Polyurethane reactive hot melt adhesive with long shelf life under heating

Abstract

This invention relates to moisture-reactive hot melt adhesive compositions prepared from combinations comprising: polyisocyanates; polyols; MA-SCA acids; one or both of inorganic fillers or organosilanes; optionally present thermoplastic polymers; and optionally present one or more additives. Available polyols include poly(hexyl adipate), polyester diols having the structure of Formula 1 or Formula 2, and combinations thereof. Formula 1 is: H-[O(CH2)] m OOC(CH2) n CO] k -O(CH2) m –OH; m and n are each even numbers; m + n = 8; m and n are each independently selected from 2, 4, or 6; k is an integer from 9 to 55; and the polyol of formula 1 has a number average molecular weight of about 2,000 to about 11,000. Formula 2, i.e., polycaprolactone polyol, is: HO-[(CH2)5COO] p -R1-[OOC(CH2)5] q -OH; R1 is an initiator, such as 1,4'-butanediol, 1,6'-hexanediol or ethylene glycol; p is an integer from 0 to 96; q is an integer from 0 to 96; p+q = 16 to 96; and the polyol has a number average molecular weight of about 2,000 to about 11,000 or less.

Description

Technical Field

[0001] This disclosure generally relates to moisture-reactive polyurethane hot melt adhesives, and more specifically to moisture-reactive polyurethane hot melt adhesives having low viscosity gain with aging and improved shelf life and / or improved adhesion to substrates. Background Technology

[0002] This section provides background information, which is not necessarily prior art to the inventive concept associated with this disclosure.

[0003] Hot melt adhesives are solid at room temperature, but melt into a liquid or fluid state when heat is applied, and are applied to a substrate in this liquid or fluid state. Upon cooling, the adhesive reverts to its solid form. One class of hot melt adhesives is the thermoplastic hot melt adhesive. Thermoplastic hot melt adhesives are typically thermoplastic and can be repeatedly heated to a fluid state and cooled to a solid state. Thermoplastic hot melt adhesives do not crosslink or cure; one or more hard phases formed upon cooling impart all the cohesive strength, toughness, creep, and heat resistance of the final adhesive. Naturally, the thermoplastic nature limits the upper temperature range at which such adhesives can be used.

[0004] Another type of hot melt adhesive is the curable or reactive hot melt adhesive. Reactive hot melt adhesives are initially developed as thermoplastic materials that can be repeatedly heated to a molten state and cooled to a solid state. However, when exposed to suitable conditions, reactive hot melt adhesives crosslink and cure to an irreversible solid form. One type of reactive hot melt adhesive is the polyurethane hot melt adhesive. Polyurethane hot melt adhesives contain isocyanate-terminated polyurethane prepolymers that react to extend the chain, thereby forming new polymers. Polyurethane prepolymers are typically obtained by reacting a polyol with an isocyanate. The polyurethane prepolymer is cured by the diffusion of moisture from the atmosphere or on the substrate into the adhesive and the subsequent reaction. The moisture reacts with the residual isocyanate to form carbamic acid. This acid is unstable and decomposes into amines and carbon dioxide. The amine reacts rapidly with the isocyanate to form urea. The final adhesive product is a crosslinked material polymerized primarily through urea and carbamate groups.

[0005] Reactive hot melt adhesives must be maintained at their melt temperature during use. However, even when kept under normally anhydrous conditions, the viscosity of reactive hot melt adhesives will slowly increase when kept in the molten state. Ultimately, the equipment must be shut down and cleaned to remove the high-viscosity hot melt adhesive. In very undesirable circumstances, reactive hot melt adhesives may gel or separate within the equipment during use. In either case, equipment shutdown, disassembly, and cleaning are required, and replacement of parts from which the gelled hot melt adhesive cannot be removed may be necessary. Reactive hot melt adhesives ideally possess thermal stability, i.e., the ability to resist viscosity changes over time when kept in the molten state. Naturally, any gelation or phase separation of reactive hot melt adhesives is considered a failure.

[0006] Additives are typically included in reactive hot melt adhesive formulations. However, large amounts of additives, such as fillers, negatively impact most reactive polyurethane hot melt adhesives, significantly reducing thermal stability to undesirable levels. The desired outcome would be to provide reactive polyurethane hot melt adhesives that incorporate high levels of sustainable, renewable, non-fossil fuel-based additives while maintaining thermal stability. Summary of the Invention

[0007] This section provides a general overview of this disclosure, but is not a full disclosure of the entire scope or all features, aspects or purposes of this disclosure.

[0008] In one embodiment, this disclosure provides a moisture-reactive hot melt adhesive composition prepared from a combination comprising: an organic polyisocyanate; at least one polyol; a MA-SCA acid; and at least one of an inorganic filler or an organosilane.

[0009] In one embodiment, the combination for preparing the moisture-reactive hot melt adhesive composition comprises a thermoplastic polymer.

[0010] In one embodiment, the polyol in the combination used to prepare the moisture-reactive hot melt adhesive composition comprises a polyether polyol, a polyester polyol, or both a polyether polyol and a polyester polyol.

[0011] In one embodiment, the composition for preparing the moisture-reactive hot melt adhesive composition comprises a polyester polyol, said polyester polyol being a polyester diol having the structure of Formula 1 or Formula 2.

[0012] Equation 1 is:

[0013] H-[O(CH2) m OOC (CH2) n CO] k -O(CH2) m-OH;

[0014] m and n are each even numbers; m + n = 8; m and n are each independently selected from 2, 4 or 6; k is an integer from 9 to 55; and the polyol of Formula 1 has a number average molecular weight of about 2,000 to about 11,000.

[0015] Equation 2 is:

[0016] HO-[(CH2)5COO] p -R1- [OOC(CH2)5] q -OH;

[0017] R1 is an initiator, such as 1,4'-butanediol, 1,6'-hexanediol, or ethylene glycol; p is an integer from 0 to 96; q is an integer from 0 to 96; p + q = 16 to 96; and the polyol has a number average molecular weight of about 2,000 to about 11,000. Formula 2 is polycaprolactone diol, which is a specific form of polyester diol. Therefore, in the following, when referring to polyester diols according to this disclosure, it is intended to include all diols having the structure of Formula 1 or 2, and / or mixtures of diols, wherein each diol in the mixture has the structure of Formula 1 or 2. In this embodiment, polyester polyols not having the structure of Formula 1 and / or Formula 2 are preferably excluded from the composition.

[0018] In one embodiment, the combination comprises a polyester diol according to formula 1 or 2 having a number average molecular weight of 2,000 to 11,000, and the polyester diol is present in an amount of 10% to 35% by weight based on the total adhesive weight.

[0019] In one embodiment, the combination comprises a polyether polyol having a number average molecular weight of 1,500 to 6,000, and the polyether polyol is present in an amount of 15% to 40% by weight based on the total adhesive weight.

