CN111909348B

CN111909348B - Reactive polyurethane hot melt adhesive composition and preparation and application thereof

Info

Publication number: CN111909348B
Application number: CN201910380703.4A
Authority: CN
Inventors: 张方涛; 王瑜润
Original assignee: HB Fuller Co
Current assignee: HB Fuller Co
Priority date: 2019-05-08
Filing date: 2019-05-08
Publication date: 2022-10-28
Anticipated expiration: 2039-05-08
Also published as: WO2020227535A1; CN111909348A

Abstract

The present invention relates to a reactive polyurethane hotmelt adhesive composition comprising an isocyanate-terminated polyurethane prepolymer (P) obtained from diphenylmethane diisocyanate and a polymer polyol mixture (M) comprising at least one polyester diol a) and at least one polyether diol b). The invention also relates to a preparation method of the reactive polyurethane hot melt adhesive composition and an application of the reactive polyurethane hot melt adhesive composition as a hot melt adhesive. The reactive polyurethane hot melt adhesive composition has the advantages of low cost, good surface drying performance during application, and excellent acid resistance and alkali resistance after curing.

Description

Reactive polyurethane hot melt adhesive composition and preparation and application thereof

Technical Field

The invention relates to a reactive polyurethane hot melt adhesive composition, a preparation method and application thereof.

Background

Polyurethane-based Hot Melt Moisture Curable (HMMC) adhesive compositions are well known in the art. It is usually a hot melt adhesive based on isocyanate group-terminated polyurethane prepolymer. The isocyanate groups of the NCO-terminated prepolymer react with moisture (e.g., moisture in the air or on the adherend) to crosslink and effect bonding, while CO is generated ₂ . Suitable NCO-terminated prepolymers can be obtained by reacting polymers reactive toward isocyanate groups, such as polymer polyols (e.g., polyether polyols and polyester polyols), with a molar excess of a polyisocyanate, such as a monomeric diisocyanate.

The polyurethane hot melt adhesive contains no water or solvent, has a solid content of 100 percent, is a high-performance environment-friendly adhesive, and meets the requirements of increasing importance on the environment at home and abroad. Compared with the common hot melt adhesive, the reactive polyurethane hot melt adhesive has excellent comprehensive performance. The hot melt adhesive has the characteristics of no solvent, high initial viscosity and quick positioning in application, and has special water resistance, heat resistance, cold resistance and creep resistance after application. They can also be applied at temperatures generally lower than the sizing temperature of conventional hot-melt adhesives (for example 150 to 180 ℃), can be used for the bonding, compounding of certain plastic parts and are favored by the modern automated assembly industry. At present, the reactive polyurethane hot melt adhesive is applied to the fields of building materials, furniture, woodwork, electricity, automobiles, book binding, shoe making, fabric processing and the like.

However, in some applications of the reactive polyurethane hot melt adhesive, the acid resistance and the alkali resistance of the existing reactive polyurethane hot melt adhesive are not enough. Hot melt adhesives gradually degrade over time and fail to function properly, requiring replacement or re-adhesion.

Some commercially available reactive polyurethane hot melt adhesives that dry quickly (lose tack on the order of seconds) include moisture curable one-component adhesives. These adhesives are suitable for bonding between different woods, metals and plastics. They can provide strong, rapid adhesion after pressing or rolling of the substrate on the assembly line. These adhesives are widely used in various fields, such as filters, because of their good properties. However, some manufacturers using these filters have found that filters bonded with these adhesives become brittle after extended use. One reason for this is that the exhaust/tail gases produced by these manufacturers contain alkaline materials and the commercially available moisture curable one component glues are not resistant to alkaline corrosion.

US patent 5530085 discloses a polyurethane prepolymer composition comprising as a binder a prepolymer obtained by reacting diphenylmethane diisocyanate (MDI) with a hydroxyl-terminated conjugated diene polymer at a temperature not exceeding 100 ℃, wherein the MDI contains at least 20% of the 2,4' -MDI isomer. The polyurethane prepolymer composition is useful as a moisture-curing hot melt adhesive claimed to be resistant to strongly acidic and alkaline solutions. However, hydroxyl-terminated conjugated diene polymers, especially polybutadiene diol, are expensive as polymer polyols for polyurethane synthesis.

U.S. Pat. No. 4,983,1414 also proposes a polyurethane polymer obtained by first reacting a diisocyanate with a mixture comprising 2,6-dialkylp-cresol and a polybutadiene polyol to obtain a prepolymer, dissolving the resulting prepolymer in a solvent to form a sprayable prepolymer solution, and then curing the resulting prepolymer solution at a temperature of 25-100 ℃ in the presence of 2,2' -diaminodiphenyl disulfide. The patent claims that the polyurethane polymer has good resistance to sulfuric acid after curing due to the use of 2,2' -diaminodiphenyl disulfide in the curing of the polyurethane prepolymer. Also, the polybutadiene polyol required to be used in this patent is also expensive.

Therefore, there is still a need for reactive hot melt adhesives that are resistant to acid and base corrosion.

Disclosure of Invention

In view of the above problems in the prior art, the present inventors have conducted extensive and intensive studies on reactive polyurethane hot melt adhesives to find an acid-resistant, alkali-resistant, and inexpensive reactive polyurethane hot melt adhesive.

It is therefore an object of the present invention to improve the alkali resistance of reactive polyurethane hot melt adhesives.

It is another object of the present invention to improve the acid resistance of the reactive polyurethane hot melt adhesives.

It is a further object of the present invention to reduce the cost of reactive polyurethane hot melt adhesives.

It is a final object of the present invention to provide a reactive polyurethane hot melt adhesive which becomes tack-free within a suitable time (e.g., not more than 50 seconds) after application and exhibits excellent acid and alkali resistance at the same time.

Accordingly, in one aspect of the present invention, there is provided a reactive polyurethane hot melt adhesive composition having excellent acid resistance and alkali resistance. Specifically, the reactive polyurethane hot melt adhesive composition, after curing, exhibits a weight loss of not more than 2.0% by weight, preferably not more than 1.5% by weight, or even not more than 1.0% by weight, after being left for 5 weeks in each of aqueous solutions having pH values of 1 and 13 (e.g., aqueous hydrochloric acid solution and aqueous sodium hydroxide solution), respectively.

In another aspect of the present invention, a reactive polyurethane hot melt adhesive composition is provided that becomes tack-free no more than 50 seconds, no more than 40 seconds, no more than 30 seconds, or even no more than 20 seconds after application.

In another aspect of the present invention, there is provided a process for preparing the reactive polyurethane hot melt adhesive composition of the present invention.

In a final aspect of the present invention, there is provided the use of the reactive polyurethane hot melt adhesive compositions of the present invention as hot melt adhesives.

