Moisture-curable polyurethane hot melt adhesive composition, and use and application of the same

Abstract

This invention relates to reactive hot melt adhesive compositions and their uses. Specifically, the invention provides an adhesive composition having (A) at least one reactive polyurethane prepolymer obtained by reacting a reaction mixture, the reaction mixture comprising: (a) at least one polyol, and (b) at least one polyisocyanate having at least two isocyanate groups in one molecule; and (B) at least one vinyl acetate homopolymer having a weight average molecular weight (Mw) of 15,000 to less than 100,000 g / mol, and present in an amount of less than 70% by weight based on the total weight of the adhesive composition.

Description

Reactive hot melt adhesive compositions and their uses This invention relates to reactive hot melt adhesive compositions and their uses. Specifically, this invention relates to reactive hot melt adhesive compositions comprising vinyl acetate homopolymers, enabling them to meet various application requirements. Moisture-curing polyurethane hot melt adhesives have a long history and wide distribution, as described by HF Hüber and H. Müller in "Shaping Reactive Hotmelts Using LMW Copolyesters," Adhesives Age, November 1987, pp. 32-35. In industrial applications, moisture-curing polyurethane hot melt adhesives are solid at room temperature, melt into a viscous liquid when heated to a moderate temperature, and are applied to the substrate to be bonded. The molten adhesive composition then cools and solidifies to form an initial bond with the substrate. It can further react with moisture to form a cross-linked structure and achieve high final strength. These adhesives may consist of a polyol component and an isocyanate component having two or more functionalities. For many applications, these adhesives are superior to other adhesives because the bonds produced using them exhibit good bond strength, flexibility, and impact and fatigue resistance. Currently, it is common in industry to blend moisture-curing polyurethane hot melt adhesives with resins (such as acrylic, ethylene-vinyl acetate (EVA), and thermoplastic polyurethane (TPU) resins) to improve the inherent cohesion and initial bond strength of the adhesive with different materials. Poly(vinyl acetate) (PVAc) has long been used in various applications across different technical fields due to its good bond strength to various substrates and low odor. For example, PVAc is a film-forming component in many water-based (latex) adhesives and paints. However, due to compatibility issues, it is rarely mixed with poly(vinyl acetate) hot melt adhesives. Therefore, this technology requires a moisture-curing polyurethane hot melt adhesive that incorporates poly(vinyl acetate) as a component to achieve an adhesive composition with a wide range of open times during curing and good initial bond strength to different substrates. This document discloses a moisture-curing polyurethane hot melt adhesive composition comprising: (A) at least one reactive polyurethane prepolymer obtained by reacting a reaction mixture, the reaction mixture comprising: (a) at least one polyol, and (b) at least one polyisocyanate having at least two isocyanate groups in one molecule; and (B) at least one vinyl acetate homopolymer having a weight average molecular weight (Mw) of 15,000 to less than 100,000 g / mol and present in an amount of less than 70% by weight based on the total weight of the adhesive composition. This article also discloses a cured product of a moisture-curing hot melt adhesive composition according to the present invention. This document also discloses a laminate comprising a first substrate, a second substrate, and an adhesive layer sandwiched between the two, wherein the first substrate and the second substrate are independently selected from glass, resin, fabric, wood, and metal, and the adhesive layer is formed by curing an adhesive composition according to the present invention. This article also discloses the use of the moisture-curing hot melt adhesive composition according to the present invention in the manufacture of consumer products, automotive parts, electronic devices and household appliances. The following section will describe the other characteristics and features of the subject matter in more detail. Those skilled in the art should understand that the descriptions in this invention are merely illustrative of exemplary embodiments and are not intended to limit the broader scope of the invention. Unless otherwise indicated, the terminology used herein shall be understood in accordance with the following definitions. Unless otherwise indicated, as used herein, the terms “a,” “an,” and “the” include both singular and plural indicators. As used herein, the terms "comprising / comprises" are synonymous with "including / includes" or "containing / contains" and are inclusive or open-ended, and do not exclude other members, elements or process steps not listed. The terms "at least one" or "one or more" used in this document to define components refer to the type of component and do not imply an exact number of molecules. For example, "one or more polyols" means a polyol of one type or a mixture of several different polyols. The term "amorphous" as used in this article refers to a material that does not undergo a melt transition when measured using differential scanning calorimetry (DSC). The term "crystallization" as used in this article refers to a melting transition when measured using differential scanning calorimetry (DSC). The term "room temperature" as used in this article refers to a temperature of approximately 20°C to approximately 25°C, preferably approximately 25°C. Unless otherwise indicated, the list of numerical endpoints includes all numerical values ​​and fractions covered in each individual range, as well as the listed endpoints. Unless otherwise specified, molecular weight refers to weight average molecular weight (Mw). Unless otherwise specified, all molecular weight data refer to values ​​obtained by gel permeation chromatography (GPC) (e.g., according to DIN 55672). In this paper, the glass transition temperature (Tg) or melting point of a particular polymer is determined using DSC according to DIN 53 765. Unless otherwise defined, all terms used in this invention (including technical and scientific terms) have the meanings commonly known to one of ordinary skill in the art to which this invention pertains. According to the first embodiment, the present invention generally relates to a moisture-curing polyurethane hot melt adhesive composition comprising: (A) at least one reactive polyurethane prepolymer obtained by reacting a reaction mixture, the reaction mixture comprising: (a) at least one polyol, and (b) at least one polyisocyanate having at least two isocyanate groups in one molecule; and (B) at least one vinyl acetate homopolymer having a weight average molecular weight (Mw) of 15,000 to less than 100,000 g / mol and being present in an amount of less than 70% by weight based on the total weight of the adhesive composition. (A) According to the present invention, the moisture-curing polyurethane hot melt adhesive composition comprises at least one reactive polyurethane prepolymer obtained by reacting a reaction mixture, the reaction mixture comprising: (a) at least one polyol, and (b) at least one polyisocyanate having at least two isocyanate groups in one molecule. In some embodiments, the reactive polyurethane prepolymer has a number average molecular weight (Mn) of 5,000 to 30,000 g / mol, preferably 8,000 to 20,000 g / mol. In some embodiments, component (A) is present in an amount from greater than 30% by weight to less than 100% by weight, more preferably from 40% by weight to 99% by weight, more preferably from 45% by weight to 90% by weight, and even more preferably from 50% by weight to 65% by weight, based on the total weight of the adhesive composition. (a) Polyol In some embodiments, reactant (a) may be selected from polyester polyols, polyether polyols and combinations thereof. In a preferred embodiment, the polyester polyol can be used as reactant (a), which can be selected from solid polyester polyols, liquid polyester polyols and combinations thereof, preferably selected from crystalline polyester polyols, amorphous polyester polyols, liquid polyester polyols and combinations thereof. If present, crystalline polyester polyols can be used in this invention, which can provide good adhesive strength for adhesive compositions. Examples of such crystalline polyester polyols can be obtained by ring-opening polymerization of lactones (such as ε-caprolactone) and / or derived from diols and diacids. Examples of diols that can be used to prepare preferred polyester polyols include ethylene glycol, diethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, and combinations thereof. Examples of diacids that can be used to prepare preferred polyester polyols include succinic acid, glutaric acid, adipic acid, octanoic acid, azelaic acid, sebacic acid, and 1,12-dodecanoic acid, dimer acids, and combinations thereof. Included in the range of useful diacids are various diacid derivatives, such as carboxylic acid esters (especially methyl and ethyl esters), acetic halides (such as acetic chlorides), and acid anhydrides, and combinations thereof. Specific examples of suitable crystalline polyester polyols include poly(hexanediol adipate) polyol, poly(butanediol adipate) polyol, poly(ε-caprolactone) polyol, poly(hexanediol dodecanoate) polyol, poly(hexanediol terephthalate) polyol, and combinations thereof. Suitable commercially available crystalline polyester polyols are those sold by Evonik Industries AG under the DYNACOLL 7300 series trademarks, including DYNACOLL 7360, 7361, 7362, 7363, 7380, 7381, 7390, etc., and by Perstorp Polyols Inc. under the CAPA series trademarks, including caprolactone polyols such as CAPA 2201, 2205, 2209, 2302, 2304, 2402, etc., as well as ARU 2720 sold by Yong Shun Chemicals Co., Ltd. If present, amorphous polyester polyols can also be used to prepare the reactive polyurethane prepolymers of this invention. Amorphous polyester polyols comprise the reaction product of a polyacid component (e.g., polyacid, polyanhydride, polyester, and polyamide) and a stoichiometric excess of polyol. At least one of the polyacid component and the polyol contains an aromatic group. Suitable polyacids include, for example, dicarboxylic acids (e.g., dicarboxylic acids), tricarboxylic acids (e.g., tricarboxylic acids), and higher acids, examples of which include aromatic dicarboxylic acids, their anhydrides, and esters (e.g., terephthalic acid, isophthalic acid, dimethyl terephthalate, diethyl terephthalate, phthalic acid, phthalic anhydride, methyl hexahydrophthalic acid, methyl hexahydrophthalic anhydride, methyl tetrahydrophthalic