Reactive polyurethane hot melt adhesive with improved adhesion to metals

Abstract

The present invention relates to isocyanate-functionalized reaction products of polyisocyanates and polyether polyols and / or polyester polyols, and structure 1: [Formula 1] Disclosed is a one-component hot-melt polyurethane adhesive composition mixed with the silicone oligomer of TIFF2026519105000008.tif47170. The aforementioned adhesive composition exhibits improved adhesive strength to metals such as aluminum compared to currently available adhesives. The composition is particularly suitable for panel lamination applications.

Description

【Technical Field】 【0001】 The present disclosure generally relates to a one-component reactive polyurethane hot melt adhesive composition, and more specifically to a one-component reactive polyurethane hot melt adhesive composition having improved adhesion to metal parts, particularly aluminum parts. The present disclosure also relates to a method for improving the adhesive strength of a one-component reactive polyurethane hot melt adhesive composition to a metal substrate, particularly an aluminum substrate, more specifically an unwashed mill grade aluminum substrate, and a method for bonding a composite structure including metal parts, particularly aluminum parts, using the one-component reactive polyurethane hot melt adhesive composition. 【Background Art】 【0002】 In this section, background information is provided that is not necessarily prior art with respect to the inventive concepts related to the present disclosure. 【0003】 Composite structures are widely used in vehicle manufacturing in the transportation field. Examples of such composite structures include commercial trailers, railway vehicles, aircraft parts, recreational vehicles, boats, and automobiles. One conventional composite structure includes a welded aluminum frame, with a polymer skin adhered to one surface, a wood skin adhered to the opposite surface, and a foam sandwiched between the polymer skin and the wood skin. For the adhesion of the polymer skin to the aluminum frame and the wood skin to the aluminum frame, a curable or reactive polyurethane adhesive is usually used. 【0004】 Hot-melt adhesives are solid at room temperature but melt into a liquid or fluid state when heated, and are applied to a substrate in this molten state. The adhesive returns to a solid state when cooled. One type of hot-melt adhesive is thermoplastic hot-melt adhesive. Thermoplastic hot-melt adhesives do not crosslink or harden, and can be repeatedly heated to a fluid state and cooled to a solid state. Because thermoplastic hot-melt adhesives do not crosslink or harden, the hard phase formed during cooling imparts cohesive strength, toughness, creep resistance, and heat resistance to the final adhesive. Naturally, due to its thermoplastic nature, the upper temperature limit at which such adhesives can be used is restricted. 【0005】 Another type of hot melt adhesive is a curable or reactive hot melt adhesive. Reactive hot melt adhesives begin with a thermoplastic material that can be repeatedly heated to melt and cooled to a solid state. However, when exposed to suitable conditions, the components of the reactive hot melt adhesive crosslink and cure into an irreversible solid. One type of reactive hot melt adhesive is polyurethane hot melt adhesive. Polyurethane hot melt adhesives contain an isocyanate-terminated polyurethane prepolymer, which reacts to extend its chains and form a new polymer. Polyurethane prepolymers are usually obtained by reacting a polyol with an isocyanate. The polyurethane prepolymer cures after moisture from the atmosphere or on the substrate diffuses into the adhesive, and the moisture reacts with the isocyanate groups in the prepolymer. The final adhesive product is an irreversibly crosslinked material. 【0006】 Reactive hot-melt adhesives need to be maintained at their melting temperature during use. However, even when kept in an anhydrous state, the viscosity of reactive hot-melt adhesives gradually increases as they remain molten. Eventually, the equipment needs to be shut down and cleaned to remove the high-viscosity hot-melt adhesive. In highly undesirable cases, the reactive hot-melt adhesive may gel or separate within the equipment during use. In either situation, unplanned equipment shutdown, disassembly, cleaning, and replacement of parts that cannot be cleaned of the gelled hot-melt adhesive are necessary. Reactive hot-melt adhesives should ideally possess thermal stability, that is, the ability to withstand viscosity changes over time when maintained in a molten state. Naturally, gelation or phase separation of reactive hot-melt adhesives is considered a defect in thermal stability. 【0007】 Reactive hot-melt adhesives typically include additives in their formulations. However, using large amounts of additives such as fillers can negatively affect most reactive polyurethane hot-melt adhesives, significantly reducing their thermal stability to undesirable levels. There is a need to provide reactive polyurethane hot-melt adhesives that maintain thermal stability while containing high concentrations of non-fossil fuel-based, sustainable, and renewable additives. 【0008】 To increase the strength of a composite structure, it is desirable that the polyurethane adhesive adheres well to each composite component. Ideally, the internal strength of the adhesive and its adhesive strength to the substrate should be higher than some or all of the substrate to which the adhesive is bonded, so that the substrate being bonded fails under stress before the adhesive or the bond created by the adhesive. Furthermore, water can penetrate the bonded composite structure. The adhesive needs to maintain its initial adhesive strength as much as possible during and after exposure to water. 【0009】 To enhance adhesive strength, manufacturers employ a multi-stage cleaning process for components before applying adhesive and assembling them into a composite structure. The first stage involves cleaning the metal frame to remove oil, grease, and dirt. Next, the frame is immersed or sprayed with a chemical coating agent, rinsed with water, and dried. The chemically coated frame is then ready for adhesive application and assembly into the composite structure. This process requires multiple large chemical tanks, lifting and drying equipment, and considerable space. Another multi-stage process involves cleaning the metal frame to remove oil, grease, and dirt. Next, workers hand-wipe the frame with towels soaked in a chemical treatment agent, such as Henkel's Alodine wipes, and dry it. The chemically coated frame is then ready for adhesive application and assembly into the composite structure. This method does not require chemical coating tanks or related equipment. However, manually wiping the entire frame is laborious and time-consuming, and there is a risk of workers overlooking parts of the frame. 【0010】 It is desirable to provide a one-component hot-melt polyurethane adhesive composition that exhibits improved adhesive strength to one or more composite components. It is also desirable to provide a one-component hot-melt polyurethane adhesive composition that exhibits improved adhesive strength without requiring chemical conversion coating of metal parts. Furthermore, it is desirable to provide a one-component hot-melt polyurethane adhesive composition that substantially maintains its improved strength during and after exposure to water. [Overview of the Initiative] [Means for solving the problem] 【0011】 This section provides an overview of the disclosures and does not comprehensively disclose their entire scope or all features, aspects, or purposes. 