Detailed Description

According to a first aspect of the present invention, there is provided a reactive polyurethane hot melt adhesive composition comprising an isocyanate-terminated polyurethane prepolymer (P) obtained from diphenylmethane diisocyanate and a polymer polyol mixture (M) comprising at least one polyester diol a) and at least one polyether diol b):

a) Polyester diol which is one or more of C ₄ -C ₁₂ Saturated aliphatic diols with one or more C ₁₀ -C ₁₈ Reaction products of saturated aliphatic dicarboxylic acids, one or more C ₁₀ -C ₁₈ Saturated aliphatic diols with one or more C ₄ -C ₁₂ A reaction product of a saturated aliphatic dicarboxylic acid, or a combination of the foregoing reaction products; and

b) A polyether diol which is at least one of polypropylene glycol b 1) and polytetrahydrofuran glycol b 2):

b1 Polypropylene glycol having a molecular weight of 200 to 2000, and

b2 Polytetrahydrofurandiol which is polytetrahydrofurandiol b 2-a) having a molecular weight of from 200 to 4000 or which is prepared according to the national standard GB/T22237-2008 at 50 ^℃ Polytetrahydrofuran diol b 2-b) having a surface tension of less than 42mN/m,

wherein the reactive polyurethane hot melt adhesive composition also meets one, two or all of the following requirements X) to Z):

x) the weight ratio of the at least one polyether diol b) to the at least one polyester diol a) is greater than 1.0;

y) the reactive polyurethane hot melt adhesive composition further comprises an ethylene/vinyl acetate copolymer (EVA) and the weight ratio of the at least one polyether diol b) to the at least one polyester diol a) is greater than or equal to 1.0; and

z) the reactive polyurethane hot melt adhesive composition after curing does not lose more than 2.0% by weight after being left for 5 weeks in each of aqueous solutions having pH values of 1 and 13, respectively, such as an aqueous hydrochloric acid solution and an aqueous sodium hydroxide solution.

In the reactive polyurethane hot melt adhesive composition of the present invention, the isocyanate group-terminated polyurethane prepolymer (P) contained therein constitutes the binder thereof. In the present invention, a binder (binder), also called an adhesive, refers to a substance that provides a main binding force to bind the respective components together in an adhesive or the like, and is also a main film-forming substance, and is sometimes called a film-forming agent. According to the invention, the starting materials for the formation of the isocyanate-terminated polyurethane prepolymer (P) comprise diphenylmethane diisocyanate (MDI). Diphenylmethane diisocyanate has three main isomers, including 4,4' -MDI, 2,4' -MDI, and 2,2' -MDI. These isomers are all useful in the present invention. In a preferred embodiment of the present invention, the MDI comprises more than 70%, preferably more than 80%, more preferably more than 90%, particularly preferably 100% of 4,4' -MDI.

According to the invention, the polymer polyol mixture (M) which can be combined with MDI to form the isocyanate-terminated polyurethane prepolymer (P) comprises at least one polyester diol a) and at least one polyether diol b). I.e. generally comprising at least one polyester diol a) and at least one polyether diol b), both polymer polyols being reacted with MDI to form chains of the polyurethane prepolymer (P).

Suitable embodiments of the polyester diols a) comprise one or more C ₄ -C ₁₂ Saturated aliphatic diols with one or more C ₁₀ -C ₁₈ Reaction products of saturated aliphatic dicarboxylic acids, one or more C ₁₀ -C ₁₈ Saturated aliphatic diols with one or more C ₄ -C ₁₂ A reaction product of a saturated aliphatic dicarboxylic acid, or a combination of the foregoing reaction products. Preferably, the polyesterdiol a) is one or more C ₆ -C ₈ A saturated aliphatic diol and one or moreMultiple C ₁₂ -C ₁₆ Reaction products of saturated aliphatic dicarboxylic acids, one or more C ₁₂ -C ₁₆ Saturated aliphatic diols with one or more C ₆ -C ₈ A reaction product of a saturated aliphatic dicarboxylic acid, or a combination of the foregoing reaction products. As the saturated aliphatic diol forming the polyester diol a), there may be mentioned butanediol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, dodecanediol, tetradecanediol, hexadecanediol or a combination thereof. As the saturated aliphatic dicarboxylic acid forming the polyester diol a), succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, tetradecanedioic acid, hexadecanedioic acid, octadecanedioic acid or combinations thereof may be mentioned. Preferably, the polyester diol a) is a poly (hexanediol sebacate) diol, a poly (hexanediol dodecandioate) diol, a poly (hexanediol tetradecanedioate) diol, a poly (hexanediol hexadecanedioate) diol, a poly (octanedionate) diol, a poly (dodecanedioate) diol, a poly (tetradecanedioate) diol, a poly (hexadecanedio adipate) diol, a poly (dodecanedioate) diol, a poly (tetradecanedioate) diol, a poly (hexadecanedioate) diol, or any combination thereof. The polyesterdiol a) may be obtained commercially, for example, from the winning Industrial Co., ltd (Essen, germany) under the trade name Dynacoll 7380 (molecular weight 3500).

In some embodiments, the reactive polyurethane hot melt adhesive composition of the present invention comprises from 20 to 45% by weight, preferably from 25 to 35% by weight, of polyester diol a) in the form of structural units incorporated into the polyurethane prepolymer (P), based on the total weight of the composition.

As polyether diol b), it is at least one of polypropylene glycol b 1) and polytetrahydrofuran diol b 2). That is to say, as polyether diols b), it is possible to use both one or more polypropylene glycols b 1) and one or more polytetrahydrofuran glycols b 2), and also combinations of one or more polypropylene glycols b 1) with one or more polytetrahydrofuran glycols b 2).

The polypropylene glycol b 1) is a polypropylene glycol having a molecular weight of 200 to 2000. The polypropylene glycol has terminal hydroxyl groups and can react with MDI to form polyurethane. The molecular weight of the polypropylene glycol b 1) is preferably from 300 to 800, more preferably from 350 to 600. The polypropylene glycol can be obtained by a conventional method in the art, for example, by ring-opening polymerization of propylene oxide, or can be obtained commercially. For example, the polypropylene glycol b 1) may be commercially available from national chemical company (seoul, korea) under the trade name DP 400 (molecular weight 400) and from dow chemical company (Midland, MI, USA) under the trade name PPG 2000 (molecular weight 2000, trade name: VORANOL 2000L) commercially available.

Polytetrahydrofuran diol b 2) is polytetrahydrofuran diol b 2-a) having a molecular weight of 200 to 4000 or polytetrahydrofuran diol b 2-b) having a surface tension of less than 42mN/m, measured at 50 ℃ according to the national standard GB/T22237-2008. The polytetrahydrofurandiol b 2) has terminal hydroxyl groups and can react with MDI to form polyurethanes.