acid, methyl tetrahydrophthalic anhydride, hexahydrophthalic acid, hexahydrophthalic acid, hexahydrophthalic acid). Acid anhydrides and tetrahydrophthalic acid), aliphatic dicarboxylic acids and their anhydrides (e.g., maleic acid, maleic anhydride, succinic acid, succinic anhydride, glutaric acid, glutaric anhydride, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, chlorobridged acid, 1,2,4-butane-tricarboxylic acid, decanedicarboxylic acid, octadecanedicarboxylic acid, dimer acids, dimerized fatty acids, trimerized fatty acids and fumaric acid), and alicyclic dicarboxylic acids (e.g., 1,3-cyclohexanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid) and mixtures thereof. Examples of suitable polyols include aliphatic polyols such as ethylene glycol, propylene glycol (e.g., 1,2-propanediol and 1,3-propanediol), butanediol (e.g., 1,3-butanediol, 1,4-butanediol and 1,2-butanediol), 1,3-butenediol, 1,4-butynediol, pentanediol (e.g., 1,5-pentanediol), pentenediol, pentynediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, neopentanediol, and dioxanediol. Ethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol (e.g., dipropylene glycol and tripropylene glycol), 1,4-cyclohexanediol, 1,4-cyclohexanediol, dimerol, bisphenol A, bisphenol F, hydrogenated bisphenol A, hydrogenated bisphenol F, glycerol, tetramethylene glycol, polytetramethylene glycol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, trimethylolpropane, isopentetrate, sorbitol, glucose, and combinations thereof. Specific examples of useful amorphous polyester polyols (if present) include poly(hexanediol phthalate) polyol, poly(neopentyl glycol adipate) polyol, poly(neopentyl glycol phthalate) polyol, poly(neopentyl glycol hexanediol phthalate) polyol, poly(diethylene glycol phthalate) polyol, poly(ethylene terephthalate adipate) polyol, polyethylene terephthalate polyol, ethylene glycol, hexanediol, neopentyl glycol, adipic acid and terephthalic acid random copolymer diols and combinations thereof. Amorphous polyester polyols are sold under various trademarks, including, for example, DYNACOLL 7110, 7130, 7140 and 7150 of Evonik Industries AG and FLP PA-1000N of Xuchuan Chemical (Suzhou) Co., Ltd. In some embodiments, the polyester polyol used in this invention can be liquid at room temperature, providing wetting properties to the adhesive composition and impact resistance to the cured product. Therefore, the liquid polyester polyol preferably has a glass transition temperature (Tg) not exceeding 0°C. If the Tg of the liquid polyester polyol is too high, it becomes more difficult for it to remain liquid. Examples of suitable liquid polyester polyols can be obtained by ring-opening polymerization of lactones (such as ε-caprolactone) and / or derivatization from diols and diacids. Examples of diols that can be used to prepare preferred polyester polyols include ethylene glycol, diethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, and combinations thereof. Examples of diacids that can be used to prepare preferred polyester polyols include succinic acid, glutaric acid, adipic acid, octanoic acid, azelaic acid, sebacic acid, and 1,12-dodecanoic acid, dimer acids, and combinations thereof. Included in the range of useful diacids are various diacid derivatives, such as carboxylic acid esters (especially methyl and ethyl esters), amide halides (such as amide chlorides), and acid anhydrides, and combinations thereof. Specific examples of suitable crystalline polyester polyols include poly(hexanediol adipate) polyol, poly(butanediol adipate) polyol, poly(ε-caprolactone) polyol, poly(hexanediol dodecanoate) polyol, poly(hexanediol terephthalate) polyol, and mixtures thereof. Suitable commercially available liquid polyester polyols are sold by Evonik Industries AG under the DYNACOLL 7200 series trademark, including DYNACOLL 7210, 7230, 7231, 7250, etc., and Stepan Corporation's Stepan PDP 70. In some embodiments, reactant (a) may be a polyether polyol. The polyether polyols used in this invention are well known to those skilled in the art. These polyether polyols are obtained by copolymerizing at least one compound selected from ethylene oxide, propylene oxide, butane oxide, tetrahydrofuran, etc., with at least one compound having an average of at least two active hydrogen atoms in one molecule (such as the polyols listed above, including ethylene glycol, propylene glycol, dipropylene glycol, glycerol, and combinations thereof). Other suitable polyols include sucrose, ethylenediamine, propylenediamine, triethanolamine, 1,2-propanedithiol, and combinations thereof. Preferred polyether polyols may be selected from polytetramethylene ether glycol, poly(propylene oxide) glycol, polyethylene oxide, polybutane, and any of the aforementioned compounds in an ethylene oxide-terminated form, or combinations thereof. The most preferred polyether polyols are polytetramethylene ether glycol, poly(propylene oxide) glycol, ethylene oxide-terminated poly(propylene oxide) glycol, or combinations thereof. In a preferred embodiment, the polyether polyol has a number average molecular weight (Mn) of 200 to 8,000 g / mol, more preferably 400 to 4,000 g / mol, and even more preferably 400 to 2,000 g / mol. Commercially available products may be used in this invention. Examples include Voranol 2104, 2110, 2120 and 2140 from Dow Chemical Company. In some embodiments, reactant (a) is a combination of polyester polyol and polyether