【0012】 In one embodiment, the disclosure provides a one-component reactive polyurethane hot-melt adhesive prepared from a mixture comprising at least one organic polyisocyanate, at least one polyol, a silicone oligomer, and optionally other components and / or additives. 【0013】 In one embodiment, the present disclosure provides a method for bonding a skin or panel to a metal frame to form a reinforced composite structure, comprising the steps of: preparing a one-component reactive polyurethane hot melt adhesive composition as described in any of the embodiments; heating the one-component reactive polyurethane hot melt adhesive composition to a molten state; placing the one-component reactive polyurethane hot melt adhesive composition on at least one surface of a panel or metal frame; placing the surface of the panel in contact with the placed adhesive and adjacent to the surface of the metal frame; and exposing the placed adhesive to conditions under which curing begins. In one preferred embodiment, the metal frame is aluminum and is not chemically coated. In one preferred embodiment, the metal frame is mill-grade aluminum. 【0014】 In one embodiment, the Disclosure includes a product comprising a one-component reactive polyurethane hot-melt adhesive composition of the Disclosure in a cured or uncured form. 【0015】 In one embodiment, the compositions of the present disclosure do not contain silane-modified polymers (SMPs). 【0016】 In one embodiment, the disclosure includes a curing reaction product of a one-component reactive polyurethane hot-melt adhesive composition of the disclosure. 【0017】 These features and advantages of the present disclosure, as well as other features and advantages, will become more apparent to those skilled in the art from the detailed description of preferred embodiments. In general, unless expressly otherwise stated, the materials and methods of the present disclosure may be formulated to include, consist of, or essentially consist of any suitable components, parts, or processes disclosed herein. The materials and methods of the present disclosure may be formulated, additionally or alternatively, to lack or substantially contain any components, materials, elements, auxiliaries, parts, species, and processes used in prior art compositions or not necessary for achieving the functions and / or purposes of the present disclosure. [Modes for carrying out the invention] 【0018】 The singular forms "a," "an," and "the" refer to multiple objects unless the context clearly indicates otherwise. 【0019】 Unless otherwise defined, "approximately" or "about" as used with respect to a number means within ±10%, preferably ±5%, and more preferably ±1% of the number. 【0020】 Unless otherwise defined, "%" refers to weight percentage. 【0021】 The term "essentially not included" is intended in this specification to mean that the group, compound, mixture, or component in question constitutes less than 10% by weight, typically less than 1% by weight, preferably less than 0.5% by weight, more preferably less than 0.1% by weight, and ideally less than or equal to trace amounts, based on the weight of the defined composition. 【0022】 Unless otherwise defined, "at least one" means one or more, i.e., 1, 2, 3, 4, 5, 6, 7, 8, 9 or more. Regarding components, this designation refers to the types of components, not the absolute number of molecules. Therefore, "at least one polymer" means, for example, that at least one type of polymer may be used, i.e., one type of polymer or a mixture of several different polymers. 【0023】 Unless otherwise defined, the terms "comprising", "comprises" and "comprised of" as used herein are synonymous with "including", "includes", "containing" or "contains", are inclusive or open-ended and do not exclude additional, unrecited members, elements or method steps. 【0024】 When amounts, concentrations, dimensions and other parameters are expressed as ranges, preferred ranges, upper limit values, lower limit values, or combinations of preferred upper and lower limit values, it is to be understood that ranges obtained by combining an upper limit value or a preferred value with a lower limit value or a preferred value are specifically disclosed, whether or not the range is explicitly recited in the context. 【0025】 The open time of an adhesive refers to the time during which the adhesive can adhere to a material. 【0026】 As used herein, "preferred" and "preferably" refer to embodiments of the present disclosure that may provide certain benefits under certain circumstances. However, the recitation of one or more preferred embodiments does not mean that other embodiments are not useful, nor is it intended to exclude those other embodiments from the scope of the present disclosure. 【0027】 Unless otherwise specified, throughout this specification and the claims, the term "molecular weight" when referring to a polymer refers to the number average molecular weight (Mn) of the polymer. The number average molecular weight Mn can be calculated based on end group analysis (OH value based on DIN EN ISO 4629, free NCO content based on EN ISO 11909), or measured by gel permeation chromatography based on DIN 55672 with THF as the eluent. Unless otherwise noted, all molecular weights described are measured by gel permeation chromatography. 【0028】 Polyurethane hot melt adhesives are widely used in panel lamination procedures. Polyurethane hot melt adhesives provide good adhesion and structural bonding to a variety of materials. Since they do not require solvents, have a fast green strength, and are excellent in heat resistance, cold resistance, and chemical resistance, they are optimal for use in the construction industry. In one embodiment, the hot melt adhesives of the present disclosure are used in the panel lamination and doors of recreational vehicles. Since the formation of these structures can involve complex laminations, in these embodiments, it is important to have an open time of more than 6 minutes or a high green strength in order to enable the positioning of the parts to be bonded. Further, the final cure strength of the bonded assembly needs to be maintained even when the assembly is exposed to extreme temperatures. It is desirable to provide a one-component reactive polyurethane hot melt adhesive that maintains cure strength at temperatures higher than conventional formulations and enables further applications. 【0029】 The hot melt adhesives of the present disclosure include an isocyanate-functional prepolymer that is a reaction product of a mixture comprising at least one polyol, an equivalent excess of at least one organic polyisocyanate, and optionally one or more additional components and / or additives. The isocyanate functional groups enable the reaction product to crosslink and cure when exposed to moisture. The hot melt adhesive can include one or more of the isocyanate-functional prepolymer, silicone oligomer, and optionally MA-SCA, inorganic filler, thermoplastic polymer, tackifier, catalyst, and additive. Preferably, the hot melt adhesive does not contain organic solvents, water, and photoinitiators. In some preferred embodiments, the prepolymer reaction product does not contain silicon atoms. 【0030】 Examples of organic polyisocyanates that can be used include alkylene diisocyanates, cycloalkylene diisocyanates, aromatic diisocyanates, and aliphatic-aromatic diisocyanates. Examples of isocyanates used in this disclosure include, but are not limited to, methylene bisphenyl diisocyanate (MDI), isophorone diisocyanate (IPDI), hydrogenated methylene bisphenyl diisocyanate (HMDI), toluene diisocyanate (TDI), ethylene diisocyanate, ethylidene diisocyanate, propylene diisocyanate, butylene diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, cyclopentylene-1,3-diisocyanate, cyclohexylene-1,4-diisocyanate, cyclohexylene-1,2-diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,2-diphenylpropane-4,4'-diisocyanate, and xylylene diisocyanate. Examples include isocyanates, 1,4-naphthylene diisocyanate, 1,5-naphthylene diisocyanate, m-phenylenediisocyanate, p-phenylenediisocyanate, diphenyl-4,4'-diisocyanate, azobenzene-4,4'-diisocyanate, diphenylsulfone-4,4'-diisocyanate, 2,4-tole diisocyanate, dichlorohexamethylene diisocyanate, furfrylidene diisocyanate, 1-chlorobenzene-2,4-diisocyanate, 4,4',4"-triisosynate triphenylmethane, 1,3,5-triisosynate benzene, 2,4,6-triisosynate toluene, and 4,4'-dimethyldiphenylmethane-2,2',5,5-tetratetraisocyanate. 