[0020] In one embodiment, the combination comprises a polyether polyol, wherein the polyether polyol is polypropylene glycol.

[0021] In one embodiment, the combination comprises a thermoplastic polymer, which is an acrylic polymer having a weight-average molecular weight of 30,000 to 80,000, and the acrylic polymer is present in an amount of 10% to 40% by weight based on the total weight of the adhesive.

[0022] In one embodiment, the combination comprises a thermoplastic polymer, said thermoplastic polymer being an acrylic polymer having a glass transition temperature of 35°C to 85°C and a hydroxyl value of less than 8.

[0023] In one embodiment, the polyisocyanate is present in an amount of 5% to 40% by weight, based on the total weight of the adhesive.

[0024] In one embodiment, the polyisocyanate comprises 4,4'-methylene diphenyl diisocyanate (4,4'-MDI).

[0025] In one embodiment, the adhesive contains 10% to 50% by weight of inorganic filler, based on the total weight of the adhesive.

[0026] In one embodiment, the adhesive comprises calcium carbonate filler.

[0027] In one embodiment, the hot melt adhesive composition further comprises additives selected from additional fillers, plasticizers, catalysts, colorants, rheology modifiers, flame retardants, UV pigments, nanofibers, defoamers, tackifiers, curing catalysts, antioxidants, stabilizers, thixotropic agents, and mixtures thereof.

[0028] In one embodiment, the hot melt adhesive composition comprises an organosilane adhesive accelerator.

[0029] In one embodiment, this disclosure includes an article comprising the disclosed hot melt adhesive in cured or uncured form.

[0030] In one embodiment, this disclosure includes the cured reaction product of the disclosed hot melt adhesive.

[0031] The disclosed compounds include any and all isomers and stereoisomers. Generally, unless otherwise expressly stated, the disclosed materials and methods may alternatively be formulated to include, consist of, or substantially consist of any suitable components, portions, or steps disclosed herein. The disclosed materials and methods may additionally or alternatively be formulated to be free of or substantially free of any components, materials, ingredients, auxiliaries, portions, types, and steps used in prior art compositions or otherwise not essential for achieving the function and / or purpose of this disclosure.

[0032] As used herein, “about” or “approximately” in relation to numerical values ​​means ±10%, preferably ±5%, more preferably ±1% or less.

[0033] These and other features and advantages of this disclosure will become more apparent to those skilled in the art from the detailed description of preferred embodiments. The following description is accompanied by accompanying drawings. Detailed Implementation

[0034] Unless the context clearly indicates otherwise, the singular forms “a”, “an”, and “the” include plural indicators.

[0035] As used herein, “about” or “approximately” in relation to numerical values ​​means ±10%, preferably ±5%, more preferably ±1% or less.

[0036] As used herein, "at least one" means one or more, i.e., 1, 2, 3, 4, 5, 6, 7, 8, 9 or more. Regarding components, this indication refers to the type of component rather than the absolute number of molecules. Therefore, "at least one polymer" means, for example, at least one type of polymer, i.e., a polymer of one type or a mixture of several different polymers.

[0037] As used herein, the terms “comprising” and “consisting of” are synonymous with “including” or “containing” and are inclusive or open-ended, and do not exclude additional, unlisted members, elements or method steps.

[0038] When quantities, concentrations, sizes, and other parameters are expressed in the form of ranges, preferred ranges, upper limits, lower limits, or preferred upper and lower limits, it should be understood that a specific disclosure is made of any range that can be obtained by combining any upper or preferred value with any lower or preferred value, regardless of whether the obtained range is explicitly mentioned in the context.

[0039] The terms “preferred” and “preferred” are used frequently herein to refer to embodiments of the present disclosure that may provide particular benefits in certain circumstances. However, the description of one or more preferred or preferred embodiments does not imply that other embodiments are not available and is not intended to exclude those other embodiments from the scope of the present disclosure.

[0040] Unless otherwise specified, throughout this specification and claims, when referring to a polymer, the term "molecular weight" means the number-average molecular weight (M). n Number-average molecular weight M n The molecular weight can be calculated based on end-group analysis (OH value according to DIN EN ISO 4629, free NCO content according to EN ISO 11909), or determined according to DIN 55672 by gel permeation chromatography using THF as the eluent. Unless otherwise specified, all given molecular weights are determined by gel permeation chromatography.

[0041] The open time of an adhesive refers to the period during which the adhesive can bond with the material.

[0042] Polyurethane hot melt adhesives are widely used in panel lamination processes. They offer excellent adhesion and structural bonding to a wide range of materials. Their lack of solvent requirements, rapid green strength, and good heat, cold, and chemical resistance make them ideal for use in the construction industry. In particular, they can be used in recreational vehicle panel laminations and doors. Because forming these structures involves complex lamination, long open times of 6 minutes or longer and high green strength are important. Furthermore, maintaining final strength is necessary even when the cured assembly is exposed to extreme temperatures. Ideally, reactive polyurethane hot melt adhesives should be provided, which maintain curing strength at higher temperatures compared to existing formulations, allowing for use in additional applications.

[0043] The present invention aims to provide a reactive polyurethane hot melt adhesive comprising a high content of sustainable, renewable, non-fossil fuel components, such as fillers, while maintaining their desired properties, such as thermal stability.

[0044] The disclosed hot melt adhesive is a reaction product of a mixture comprising at least one of: an organic polyisocyanate; a polyol; MA-SCA; and an inorganic filler or an organosilane. The mixture may optionally contain one or more of a thermoplastic polymer, a catalyst, and additives. After the reaction, non-reactive components such as inorganic fillers and thermoplastic polymers may also be added to the reaction product. Preferably, the hot melt adhesive is free of organic solvents, water, and photoinitiators.

[0045] Suitable organic polyisocyanates 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 diphenyl diisocyanate (MDI), isophorone diisocyanate (IPDI), hydrogenated methylene diphenyl diisocyanate (HMDI), toluene diisocyanate (TDI), and ethylene diisocyanate. diisocyanate, ethylidenediisocyanate, propylene diisocyanate, butylidene diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, cyclopentyl-1,3-diisocyanate, cyclohexylene-1,4-diisocyanate, cyclohexylene-1,2-diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,2-diphenylpropane-4,4'-diisocyanate, phenylenediamine diisocyanate, 1,4-naphthylene diisocyanate, 1,5-naphthylene diisocyanate, m-phenylene diisocyanate, p- Phenylidene diisocyanate, diphenyl-4,4'-diisocyanate, azobenzene-4,4'-diisocyanate, diphenylsulfone-4,4'-diisocyanate, 2,4-methylenephenyl diisocyanate, dichlorohexamethylene diisocyanate, furfuryl diisocyanate, 1-chlorobenzene-2,4-diisocyanate, 4,4',4''-triisocyanotriphenylmethane, 1,3,5-triisocyano-benzene, 2,4,6-triisocyano-toluene, 4,4'-dimethyldiphenyl-methane-2,2',5,5-tetratetraisocyanate, etc. Although these compounds are commercially available, their synthetic methods are well known in the art. Preferred isocyanate-containing compounds are isomers of methylene diphenyl diisocyanate (MDI), isophorone diisocyanate (IPDI), hydrogenated MDI (HMDI), and toluene diisocyanate (TDI).