polyol. Preferably, reactant (a) does not include polyether polyol to form the reactive polyurethane prepolymer of the present invention. Particularly preferably, reactant (a) may be present in an amount from 20% to 85% by weight, and more preferably from 40% to 80% by weight, based on the total weight of the adhesive composition. (b) According to the present invention, the moisture-curing polyurethane hot melt adhesive composition comprises at least one reactive polyurethane prepolymer obtained by reacting a reaction mixture, the reaction mixture comprising (a) at least one polyol, and (b) at least one polyisocyanate having at least two isocyanate groups in one molecule. The useful polyisocyanate as reactant (b) includes any suitable isocyanate having at least two isocyanate groups in a molecule, including, for example, aliphatic, cycloaliphatic, aryliphatic, aralkyl and aromatic isocyanates and combinations thereof. Preferred reactant (b) may be selected from 4,4'-diphenylmethane diisocyanate (MDI), hydrogenated MDI (H12MDI), or partially hydrogenated MDI. (H6MDI), phenyl dimethyl diisocyanate (XDI), tetramethylphenyl dimethyl diisocyanate (TMXDI), 4,4'-diphenyl dimethylmethane diisocyanate, diphenyl diphenylmethane diisocyanate, tetraphenyl diphenylmethane diisocyanate, 4,4'-diphenylmethyl diisocyanate, 1,3-phenyl diisocyanate, 1,4-phenyl diisocyanate, isomers of toluene diisocyanate (TDI), 1-methyl-2,4-diisocyanocyclohexane, 1,6-diisocyano-2,2,4-trimethylhexane, 1,6-diisocyano-2,4,4-trimethylhexane, 1-isocyanomethyl-3-isocyano-1,5,5-trimethylcyclohexane (IPDI), tetramethoxybutane -1,4-diisocyanate, naphthalene-1,5-diisocyanate (NDI), butane-1,4-diisocyanate, hexane-1,6-diisocyanate (HDI), dicyclohexylmethane diisocyanate, 2,2,4-trimethylhexane-2,3,3-trimethylhexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, ethylenyl diisocyanate, methylene triphenyl triisocyanate (MIT), ethyl phthalate diisocyanate, trimethylhexamethylene diisocyanate, 1,4-diisocyanobutane, 1,12-diisocyanododecane, dimer fatty acid diisocyanate, lysine diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 1,3-cyclohexane or 1,4-cyclohexane diisocyanate, and combinations thereof. The optimal polyisocyanate system includes 4,4'-diphenylmethane diisocyanate (MDI) and its isomers, extended chain MDI and combinations thereof. Useful commercially available polyisocyanates used as reactant (b) include Covestro’s DESMODUR 44 C FUSED, Desmodur 0118 I and Desmodur 44M, Wanhua Chemicals’ Vannate MDI 100F and HUNTSMAN’s Supersec 1809. Particularly preferably, reactant (b) may be present in an amount from 5% to 25% by weight, and more preferably from 10% to 20% by weight, based on the total weight of the adhesive composition. (B) Vinyl acetate homopolymer According to the present invention, the moisture-curing polyurethane hot melt adhesive composition comprises (B) at least one vinyl acetate homopolymer having a weight average molecular weight (Mw) of 15,000 to less than 100,000 g / mol and being present in an amount of less than 70% by weight based on the total weight of the adhesive composition. In a preferred embodiment, component (B) used in the present invention may be a vinyl acetate homopolymer having a weight average molecular weight (Mw) in the range of 30,000 to 60,000 g / mol, more preferably in the range of 45,000 to 55,000 g / mol. Suitable vinyl acetate homopolymers used as component (B) of the present invention can generally be prepared by emulsion polymerization, wherein, in addition to vinyl acetate monomer and water, they may contain small amounts of wetting agents, protective colloids, polymerization initiators and molecular weight regulators. The useful commercially available vinyl acetate homopolymer used as component (B) of this invention comprises Vinnapas from Wacker Chemicals (China) Co., Ltd. TM N 1.5 SP, Vinnapas TM N 17 SP, Vinnapas TM N 30 SP. Particularly preferably, component (B) may be present in an amount ranging from greater than 0 to less than 70% by weight, more preferably from 1% by weight to 60% by weight, and even more preferably from 5% by weight to 45% by weight, based on the total weight of the adhesive composition. (C) If necessary, the moisture-curing polyurethane hot melt adhesive composition may also include a catalyst (C) to promote the reaction between (a) a polyol and (b) a polyisocyanate having at least two isocyanate groups in one molecule. Suitable component (C) includes, for example, strongly basic amides such as 2,3-dimethyl-3,4,5,6-tetrahydropyrimidine, tris(dialkylaminoalkyl)-s-hexahydrotriazine, such as tris(N,N-dimethylaminopropyl)-s-hexahydrotriazine, or common tertiary amines such as triethylamine, tributylamine, dimethylbenzylamine, N-ethyl-, N-methyl-, N-cyclo-hexylmorpholine, dimethylcyclohexylamine, bis(meth)-methyl ... Linyl diethyl ether, 2-(dimethylaminoethoxy)ethanol, 1,4-diazabicyclo[2,2,2]octane, 1-azabicyclo[3,3,0]octane, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethylbutanediamine, N,N,N',N'-tetramethylhexane-1,6-diamine, pentamethyldiethylenetriamine, tetramethyldiaminoethyl ether, bis-(dimethylamine) (4-(4-N,N-dimethylaminocyclohexyl)-urea, N,N'-dimethylpiperazine, 1,2-dimethylimidazole, di-(4-N,N-dimethylaminocyclohexyl)-methane and such and organometallic compounds, such as titanates, iron compounds (e.g., ferric acetopyruvate (III)), tin compounds (e.g., tin (II) salts of organic carboxylic acids, such as tin (II) diacetate, tin (II) salts of 2-ethylhexanoate (tin (II) octanoate), tin (II) dilaurate, or dialkyltin (IV) salts of organic carboxylic acids (e.g., dibutyltin (IV) diacetate, dibutyltin (IV) dilaurate, dibutyltin (IV) maleate, or dioctyltin (IV) diacetate, or such and dibutyltin (IV) dithiol, or mixtures of two or more of the mentioned catalysts and synergistic combinations of strong basic amines and organometallic compounds. More preferably, the catalyst may be present in an amount from 0 to 1% by weight of the total weight of the adhesive composition, and more preferably from 0.01% to 0.5% by weight. (D) Additives may be included as needed in moisture-curing polyurethane hot melt adhesive compositions. These additives may be those commonly used in this art, such as colorants, antioxidants, leveling agents, anti-yellowing additives, etc. Examples of colorants include pigments that can be selected from: metal oxide pigments, titanium dioxide, zirconium oxide or cerium oxide with optional surface treatment, zinc oxide, iron oxide (black, yellow or red), chromium oxide, manganese and combinations thereof. Examples of antioxidants include phenols such as BHT (butylated hydroxytoluene), octadecyl-3,5-bis(1,1-dimethyl)-4-hydroxyphenyl propionate and gallophenol; phosphites such as triphenyl phosphite, tris(nonylphenyl) phosphite; or thioesters such as dilaurate thiodipropionate and combinations thereof. Particularly preferably, the additive may be present in an amount from 0 to 5% by weight of the total weight of the adhesive composition, and more preferably from 0.05% by weight to 2% by weight. In a particularly preferred embodiment, the moisture-curing polyurethane hot melt adhesive composition comprises, based on the total weight of the adhesive composition: From greater than 30 wt% to less than 100 wt%, preferably from 40 wt% to 99 wt%, more preferably from 45 wt% to 90 wt%, and even more preferably from 50 wt% to 65 wt%, (A) at least one reactive polyurethane prepolymer obtained by reacting a reaction mixture, the reaction mixture comprising: (a) at least one polyol, and (b) at least one polyisocyanate having at least two isocyanate groups in one molecule; From greater than 0 to less than 70 wt%, preferably from 1 wt% to 60 wt%, and more preferably from 5 wt% to 45 wt%, (B) at least one vinyl acetate homopolymer having a weight average molecular weight (Mw) of 15,000 to less than 100,000 g / mol; From 0 wt% to 1 wt%, preferably from 0.01 wt% to 0.5 wt%, (C) a catalyst; and From 0 wt% to 5 wt%, preferably from 0.05 wt% to 2 wt%, (D) an additive. The moisture-curing polyurethane hot melt adhesive composition according to the present invention can be prepared by the following steps: (i) mixing reactant (a) with component (B) at a temperature of 125°C to 150°C and then evacuating; (ii) lowering the temperature to 100°C to 120°C and adding reactant (b), and controlling the reaction temperature at 120°C to 130°C; and (iii) mixing under vacuum for 1 to 2 hours until homogeneous, and then discharging. There are no particular limitations on the apparatus used for such mixing, stirring, dispersing, and the like. Automated mortars equipped with stirrers and heaters, Henschel mixers, three-roll mills, ball mills, planetary mixers, bead mills, etc., can be used. Similarly, suitable combinations of these apparatuses can be used. There are no particular limitations on the preparation method of this moisture-curing polyurethane hot-melt adhesive composition, as long as the above-mentioned components in the composition are homogeneously mixed. solidified products thing The moisture-curing polyurethane hot melt adhesive composition of the present invention can be cured for 1 to 7 days at 15°C to 35°C, preferably at room temperature and 50% relative humidity. As should be understood, the time and temperature curing profiles of various moisture-curing polyurethane hot melt adhesive compositions will differ, and different compositions can be designed to provide curing profiles suitable for specific industrial manufacturing processes. According to a second aspect of the present invention, the cured product of the moisture-curing polyurethane hot melt adhesive of the present invention is provided herein. According to a third aspect of the present invention, a laminate is provided herein comprising a first substrate, a second substrate and an adhesive layer sandwiched between the two, wherein the first substrate and the second substrate are independently selected from glass, resin, fabric, wood and metal, and the adhesive layer is formed by curing the adhesive composition of the present invention. Specifically, the moisture-curing polyurethane reactive hot-melt adhesive composition according to the present invention can be used to bond fabrics to fabrics, or to bond fabrics to sponges in clothing. The moisture-curing polyurethane reactive hot-melt adhesive composition according to the present invention has component (B) present in an amount of less than 30% by weight, preferably less than 20% by weight, based on the total weight of the adhesive composition. Although the moisture-curing polyurethane reactive hot-melt adhesive composition according to the present invention can be used to bond wood substrates, the moisture-curing polyurethane reactive hot-melt adhesive composition according to the present invention has component (B) present in an amount of from 30% by weight to less than 70% by weight, preferably from 45% by