【0031】 Organic polyisocyanates having at least three functional groups can also be used. These are the trimerized and oligomerized products of the polyisocyanates already described, and are obtained by appropriately reacting polyisocyanates, preferably diisocyanates, with the formation of isocyanurate rings. When using oligomerized products, those with an average degree of oligomerization of about 3 to about 5 are particularly suitable. Diisocyanates already described are suitable isocyanates for the production of trimers, and particularly preferred are the trimerized products of isocyanates HDI, MDI, or IPDI. Similarly, polymeric isocyanates, such as those obtained as residues at the bottom of distillation obtained from the distillation of diisocyanates, are also suitable for use. Particularly suitable in this context is polymeric MDI obtained as a distillation residue from the distillation of MDI. 【0032】 Examples of usable organic polyisocyanates include one or more isocyanate-functionalized polyurethane prepolymers. Polyurethane prepolymers are compounds obtained, for example, from the reaction of a polyol component (or other active hydrogen-functionalized compound) with at least one excess amount of polyisocyanate having at least two functional groups. The term "polyurethane prepolymer" includes not only relatively low molecular weight compounds, such as those obtained from the reaction of a polyol with an excess amount of polyisocyanate, but also oligomeric or polymeric compounds. Similarly, the term "polyurethane prepolymer" also includes compounds obtained, for example, from the reaction of a trivalent or tetravalent polyol with a molar excess amount of polyisocyanate relative to the polyol. Such compounds are commercially available, and methods for synthesizing such compounds are well known in the art. Preferred isocyanate-containing compounds are isomers of methylene bisphenyl diisocyanate (MDI), isophorone diisocyanate (IPDI), hydrogenated MDI (HMDI), and toluene diisocyanate (TDI). 【0033】 Examples of polyols that can be used include, but are not limited to, polyols used in the manufacture of polyurethane, such as polyether polyols, polyester polyols, polycarbonate polyols, polyacetal polyols, polyamide polyols, polyesteramide polyols, polyalkylene polyether polyols, polythioether polyols, and mixtures thereof, preferably polyether polyols, polyester polyols, polycarbonate polyols, and mixtures thereof. 【0034】 Useful polyester polyols include those obtained by polycondensation reactions of dicarboxylic acids and polyols. The dicarboxylic acid may be aliphatic, alicyclic, aromatic, and / or derivatives thereof (anhydrides, esters, acid chlorides, etc.). Specific examples include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanediic acid, phthalic acid, terephthalic acid, isophthalic acid, trimellitic acid, phthalic anhydride, tetrahydrophthalic anhydride, glutaric anhydride, maleic acid, maleic anhydride, fumaric acid, dimeric fatty acids, dodecanediic acid, and dimethyl terephthalate. Suitable polyols include monoethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 3-methylpentane-1,5-diol, neopentyl glycol (2,2-dimethyl-1,3-propanediol), 1,6-hexanediol, 1,8-octane glycol, cyclohexanedimethanol, 2-methylpropane-1,3-diol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, polypropylene glycol, dibutylene glycol, tributylene glycol, tetrabutylene glycol, and polybutylene glycol. Alternatively, they may also be obtained by ring-opening polymerization of cyclic esters, preferably caprolactone. Polyester polyols are commercially available, such as Piotan polyol from Panoram Industries International and Dynacol polyol from Evonik. Other suppliers include Stepan, COIM, and Lanxess. In some embodiments, polyhexanediol adipate polyols are preferred. 【0035】 Useful polyether polyols that can be used include linear and branched polyethers having hydroxyl groups. Examples of polyether polyols include polyoxyalkylene polyols such as polyethylene glycol, polypropylene glycol, and polybutylene glycol. Furthermore, homopolymers and copolymers of these polyoxyalkylene polyols may also be used. Particularly preferred copolymers of polyoxyalkylene polyols 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-diol, glycerin, 1,2,6-hexanetriol, trimethylolpropane, trimethylolethane, tris(hydroxyphenyl)propane, triethanolamine, triisopropanolamine, ethylenediamine, and ethanolamine. Most preferably, the polyether polyol contains polypropylene glycol. Preferably, the number-average molecular weight of the polyether polyol is 1,500 to 6,000, and more preferably in the range of 2,000 to 4,000 daltons. The polyether polyol may be a mixture of multiple polyether polyols. 【0036】 Useful polycarbonate polyols can be obtained by the reaction of a carboxylic acid derivative such as diphenyl carbonate, dimethyl carbonate, or phosgene with a diol. Suitable examples of such diols include ethylene glycol, 1,2- and 1,3-propanediol, 1,3- and 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, neopentyl glycol, 1,4-bishydroxymethylcyclohexane, 2-methyl-1,3-propanediol, 2,2,4-trimethylpentanediol-1,3, dipropylene glycol, polypropylene glycol, dibutylene glycol, polybutylene glycol, bisphenol A, bisphenol F, tetrabromobisphenol A, and lactone-modified diols. In some embodiments, the diol component preferably contains 40-100% by weight of hexanediol, preferably 1,6-hexanediol and / or a hexanediol derivative. More preferably, the diol component has an ether group or an ester group in addition to the terminal OH group. Polycarbonate polyols should be substantially linear. However, they can be optionally slightly branched by incorporating polyfunctional components, particularly low molecular weight polyols. Suitable examples include glycerol, trimethylolpropane, hexanetriol-1,2,6, butanetriol-1,2,4, trimethylolpropane, pentaerythritol, quinitol, mannitol, sorbitol, methyl glycoside, and 1,3,4,6-dianehydrohexite. 【0037】 Useful polyols further include hydroxy-functionalized polymers, such as hydroxy-functionalized siloxanes, and polyols containing additional functional groups such as vinyl or amino groups. 【0038】 The adhesive contains a silicone oligomer of structure 1. [ka] In the formula, each R' is identical or different and independently selected from a hydrocarbon residue having a hydrogen atom or 1 to 12 carbon atoms, preferably a methyl group or an ethyl group, more preferably a methyl group. Ar is selected from aryl groups, which may be linked or condensed polycyclic aryl groups. Ar is preferably a phenyl group. n is an integer selected from 0 to 12, preferably 1 to 12. CAS number 17938-09-9 (diphenyltetramethoxydisiloxane, n=1) is an example of a silicone oligomer of structure 1. CAS number 2996-92-1 (phenyltrimethoxysiloxane, n=0) is an example of a silicone oligomer of structure 1. Silicone oligomers are commercially available or can be synthesized using the procedure described in U.S. Patent No. 10800881 by Despotplu et al. (the contents of which are incorporated herein by reference). 