The molecular weight of the polytetrahydrofuran diol b 2-a) is generally from 200 to 4000, preferably from 800 to 3500, more preferably from 2500 to 3500. Preferably, the polytetrahydrofurandiol b 2-a) is used in accordance with the national standard GB/T22237-2008 at 50 ^℃ The surface tension measured below is less than 42mN/m, preferably less than 33mN/m, more preferably less than 30mN/m.

Alternatively, as polytetrahydrofuranediol b 2), polytetrahydrofuranediol b 2-b) can also be used. Polytetrahydrofuranediol b 2-b) according to the national standard GB/T22237-2008 at 50 ^℃ The surface tension measured below is generally less than 42mN/m, preferably less than 33mN/m, more preferably less than 30mN/m.

In some embodiments, the polytetrahydrofuran diol b 2) may be prepared by conventional methods in the art, for example by ring opening polymerization of tetrahydrofuran, or may be obtained commercially. For example, polytetrahydrofuran diol b 2) may be commercially available from basf corporation (Ludwigshafen, germany) under the trade name Poly THF 1000 (molecular weight 1000) and from taiwan chemical corporation, china under the trade name PTG 3000 (molecular weight 3000).

In a preferred embodiment of the present invention, the at least one polyether diol b) is a combination of polypropylene glycol b 1) and polytetrahydrofuran diol b 2). In this case, the weight ratio of polypropylene glycol b 1) to polytetrahydrofuran glycol b 2) is advantageously from 2.

In some embodiments, the reactive polyurethane hotmelt adhesive compositions of the invention comprise from 8 to 35% by weight, preferably from 9 to 30% by weight, based on the total weight of the reactive polyurethane hotmelt adhesive composition, of a polyether diol b) in the form of structural units incorporated in the polyurethane prepolymer (P)

In some embodiments, the reactive polyurethane hot melt adhesive compositions of the present invention are required to meet one, two, or all of requirements X) -Z):

y) the reactive polyurethane hot melt adhesive composition further comprises an ethylene/vinyl acetate copolymer (EVA) and the weight ratio of the at least one polyether diol b) to the at least one polyester diol a) is greater than 1.0; and

z) the reactive polyurethane hot melt adhesive composition does not lose more than 2.0% by weight after being left for 5 weeks in each of aqueous solutions having pH values of 1 and 13, respectively, such as an aqueous hydrochloric acid solution and an aqueous sodium hydroxide solution, after curing.

According to the invention, in the requirement X), the weight ratio of the at least one polyether diol b) to the at least one polyester diol a) is generally greater than 1.0. If the weight ratio is less than 1.0. In claim X), the weight ratio of the at least one polyether diol b) to the at least one polyester diol a) is preferably greater than 1.1.

According to the present invention, in requirement Y), the reactive polyurethane hot melt adhesive composition further comprises an ethylene/vinyl acetate copolymer (EVA) and the weight ratio of the at least one polyether diol b) to the at least one polyester diol a) is greater than or equal to 1.0. In requirement Y), the weight ratio of the at least one polyether diol b) to the at least one polyester diol a) is preferably from 1.0 to 1.0. In some particularly preferred embodiments, in requirement Y), the reactive polyurethane hot melt adhesive composition of the present invention comprises from 10 to 25% by weight, more preferably from 15 to 20% by weight, based on the total weight thereof, of ethylene/vinyl acetate copolymer.

In accordance with the present invention, in requirement Z), the weight loss after 5 weeks of standing in each of the aqueous solutions having pH values of 1 and 13 (e.g., aqueous hydrochloric acid solution and aqueous sodium hydroxide solution), respectively, after curing of the reactive polyurethane hot melt adhesive composition is not more than 2.0% by weight, not more than 1.5% by weight, or even not more than 1.0% by weight.

The polymer polyol mixture (M) used to form the isocyanate group-ended polyurethane prepolymer (P) may also contain other polymer polyols. For example, the polymer polyol mixture (M) may further comprise one or more of the following polymer polyol compounds:

i) Hydroxyl-terminated polybutadiene diols having a molecular weight of 2000 to 10000, preferably 4000 to 6000 and partially hydrogenated products thereof,

ii) phthalic acid and/or anhydride thereof with a molecular weight of 300 to 1000, preferably 400 to 700, with C ₂ -C ₄ Alkylene glycol and/or di (C) ₂ -C ₄ Alkylene glycol), and

iii) Polyester diols based on dimers of unsaturated fatty acids comprising at least 12 carbon atoms and/or hydrogenation products thereof.

In some embodiments, the polymer polyol compound i) can be either the hydroxyl terminated polybutadiene diol itself, a partially hydrogenated product of the hydroxyl terminated polybutadiene diol, or a combination thereof. The molecular weight is generally 2000 to 10000, preferably 4000 to 6000. As such polymer polyols there may be mentioned those available under the trade name Cray Valley from Paris, france

LBH-P 2000、

LBH-P 3000、

LBH-P5000 and

LBH-P10000 and the like.

In some embodiments, the reactive polyurethane hot melt adhesive composition of the present invention comprises 5 to 18% by weight, preferably 8 to 14% by weight, based on the total weight thereof, of the aforementioned hydroxyl-terminated polybutadiene diol and/or its partial hydrogenation product i).

In some embodiments, the polymer polyol compound ii) may be phthalic acid and/or anhydride thereof with C ₂ -C ₄ Alkylene glycol and/or di (C) ₂ -C ₄ Alkylene glycol) hydroxyl terminated polyester glycol. As C herein ₂ -C ₄ The alkylene glycol can be ethylene glycol, propylene glycol and butylene glycol, and is preferably ethylene glycol. As di (C) herein ₂ -C ₄ Alkylene glycols) which may be diethylene glycol, dipropylene glycol and dibutylene glycol, preferably diethylene glycol. For example, the polymer polyol compound ii) may be phthalic anhydride and di (C) ₂ -C ₄ Alkylene glycol) and especially a hydroxyl terminated polyester glycol formed from phthalic anhydride and diethylene glycol. The molecular weight of the polymer polyol compounds ii) is generally from 300 to 1000, preferably from 400 to 700.

In some embodiments, the polymer polyol compound iii) may be a polyester diol based on an unsaturated fatty acid dimer comprising at least 12 carbon atoms and/or a hydrogenation product thereof. Unsaturated fatty acid dimers are a complex mixture of constituents whose major constituent contains two carboxylic acid groups. Unsaturated fatty acid dimers are typically obtained by mutual polymerization using unsaturated fatty acids containing at least one, such as two or three, olefinic double bonds, such as oleic acid and linoleic acid. Specifically, the unsaturated fatty acid dimer containing at least 12 carbon atoms is usually obtained by refining vegetable oils such as drying oil and semi-drying oil, for example, natural oils and fats containing high linoleic acid and oleic acid such as soybean oil, cotton seed oil and rice bran oil to obtain fatThe acid is prepared by processes such as intermittent pressure catalytic polymerization or continuous catalytic polymerization. The common fatty acid dimer is octadecadienoic acid dimer. The unsaturated fatty acid dimer is used as a raw material to further synthesize the polyester diol. These polyester diols sometimes also contain ethylenically unsaturated double bonds, depending on the starting materials, and can therefore also be partially or completely hydrogenated. As examples of polymer polyol compounds iii) there may be mentioned the commercial products commercially available from BASF under the trade name SOVERMOL 908 (polyester diol) which is hydrogenated dimer C ₁₈ Unsaturated fatty acid dimethyl ester diol.