[0046] The polyols that can be used include those used to prepare polyurethanes, including but not limited to: polyether polyols, polyester polyols, polycarbonate polyols, polyacetal polyols, polyamide polyols, polyesteramide polyols, polyalkylene polyether polyols, polysulfide polyols, and mixtures thereof, preferably polyether polyols, polyester polyols, polycarbonate polyols, and mixtures thereof.

[0047] Available polyester polyols include those that can be obtained by reacting a dicarboxylic acid with a polyol in a polycondensation reaction. The dicarboxylic acid can be aliphatic, alicyclic, or aromatic and / or derivatives thereof, such as acid anhydrides, esters, or acyl chlorides. Specific examples of these are succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, dodecanoic acid, phthalic acid, terephthalic acid, isophthalic acid, trimellitic acid, phthalic anhydride, tetrahydrophthalic anhydride, glutaric anhydride, maleic acid, maleic anhydride, fumaric acid, dimer fatty acids, dodecanoic acid, and dimethyl terephthalate. Examples of suitable polyols are ethylene 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-octanediol, 1,8-otaneglycolcyclohexanedimethanol, 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 polybutanediol. Alternatively, they can be obtained by ring-opening polymerization of cyclic esters, preferably caprolactone. Polyester polyols are commercially available, such as Piotane polyol from Panolam Industries International and Dynacoll polyol from Evonik. Other suppliers include Stepan, COIM, and Lanxess. In some embodiments, polyhexane adipate polyol is preferred.

[0048] Available polyether polyols include linear and branched polyethers having hydroxyl groups. Examples of polyether polyols may include polyalkylene oxide polyols, such as polyethylene glycol, polypropylene glycol, polybutane glycol, etc. Additionally, homopolymers and copolymers of polyalkylene oxide polyols may be used. Particularly preferred copolymers of polyalkylene oxide polyols may comprise adducts of at least one compound selected from ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, 2-ethylhexanediol-1,3, glycerol, 1,2,6-hexanetriol, trimethylolpropane, trimethylolethane, tri(hydroxyphenyl)propane, triethanolamine, triisopropanolamine, ethylenediamine, and ethanolamine. Most preferably, the polyether polyol comprises polypropylene glycol. Preferably, the polyether polyol has a number average molecular weight of 1,500 to 6,000, more preferably in the range of 2,000 to 4,000 Daltons. Polyether polyols may comprise mixtures of polyether polyols.

[0049] Usable polycarbonate polyols can be obtained by reacting carbonate derivatives such as diphenyl carbonate, dimethyl carbonate, or phosgene with diols. 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-dimethylolcyclohexane, 2-methyl-1,3-propanediol, 2,2,4-trimethylpentanediol-1,3, dipropylene glycol, polypropylene glycol, dibutylene glycol, polybutanediol, bisphenol A, bisphenol F, tetrabromobisphenol A, and lactone-modified diols. In some embodiments, the diol component preferably contains 40% to 100% by weight of hexanediol, preferably 1,6-hexanediol and / or hexanediol derivatives. More preferably, the diol component includes examples that exhibit ether or ester groups in addition to the terminal OH groups. The polycarbonate polyol should be substantially linear. However, they can optionally be slightly branched by the addition of multifunctional components, particularly low-molecular-weight polyols. Suitable examples include glycerol, trimethylolpropane, glycerol-1,2,6, glycerol-1,2,4, trimethylolpropane, pentaerythritol, p-cyclohexanediol, mannitol and sorbitol, methyl glycosides, and 1,3,4,6-dianhydrohexites.

[0050] Available polyols also include: polyols that are hydroxyl-functionalized polymers, such as hydroxyl-functionalized siloxanes; and polyols containing additional functional groups such as vinyl or amino groups.

[0051] In one embodiment, the reaction mixture either comprises a polyester glycol polymer having the structure of Formula 1 or Formula 2 alone, or comprises a polyester glycol polymer having the structure of Formula 1 or Formula 2 in combination with one or more additional polyols. The polyester glycol polymer of Formula 1 or Formula 2 preferably has a number average molecular weight of 2,000 to 11,000 Daltons, more preferably 2,000 to 10,000, and even more preferably 2,500 to 6,000. For this polyester glycol polymer, according to this disclosure, the number average molecular weight (M...) is... n The relationship between the functionality (f) and hydroxyl value (OH#) of a polyol can be expressed by the following equation M n = (f) It is represented by (56100 / OH#). Formula 1 is:

[0052] H-[O(CH2) m OOC (CH2) n CO] k -O(CH2) m -OH;

[0053] m and n are even numbers; m + n = 8; m and n are independently selected from 2, 4 or 6; k is an integer from 9 to 55; and the polyol of formula I has a number average molecular weight of about 2,000 to 11,000.

[0054] Formula 2, polycaprolactone, is:

[0055] HO-[(CH2)5COO] p -R1- [OOC(CH2)5] q -OH;

[0056] R1 is an initiator, such as 1,4'-butanediol, 1,6'-hexanediol, or ethylene glycol; p is an integer from 0 to 96; q is an integer from 0 to 96; p + q = 16 to 96; and the polyol has a number average molecular weight of about 2,000 to 11,000.

[0057] The combination comprises MA-SCA acids. MA-SCA acids are a subset of multibasic acids having an acidic group ultimately attached to a single central atom. Examples of MA-SCA acids include sulfuric acid, phosphonic acid, phosphoric acid, and diphosphonic acid (pyrophosphate). Examples of other acids that are not MA-SCA acids and should not be used in the disclosed compositions include hydrochloric acid, nitric acid, phosphonic acid, p-toluenesulfonic acid, ethanesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, acetic acid, propionic acid, fumaric acid, maleic acid, oxalic acid, and adipic acid.

[0058] MA-SCA acid unexpectedly prolongs the time that the hot melt adhesive can remain at its operating temperature before the viscosity rises to an objectional level. In other words, when the hot melt adhesive is maintained at its operating temperature, adding MA-SCA acid to the hot melt adhesive unexpectedly reduces the rate of viscosity increase.