weight to less than 70% by weight, based on the total weight of the adhesive composition. The first substrate and / or the second substrate may be a single material and a single layer, or may contain multiple layers of the same or different materials. These layers may be continuous or discontinuous. The substrate of the object described herein may have a variety of properties, including rigidity (e.g., a rigid substrate, i.e., the substrate cannot be bent by an individual with two hands or will break if an attempt is made to bend the substrate with two hands), flexibility (e.g., a flexible substrate, which can be bent with a force no greater than that of two hands), porosity, conductivity, low conductivity, and combinations thereof. The substrate of the object can take many forms, including, for example, fibers, threads, yarns, woven fabrics, nonwoven fabrics, films (e.g., polymer films, metallized polymer films, continuous films, discontinuous films, and combinations thereof), foils (e.g., metal foils), sheets (e.g., metal sheets, polymer sheets, continuous sheets, discontinuous sheets, and combinations thereof) and combinations thereof. In a preferred embodiment, at least one of the substrates may be selected from metals such as metal sintering paste, aluminum, tin, molybdenum, silver, conductive metal oxides such as indium tin oxide (ITO), fluorine-doped tin oxide, aluminum-doped zinc oxide, etc.; glass, such as ink-coated glass, bare glass; resins such as polycarbonate, polybutylene terephthalate, polyethylene terephthalate, polyamide, and polyvinyl chloride. Other suitable metals include copper, gold, palladium, platinum, aluminum, indium, silver-coated copper, silver-coated aluminum, tin, and tin-coated copper. Preferably, both substrates are selected from one of the aforementioned materials. The moisture-curing polyurethane hot melt adhesive composition of this invention can be applied to a substrate using any suitable application method, including, for example, automated fine-line dispensing, jet dispensing, slot die coating, roller coating, gravure coating, transfer coating, pattern coating, screen printing, spraying, filament coating, extrusion, air knife, drag-blade coating, brush coating, dip coating, doctor blade coating, offset gravure coating, roller gravure coating, and combinations thereof. This moisture-curing polyurethane hot melt adhesive composition can be applied as a continuous or discontinuous coating, in single or multiple layers, or combinations thereof. Applications: According to the present invention, the moisture-curing polyurethane reactive hot melt adhesive composition can be used in the manufacture of consumer products, automotive parts, electronic devices and household appliances. These suitable consumer goods include, but are not limited to, textiles and clothing, woodworking tools and furniture, paper and plastic packaging, and other components. Such suitable electronic devices include, but are not limited to, wearable electronic devices (e.g., watches and glasses), handheld electronic devices (e.g., telephones (e.g., mobile phones and smartphones), cameras, tablets, e-readers, monitors (e.g., hospital monitors and monitors used by healthcare workers, athletes and individuals), watches, calculators, mice, touchpads and joysticks), computers (e.g., desktop computers and laptops), computer monitors, televisions, media players or other electronic components. Suitable household appliances include, but are not limited to, refrigerators, washing machines, dryers, ovens and microwave ovens, light bulbs (e.g., incandescent bulbs, light-emitting diodes and fluorescent bulbs) and other items. The following examples are intended to help those skilled in the art to better understand and practice the invention. The scope of the invention is not limited by these examples, but is defined in the appended claims. Unless otherwise stated, all parts and percentages are based on weight. The raw material ARU 2720 is a polyester polyol available from Yong Shun Chemicals Co., Ltd. Desmodur TM 4,4'-MDI is available from Covestro. Vinnapas TM N 17 SP is a vinyl acetate homopolymer available from Wacker Chemicals (China) Co. Ltd., with a weight average molecular weight (Mw) of 45,000 g / mol. TMN 1.5 SP is a vinyl acetate homopolymer available from Wacker Chemicals (China) Co. Ltd., with a weight average molecular weight (Mw) of 15,000 g / mol. TM N 30 SP is a vinyl acetate homopolymer available from Wacker Chemicals (China) Co. Ltd., with a weight average molecular weight (Mw) of 55,000 g / mol. TM N 100 SP is a vinyl acetate homopolymer available from Wacker Chemicals (China) Co. Ltd., with a weight average molecular weight (Mw) of 100,000 g / mol. Hanwha 1540 is an ethylene-vinyl acetate copolymer available from Hanwha Chemicals. Elvacite TM The 2013 series is an acrylic resin available from Mitsubishi Chemical Corporation. Pearlbond TM The 521 series is a polycaprolactone-copolyester polyurethane available from Lubrizol. Sample preparation was performed according to the formulations listed in Tables 1, 2 and 3. The total weight of all components was 100 parts by weight. In the table below, the compositions were prepared by the following steps: (i) mixing reactant (a) with component (B) or other resins that replace component (B) at a temperature of 125°C to 150°C and then evacuating; (ii) lowering the temperature to 100°C to 120°C and adding reactant (b), and controlling the reaction temperature at 120°C to 130°C; and (iii) mixing under vacuum for 1 to 2 hours and then discharging. The state of the resulting composition is recorded as "homogeneous" or "phase-separated" by visual observation. A composition exhibiting "phase separation" means that the components in the individual composition have compatibility issues, resulting in low processability and thus being unacceptable. Test method: Viscosity of hot melt adhesive composition The viscosity measured in this invention is measured using a 27# mandrel and a Brookfield viscometer within a temperature range of 130°C. Viscosities less than 10,000 cps are acceptable. 