When the reactive polyurethane hot melt adhesive composition of the present invention comprises one or more of the polymer polyol compounds i), ii) and iii), the total amount thereof does not exceed 50% by weight of the total amount of the polyester diol a), preferably does not exceed 40% by weight of the total amount of the polyester diol a).

The polyurethane hot melt adhesive compositions of the present invention are reactive and comprise polyurethane prepolymers (P) containing terminal isocyanate groups which react with moisture to release carbon dioxide when cured after application. Therefore, in a preferred embodiment of the present invention, the molar ratio of isocyanate groups contained in MDI used for forming the polyurethane prepolymer (P) to hydroxyl groups contained in the polymer polyol is generally 1.4 to 1.0, preferably 1.5 to 1.0 to 3.5, more preferably 1.5. In another preferred embodiment of the present invention, the isocyanate-terminated polyurethane prepolymer comprises 0.4 to 4.0 wt.%, preferably 0.6 to 3.7 wt.%, more preferably 0.7 to 3.3 wt.%, based on its total weight, of unreacted (i.e. free) isocyanate groups.

The reactive polyurethane hot melt adhesive compositions of the present invention may also optionally comprise a non-reactive polymer. By "non-reactive" is meant that the polymer does not participate in any chemical reaction during the preparation, application and curing of the reactive polyurethane hot melt adhesive composition of the present invention. The addition of this type of polymer can increase the bulk strength of the hot melt adhesive composition after it is cured. In some embodiments, typical examples of the non-reactive polymer include ethylene/vinyl acetate (EVA) when requirement Y is not satisfied, thermoplastic Polyurethane (TPU), amorphous poly-alpha-olefins (APAO), thermoplastic elastomers (TPE) such as olefinic thermoplastic elastomers (TPO or TPEs) or thermoplastic amides (TPA), and the like.

In a preferred embodiment of the invention, as non-reactive polymer, it is a Thermoplastic Polyurethane (TPU), ethylene/vinyl acetate copolymer (EVA) when Y is not satisfied), amorphous poly-alpha-olefin (APAO) or a combination thereof. Particularly suitable examples include ethylene/vinyl acetate copolymers (when Y is not satisfied). These non-reactive polymers may be obtained, for example, from Corsia Polymer (China) Ltd under the trade name DESMOCOLL 540/1 (TPU), from Exxon Mobil (Irving, TX, USA) under the trade name ESCORENE UL7710 (EVA), and from Yingchun Kogyo (Essen, germany) under the trade name VESTOPLAST 508 (APAO).

The non-reactive polymer may be selected in an amount effective to enhance the cohesion of the reactive polyurethane hot melt adhesive composition after curing without significantly impairing the acid resistance, alkali resistance and tack-free properties of the hot melt adhesive composition of the present invention. The amount of non-reactive polymer used is generally not more than 40%, preferably from 5 to 30%, more preferably from 10 to 25%, and particularly preferably from 15 to 20% by weight, based on the total weight of the reactive polyurethane hot melt adhesive composition.

The molecular weights mentioned herein are all measured by Gel Permeation Chromatography (GPC) unless otherwise specified, and refer to weight average molecular weight (Mw)

The polyurethane hot melt adhesive compositions of the present invention may also contain polyurethane curing catalysts, especially catalysts suitable for one-component moisture curing, to reduce the curing time. Useful curing catalysts include ether and morpholine functional groups, examples of which include 2,2 '-dimorpholinoethyl ether, bis (2, 6-dimethylmorpholinoethyl) ether, and 4,4' - (oxydi-2, 1-ethanediyl) dimorpholine. Suitable commercially available catalysts include, for example, JEFFCAT DMDEE 4,4' - (oxydi-2, 1-ethanediyl) dimorpholine, available from Huntsman Corp. Various metal catalysts are also suitable, including, for example, tin-based (e.g., dibutyltin dilaurate and dibutyltin acetate), bismuth, zinc, and potassium-based catalysts.

When the reactive polyurethane hot melt adhesive composition of the present invention comprises a polyurethane curing catalyst, the curing catalyst may be contained in an amount of 0.01 to 2% by weight, preferably 0.05 to 1% by weight, based on the total weight of the polyurethane hot melt adhesive composition.

The reactive polyurethane hot melt adhesive composition of the present invention may further comprise various other conventional additives which are generally contained in the reactive polyurethane hot melt adhesive composition. Such additives include, for example: tackifiers, plasticizers, waxes, stabilizers, antioxidants, fillers (talc, clay, silica and treated versions thereof, carbon black and mica), particulates including, for example, microspheres (such as glass microspheres, polymeric microspheres, and combinations thereof)), ultraviolet scavengers and absorbers, colorants (such as pigments and dyes), fluorescers, odor masks, biocides, corrosion inhibitors, adhesion promoters, surfactants, defoamers, flame retardants, and combinations thereof.

Useful tackifiers include, for example, aromatic, aliphatic, and cycloaliphatic hydrocarbon resins, mixed aromatic and aliphatic modified resins, aromatic modified hydrocarbon resins, and hydrogenated versions thereof; terpenes, modified terpenes, and hydrogenated variants thereof; rosin esters; and combinations thereof.

Useful waxes include, for example, hydroxyl modified waxes, carbon monoxide modified waxes, hydroxystearamide waxes, fatty amide waxes, hydrocarbon waxes including, for example, high density low molecular weight polyethylene waxes, paraffin waxes and microcrystalline waxes, and combinations thereof.

Useful stabilizers include carbodiimide stabilizers, such as are commercially available from Rhein Chemie, germany under the trade name STABAXOL 7000.

Examples of useful commercially available antioxidants include hindered phenolic antioxidants from Ciba-Geigy (Basel, switzerland) under the trade names IRGANOX 565,1010 and 1076, and hindered phenolic antioxidants from Great Lakes Chemicals (West Lafayette, IN, USA) under the trade name ANOX 20. These antioxidants can function as free radical scavengers and can be used alone or in combination with other antioxidants. The reactive polyurethane hot melt adhesive compositions of the present invention optionally contain up to 2 weight percent antioxidant.