【0039】 Adhesives can optionally contain MA-SCA acids. MA-SCA acids are a subset of polybasic acids that ultimately have an acidic group bonded to a single central atom. Examples of MA-SCA acids include sulfuric acid, phosphonic acid, phosphoric acid, and diphosphate (pyrophosphate). MA-SCA acids dramatically increase the time it takes for hot-melt adhesives to be maintained at operating temperature and for their viscosity to rise to a problem level. In other words, adding MA-SCA acids to hot-melt adhesives dramatically reduces the rate at which the viscosity of the hot-melt adhesive rises when maintained at operating temperature. 【0040】 Polyurethane adhesives and sealants used at room temperature can be easily supplemented with large amounts of fillers. However, adding large amounts of fillers to hot-melt adhesives, such as 10% or more by weight or 20% or more by weight, reduces the thermal stability of the hot-melt adhesive, and in some cases, the high-filler hot-melt adhesive may reach a commercially undesirable level. Surprisingly, adding MA-SCA acid to high-filler hot-melt adhesives improves their thermal stability. Although MA-SCA acid is expected to interact with fillers in an undesirable way, no such interactions have been observed. 【0041】 Adhesives may optionally contain fillers. Suitable fillers include inorganic materials such as calcium carbonate, kaolin, and dolomite. Calcium carbonate is known as a sustainable and renewable material that is not based on fossil fuels. Other examples of suitable fillers are described in the "Fillers Handbook" (George Witchick, 3rd edition, 2009) and the "Fillers and Reinforcements Handbook for Plastics" (Harry Katz and John Milefsky, 1978). Inorganic fillers are present in an amount of preferably about 10% to about 50% by weight, more preferably 20% to 30% by weight, based on the total weight of the adhesive. Previous attempts to use large amounts of such fillers have resulted in problems such as short open times for hot-melt adhesives and undesirable increases in molten hot-melt adhesive during use. 【0042】 The adhesive may optionally, but preferably, include a tackifier. Examples of tackifiers include natural substances, petroleum-derived substances, and combinations thereof, as described in C.W. Paul, "Hot Melt Adhesives," Adhesion Science and Engineering-2, Surfaces, Chemistry and Applications, edited by M. Choudhury and A.V. Pocius, Elsevier, New York, 2002, p. 718. Useful tackifiers include rosin esters, aromatic hydrocarbon resins, aliphatic-modified aromatic hydrocarbon resins, phenol-modified terpene resins, phenol-modified aromatic resins, and pure monomer resins. 【0043】 Adhesives are preferably free of organosilanes because these compounds tend to destabilize the adhesive when held at the operating temperature. In some embodiments, organosilanes may be useful when the stability of the adhesive at the operating temperature is not critical. Usable organosilanes differ in structure from the silicone oligomer of Structure 1 and include aminosilanes such as secondary aminosilanes. One useful silane contains at least two silyl groups, three methoxy groups bonded to each silane, a sterically hindered secondary amino group, or any combination thereof. An example of such a commercially available aminosilane is bis(trimethoxysilylpropyl)amine, such as Silquest A-1170. Other examples of useful organosilanes include silanes having hydroxyl functional groups, mercapto functional groups, or both, such as 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrismethoxy-ethoxyethoxysilane, 3-aminopropyl-methyl-diethoxysilane, N-methyl-3-aminopropyltrimethoxysilane, N-butyl-3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-mercaptopropyl-methyl-dimethoxysilane. Examples include (N-cyclohexylaminomethyl)methyldiethoxysilane, (N-cyclohexylaminomethyl)triethoxysilane, (N-phenylaminomethyl)methyldimethoxysilane, (N-phenylaminomethyl)tri-methoxysilane, N-ethyl-aminoisobutyltrimethoxysilane, 4-amino-3,3-dimethylbutyltrimethoxysilane, N-(n-butyl)-3-aminopropyltriethoxysilane, N-(n-butyl)-3-aminopropylalkoxydiethoxysilane, bis(3-triethoxysilylpropyl)amine, and combinations thereof. Organosilanes are commercially available from many suppliers, such as Momentive Performance Materials (Silquest) and Evonik (Dynasilane).Some useful examples include Silquest Alink15 (N-ethyl-3-trimethoxysilyl l-2-methylpropanamine), Silquest Alink35 (gamma-isocyanate propyltrimethoxysilane), Silquest A174NT (gamma-methacryloxypropyltrimethoxysilane), Silquest A187 (gamma-glycidoxypropyltrimethoxysilane), Silquest A189 (gamma-mercaptopropyltrimethoxysilane), and Silquest A597 (tri Examples include (3-(trimethoxysilyl l)propyl) isocyanurate), Silquest A1110 (gamma-aminopropyltrimethoxysilane), Silquest A1170 (bis(trimethoxysilylpropyl)amine), Dynasilane 1189 (N-butyl-3-aminopropyltrimethoxysilane), Silquest A1289 (bis-(triethoxysilylpropyl tetrasulfide), and Silquest Y9669 (N-phenyl-gamma-aminopropyltrimethoxysilane). 【0044】 The adhesive may optionally, preferably, include a thermoplastic polymer or copolymer such as acrylic or EVA. The thermoplastic polymer may be functional, or non-functional, having moieties such as active hydrogen atoms, hydroxyl, amino, or (meth)acrylate that can react with other components in the adhesive. Usable acrylic polymers include acrylic polymers formed from acrylates, methacrylates, and mixtures thereof known in the art, as well as acrylic copolymers containing at least one of methyl methacrylate monomer and n-butyl methacrylate monomer. Examples of these acrylic copolymers include Elvasite® 2013, a copolymer of methyl methacrylate and n-butyl methacrylate with a weight-average molecular weight of 34,000; Elvasite® 2016, a copolymer of methyl methacrylate and n-butyl methacrylate with a weight-average molecular weight of 60,000; and Elvasite® 4014, a copolymer of methyl methacrylate, n-butyl methacrylate, and hydroxyethyl methacrylate with a weight-average molecular weight of 60,000. Elvasite® polymers are available from Lucite International. Further examples of suitable acrylic polymers are described in U.S. Patents 6,465,104 and 5,021,507, which are incorporated herein by reference. The weight-average molecular weight of the acrylic polymer is preferably 8,000 to 150,000, more preferably 25,000 to 100,000. The acrylic polymer content is preferably about 5 to 40% by weight, more preferably 10 to 30% by weight, relative to the total weight of the adhesive. The OH value of the acrylic polymer is preferably less than 8, more preferably less than 5. The glass transition temperature Tg of the acrylic polymer is preferably about 35 to about 85°C, more preferably 45 to 75°C. 【0045】 EVA copolymers are copolymers of ethylene and vinyl acetate. The two monomers can be copolymerized in any ratio. The resulting copolymers are characterized by the statistical distribution of monomer units in the polymer chain, and the properties of EVA copolymers can vary widely depending on the molar ratio of ethylene to vinyl acetate. For example, products with an ethylene content of less than 30 wt% are partially crystalline and thermoplastic, while products with a vinyl acetate content of about 40 to about 70 wt% are substantially amorphous. EVA copolymers are generally produced by bulk polymerization, emulsion polymerization, or solution polymerization. The molecular weight of the EVA copolymers used according to the present invention ranges from about 10,000 to about 1,500,000. The vinyl acetate content in the EVA copolymers used according to the present invention ranges from 9 to 70 wt%, preferably from 20 to 55 wt%. An example of a suitable ethylene / vinyl acetate copolymer is the commercially available Elbax product from Dow, which has a vinyl acetate content of about 27 to 42 wt%. Furthermore, other monomers can be incorporated into the EVA copolymer to obtain desirable properties such as isocyanate-reactive functional groups. 