2 minutes and 10 The initial bond strength at 105°C was obtained by coating two PET films (1 m * 0.18 m in size, available from Lianrui Corporation in Dongguan) with a thickness of 50 μm between them using a roller heater (available from Weite Corporation in Taiwan) at 105°C. The laminated samples were cured at 23°C and 50% relative humidity for 2 minutes. The 180° peel strength was recorded as the initial bond strength of the cured laminated sample. The laminated samples were placed in a tensile testing machine (available from Shenzhen SANS Testing Machine Co., Ltd.) and the initial bond strength was measured at a peel speed of 300 mm / min. Each initial bond strength was measured three times at 2 minutes, and the average value was recorded. An initial bond strength of not less than 0.2 N / inch at 10 minutes is acceptable under 100% cohesive failure mode. As described herein, "cohesive failure mode" refers to adhesive breakage with a portion of the adhesive still adhering to the bonded surfaces. The failure mode in which the adhesive is cleanly removed from the substrate is referred to as "adhesive failure mode". Adhesives with cohesive failure modes are considered stronger than adhesives with adhesive failure modes. The laminated samples were cured at 23°C and 50% relative humidity for 10 minutes. The initial bond strength of the cured laminated samples was measured according to JIS L1093 Method A-1. Each initial bond strength was measured three times at 10 minutes, and the average value was recorded. An initial bond strength of not less than 0.2 N / inch at 10 minutes is acceptable under 100% cohesive failure mode. The open time was determined by applying 10 g of the adhesive composition prepared as described above onto paper at 130°C to a thickness of 100 μm using an automated film applicator (4340, available from Elecometer Corporation). Paper strips measuring 2.5 cm * 10 cm were then attached to the coated paper by pressing with a finger every 10 to 30 seconds. The open time was defined as the time during which fiber breakage of the paper strip was observed. Adhesive compositions with open times of 1 to greater than 20 minutes were acceptable. Inventive Examples 1 and comparative examples 1 to 3. In this set of examples, a moisture-curing polyurethane reactive hot melt adhesive composition of the present invention (Example 1) and three compositions (Comparative Examples 1 to Comparative Examples 3) in which other resins were substituted for component (B) of the present invention were prepared according to the weight percentages specified in Table 1. Table 1 Note: N / A refers to individual tests that could not be performed due to the inability to achieve a homogeneous composition. As can be seen from Table 1, the compositions of Comparative Examples 1 to 3, which have resins other than component (B), have compatibility issues, while the composition of the present invention (Example 1) exhibits excellent performance. Inventive Examples 2 to 4 and comparative examples 4 to 5. In this set of examples, the moisture-curing polyurethane reactive hot melt adhesive compositions of the present invention (Examples 2 to 4) and two compositions having weight percentages exceeding those claimed in Table 2 were prepared according to the weight percentages specified in Table 2 (Comparative Examples 4 to 5). Table 2 As can be seen from Table 2, compositions (Comparative Examples 4 to 5) containing a weight percentage of component (B) exceeding that claimed in this invention have an open time of almost 0, or unacceptable initial bond strength at 2 minutes and 10 minutes, while the compositions of this invention (Examples 2 to 4) exhibit excellent performance. Inventive Examples 5 to 7 and comparative examples 6. In this set of examples, moisture-curing polyurethane reactive hot melt adhesive compositions were prepared according to the weight percentages specified in Table 3, comprising components (B) with different weight average molecular weights (Mw). Table 3 Note: N / A refers to individual tests that could not be performed due to the inability to achieve a homogeneous composition. As shown in the test results in Table 3, the adhesive composition (Comparative Example 6) including component (B) having a weight average molecular weight (Mw) of 100,000 g / mol resulted in phase separation. Without departing from the spirit and scope of this invention, those skilled in the art can make these and other modifications and changes to the invention. Furthermore, it should be understood that the various embodiments can be completely or partially interchanged. Moreover, those skilled in the art will understand that the foregoing description is merely illustrative and is not intended to limit the invention further described in the appended claims.