[0059] Polyurethane adhesives and sealants used at room temperature can contain large amounts of filler without any problems. However, adding large amounts of filler, such as 10% by weight or more, or 20% by weight or more, to hot melt adhesives will reduce the thermal stability of the hot melt adhesive, in some cases to a level that makes highly filled hot melt adhesives commercially undesirable. Adding MA-SCA acid to highly filled hot melt adhesives unexpectedly increases the thermal stability of the highly filled hot melt adhesives. Although undesirable interactions between MA-SCA acid and filler might be expected, such interactions have not been observed.

[0060] Surprisingly, acids structurally similar to MA-SCA acids, such as maleic acid and adipic acid, also contain multiple acidic groups in their molecules. However, since these two acidic groups are not ultimately attached to a single central atom (in their case, they are attached to two different carbon atoms), they unexpectedly reduce the stability of hot melt adhesives at certain temperatures.

[0061] Surprisingly, there are no "neutral" acids. MA-SCA acids improve the stability of hot melt adhesives at certain temperatures. Other acids reduce the stability of hot melt adhesives at certain temperatures.

[0062] Fillers may be used optionally. Suitable fillers include inorganic materials such as calcium carbonate, kaolin, and dolomite. Calcium carbonate has been described as a sustainable and renewable material based on non-fossil fuels. Other examples of suitable fillers can be found in *Handbook of Fillers*, George Wypych, 3rd edition, 2009, and *Handbook of Fillers and Reinforcements for Plastics*, Harry Katz and John Milewski, 1978. Based on the total binder weight, inorganic fillers are preferably present in an amount of about 10% to about 50% by weight, more preferably 20% to 30% by weight. Previous attempts using large quantities of such fillers have resulted in hot melt adhesives with short open times and problems such as an undesirable increase in viscosity of the molten hot melt adhesive during use.

[0063] Organosilanes may be used optionally. Suitable organosilanes include aminosilanes, such as secondary aminosilanes. An attractive silane comprises at least two silyl groups, wherein three methoxy groups are bonded to each of the silanes having a 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 available organosilanes include silanes having hydroxyl, mercapto, or both functionalities, such as 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxy-ethoxyethoxysilane, 3-aminopropyl-1-methyl-1-diethoxysilane, N-methyl-3-aminopropyltrimethoxysilane, N-butyl-3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-thiopropyltriethoxysilane, 3-mercaptopropyl-1-methyl-dimethoxysilane, (N-cyclohexylaminomethyl)methyldiethoxysilane, (N-cyclohexylaminomethyl)triethoxysilane, (N-phenylamino-methyl)methyldimethoxysilane (N-phenylaminomethyl)methoxysilane, etc. (N-ethyl)methyldimethoxysilane, (N-phenylaminomethyl)tri-methoxysilane, N-ethyl-aminoisobutyltrimethoxysilane, 4-amino-3,3-dimethylbutyltrimethoxysilane, N-(n-butyl)-3-aminopropyltriethoxysilane, N-(n-butyl)-3-aminopropylalkoxydiethoxysilane, di(3-triethoxymethsilylpropyl)amine and any combination thereof.

[0064] Organosilanes are commercially available from many sources such as Momentive Performance Materials (Silquest) and Evonik (Dynasylan). Some available examples include Silquest Alink 15 (N-ethyl-3-trimethoxysilyl-2-methylpropylamine), Silquest Alink 35 (γ-isocyanopropyltrimethoxysilane), Silquest A174NT (γ-methacryloyloxypropyltrimethoxysilane), Silquest A187 (γ-epoxypropoxypropyltrimethoxysilane), Silquest A189 (γ-mercaptopropyltrimethoxysilane), Silquest A 597 (tris(3-(trimethoxysilyl)propyl)isocyanurate), Silquest A1110 (γ-aminopropyltrimethoxysilane), Silquest A1170 (di(trimethoxysilylpropyl)amine), Dynasylan 1189 (N-butyl-3-aminopropyltrimethoxysilane), Silquest A1289 (di-(triethoxysilylpropyltetrasulfide), and Silquest Y9669. (N-Phenyl-γ-aminopropyltrimethoxysilane).

[0065] Thermoplastic polymers may optionally be used. Suitable thermoplastic polymers include acrylic polymers formed from acrylates, methacrylates, and mixtures thereof, as known in the art. Acrylic copolymers containing at least one of methyl methacrylate monomers and n-butyl methacrylate monomers are preferred. Examples of these preferred acrylic copolymers include Elvacite® 2013, a copolymer of methyl methacrylate and n-butyl methacrylate having a weight-average molecular weight of 34,000; Elvacite® 2016, a copolymer of methyl methacrylate and n-butyl methacrylate having a weight-average molecular weight of 60,000; and Elvacite® 4014, a copolymer of methyl methacrylate, n-butyl methacrylate, and hydroxyethyl methacrylate having a weight-average molecular weight of 60,000. Elvacite® polymers are available from Lucite International. Additional examples of suitable acrylic polymers can be found in U.S. Patent Nos. 6,465,104 and 5,021,507, which are incorporated herein by reference. Acrylic polymers may or may not contain active hydrogen. Preferably, the acrylic polymer has a weight-average molecular weight of 30,000 to 80,000, more preferably 45,000 to 70,000. Based on the total adhesive weight, the acrylic polymer is preferably present in an amount of about 10% to 40% by weight, more preferably 15% to 25% by weight. The acrylic polymer preferably has an OH value of less than 8, more preferably less than 5. The acrylic polymer preferably has a glass transition temperature Ti of about 35°C to about 85°C, more preferably 45°C to 75°C. g .

[0066] The adhesive formulation may optionally contain one or more of a variety of known hot melt adhesive additives, such as catalysts, additional fillers, plasticizers, colorants, rheology modifiers, flame retardants, UV pigments, nanofibers, defoamers, compatibility tackifiers, curing catalysts, antioxidants, stabilizers, thixotropic agents such as fumed silica, etc. Optional catalysts include, for example, 2,2'-dimorpholinodiethyl ether, triethylenediamine, dibutyltin dilaurate, and stannous octoate. A preferred catalyst is 2,2'-dimorpholinodiethyl ether. Conventional additives compatible with the composition according to the invention can be determined simply by combining potential additives with the composition and determining their compatibility. If the additive is homogeneous within the product at room temperature and at the operating temperature, it is compatible.

[0067] In one embodiment, the hot melt adhesive comprises a reaction product of a mixture, the mixture comprising:

[0068]

[0069] The disclosed hot melt adhesive can be prepared using the following procedure. Note that moisture must be removed from the polyurethane reaction. Add the polyol, any thermoplastic polymer, and any filler to the reactor and place it under heating and vacuum to remove moisture. Once the dried polyisocyanate is added to the reactor, maintain the reactor under heating and an inert gas barrier to remove moisture. After the reaction time, any catalyst can be added to the reaction product and mixed. Transfer the final product to a moisture-proof container and seal it immediately. Organosilanes, if used, can be added with the polyol or after the reaction. Alternatively, the filler can be dried and added to the reaction product.