【0046】 The adhesive can optionally contain catalysts conventionally used in polyurethane reactions. Some useful catalysts include, for example, 2,2'-dimorpholinodiethyl ether, triethylenediamine, dibutyltin dilaurate, and tin octanoate. A preferred catalyst is 2,2'-dimorpholinodiethyl ether (DMDEE). 【0047】 The composition may optionally include at least one filler selected from the following: inorganic fillers such as calcium carbonate, powdered limestone, precipitated silica and / or pyrolytic silica, zeolite, bentonite, magnesium carbonate, diatomaceous earth, alumina, clay, animal fat, titanium dioxide, iron oxide, zinc oxide, sand, quartz, flint, mica, powdered glass, and crushed minerals; organic fillers such as carbon black, graphite, wood fibers, wood flour, sawdust, cellulose, cotton, pulp, wood chips, shredded straw, rice husks, and crushed walnut shells; short-cut fibers such as glass fibers, glass filaments, polyacrylonitrile fibers, carbon fibers, Kevlar fibers, and polyethylene fibers; and hollow spheres having a mineral shell or plastic shell (such as hollow glass spheres marketed as Glass Bubbles® and hollow plastic spheres marketed as Expancel® or Dualite®). These hollow sphere fillers are composed of inorganic or organic materials with a diameter of 1 mm or less, preferably 500 μm or less. In one embodiment, calcium carbonate, which is considered a sustainable, renewable, and fossil fuel-free filler, can be used as a filler. 【0048】 The adhesive may contain one or more of the following known hot-melt adhesive additives: plasticizers, colorants, rheological modifiers, flame retardants, UV pigments, nanofibers, defoamers, antioxidants, stabilizers, thixotropic agents such as fumed silica, etc. Conventional additives compatible with the composition of the present invention can be easily determined by simply mixing candidate additives with the composition and determining whether they are compatible. Additives are compatible if they are homogeneous within the product at room temperature and the operating temperature. 【0049】 In one embodiment, the hot melt adhesive comprises a reaction product of a mixture including the following: 【0050】 [Table 1] 【0051】 The adhesive composition may typically contain 30-99.9% polyurethane prepolymer reaction product, more preferably 50-99.9% polyurethane prepolymer reaction product. 【0052】 The hot-melt adhesive of this disclosure can be manufactured by the following procedure. Note that it is necessary to remove moisture from the polyurethane reaction. Add the polyol, thermoplastic polymer, and filler to the reactor and remove moisture by heating and vacuum. After drying, add the excess polyisocyanate to the reactor, which has been kept heated and under an inert gas barrier to remove moisture. After a suitable reaction time, the silicone oligomer and optionally the catalyst can be added to the reaction product and mixed. The final product, which contains the isocyanate-functionalized prepolymer and the remaining components, is transferred to a moisture-proof container and sealed immediately. If any components and additives are used, they can be added together with the polyol or after the reaction. Drying of any components may be necessary to prevent reaction with the isocyanate portion in the adhesive composition. 【0053】 The hot melt adhesives of this disclosure can be applied by various methods, including spraying, roller application, extrusion, and bead application. The hot melt adhesives of this disclosure remain stable during storage, provided they are protected from moisture. They can be applied to a variety of substrates, including metals, wood, plastics, glass, and textiles. 【0054】 The hot-melt adhesives of this disclosure do not gel or undergo phase separation even when held at temperatures and times used in commercial dispensing equipment. For example, the hot-melt adhesives can be held at 121°C for 24 hours. In some embodiments, the hot-melt adhesives of this disclosure exhibit a viscosity increase of 500% or less, preferably 200% or less, and more preferably 100% or less, even when held at temperatures and times used in commercial dispensing equipment. Commercial conditions were approximated by holding the sample at 121°C for 24 hours in a sealed container (e.g., a container that blocks air and moisture). 【0055】 The present invention also provides a method for bonding articles, comprising the steps of: cooling a reactive hot-melt adhesive to prepare it typically in a solid state; heating the reactive hot-melt adhesive to a molten state; applying the molten reactive hot-melt adhesive composition to a first article; contacting a second article with the composition applied to the first article; cooling the adhesive to solidify; and exposing the applied composition to conditions (including moisture) that cause it to completely cure into an irreversible solid state. Hot-melt adhesives are typically distributed and stored in a solid state, and are kept moisture-free to prevent curing during storage. The composition is heated to a molten state before application and applied in a molten state. Typical application temperatures range from about 80°C to about 145°C, and are typically about 120°C. Thus, the present disclosure encompasses reactive polyurethane hot-melt adhesive compositions in both an uncured solid state typically stored and distributed, a molten state after being melted immediately before application, and an irreversible solid state after curing. 【0056】 After application, the reactive hot-melt adhesive composition is subjected to conditions that cause it to solidify and harden into an irreversible solid state in order to bond the articles together. Solidification or hardening occurs when the molten liquid begins to cool from the application temperature to room temperature. Hardening, i.e., the composition becoming an irreversible solid state due to chain extension, occurs in the presence of ambient moisture. 【0057】 The reactive polyurethane hot-melt adhesive compositions of this disclosure are particularly suitable as adhesives in reinforced composite structures. One example is a large reinforced composite panel used in the manufacture of recreational vehicles. Such reinforced composite panels typically comprise one or two panels, or "skins," laminated on both sides of a reinforced metal frame. The skins may include, for example, wood or wood products, plastics, fiber-reinforced plastics (FRP), metals or metal foils, high-pressure laminate (HPL) skins, or other materials. Typically, the outer skin is plastic or plastic composite for weather resistance. If an inner skin is required, it is typically wood or laminated wood such as lauan plywood. The frame is typically formed by welding a plurality of tubular metal members to create a structural frame. Generally, the tubular metal members have a rectangular cross-section with adhesive surfaces defined on their opposing sides. Structural aluminum pieces are used almost without exception in recreational vehicles to reduce the weight of the frame and the vehicle. Materials such as expanded polystyrene (EPS) foam sheets can be placed between the skins in the spaces not occupied by the frame. The panel lamination process includes the steps of placing a molten, one-component hot-melt polyurethane adhesive on a portion of the surface to be laminated, optionally spraying water to accelerate curing, bringing a skin into contact with the adhesive placed on the frame surface, applying pressure to the assembled parts by passing them through a nip press, and stacking, routing, or stocking the assembled parts after the initial curing and / or curing of the adhesive. The one-component reactive polyurethane hot-melt adhesive composition of the present disclosure provides improved adhesive strength to aluminum frames, particularly untreated aluminum frames, compared to conventional adhesives. 