Examples of useful commercially available fillers include MISTRON vapo talc from Luzenac America, inc. The reactive polyurethane hot melt adhesive compositions of the present invention optionally contain from about 3, 4, 5, or about 7 to about 12, 13, 15, or about 20 weight percent filler, or optionally contain a weight percent filler that is between any pair of the foregoing values.

The reactive polyurethane hot melt adhesive composition is solid at room temperature/ambient temperature and does not contain a solvent. The content of the polyurethane prepolymer (P) is generally from 15 to 95% by weight, preferably from 50 to 85% by weight, more preferably from 60 to 75% by weight, based on the total weight of the reactive polyurethane hot melt adhesive composition of the present invention.

The reactive polyurethane hot melt adhesive compositions of the present invention generally have a viscosity at 140 ℃ of less than 100,000cps, preferably from 3000 to 80,000cps, especially from 3000 to 50000cPs.

According to a second aspect of the present invention, there is provided a process for preparing the reactive polyurethane hot melt adhesive composition of the present invention, comprising reacting diphenylmethane diisocyanate with the polymer polyol mixture (M) comprising at least one polyester diol a) and at least one polyether diol b) as described above to give the isocyanate-terminated polyurethane prepolymer (P).

The method for obtaining the isocyanate group-ended polyurethane prepolymer (P) by reacting MDI with the polymer polyol mixture (M) may include any suitable method known to those skilled in the art. In general, the reaction mixture comprising MDI, at least one polyester diol a) and at least one polyether diol b) is reacted at elevated temperature, generally from 60 to 160 ℃, preferably from 80 to 120 ℃, under removal of moisture. The reaction time is usually 1 to 2 hours. For example, the polymer polyol mixture (M) is first introduced into a reactor, heated to reaction temperature and dried under vacuum to remove ambient moisture absorbed by the polyol, and then MDI is added to the reactor. The reaction of MDI with the polymer polyol can be carried out under vacuum or in an inert gas such as nitrogen.

To obtain the isocyanate group-ended polyurethane prepolymer (P), MDI is used in molar excess relative to the polymer polyol. In one embodiment of the present invention, the reaction between MDI and polymer polyol is typically carried out at an NCO: OH molar ratio of 1.4 to 1.0, preferably 1.5 to 1.0 to 3.5, more preferably 1.0 to 1.7.

Since the reactive polyurethane hot melt adhesive composition of the present invention is susceptible to a curing reaction with moisture, it is advantageous that after the composition is prepared, it is stored in a moisture-proof container to suppress unwanted reactions.

The reactive polyurethane hot melt adhesive composition of the present invention can be cured using various mechanisms. The curing reaction takes place predominantly between the compounds having available active hydrogen atoms and the NCO groups of the polyurethane prepolymer (P). Various reactive compounds having free active hydrogen are known in the art, including water, hydrogen sulfide, polyols, ammonia, and other active compounds. The moisture-curable reactive polyurethane hot melt adhesive composition of the present invention is preferably used for cost, environmental protection and simplicity of operation.

Therefore, in a preferred embodiment of the present invention, the reactive polyurethane hot melt adhesive composition of the present invention is a one-component moisture-curable hot melt adhesive composition.

One-component moisture-cure polyurethane adhesives cure primarily by moisture in the air, and therefore should maintain a suitable air humidity, preferably slow curing at room temperature (e.g., about 22 ℃ to about 25 ℃). If air dried, a small amount of water may be applied to the rubberized surfaces to promote curing. If the adhesive is sandwiched between dry and hard adherends and the adhesive layer is thick, moisture on the interface and the outside is not easy to permeate into the adhesive, the adhesive is easy to be incompletely cured, and in this case, a very small amount of moisture can be injected into the adhesive.

According to a final aspect of the present invention, there is provided the use of the reactive polyurethane hot melt adhesive composition of the present invention as a hot melt adhesive. The reactive polyurethane hot melt adhesive compositions of the present invention can be used for all of the generally known uses of HMMC adhesives. Preferably, the reactive polyurethane hot melt adhesive composition of the present invention is used as a hot melt adhesive, especially as a one-component moisture-curing hot melt adhesive, in the fields of building materials, furniture and woodworking, electrical, automotive, bookbinding, shoe making, filter assembly and textile processing.

The reactive polyurethane hot melt adhesive composition of the present invention can be applied to a substrate using any suitable application method including, for example, automatic string dispensing, spray dispensing, slot die coating, roll coating, gravure coating, transfer coating, pattern coating, screen printing, spray coating, filament coating, extrusion, air knife, drag knife, brush coating, dip coating, knife coating, gravure offset coating, rotogravure coating, and combinations thereof. The moisture-curable adhesive composition may be applied in continuous or discontinuous coatings, in single or multiple layers, and combinations thereof. The moisture curable adhesive composition may be applied at any suitable temperature, typically a use temperature of from 60 to 200 deg.C, preferably from 80 to 175 deg.C, more preferably from 110 to 150 deg.C.

Optionally, the surface of the substrate to which the reactive polyurethane hot melt adhesive composition of the present invention is applied is surface treated to enhance adhesion using any suitable method for enhancing the adhesion of the substrate surface, including, for example, corona treatment, chemical treatment (e.g., chemical etching), flame treatment, rubbing, and combinations thereof.

For one-component moisture-curing adhesives, heating cannot be carried out too quickly, otherwise NCO groups react with moisture in the adhesive or on the surface of the substrate, in the air at an accelerated rate, and CO is formed ₂ The gas has no time to diffuse, the viscosity of the glue layer increases rapidly, and air bubbles are left in the glue layer. All parts, ratios, percentages, and amounts described herein are by weight unless otherwise indicated.

The present invention relates to the following embodiments:

1. a reactive polyurethane hot melt adhesive composition comprising an isocyanate-terminated polyurethane prepolymer (P) derived from diphenylmethane diisocyanate and a polymer polyol mixture (M) comprising at least one polyester diol a) and at least one polyether diol b):

a) A polyester diol which is one or more C ₄ -C ₁₂ Saturated aliphatic diols with one or more C ₁₀ -C ₁₈ Reaction products of saturated aliphatic dicarboxylic acids, one or more C ₁₀ -C ₁₈ Saturation ofAliphatic diols with one or more C ₄ -C ₁₂ A reaction product of a saturated aliphatic dicarboxylic acid, or a combination of the foregoing reaction products; and

b1 Polypropylene glycol having a molecular weight of 200 to 2000, preferably 300 to 800, more preferably 350 to 600, and

b2 Polytetrahydrofuran diols) which are polytetrahydrofuran diols b 2-a) having molecular weights of from 200 to 4000, preferably from 800 to 3500, more preferably from 2500 to 3500, or polytetrahydrofuran diols b 2-b) having surface tensions of less than 42mN/m, preferably less than 33mN/m, more preferably less than 30mN/m, determined at 50 ℃ according to the national standard GB/T22237-2008,

wherein the reactive polyurethane hotmelt adhesive composition also meets one, two or all of the following requirements X) to Z):

x) the weight ratio of the at least one polyether diol b) to the at least one polyester diol a) is from more than 1.0, preferably from more than 1.1, 3.0, more preferably from 1.2, 3.0 to 1.0.

z) the reactive polyurethane hot melt adhesive composition, after curing, exhibits a weight loss after 5 weeks of storage in each of aqueous solutions having pH values of 1 and 13 (e.g., aqueous hydrochloric acid solution and aqueous sodium hydroxide solution) of not more than 2.0% by weight, not more than 1.5% by weight, or even not more than 1.0% by weight.