[0070] The hot melt adhesive according to this disclosure can be applied in various ways, including by spraying, roller coating, extrusion, and as beads. The disclosed hot melt adhesive can be prepared within a certain viscosity range and is stable during storage, provided moisture is removed. It can be applied to a variety of substrates, including metals, wood, plastics, glass, and fabrics.

[0071] When held at the temperatures and for the time required for use in commercial application equipment, the hot melt adhesive according to this disclosure will not gel or separate into multiple phases. In some embodiments, the disclosed hot melt adhesive has a viscosity increase of 1000% or less, more typically 500% or less, and preferably 200% or less, when held at the temperatures and for the time required for use in commercial application equipment. Samples are held in a sealed container (e.g., excluding air and moisture) at 121°C for 24 hours to approximate commercial conditions.

[0072] The present invention also provides a method for bonding articles together, the method comprising: providing the reactive hot melt adhesive in a cooled, generally solid form; heating the reactive hot melt adhesive to a molten form; applying the molten reactive hot melt adhesive composition to a first article in a molten form; contacting a second article with the composition applied to the first article; cooling and solidifying the adhesive; and subjecting the applied composition to conditions that would cause the composition to completely cure to an irreversible solid form, said conditions including moisture. Typically, hot melt adhesives are dispensed and stored in their solid form and stored in the absence of moisture to prevent curing during storage. The composition is heated to a molten form and applied in that molten form prior to application. Typical application temperatures are from about 80°C to about 145°C. Therefore, this disclosure includes reactive polyurethane hot melt adhesive compositions in the following forms: their uncured solid form, as they are normally stored and dispensed; their molten form after being melted just before application; and their irreversible solid form after curing.

[0073] After application, in order to bond articles together, the reactive hot melt adhesive composition is subjected to conditions that cause it to solidify and harden into a composition having an irreversible solid form. Solidification or setting occurs as the liquid melt begins to cool from its application temperature to room temperature. In the presence of ambient moisture, curing (i.e., chain extension) occurs into the composition having an irreversible solid form.

[0074] The invention is further illustrated by the following non-limiting embodiments.

[0075] Example

[0076] The following components were used in the following examples.

[0077]

[0078] After equilibration at 121°C for 30 minutes, the viscosity was measured on a Brookfield DV-I+ viscometer using a heated sample cup and a #27 spindle.

[0079] 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 exclude air and moisture. The tube and sample were then thermally aged in an oven at 121°C for 24 hours. After aging, the viscosity of the sample was measured before and after thermal aging using a Brookfield viscometer (#27 rotor), and the percentage increase in viscosity was recorded. Exclusion of air and moisture helps prevent the aged sample from reacting with moisture. The aging test is an approximation of how the hot melt adhesive will react over time when held at its melt temperature, as it would during use.

[0080] If the sample gels or separates after thermal aging, the viscosity after aging is not measured, and its thermal stability is considered unacceptable and ineffective. If the viscosity increase of the composition containing the acid is less than that of the same composition without the acid, we call it an improvement and refer to the acid or one or more as a "favorable acid." If the viscosity increase of the composition containing one or more acids is greater than that without the acid or one or more acids, or if the system gels, we call the acid or one or more as a "disadvantageous acid." If the viscosity increase remains substantially the same with or without the acid or one or more acids, we call the acid or one or more as a "neutral acid." As shown in the results, an acid is either a favorable acid or a disadvantageous acid. Surprisingly, we did not find any neutral acids.

[0081] Examples were prepared as described below. In each case, the material was moisture-reactive, and therefore the reaction, packaging, and storage were carried out under moisture-free conditions.

[0082] Example 1 - Comparison

[0083] 194.95 parts of polypropylene glycol (PPG 2000), OH value 56, were introduced into a heated stirred tank reactor with a vacuum connection, in which 133 parts of Elvacite 2016 acrylic resin and 98 parts of polybutylene adipate (OH value 22) were dissolved. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 65 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) were added and stirred under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0084] Example 2 - Comparison

[0085] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, into which 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (OH value 22), and 175 parts of calcium carbonate were melted. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) were added and stirred under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0086] Example 3 - Comparison

[0087] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, into which 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (OH value 22), and 175 parts of calcium carbonate were melted. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and the reaction product was transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0088] Example 4 - The Invention

[0089] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, into which 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (OH value 22), 0.238 parts of phosphoric acid, and 175 parts of calcium carbonate were melted. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and the reaction product was transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0090] Example 5 - Comparison

[0091] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, into which 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (OH value 22), 0.609 parts of phosphoric acid, and 175 parts of calcium carbonate were melted. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) were added and stirred under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0092] Example 6 - Comparison

[0093] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, into which 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (OH value 22), 0.21 parts of ethanesulfonic acid, and 175 parts of calcium carbonate were melted. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and the reaction product was transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0094] Example 7 - Comparison

[0095] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, into which 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (OH value 22), 0.14 parts of HCl, and 175 parts of calcium carbonate were melted. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) were added and stirred under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0096] Example 8 - Comparison

[0097] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, into which 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (OH value 22), 0.175 parts of nitric acid, and 175 parts of calcium carbonate were melted. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) were added and stirred under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0098] Example 9 - The Invention

[0099] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, into which 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (OH value 22), 0.175 parts of sulfuric acid, and 175 parts of calcium carbonate were melted. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) were added and stirred under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0100] Example 10 - The Invention

[0101] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, into which 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (OH value 22), and 175 parts of calcium carbonate were melted. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) and 0.175 parts of sulfuric acid were added, followed by stirring under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0102] Example 11 - Comparison

[0103] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, and 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (OH value 22), 0.14 parts of hypophosphite, and 175 parts of calcium carbonate were melted therein. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, and then stirred under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) were added and stirred under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0104] Example 12 - The Invention

[0105] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, and 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (OH value 22), 0.28 parts of phosphonic acid (phosphorous acid), and 175 parts of calcium carbonate were melted therein. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, and then stirred under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) were added, followed by stirring under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0106] Example 13 - The Invention

[0107] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, into which 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (OH value 22), 0.28 parts of phosphoric acid, and 175 parts of calcium carbonate were melted. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) were added and stirred under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0108] Example 14 - The Invention

[0109] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, into which 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (OH value 22), and 175 parts of calcium carbonate were melted. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) and 0.28 parts of phosphoric acid were added, followed by stirring under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0110] Example 15 - The Invention

[0111] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, and 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (OH value 22), 0.28 parts of diphosphoric acid (pyrophosphate), and 175 parts of calcium carbonate were melted therein. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, and then stirred under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) were added, followed by stirring under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0112] Example 16 - Comparison