【0058】 For reinforced composite panels used in vehicles, a bonding percentage of at least about 30%, preferably at least about 50%, more preferably at least about 70%, and most preferably at least about 90% is desirable. A bonding percentage of 100% is ideal because it means the substrate will break before adhesive bonding occurs. Some of these bonding strengths can be achieved by combining conventional reactive polyurethane hot melt adhesives with anodized or chemically coated aluminum frame members, but when conventional reactive polyurethane hot melt adhesives are used with factory-grade aluminum frame members, such as untreated aluminum frame members received from the factory that have not been washed, chemically coated, or anodized, it has been impossible to consistently achieve even a 30% bonding strength. [Examples] 【0059】 Experimental data Using a heated sample cup and a No. 27 spindle, the viscosity (centipoise (cP)) of the product was measured at 121°C using a Brookfield DV-I+ viscometer after 30 minutes of temperature equilibrium. 【0060】 The thermal stability was measured using the following aging test. Uncured polyurethane hot melt adhesive was filled into an aluminum tube, and the tube was sealed to block out air and moisture. The tube and sample were heated in an oven at 121°C for 24 hours. After aging, the viscosity of the sample before and after thermal aging was measured using a Brookfield viscometer (27 spindle), and the viscosity increase rate was recorded. Blocking out air and moisture prevents the aged sample from reacting with moisture. The aging test approximates how the hot melt adhesive will react when held at its melting temperature for an extended period, as would occur during use. Viscosity change is defined as follows: (final viscosity - initial viscosity) / final viscosity. If the sample has gelled or undergone phase separation after thermal aging, the viscosity after aging will not be measured, the thermal stability will be unacceptable, and the sample will be considered unacceptable. 【0061】 NCO% was measured using a Brinkmann-Metrohm automated titrator. 【0062】 Adhesion % was tested by applying the test composition to untreated mil-grade hollow rectangular aluminum tubes at an effective coating rate of 10–12 grams / square foot (gsf). The mil-grade aluminum was used as received and was not washed, anodized, or chemically treated before testing. Lauan plywood (approximately 3 mm thick) was placed on top of the applied adhesive and vacuum-pressed to the tube and adhesive for 1 hour. The laminate was cured for 2 days under room temperature and ambient humidity conditions. The adhesion between the lauan plywood and aluminum was tested by attempting to peel the plywood from the tube using a spatula. The failure rate of the lauan plywood was visually assessed based on the amount of wood remaining bonded to the aluminum. For example, an adhesion rate of 90% means that 90% of the wood remains bonded (good result), and an adhesion rate of 10% means that 10% of the wood remains bonded (fail). The uncertainty range for adhesion % is approximately +5% or -5%. The results were recorded. The uncertainty range for the adhesion percentage is approximately +5% or -5%. 【0063】 Silicone oligomer Silicone oligomers are commercially available. Alternatively, they can be synthesized. 【0064】 Synthesis of diphenyltetramethoxydisiloxane (in formula 1, n=1) 195.2 g of phenyltrimethoxysilane was placed in a 0.5 L three-necked round-bottom flask equipped with a magnetic stirrer, thermometer, and dropping funnel. 8.8 g of 1N hydrochloric acid (water:methoxy molar ratio 6:1) was added dropwise to the silane over 7 hours, ensuring the temperature of the mixture did not exceed 40°C. After stirring the mixture for 10 hours, the reaction was stopped, and the mixture was stored at 25°C for at least one day before distillation. The reaction mixture was purified by vacuum distillation. Two fractions were separated under a vacuum of 1 mbar. The first fraction, obtained at 130°C, contained unreacted phenyltrimethoxysilane. The second fraction, separated at 230°C, contained the target product, 1,2-diphenyltetramethoxydisiloxane (yield 36%). 【0065】 The following materials were used in the examples. [Table 2] 【0066】 The examples were prepared as shown below. The quantities are parts by weight based on the total weight of the composition. 【0067】 The examples were prepared as shown below. In all cases, since the materials react with moisture, the reaction, packaging, and storage were carried out under conditions that eliminated moisture. 【0068】 Example 1 - Comparison 185 parts PPG2000 and 185 parts PPG4000 were added to a heated and stirred tank reactor equipped with a vacuum connection, and 165 parts Elbasite 2016, 115 parts Elbax 210, 115 parts Crystalex 3100, and 140 parts polyester polyol were mixed and melted. The mixture was then dehydrated under vacuum at 121°C for 2 hours. The reactor was purged with nitrogen, 88.2 parts 4,4'-diphenylmethane-diisocyanate (MDI) was added, and the reactor contents were stirred under nitrogen at 121°C for 15 minutes, followed by stirring under vacuum at 121°C for 2 hours. The reactor was purged with nitrogen, 1.5 parts 2,2'-dimorpholinyl diethyl ether (DMDEE) was added, and the mixture was stirred under a nitrogen atmosphere for 15 minutes. The product was then transferred to a moisture-proof container and immediately sealed for subsequent testing. 【0069】 Example 2 - The present invention 185 parts PPG2000 and 185 parts PPG4000 were added to a heated and stirred tank reactor equipped with a vacuum connection, and 165 parts Elbasite 2016, 115 parts Elbax 210, 115 parts Crystalex 3100, and 140 parts polyester polyol were mixed and melted. Then, water was removed under vacuum at 121°C for 2 hours. Next, the reactor was purged with nitrogen, and 88.2 parts 4,4'-diphenylmethane-diisocyanate (MDI) was added. The reactor contents were stirred under nitrogen at 121°C for 15 minutes, and then stirred under vacuum at 121°C for 2 hours. The reactor was purged with nitrogen, and 1.5 parts 2,2'-dimorpholinyl diethyl ether (DMDEE), 0.3 parts 85% phosphoric acid, and 5 parts 1,3-diphenyltetramethoxydisiloxane were added, and the mixture was stirred under a nitrogen atmosphere for 15 minutes. The product was then transferred to a moisture-proof container and immediately sealed for later testing. 【0070】 Example 3 - The present invention 185 parts PPG2000 and 185 parts PPG4000 were added to a heated and stirred tank reactor equipped with a vacuum connection, and 165 parts Elbasite 2016, 115 parts Elbax 210, 115 parts Crystalex 3100, and 140 parts polyester polyol were mixed and melted. Then, water was removed under vacuum at 121°C for 2 hours. Next, the reactor was purged with nitrogen, and 88.2 parts 4,4'-diphenylmethane-diisocyanate (MDI) was added. The reactor contents were stirred under nitrogen at 121°C for 15 minutes, and then stirred under vacuum at 121°C for 2 hours. The reactor was purged with nitrogen, and 1.5 parts 2,2'-dimorpholinyl diethyl ether (DMDEE) and 5 parts 1,3-diphenyltetramethoxydisiloxane were added. The mixture was stirred under a nitrogen atmosphere for 15 minutes. The product was then transferred to a moisture-proof container and immediately sealed for later testing. 