Claims

1. A moisture-curing polyurethane hot melt adhesive composition, comprising: (A) At least one reactive polyurethane prepolymer obtained by reacting a reaction mixture, the reaction mixture comprising: (a) at least one polyol, and (b) at least one polyisocyanate having at least two isocyanate groups in one molecule; (B) at least one vinyl acetate homopolymer having a weight average molecular weight (Mw) of 15,000 to less than 100,000 g / mol and being present in an amount of less than 70% by weight based on the total weight of the adhesive composition.

2. The moisture-curing polyurethane hot melt adhesive composition of claim 1, wherein the reactant (a) is selected from polyester polyols, polyether polyols and combinations thereof.

3. The moisture-curing polyurethane hot melt adhesive composition of claim 2, wherein the polyester polyol used as reactant (a) is selected from solid polyester polyols, liquid polyester polyols and combinations thereof.

4. The moisture-curing polyurethane hot melt adhesive composition of claim 3, wherein the polyester polyol used as reactant (a) has a number average molecular weight (Mn) of 800 to 20,000 g / mol.

5. The moisture-curing polyurethane hot melt adhesive composition of claim 2, wherein the polyether polyol used as reactant (a) is selected from polytetramethylene ether glycol, poly(propylene oxide) glycol, polyethylene oxide, polybutane oxide and any of the aforementioned compounds in an ethylene oxide-terminated form and combinations thereof.

6. The moisture-curing polyurethane hot melt adhesive composition of claim 1, wherein the reactant (b) is selected from 4,4'-diphenylmethane diisocyanate (MDI), hydrogenated MDI (H12MDI), and partially hydrogenated MDI. (H6MDI), phenyl dimethyl diisocyanate (XDI), tetramethylphenyl dimethyl diisocyanate (TMXDI), 4,4-diphenyl dimethylmethane diisocyanate, dialkyl diphenylmethane diisocyanate, tetraalkyl diphenylmethane diisocyanate, 4,4'-diphenylmethyl diisocyanate, 1,3-phenyl diisocyanate, 1,4-phenyl diisocyanate, isomers of toluene diisocyanate (TDI), 1-methyl-2,4-diisocyanocyclohexane, 1,6-diisocyano-2,2,4-trimethylhexane, 1,6-diisocyano-2,4,4-trimethylhexane, 1-isocyanomethyl-3-isocyano-1,5,5-trimethylcyclohexane (IPDI), tetramethoxybutane -1,4-diisocyanate, naphthalene-1,5-diisocyanate (NDI), butane-1,4-diisocyanate, hexane-1,6-diisocyanate (HDI), dicyclohexylmethane diisocyanate, 2,2,4-trimethylhexane-2,3,3-trimethylhexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, ethylenyl diisocyanate, methylene triphenyl triisocyanate (MIT), ethyl phthalate diisocyanate, trimethylhexamethylene diisocyanate, 1,4-diisocyanobutane, 1,12-diisocyanododecane, dimer fatty acid diisocyanate, lysine diisocyanate, 4,4-dicyclohexylmethane diisocyanate, 1,3-cyclohexane or 1,4-cyclohexane diisocyanate, and combinations thereof.

7. A moisture-curing polyurethane hot melt adhesive composition as claimed in any one of claims 1 to 6, wherein component (B) has a weight average molecular weight (Mw) in the range of 30,000 to 60,000 g / mol.

8. A moisture-curing polyurethane hot melt adhesive composition as claimed in any one of claims 1 to 6, wherein the adhesive composition further comprises at least one catalyst (C) selected from: strongly basic amide, triethylamine, tributylamine, dimethylbenzylamine, N-ethyl-, N-methyl-, N-cyclo-hexylmorpholine, dimethylcyclohexylamine, bismorpholino diethyl ether, 2-(dimethylaminoethoxy)ethanol, 1,4-diazabicyclo[2,2,2]octane, 1-azabicyclo[2,2,2]octane, etc. Cyclo[3,3,0]octane, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethylbutanediamine, N,N,N',N'-tetramethylhexane-1,6-diamine, pentamethyldiethylenetriamine, tetramethyldiaminoethyl ether, bis-(dimethylaminopropyl)-urea, N,N'-dimethylpiperazine, 1,2-dimethylimidazole, di-(4-N,N-dimethylaminocyclohexyl)-methane, organometallic compounds and combinations thereof.

9. A moisture-curing polyurethane hot melt adhesive composition as claimed in any one of claims 1 to 6, wherein the adhesive composition further comprises at least one (D) additive.

10. A moisture-curing polyurethane hot melt adhesive composition as claimed in any one of claims 1 to 6, wherein the reactant (a) is present in an amount from 20% to 85% by weight based on the total weight of the adhesive composition.

11. A moisture-curing polyurethane hot melt adhesive composition as claimed in any one of claims 1 to 6, wherein the reactant (b) is present in an amount from 5% to 25% by weight based on the total weight of the adhesive composition.

12. A moisture-curing polyurethane hot melt adhesive composition as claimed in any one of claims 1 to 6, wherein the component (B) is present in an amount from 1% to 60% by weight based on the total weight of the adhesive composition.

13. A cured product of a moisture-curing polyurethane hot melt adhesive composition as claimed in any one of claims 1 to 12.

14. A laminate comprising a first substrate, a second substrate, and an adhesive layer sandwiched between the two, wherein the first substrate and the second substrate are independently selected from glass, resin, fabric, wood, and metal, and the adhesive layer is formed by curing an adhesive composition of any one of claims 1 to 12.

15. Use of a moisture-curing polyurethane hot melt adhesive composition as claimed in any one of claims 1 to 12 in the manufacture of consumer products, automotive parts, electronic devices and household appliances.