[0113] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, and 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (OH value 22), 0.14 parts of phosphoric acid, 0.14 parts of ethanesulfonic acid, and 175 parts of calcium carbonate were melted therein. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, and then stirred under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) were added, followed by stirring under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0114] Example 17 - Comparison

[0115] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, into which 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (OH value 22), 0.28 parts of p-toluenesulfonic acid, and 175 parts of calcium carbonate were melted. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) were added and stirred under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0116] Example 18 - Comparison

[0117] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, and 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (OH value 22), and 175 parts of calcium carbonate were melted therein. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, and then stirred under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) and 0.28 parts of p-toluenesulfonic acid were added, followed by stirring under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0118] Example 19 - Comparison

[0119] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, into which 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (OH value 22), 0.28 parts of ethanesulfonic acid, and 175 parts of calcium carbonate were melted. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) were added and stirred under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0120] Example 20 - Comparison

[0121] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, into which 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (OH value 22), and 175 parts of calcium carbonate were melted. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) and 0.28 parts of ethanesulfonic acid were added, followed by stirring under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0122] Example 21 - Comparison

[0123] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, into which 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (OH value 22), 0.28 parts of methanesulfonic acid, and 175 parts of calcium carbonate were melted. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) were added and stirred under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0124] Example 22 - Comparison

[0125] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, and 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (diol) (OH value 22), and 175 parts of calcium carbonate were melted therein. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, and then stirred under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) and 0.28 parts of methanesulfonic acid were added, followed by stirring under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0126] Example 23 - Comparison

[0127] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, and 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (OH value 22), 0.28 parts of trifluoromethanesulfonic acid, and 175 parts of calcium carbonate were melted therein. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, and then stirred under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) were added, followed by stirring under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0128] Example 24 - Comparison

[0129] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, and 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (OH value 22), and 175 parts of calcium carbonate were melted therein. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, and then stirred under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) and 0.28 parts of trifluoromethanesulfonic acid were added, followed by stirring under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0130] Example 25 - Comparison

[0131] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, into which 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (OH value 22), 0.28 parts of acetic acid, and 175 parts of calcium carbonate were melted. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) were added and stirred under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0132] Example 26 - Comparison

[0133] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, and 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (OH value 22), and 175 parts of calcium carbonate were heated therein. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) and 0.28 parts of acetic acid were added, followed by stirring under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0134] Example 27 - Comparison

[0135] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, and 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (OH value 22), 0.28 parts of propionic acid, and 175 parts of calcium carbonate were heated therein. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) were added and stirred under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0136] Example 28 - Comparison

[0137] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, and 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (OH value 22), and 175 parts of calcium carbonate were heated therein. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) and 0.28 parts of propionic acid were added, followed by stirring under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0138] Example 29 - Comparison

[0139] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, along with 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (OH value 22), 0.28 parts of fumaric acid, and 175 parts of calcium carbonate. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) were added, followed by stirring under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0140] Example 30 - Comparison

[0141] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, and 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (OH value 22), 0.28 parts of maleic acid, and 175 parts of calcium carbonate were heated therein. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) were added and stirred under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0142] Example 31 - Comparison

[0143] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, and 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (OH value 22), 0.28 parts of oxalic acid, and 175 parts of calcium carbonate were heated therein. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) were added, followed by stirring under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0144] Example 32 - Comparison

[0145] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, and 133 parts of Elvacite 2016 acrylic resin, 98 parts of polybutylene adipate (OH value 22), 0.28 parts of oxalic acid, and 175 parts of calcium carbonate were heated therein. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 98 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) were added, followed by stirring under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0146] Example 33 - Comparison

[0147] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, into which 133 parts of Elvacite 2016 acrylic resin and 98 parts of polyhexyl adipate (OH value 30) were melted. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 58 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) were added and stirred under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0148] Example 34 - Comparison

[0149] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, into which 133 parts of Elvacite 2016 acrylic resin, 98 parts of polyhexyl adipate (OH value 30), and 175 parts of calcium carbonate were melted. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 77 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) were added and stirred under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0150] Example 35 - This Invention

[0151] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, and 133 parts of Elvacite 2016 acrylic resin, 98 parts of polyhexyl adipate (OH value 30), 0.28 parts of phosphoric acid, and 175 parts of calcium carbonate were heated therein. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 77 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) were added and stirred under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0152] Example 36 - The Invention

[0153] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, into which 133 parts of Elvacite 2016 acrylic resin, 98 parts of polyhexyl adipate (OH value 30), and 175 parts of calcium carbonate were melted. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 77 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) and 0.28 parts of phosphoric acid were added, followed by stirring under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0154] Example 37 - Comparison

[0155] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, and 133 parts of Elvacite 2016 acrylic resin, 98 parts of polyhexyl adipate (OH value 30), 0.28 parts of ethanesulfonic acid, and 175 parts of calcium carbonate were heated therein. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 77 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) were added and stirred under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0156] Example 38 - Comparison

[0157] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, and 133 parts of Elvacite 2016 acrylic resin, 98 parts of polyhexyl adipate (OH value 30), and 175 parts of calcium carbonate were heated therein. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 77 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) and 0.28 parts of ethanesulfonic acid were added, followed by stirring under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0158] Example 39 - Comparison

[0159] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, and 133 parts of Elvacite 2016 acrylic resin, 98 parts of polyhexyl adipate (OH value 30), 0.28 parts of acetic acid, and 175 parts of calcium carbonate were heated therein. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 77 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) were added and stirred under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0160] Example 40 - Comparison

[0161] 194.95 parts of polypropylene glycol (OH value 56) were introduced into a heated stirred tank reactor with a vacuum connection, into which 133 parts of Elvacite 2016 acrylic resin, 98 parts of polyhexyl adipate (OH value 30), and 175 parts of calcium carbonate were melted. Moisture was then removed under vacuum at 121°C for 1.5 hours. The reactor was then purged with nitrogen, and 77 parts of 4,4'-diphenylmethane diisocyanate (MDI) were added. The contents of the reactor were stirred at 121°C under nitrogen for 15 minutes, followed by stirring under vacuum at 121°C for 3 hours. The reactor was then purged with nitrogen, and 0.77 parts of 2,2'-dimorpholinodiethyl ether (DMDEE) and 0.28 parts of acetic acid were added, followed by stirring under nitrogen for 15 minutes. The reaction product was then transferred to a moisture-proof container and immediately sealed for subsequent testing.

[0162] The initial viscosity and aged viscosity of the above-described embodiments at 121°C were tested. The results are summarized in the table below.

[0163]

[0164]

[0165] Previously = acid was added before the reaction with polyisocyanates.

[0166] Then, acid was added after the polyisocyanate reacted with the polyol.