【0071】 Example 4 - The present invention 185 parts PPG2000 and 185 parts PPG4000 were added to a heated and stirred tank reactor equipped with a vacuum connection, and 165 parts Elbasite 2016, 115 parts Elbax 210, 115 parts Crystalex 3100, and 140 parts polyester polyol were mixed and melted. Then, water was removed under vacuum at 121°C for 2 hours. Next, the reactor was purged with nitrogen, and 88.2 parts 4,4'-diphenylmethane-diisocyanate (MDI) was added. The reactor contents were stirred under nitrogen at 121°C for 15 minutes, and then stirred under vacuum at 121°C for 2 hours. The reactor was purged with nitrogen, and 1.5 parts 2,2'-dimorpholinyl diethyl ether (DMDEE), 0.3 parts 85% phosphoric acid, and 5 parts phenyltrimethoxysilane were added, and the mixture was stirred under a nitrogen atmosphere for 15 minutes. The product was then transferred to a moisture-proof container and immediately sealed for later testing. 【0072】 Example 5 - Comparison 185 parts PPG2000 and 185 parts PPG4000 were added to a heated and stirred tank reactor equipped with a vacuum connection, and 165 parts Elbasite 2016, 115 parts Elbax 210, 115 parts Crystalex 3100, and 140 parts polyester polyol were mixed and melted. Then, water was removed under vacuum at 121°C for 2 hours. Next, the reactor was purged with nitrogen, and 88.2 parts 4,4'-diphenylmethane-diisocyanate (MDI) was added. The reactor contents were stirred under nitrogen at 121°C for 15 minutes, and then stirred under vacuum at 121°C for 2 hours. The reactor was purged with nitrogen, and 1.5 parts 2,2'-dimorpholinyl diethyl ether (DMDEE), 0.3 parts 85% phosphoric acid, and 5 parts A-1110 were added. The mixture was stirred under a nitrogen atmosphere for 15 minutes. The product was then transferred to a moisture-proof container and immediately sealed for later testing. 【0073】 Example 6 - Comparison 185 parts PPG2000 and 185 parts PPG4000 were added to a heated and stirred tank reactor equipped with a vacuum connection, and 165 parts Elbasite 2016, 115 parts Elbax 210, 115 parts Crystalex 3100, and 140 parts polyester polyol were mixed and melted. Then, water was removed under vacuum at 121°C for 2 hours. Next, the reactor was purged with nitrogen, and 88.2 parts 4,4'-diphenylmethane-diisocyanate (MDI) was added. The reactor contents were stirred under nitrogen at 121°C for 15 minutes, and then stirred under vacuum at 121°C for 2 hours. The reactor was purged with nitrogen, and 1.5 parts 2,2'-dimorpholinyl diethyl ether (DMDEE) and 5 parts A-1110 were added. The mixture was stirred under a nitrogen atmosphere for 15 minutes. The product was then transferred to a moisture-proof container and immediately sealed for subsequent testing. 【0074】 Example 7 - The present invention 185 parts PPG2000 and 185 parts PPG4000 were added to a heated and stirred tank reactor equipped with a vacuum connection, and 185 parts polyester polyol were mixed and melted. Then, water was removed under vacuum at 121°C for 2 hours. Next, the reactor was purged with nitrogen, 50 parts 4,4'-diphenylmethane-diisocyanate (MDI) were added, and the reactor contents were stirred under nitrogen at 121°C for 15 minutes, followed by stirring under vacuum at 121°C for 2 hours. The reactor was purged with nitrogen, 1.5 parts 2,2'-dimorpholinyl diethyl ether (DMDEE) and 5 parts 1,3-diphenyltetramethoxydisiloxane were added, and the mixture was stirred under a nitrogen atmosphere for 15 minutes. The product was then transferred to a moisture-proof container and immediately sealed for subsequent testing. 【0075】 Example 8 - The present invention 185 parts PPG2000 and 185 parts PPG4000 were added to a heated and stirred tank reactor equipped with a vacuum connection, and 165 parts Elbasite 2016, 115 parts Elbax 210, 115 parts Folarin 5020F, and 140 parts polyester polyol were mixed and melted. Then, water was removed under vacuum at 121°C for 2 hours. Next, the reactor was purged with nitrogen, and 88.2 parts 4,4'-diphenylmethane-diisocyanate (MDI) was added. The reactor contents were stirred under nitrogen at 121°C for 15 minutes, and then stirred under vacuum at 121°C for 2 hours. The reactor was purged with nitrogen, and 1.5 parts 2,2'-dimorpholinyl diethyl ether (DMDEE) and 5 parts 1,3-diphenyltetramethoxydisiloxane were added. The mixture was stirred under a nitrogen atmosphere for 15 minutes. The product was then transferred to a moisture-proof container and immediately sealed for later testing. 【0076】 Example 9 - The present invention 185 parts PPG2000 and 185 parts PPG400 were added to a heated and stirred tank reactor equipped with a vacuum connection, and 165 parts Elbasite 2016, 115 parts Elbax 210, 115 parts Silvaleth SA100, and 140 parts polyester polyol were mixed and melted. Then, water was removed under vacuum at 121°C for 2 hours. Next, the reactor was purged with nitrogen, and 88.2 parts 4,4'-diphenylmethane-diisocyanate (MDI) was added. The reactor contents were stirred under nitrogen at 121°C for 15 minutes, and then stirred under vacuum at 121°C for 2 hours. The reactor was purged with nitrogen, and 1.5 parts 2,2'-dimorpholinyl diethyl ether (DMDEE) and 5 parts 1,3-diphenyltetramethoxydisiloxane were added and stirred under a nitrogen atmosphere for 15 minutes. The product was then transferred to a moisture-proof container and immediately sealed for later testing. 【0077】 Example 10 - The present invention 255 parts PPG2000 and 255 parts PPG4000 were added to a heated and stirred tank reactor equipped with a vacuum connection, and 165 parts Elbasite 2016, 115 parts Elbax 210, and 115 parts Crystalex 310 were mixed and melted. Then, water was removed under vacuum at 121°C for 2 hours. Next, the reactor was purged with nitrogen, and 80.2 parts 4,4'-diphenylmethane-diisocyanate (MDI) was added. The reactor contents were stirred under nitrogen at 121°C for 15 minutes, and then stirred under vacuum at 121°C for 2 hours. The reactor was purged with nitrogen, and 1.5 parts 2,2'-dimorpholinyl diethyl ether (DMDEE) and 5 parts 1,3-diphenyltetramethoxydisiloxane were added. The mixture was stirred under a nitrogen atmosphere for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for later testing. 【0078】 Example 11 - The present invention 106 parts polyester-2 and 264 parts polyester-3 were placed in a heated and stirred tank reactor equipped with a vacuum connection, and 165 parts elbasite 2016, 115 parts elbax 210, 115 parts crystallex 3100, and 140 parts polyester polyol were mixed and melted. The mixture was then dehydrated under vacuum at 121°C for 2 hours. Next, the reactor was purged with nitrogen, 84.2 parts 4,4'-diphenylmethane-diisocyanate (MDI) were added, and the reactor contents were stirred under nitrogen at 121°C for 15 minutes, followed by stirring under vacuum at 121°C for 2 hours. The reactor was then purged with nitrogen, 1.5 parts 2,2'-dimorpholinyl diethyl ether (DMDEE) and 5 parts 1,3-diphenyltetramethoxydisiloxane were added, and the mixture was stirred under a nitrogen atmosphere for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing. 【0079】 [Table 3] 【0080】 As can be seen from the results in the table above: Example 1 shows a conventional polyurethane reactive hot-melt adhesive, which has good thermal stability but very poor adhesion to untreated aluminum substrates. Example 7 demonstrates that a polyurethane reactive hot melt containing the silicone oligomer (1,3-diphenyltetramethoxydisiloxane, n=1 in Formula 1) of this disclosure can achieve both good adhesion to an untreated aluminum substrate and good heat stability. Note that Example 7 does not contain Elbax 210, Crystalex 3100, or Elbasite 2016. Examples 5 and 6 demonstrate that polyurethane reactive hot-melt adhesives containing appropriate silanes improve adhesion to untreated aluminum frames (the wood substrate was damaged before the adhesive bonded to the aluminum substrate). However, thermal stability was not as expected, and unacceptable gelation occurred during use. Example 4 demonstrates that a polyurethane reactive hot-melt adhesive containing the silicone oligomer (phenyltrimethoxysilane, in formula 1, n=0) of the present disclosure can have both good adhesion to an untreated aluminum substrate and good thermal stability. Example 3 demonstrates that a polyurethane reactive hot-melt adhesive containing the silicone oligomer (1,3-diphenyltetramethoxydisiloxane, in Formula 1, n=1) of the present disclosure can have both excellent adhesion to untreated aluminum substrates and good thermal stability. Example 2 demonstrates that a polyurethane reactive hot-melt adhesive containing both the silicone oligomer (1,3-diphenyltetramethoxydisiloxane, in Formula 1, n=1) and MA-SCA of the present disclosure can exhibit both superior adhesion to untreated aluminum substrates and even greater thermal stability compared to Example 3, which does not contain MA-SCA. Most of the examples of the present invention use a combination of polyether polyol and polyester polyol, and excellent results were obtained. Examples 10 and 11 show that excellent results can also be obtained with polyurethane reactive hot melt adhesives containing only polyether polyol or only polyester polyol. 