2. The composition according to embodiment 1, wherein the composition meets requirement Y), comprises from 10 to 25% by weight, more preferably from 15 to 20% by weight, of ethylene/vinyl acetate copolymer, based on the total weight of the reactive polyurethane hot melt adhesive composition.

3. The composition according to embodiment 1 or 2, wherein the at least one polyether diol b) is a combination of a polypropylene glycol b 1) and a polytetrahydrofuran diol b 2), when preferably the weight ratio of polypropylene glycol b 1) to polytetrahydrofuran diol b 2) is 2.

4. The composition according to any of embodiments 1 to 3, wherein the diphenylmethane diisocyanate comprises more than 70%, preferably more than 80%, more preferably more than 90%, particularly preferably 100% of 4,4' -diphenylmethane diisocyanate.

5. A composition according to any of embodiments 1 to 4, wherein the polytetrahydrofuran diol b 2-a) has a surface tension of less than 42mN/m, preferably less than 33mN/m, more preferably less than 30mN/m, determined at 50 ℃ according to the national standard GB/T22237-2008.

6. The composition according to any of embodiments 1 to 5, wherein the polyesterdiol a) is one or more C ₆ -C ₈ Saturated aliphatic diols with one or more C ₁₂ -C ₁₆ Reaction products of saturated aliphatic dicarboxylic acids, one or more C ₁₂ -C ₁₆ Saturated aliphatic diols with one or more C ₆ -C ₈ A reaction product of a saturated aliphatic dicarboxylic acid, or a combination of the foregoing reaction products.

7. The composition according to any of embodiments 1 to 6, wherein the polymer polyol mixture (M) further comprises a hydroxyl-terminated polybutadiene diol having a molecular weight of 2000 to 10000, preferably 4000 to 6000, and/or a partially hydrogenated product thereof, preferably in an amount of 5 to 18% by weight, more preferably 8 to 14% by weight, based on the total weight of the reactive polyurethane hot melt adhesive composition.

8. The composition according to any one of embodiments 1 to 7, wherein the molar ratio of isocyanate groups contained by the MDI to hydroxyl groups contained by the polymer polyol is 1.4.

9. The composition according to any of embodiments 1 to 8, wherein the isocyanate group-ended polyurethane prepolymer (P) comprises 0.4 to 4.0% by weight, preferably 0.6 to 3.7% by weight, more preferably 0.7 to 3.3% by weight, based on its total weight, of unreacted isocyanate groups.

10. The composition according to any one of embodiments 1 to 9, wherein the composition comprises 20 to 45% by weight, preferably 25 to 35% by weight, of the polyester diol a) in the form of structural units incorporated into the polyurethane prepolymer (P), based on the total weight of the reactive polyurethane hot melt adhesive composition.

11. The composition according to any of embodiments 1 to 10, wherein the composition comprises 8 to 35 wt. -%, preferably 9 to 30 wt. -%, based on the total weight of the reactive polyurethane hotmelt composition, of polyether diol b) in a form incorporated in the polyurethane prepolymer.

12. The composition according to any one of embodiments 1 to 11, wherein the composition comprises 3 to 20% by weight, preferably 5 to 15% by weight, of filler, based on the total weight of the reactive polyurethane hot melt adhesive composition.

13. The composition according to any of embodiments 1 to 12, which is a one-component moisture-curing polyurethane hot melt adhesive composition.

14. A process for preparing a reactive polyurethane hot melt adhesive composition according to any one of embodiments 1 to 13, comprising reacting diphenylmethane diisocyanate with a polymer polyol mixture (M) comprising the at least one polyester diol a) and the at least one polyether diol b) to give an isocyanate-terminated polyurethane prepolymer (P).

15. Use of the reactive polyurethane hot melt adhesive composition according to any of embodiments 1 to 13 as a hot melt adhesive, preferably in the fields of building materials, furniture and woodworking, electrical, automotive, bookbinding, shoemaking, filter assembly and textile processing, in particular as a one-component moisture-curing hot melt adhesive.

Examples

The following non-limiting examples are included to further illustrate various embodiments of the present disclosure, but do not limit the scope of the present disclosure.

Surface tension measurement

The surface tension referred to herein is determined at 50 ℃ according to the national standard GB/T22237-2008.

Raw material information

DP 400: polypropylene glycol, mw =400, surface tension 30.324mN/m, available from Doudou chemical Co

Poly THF 1000: polytetrahydrofuran diol, mw =1000, available from Basff corporation

PTG 3000: polytetrahydrofuran diol, mw =3000, surface tension 27.951mN/m, purchased from Taiwan chemical company of Dalian province

SOVERMOL 908 hydrogenated dimeric C ₁₈ Unsaturated fatty acid dimethyl ester diol, mw =543.7, surface tension 32.853mN/m, available from Pasteur Corp

PS 2002 polyester diol obtained by reacting phthalic anhydride with diethylene glycol, mw =575, surface tension 41.631mN/m, available from Spilan chemical company;

KRASOL LBH-P5000 polybutadiene diol, mw =5000, surface tension 26.581mN/m, available from Cray Valley Co

Dynacoll 7380 polyester diol, mw =3500, available from winning Industrial Co

Mistron Vapor talc, available from Luzenac America, inc. (Englewood, colorado)

Evernox 10GF antioxidant from Everpring

ESCORENE UL7710: EVA, VA:26.7%, MI:420g/10min @190 ℃ from Exxon Mobil

VESTOPLAST 508 amorphous poly-alpha-olefins, purchased from winning Industrial Co., ltd

Desmodur CD-C carbodiimide isocyanate from Korsaw polymers (China) Co.Ltd

DMDEE 4,4' - (oxydi-2, 1-ethanediyl) dimorpholine, from Huntsman Corp. (Houston, texas)

Preparation of Hot melt adhesive compositions

All the components except MDI and a curing catalyst DMDEE in the formula of each composition shown in the following table 1 are added into a reactor according to the amount shown in the following table 1, the temperature is increased to 130-140 ℃, the vacuum pumping is carried out to remove moisture, then the temperature is reduced to 100 ℃, MDI is added, the stirring and the heat preservation are carried out for 1 hour, then the curing catalyst DMDEE with the amount shown in the following table 1 is added, the stirring is carried out for 20 minutes, and the temperature is reduced to the room temperature, so as to prepare each polyurethane melt adhesive composition.