[0167] # = Example number; I = Example of the present invention; C = Comparative example

[0168] Examples 1, 2, and 3 show that adding fillers to reactive hot melt adhesives reduces the thermal stability of the adhesive, even if the composition does not contain a catalyst.

[0169] Example 4 shows that adding approximately 300 ppm of MA-SCA phosphoric acid restored the reactive hot melt adhesive composition to ideal thermal stability. However, Example 5 shows that adding too much (approximately 900 ppm) of the same MA-SCA phosphoric acid resulted in phase separation and loss of thermal stability.

[0170] Examples 6 through 8 demonstrate that not all acids can improve thermal stability, enhancing the unexpected effects of MA-SCA acids. Examples 11-12, 17-32, and 37-40 further demonstrate that an improvement in thermal stability is provided by a surprisingly narrow range of acids. Other acids can reduce the thermal stability of reactive hot melt adhesives.

[0171] The use of MA-SCA acids can improve thermal stability. Surprisingly, the use of a combination of MA-SCA acids and non-MA-SCA acids, as in Example 16, does not improve thermal stability and leads to gelation.

[0172] Examples 33 and 34 again demonstrate that adding fillers reduces thermal stability. Examples 35 and 36 demonstrate that adding approximately 400 ppm of the desired beneficial phosphoric acid increases the thermal stability of this reactive hot melt adhesive composition.

[0173] Many acids do not provide an arbitrary increase in thermal stability, and may even decrease it. While approximately 300 ppm of phosphoric acid increases thermal stability, similar amounts of ethanesulfonic acid (Examples 6, 19, 20, 37, 38), hydrochloric acid (Example 7), nitric acid (Example 8), phosphonic acid (Example 11), toluenesulfonic acid (Examples 17, 18), methanesulfonic acid (Examples 21, 22), trifluoromethanesulfonic acid (Examples 23, 24), acetic acid (Examples 25, 26, 39, 40), propionic acid (Examples 27, 28), fumaric acid (Example 29), maleic acid (Example 30), and adipic acid (Example 32) do not provide the same increase in thermal stability. Many of these examples exhibit undesirable gelling or phase separation failures.

[0174] Other examples were prepared using the following methods and formulations. Percentages are based on the weight percentage of the total composition.

[0175]

[0176] Note that the total deviates slightly from 100% by weight due to rounding.

[0177] 1 4,4' MDI

[0178] 2 PPG2000, from Covestro

[0179] 3 Piothane 3500HA, from Panolam Industries International

[0180] 4. Elvacite 2016, from Lucite

[0181] 5,2'-Dimorpholinodiethyl ether (Jeffcat DMDEE, from Huntsman)

[0182] 6. The materials and quantities are shown in the results table.

[0183] The disclosed hot melt adhesive can be prepared using the following procedure. Note that moisture must be removed from the polyurethane reaction. The polyol, any thermoplastic polymer, and any filler are added to the reactor and placed under heating and vacuum to remove moisture. Once the dried polyisocyanate is added to the reactor, the reactor is maintained under heating and an inert gas barrier to remove moisture. After the reaction time, any catalyst can be added to the reaction product and mixed. The final product is transferred to a moisture-proof container and sealed immediately. Organosilanes, if used, can be added with the polyol or after the reaction. The filler can also be dried and added to the reaction product.

[0184] The sample was prepared using the above formulation. The adhesion of the sample to different substrates was tested according to the following procedure. The sample of the moisture-reactive hot melt adhesive was heated to approximately 121°C and extruded onto the surface of a 1-inch × 4-inch strip of untreated substrate (glass, aluminum, stainless steel, and ABS). The extruded adhesive beads had a diameter of approximately 3 mm and adhered automatically to the substrate surface. The substrate with the adhered adhesive was stored under ambient conditions (room temperature and humidity) for 5 days to allow for complete curing. After curing, the adhesive beads were manually peeled off the substrate using a narrow putty knife.

[0185] The results are summarized in the table below.

[0186]

[0187] The adhesion results were evaluated as follows: E: Excellent bond strength; the bond will not break without damaging the substrate or experiencing more than 50% cohesive failure. G: Good bond; the bond will not break without some (less than 1 / 3) cohesive failure or some minor substrate failure. F: Moderate bond strength; the bond can break without substrate or cohesive failure, but some force is required to separate it; it is typically 100% bond failure. P: Poor bond strength; the bond can be separated very easily without requiring virtually no force; bond failure.

[0188] Example 41 exhibited poor adhesion to glass and aluminum substrates, poor to moderate adhesion to steel, and good to excellent adhesion to ABS polymers. The addition of phosphoric acid slightly increased adhesion to steel but not to other substrates. The addition of sulfuric acid slightly increased adhesion to all substrates.

[0189] Example 44 includes the organosilane Silquest A 1170. Compared to Example 41, which has the same composition but without the organosilane, the addition of this organosilane substantially increases adhesion to all substrates. The addition of phosphoric acid or sulfuric acid substantially does not change the adhesion to any substrate.

[0190] Example 47 includes the organosilane Dynasylan 1189. Compared to Example 41, which has the same composition but without the organosilane, the addition of this organosilane substantially increases adhesion to all substrates. The addition of phosphoric acid or sulfuric acid substantially does not change adhesion to any substrate.

[0191] Example 50 includes the organosilane Silquest Y9669. Compared to Example 41, which has the same composition but without the organosilane, the addition of this organosilane substantially increases adhesion to all substrates. The addition of phosphoric acid or sulfuric acid substantially does not change adhesion to any substrate.

[0192] The initial viscosity of Examples 41 to 52 at 121°C and the viscosity after aging at 121°C in a sealed environment excluding air and moisture for 24 hours were tested.

[0193]

[0194] Example 41 had an initial viscosity of 13,380 cP, which increased to 25,600 cP after aging in a closed container at 250°F for 24 hours. This represents a 91% increase in viscosity. Adding phosphoric acid or sulfuric acid to the composition reduced both the initial viscosity and the aged viscosity.

[0195] Example 44, containing the organosilane Silquest A1170, had an initial viscosity of 12,180 cP, which was lower than the control sample prepared without the organosilane. After aging, the viscosity was 128,300 cP, representing an increase of over 900%. The addition of phosphoric acid slightly reduced the initial viscosity and significantly reduced the aged viscosity. The addition of sulfuric acid slightly increased the initial viscosity and slightly reduced the aged viscosity.

[0196] Example 47, containing the organosilane Dynasylan 1189, had an initial viscosity of 12,080 cP, which was lower than the control sample prepared without the organosilane. After aging, the viscosity was 77,750 cP, representing an increase of over 500%. The addition of phosphoric acid slightly reduced the initial viscosity and significantly reduced the aged viscosity. The addition of sulfuric acid slightly reduced the initial viscosity and significantly reduced the aged viscosity.