【0081】 The tests described above focused on improving the adhesion of the polyurethane reactive hot melt adhesive of this disclosure to aluminum substrates. Furthermore, a series of tests were conducted on uncleaned stainless steel substrates using the adhesive of Example 2. These tests were performed using the same test protocol as the previous tests on aluminum substrates. After six tests, the average failure rate of the wood substrates was 45%. These tests demonstrate that the polyurethane reactive hot melt adhesive of this disclosure can improve the adhesive strength to stainless steel substrates. 【0082】 The results demonstrate that introducing a specific group of silicone oligomers, and optionally MA-SCA acid, into a specific polyurethane reactive hot-melt adhesive can provide a reactive polyurethane hot-melt adhesive that exhibits excellent adhesion to untreated metals while maintaining good stability under heating. 【0083】 The terms used herein are for the sole purpose of describing specific embodiments and are not limiting. The methods, steps, processes, and operations described herein should not be construed as requiring them to be performed in a specific order described or illustrated, unless otherwise specified as such. It should also be understood that additional or alternative steps may be employed.

Claims

[Claim 1] An isocyanate-functionalized prepolymer reaction product of a mixture comprising at least one polyisocyanate and at least one polyol, Silicone oligomer of structure 1, 【Chemistry 1】 (In the formula, each R' is the same or different and is independently selected from a hydrocarbon residue having a hydrogen atom or 1 to 12 carbon atoms, R' is preferably a methyl group or an ethyl group, R' is more preferably a methyl group, Ar is selected from an aryl group, Ar is preferably a phenyl group, and n is an integer selected from 0 to 12, preferably 1 to 12.) A one-component reactive polyurethane hot melt adhesive containing [specific ingredient]. [Claim 2] The one-component reactive polyurethane hot melt adhesive according to claim 1, wherein the polyol in the mixture comprises a polyether polyol, a polyester polyol, or a mixture of a polyether polyol and a polyester polyol. [Claim 3] The one-component reactive polyurethane hot melt adhesive according to claim 1 or 2, wherein the polyol in the mixture comprises a first polyether polyol having a certain molecular weight, a second polyether polyol having a molecular weight different from that of the first polyether polyol, and a polyester polyol. [Claim 4] The one-component reactive polyurethane hot melt adhesive according to any one of claims 1 to 3, wherein the isocyanate-functionalized prepolymer does not contain Si atoms. [Claim 5] A one-component reactive polyurethane hot melt adhesive according to any one of claims 1 to 4, further comprising 10 to 50% by weight of an inorganic filler or 0 to 1% by weight of MA-SCA acid. [Claim 6] A one-component reactive polyurethane hot melt adhesive according to any one of claims 1 to 5, further comprising one or more thermoplastic resins, tackifiers, or catalysts. [Claim 7] A one-component reactive polyurethane hot melt adhesive according to any one of claims 1 to 6, further comprising a thermoplastic resin selected from acrylic resin, EVA resin, and a tackifier. [Claim 8] A one-component reactive polyurethane hot melt adhesive according to any one of claims 1 to 7, further comprising 0 to 1% by weight of nitric acid, sulfuric acid, phosphonic acid, phosphoric acid, diphosphate (pyrophosphate), and MA-SCA acid selected from combinations thereof. [Claim 9] A one-component reactive polyurethane hot melt adhesive according to any one of claims 1 to 8, wherein the curing reaction product of the adhesive has an adhesion percentage of at least 50%. [Claim 10] A step of preparing an aluminum frame having a first bonding surface, Steps to prepare a first panel having an adhesive surface, A step of preparing a one-component reactive polyurethane hot melt adhesive, wherein the adhesive composition comprises an isocyanate-functionalized prepolymer reaction product of a mixture containing at least one polyisocyanate and at least one polyol, and a silicone oligomer of structure 1. 【Chemistry 2】 (In the formula, each R' is the same or different and is independently selected from a hydrocarbon residue having a hydrogen atom or 1 to 12 carbon atoms, where R' is preferably a methyl group or an ethyl group, and R' is more preferably a methyl group; Ar is selected from an aryl group, where Ar is preferably a phenyl group; and n is an integer selected from 0 to 12, preferably 1 to 12.) A step of heating the adhesive until it reaches a molten state, A step of applying the molten adhesive to at least one bonding surface, The steps include: positioning the adhesive surface of the first panel in contact with the adhesive surface of the applied adhesive and the frame to form a composite structure; and A step of curing the adhesive and bonding the first panel to the metal frame, A method for producing an adhesive-reinforced composite structure, including [a specific component]. [Claim 11] The aluminum frame has a rectangular cross-section and a second adhesive surface facing the first adhesive surface, A step of preparing a second panel having an adhesive surface, A step of applying the adhesive to at least one of the second adhesive surface of the frame or the adhesive surface of the second panel, The process of positioning the adhesive surface of the second panel in contact with the applied adhesive and the second adhesive surface of the frame, A step of curing the adhesive and bonding the second panel to the metal frame, The method according to claim 10, including the method described in claim 10. [Claim 12] The method according to claim 10 or 11, wherein at least one aluminum bonding surface is mill-grade and uncleaned. [Claim 13] The method according to any one of claims 10 to 12, wherein at least one aluminum bonding surface is not surface chemically coated and / or anodized. [Claim 14] The method according to any one of claims 10 to 13, wherein at least one aluminum bonding surface is chemically coated. [Claim 15] The method according to any one of claims 10 to 14, wherein the first panel comprises a cured polymer and / or plywood. [Claim 16] The method according to any one of claims 10 to 15, wherein the composite structure does not have a mechanical fastener for holding the first panel to the frame. [Claim 17] The method according to any one of claims 10 to 16, further comprising placing an insulating material in the void region defined by the frame and the first panel bonding surface. [Claim 18] To bond the material to aluminum, use of a one-component reactive polyurethane hot melt adhesive according to any one of claims 1 to 9.

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