Performance testing of Hot melt adhesive compositions

Viscosity measurement

Viscosity was measured using a Brookfield Thermosel viscometer (AMETEK Brookfield of Middleboro, MA, USA) and spindle 27. The viscosity was measured at 140 ℃.

Tack free time test

The hot melt adhesive composition was melted at a temperature of 140 ℃ and applied to the non-release side of the PET release film in a thickness of 100 μm, immediately after timing. The surface of the adhesive layer was pressed with the index finger every 1-2 seconds. The time when the hands no longer feel sticky is the tack free time, which is up to 60 seconds.

Acid and alkali resistance test

The prepared hot melt adhesive composition was coated on a release PET film and cured at room temperature for 7 days at ambient humidity (about 50%) to obtain an adhesive film having a thickness of 100 μm. The multilayer adhesive films were laminated together at 120 ℃ using a press vulcanizer, cut into 15mm × 20mm × 2mm thin sheet samples, and weighed.

An aqueous hydrochloric acid solution having a pH of 1 and an aqueous sodium hydroxide solution having a pH of 13 were each placed in an oven and heated to 80 ℃. The sheet samples were then soaked in these two solutions separately. Samples were removed after a given number of days of soaking, rinsed, dried, weighed, and the percent weight loss of each sample was calculated.

The formulations and experimental results for all hot melt adhesive compositions except comparative example C-1 are summarized in Table 1 below.

HL9810 is a moisture-curing polyurethane hot melt adhesive available from h.b. fuller, st.paul, MN USA. The hot melt adhesive was labeled comparative example C-1. The hot melt adhesive was tested for various properties according to the test methods described above. It is noted that in testing viscosity, the viscosity test temperature for HL9810 was 163 ℃, rather than 140 ℃. The results are summarized in table 2 below.

TABLE 2

As can be seen from tables 1 and 2 above, the comparison of comparative example C-1 with inventive examples 1-8 shows that the hot melt adhesive compositions of the present invention are better than HL9810 in terms of acid and alkali resistance. Furthermore, the drying speed of the hot melt adhesive composition of the present invention is faster than that of C-1.

Comparison of comparative examples C-3 and C-4 with inventive examples 1 to 8 shows that the use of MDI as the polyisocyanate has a much improved resistance to acids and bases, in particular a significantly improved resistance to bases, compared to the use of carbodiimide diisocyanate.

Comparison of comparative examples C-2, C-6, C-7 and C-8 with inventive examples 1 to 8 shows that, when the polyether diol b) of the invention is not used, but instead of the preparation of the polyurethane prepolymer, other polyester diols and polybutadiene diols are used, the hot-melt adhesive compositions obtained either have poor resistance to acids and bases, in particular poor resistance to bases, or have a long open time and remain tacky at the surface 60 seconds after application.

Comparison of comparative examples C-5 with inventive examples 1-8 shows that, when the polyether glycol b) used according to the invention is used in smaller amounts and no EVA is used, the tack free time of the resulting hot melt adhesive composition is long, the surface is still tacky 60 seconds after application and the alkali resistance is also inferior to that of the hot melt adhesive composition of the invention.

Claims

1. A reactive polyurethane hot melt adhesive composition comprising an isocyanate-terminated polyurethane prepolymer P derived from diphenylmethane diisocyanate and a polymer polyol mixture M comprising at least one polyester diol a) and at least one polyether diol b):

polyester diols a) which are one or more C ₄ -C ₁₂ Saturated aliphatic diols with one or more C ₁₀ -C ₁₈ Reaction products of saturated aliphatic dicarboxylic acids, or one or more C ₁₀ -C ₁₈ Saturated aliphatic diols with one or more C ₄ -C ₁₂ A reaction product of a saturated aliphatic dicarboxylic acid, or a combination of the foregoing reaction products; and

polyether glycol b) which is at least one of polypropylene glycol b 1) and polytetrahydrofuran glycol b 2):

polypropylene glycol b 1) having a molecular weight of from 200 to 2000, and

polytetrahydrofuran diol b 2) having a molecular weight of 200 to 4000, or polytetrahydrofuran diol b 2-b) having a surface tension of less than 42mN/m, measured at 50 ℃ according to the national standard GB/T22237-2008,

wherein the reactive polyurethane hot melt adhesive composition also meets the following requirement Y):

y) the reactive polyurethane hot melt adhesive composition further comprises an ethylene/vinyl acetate copolymer, EVA, and the weight ratio of the at least one polyether diol b) to the at least one polyester diol a) is greater than or equal to 1.0;

wherein the composition comprises 10 to 25 weight percent of an ethylene/vinyl acetate copolymer, based on the total weight of the reactive polyurethane hot melt adhesive composition; and

wherein the composition comprises from 8 to 35% by weight, based on the total weight of the reactive polyurethane hotmelt adhesive composition, of a polyether diol b) in the form of structural units incorporated in the polyurethane prepolymer.

2. The composition according to claim 1, wherein the polypropylene glycol b 1) has a molecular weight of from 300 to 800.

3. The composition according to claim 2, wherein the polypropylene glycol b 1) has a molecular weight of 350 to 600.

4. A composition according to claim 1, wherein the polytetrahydrofuran diol b 2-a) has a molecular weight of 800 to 3500.

5. The composition according to claim 4, wherein the polytetrahydrofuran diol b 2-a) has a molecular weight of from 2500 to 3500.

6. A composition according to claim 1, wherein the polytetrahydrofuran diol b 2-b) has a surface tension of less than 33mN/m, determined according to the national standard GB/T22237-2008 at 50 ℃.

7. A composition according to claim 6, wherein the polytetrahydrofuran diol b 2-b) has a surface tension of less than 30mN/m, determined according to the national standard GB/T22237-2008 at 50 ℃.

8. The composition according to claim 1, wherein the weight ratio of the at least one polyether diol b) to the at least one polyester diol a) is from 1.0 to 1.0.

9. The composition according to claim 1, wherein the reactive polyurethane hotmelt adhesive composition also meets one or both of the following requirements X) and Z):

x) the weight ratio of the at least one polyether diol b) to the at least one polyester diol a) is greater than 1.0; and

z) the reactive polyurethane hot melt adhesive composition, after curing, exhibited a weight loss of not more than 2.0% after 5 weeks of standing in each of aqueous solutions having pH values of 1 and 13, respectively.

10. The composition according to claim 9, wherein the weight ratio of the at least one polyether diol b) to the at least one polyester diol a) is greater than 1.1.

11. The composition according to claim 10, wherein the weight ratio of the at least one polyether diol b) to the at least one polyester diol a) is from 1.2.

