at least about 100, more preferably at least about 110, and even more preferably about 125 or less; and (iv) combinations thereof; A two-component adhesive composition comprising one or more adhesive properties of:

2. 10. The adhesive of claim 1, further comprising a fourth component selected from the group of at least one of an epoxy-functional silane adhesion promoter, a polyether diamine, a monoether, and combinations thereof, wherein the concentration of said fourth component is less than or equal to about 20 wt%, preferably at least about 0.5 wt%.

3. The adhesive of claim 2 , wherein the fourth component comprises the monoether, and preferably the monoether comprises polypropylene glycol monobutyl ether.

4. 4. The adhesive of claim 1, wherein the second polyol of the second component comprises a polymer-modified polyol, preferably a modified polyether polyol, and wherein the concentration of the polymer-modified polyol is about 70% by weight or less of the second component.

5. The adhesive of any one of claims 1 to 4, further comprising a flame retardant package, said flame retardant package comprising up to about 25% by weight of said adhesive composition.

6. 6. The adhesive composition of any one of claims 1 to 5, wherein the composition comprises less than about 10% by weight of plasticizer, preferably less than about 5% by weight, more preferably less than about 4% by weight, even more preferably less than about 2% by weight, and most preferably less than about 1% by weight.

7. 7. The adhesive composition according to claim 1, further comprising a tertiary amine, preferably comprising at least one of 1,4-diazabicyclo[2.2.2]octane solution, diazabicycloundecene, 1,4-diazabicyclooctane, and combinations thereof.

8. 8. The adhesive composition of any one of claims 1 to 7, further comprising a chain extender comprising a polyol having at least two functional groups, preferably having an NCO % of the adhesive of about 30% or less, more preferably about 25% or less, even more preferably about 20% or less by weight, and most preferably at least about 10%.

9. 9. A laminate comprising a first substrate and a second substrate, with the adhesive according to any one of claims 1 to 8 sandwiched between said first substrate and said second substrate, wherein the coefficient of thermal expansion of said first substrate differs from the coefficient of thermal expansion of said second substrate by at least about 5%, preferably at least about 10%, more preferably at least about 15%, measured in a temperature range of from about -30°C to about 82°C.

10. 10. The laminate of claim 9, wherein the laminate does not include a primer in an amount sufficient to assist in bonding the adhesive to either the first substrate or the second substrate.

11. 11. The laminate of claim 9 or 10, wherein the first substrate comprises one of a metal, a coated metal, a thermoplastic, a composite, preferably the composite comprises carbon fiber, a sheet molding compound, preferably the metal may comprise at least one of aluminium, steel, stainless steel, galvanised steel, carbon steel and alloys thereof, preferably the thermoplastic comprises at least one of polyamide, polyolefin and combinations thereof, preferably the coating of the coated metal comprises nickel, preferably the polyolefin comprises polycarbonate, polyethylene terephthalate, polybutylene terephthalate and combinations thereof.

12. 1. A method for manufacturing a laminate, comprising: a. applying the adhesive of any one of claims 1 to 8 to a first substrate and a second substrate; b. adhering the first substrate to the second substrate, wherein the coefficient of thermal expansion of the first substrate differs from the coefficient of thermal expansion of the second substrate by at least about 5% as measured over a temperature range of about -30°C to about 82°C.

13. 13. The method of claim 12, wherein the method does not include applying a primer to either the first substrate or the second substrate, preferably to both the first substrate and the second substrate.

14. 14. The method of claim 12 or 13, which does not include the step of mechanically pre-treating either the first substrate or the second substrate, preferably both the first substrate and the second substrate, prior to applying the adhesive.

15. 15. The method of any one of claims 12 to 14, further comprising curing the adhesive at a temperature below about 140°C, preferably below about 120°C, even more preferably below about 105°C, more preferably below about 100°C, even more preferably below about 90°C, and even more preferably below about 80°C.

16. 9. The two-component adhesive of any one of claims 1 to 8, wherein the second polyol of the second component comprises a curing agent, and wherein the volume ratio of the NCO prepolymer to the curing agent is from about 1:10 to about 10:1, with preferred volume ratios being about 1:1, at least about 1.5:1, at least about 4:1, and at least about 2:1.

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