[0197] Example 50, containing the organosilane Silquest Y9669, had an initial viscosity of 10,100 cP, which was lower than the control sample prepared without the organosilane. After aging, the viscosity was 52,100 cP, representing an increase of over 400%. The addition of phosphoric acid very slightly increased the initial viscosity and very slightly decreased the aged viscosity. The addition of sulfuric acid increased the initial viscosity and very slightly decreased the aged viscosity.

[0198] The embodiments illustrate that adding organosilanes to moisture-reactive hot melt adhesives can ideally increase the adhesive's bond strength to a variety of substrates. This increased bond strength is accompanied by an undesirable decrease in the thermal stability of the hot melt adhesive. These large viscosity increases can be problematic when the hot melt adhesive remains at its melt temperature during use. In the worst case, this large viscosity increase may necessitate shutting down unwanted equipment so that the sticky hot melt adhesive can be removed and cleaned from the equipment.

[0199] Adding MA-SCA acid to hot melt adhesives that do not contain fillers or organosilanes can provide some minor benefits by reducing initial viscosity and aging viscosity. Adding MA-SCA acid to hot melt adhesives containing organosilane components does not reduce the adhesive improvement provided by the organosilanes. Adding MA-SCA acid to hot melt adhesives containing organosilane components provides an unexpected and surprising reduction in aging viscosity.

[0200] The foregoing description of embodiments has been provided for illustrative and descriptive purposes. It is not intended to be exhaustive or limiting of this disclosure. Elements or features of a particular embodiment are generally not limited to the particular embodiment described, but are interchangeable where applicable and may be used in selected embodiments even if not specifically shown or described. They may also vary in many ways. Such variations should not be considered as departing from this disclosure, and all such modifications are intended to be included within the scope of this disclosure.

Claims

1. A moisture-reactive hot melt adhesive polyurethane composition, which is a product comprising a mixture of the following components: polyisocyanate; polyol; MA-SCA acid; one or both of inorganic fillers or organosilanes. The MA-SCA acid mentioned above is selected from sulfuric acid, phosphonic acid, diphosphoric acid, and any combination thereof. in, Based on the total weight of the mixture, the MA-SCA acid is present in an amount of not less than 100 and less than 800 ppm.

2. The moisture-reactive hot melt adhesive polyurethane composition according to claim 1, wherein the polyol is selected from polyhexyl adipate or polyester diol having the structure of formula 1 or formula 2. Equation 1 is: H-[O(CH2) m OOC (CH2) n CO] k -O(CH2) m –OH; m and n are each even numbers; m + n = 8; m and n are each independently selected from 2, 4, or 6; k is an integer from 9 to 55; and the polyol of formula 1 has a number average molecular weight of 2,000 to 11,000; and Equation 2 is: HO-[(CH2)5COO] p -R1- [OOC(CH2)5] q -OH; R1 is an initiator; p is an integer from 0 to 96; q is an integer from 0 to 96; p + q = 16 to 96; and the polyol has a number average molecular weight of 2,000 to 11,000.

3. The moisture-reactive hot melt adhesive polyurethane composition according to claim 2, wherein the moisture-reactive hot melt adhesive polyurethane composition comprises both polyhexamethylene adipate and a polyester diol having the structure of formula 1 or formula 2.

4. The moisture-reactive hot melt adhesive polyurethane composition according to claim 2, wherein R1 is a residue of a diol initiator selected from 1,4′-butanediol, 1,6′-hexanediol, ethylene glycol, and combinations thereof.

5. The moisture-reactive hot melt adhesive polyurethane composition according to any one of claims 2 to 4, wherein the polyol has a number average molecular weight of 2,000 to 10,000 and is present in an amount of 10% to 35% by weight based on the total adhesive weight.

6. The moisture-reactive hot melt adhesive polyurethane composition according to claim 1, wherein the polyol is a polyether polyol having a number average molecular weight of 1,500 to 6,000 and is present in an amount of 15% to 40% by weight based on the total adhesive weight.

7. The moisture-reactive hot melt adhesive polyurethane composition according to claim 1, wherein the polyol comprises at least one polypropylene glycol.

8. The moisture-reactive hot melt adhesive polyurethane composition according to any one of claims 1 to 4 or 6 to 7, wherein the moisture-reactive hot melt adhesive polyurethane composition further comprises a thermoplastic polymer.

9. The moisture-reactive hot melt adhesive polyurethane composition according to claim 8, wherein the thermoplastic polymer is an acrylic polymer having a weight-average molecular weight of 30,000 to 80,000, and is present in an amount of 10% to 40% by weight based on the total adhesive weight.

10. The moisture-reactive hot melt adhesive polyurethane composition according to claim 8, wherein the thermoplastic polymer is an acrylic polymer having a glass transition temperature of 35°C to 85°C and a hydroxyl value of less than 8.

11. The moisture-reactive hot melt adhesive polyurethane composition according to any one of claims 1 to 4 or 6 to 7, wherein, The polyisocyanate is present in an amount of 5% to 40% by weight based on the total adhesive weight; and / or, the polyisocyanate comprises 4,4'-methylene diphenyl diisocyanate (MDI).

12. The moisture-reactive hot melt adhesive polyurethane composition according to any one of claims 1 to 4 or 6 to 7, wherein, The inorganic filler is present in an amount of 10% to 70% by weight based on the total binder weight; and / or, the inorganic filler is present and includes calcium carbonate.

13. The moisture-reactive hot melt adhesive polyurethane composition according to any one of claims 1 to 4 or 6 to 7, wherein the moisture-reactive hot melt adhesive polyurethane composition further comprises an additive selected from additional fillers, plasticizers, catalysts, colorants, rheology modifiers, flame retardants, UV pigments, nanofibers, defoamers, tackifiers, curing catalysts, antioxidants, adhesion promoters, stabilizers, thixotropic agents, and mixtures thereof.

14. The moisture-reactive hot melt adhesive polyurethane composition according to any one of claims 1 to 4 or 6 to 7, wherein the moisture-reactive hot melt adhesive polyurethane composition further comprises 2,2'-dimorpholinodiethyl ether (DMDEE).

15. An article comprising a moisture-reactive hot melt adhesive polyurethane composition according to any one of claims 1 to 14.

16. A method for bonding two substrates together, the method comprising applying a moisture-reactive hot melt adhesive polyurethane composition according to any one of claims 1 to 4 or 6 to 7 in molten form to a first substrate, then contacting a second substrate with the moisture-reactive hot melt adhesive polyurethane composition on the first substrate, and cooling and curing the moisture-reactive hot melt adhesive polyurethane composition to an irreversible solid form.

17. The cured reaction product of the moisture-reactive hot melt adhesive polyurethane composition according to any one of claims 1 to 4 or 6 to 7.

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