12. The composition according to claim 9, wherein the reactive polyurethane hot melt adhesive composition, after curing, has a weight loss of no more than 1.5 percent after being placed in each of the aqueous solutions having pH values of 1 and 13, respectively, for 5 weeks.

13. The composition according to claim 12, wherein the reactive polyurethane hot melt adhesive composition, after curing, exhibits a weight loss of not more than 1.0% by weight after 5 weeks of standing in each of aqueous solutions having pH values of 1 and 13, respectively.

14. The composition according to claim 9, wherein the aqueous solution having a pH of 1 is an aqueous hydrochloric acid solution.

15. A composition according to claim 9 wherein the aqueous solution having a pH of 13 is an aqueous sodium hydroxide solution.

16. The composition according to claim 1, wherein the composition comprises from 15 to 20% by weight of ethylene/vinyl acetate copolymer, based on the total weight of the reactive polyurethane hot melt adhesive composition.

17. The composition according to any one of claims 1 to 16, wherein the at least one polyether diol b) is a combination of a polypropylene diol b 1) and a polytetrahydrofuran diol b 2).

18. The composition according to claim 17, wherein the weight ratio of polypropylene glycol b 1) to polytetrahydrofuran glycol b 2) is from 2.

19. The composition according to claim 18, wherein the weight ratio of polypropylene glycol b 1) to polytetrahydrofuran glycol b 2) is 1.5.

20. The composition of any of claims 1-16, wherein the diphenylmethane diisocyanate comprises greater than 70% of 4,4' -diphenylmethane diisocyanate.

21. The composition of claim 20 wherein the diphenylmethane diisocyanate comprises greater than 80% of 4,4' -diphenylmethane diisocyanate.

22. The composition of claim 20 wherein the diphenylmethane diisocyanate comprises greater than 90% of 4,4' -diphenylmethane diisocyanate.

23. A composition according to claim 20, wherein the diphenylmethane diisocyanate comprises 100% 4,4' -diphenylmethane diisocyanate.

24. A composition according to any one of claims 1 to 16, wherein the polytetrahydrofuran diol b 2-a) has a surface tension of less than 42mN/m, determined according to the national standard GB/T22237-2008 at 50 ℃.

25. A composition according to claim 24, wherein the polytetrahydrofuran diol b 2-a) has a surface tension of less than 33mN/m, measured at 50 ℃ according to the national standard GB/T22237-2008.

26. A composition according to claim 25, wherein the polytetrahydrofuran diol b 2-a) has a surface tension of less than 30mN/m, measured at 50 ℃ according to the national standard GB/T22237-2008.

27. The composition of any of claims 1 to 16 wherein the polyesterdiol a) is one or more C ₆ -C ₈ Saturated aliphatic diols with one or more C ₁₂ -C ₁₆ Reaction products of saturated aliphatic dicarboxylic acids, or one or more C ₁₂ -C ₁₆ Saturated aliphatic diols with one or more C ₆ -C ₈ A reaction product of a saturated aliphatic dicarboxylic acid, or a combination of the foregoing reaction products.

28. The composition according to any one of claims 1 to 16, wherein the polymer polyol mixture M further comprises a hydroxyl-terminated polybutadiene diol having a molecular weight of 2000 to 10000 and/or a partially hydrogenated product thereof in an amount of 5 to 18% by weight, based on the total weight of the reactive polyurethane hot melt adhesive composition.

29. The composition according to claim 28, wherein the polymer polyol mixture M further comprises a hydroxyl-terminated polybutadiene diol having a molecular weight of 4000 to 6000 and/or a partially hydrogenated product thereof, in an amount of 8 to 14% by weight, based on the total weight of the reactive polyurethane hot melt adhesive composition.

30. The composition according to any one of claims 1 to 16, wherein the MDI has a molar ratio of isocyanate groups to hydroxyl groups contained in the polymer polyol of 1.4.

31. The composition according to claim 30, wherein the molar ratio of isocyanate groups contained in the MDI to hydroxyl groups contained in the polymer polyol is from 1.5 to 1.0 to 3.5.

32. The composition according to claim 31, wherein the molar ratio of isocyanate groups contained in the MDI to hydroxyl groups contained in the polymeric polyol is from 1.5 to 1.0.

33. The composition according to any of claims 1 to 16, wherein the isocyanate-terminated polyurethane prepolymer P comprises from 0.4 to 4.0% by weight of unreacted isocyanate groups, based on the total weight thereof.

34. The composition according to claim 33, wherein the isocyanate-terminated polyurethane prepolymer P contains 0.6 to 3.7% by weight of unreacted isocyanate groups, based on the total weight of the prepolymer P.

35. The composition according to claim 34, wherein the isocyanate-terminated polyurethane prepolymer P contains 0.7 to 3.3% by weight of unreacted isocyanate groups, based on the total weight of the prepolymer P.

36. The composition according to any one of claims 1 to 16, wherein the composition comprises from 20 to 45% by weight, based on the total weight of the reactive polyurethane hot melt adhesive composition, of a polyester diol a) in the form of structural units incorporated into the polyurethane prepolymer P.

37. The composition according to claim 36, wherein the composition comprises from 25 to 35% by weight, based on the total weight of the reactive polyurethane hot melt adhesive composition, of a polyester diol a) in the form of structural units incorporated into the polyurethane prepolymer P.

38. The composition according to any one of claims 1 to 16, wherein the composition comprises from 9 to 30% by weight, based on the total weight of the reactive polyurethane hotmelt composition, of polyether diols b) in the form of structural units incorporated in the polyurethane prepolymer.

39. The composition according to any one of claims 1 to 16, wherein the composition comprises 3 to 20% by weight of filler, based on the total weight of the reactive polyurethane hot melt adhesive composition.

40. The composition according to claim 39, wherein the composition comprises from 5 to 15% by weight of filler, based on the total weight of the reactive polyurethane hot melt adhesive composition.

41. The composition according to any one of claims 1 to 16, which is a one-component moisture-curing polyurethane hot melt adhesive composition.

42. A process for preparing the reactive polyurethane hot melt adhesive composition according to any one of claims 1 to 41, comprising reacting diphenylmethane diisocyanate with a polymer polyol mixture M comprising the at least one polyester diol a) and the at least one polyether diol b) to give an isocyanate-terminated polyurethane prepolymer P.

43. Use of the reactive polyurethane hot melt adhesive composition according to any one of claims 1 to 41 as a hot melt adhesive.

44. The use according to claim 43, wherein the reactive polyurethane hot melt adhesive composition is used as a hot melt adhesive in the fields of building materials, furniture and woodworking, electrical, automotive, bookbinding, shoemaking, filter assembly and textile processing.

45. The use according to claim 43, wherein said reactive polyurethane hot melt adhesive composition is used as a one-component moisture-curing hot melt adhesive.