Reactive hot melt adhesive composition and its uses

Abstract

The present invention provides a reactive hot melt adhesive composition and its use. The reactive hot melt adhesive composition comprises at least one NCO-terminated polyurethane prepolymer, and the NCO-terminated polyurethane prepolymer comprises the reaction product of the following components: a) at least one polyisocyanate, b) at least one polyol selected from the following: polytetrahydrofuran, polybutadiene polyol, hydrogenated polybutadiene polyol, polycarbonate polyol, and combinations thereof, and c) optionally at least one polyol different from component b), wherein the NCO / OH ratio is greater than 1, preferably about 1.5 to about 2.5, and the NCO / OH ratio is the molar ratio of the NCO groups of component a) to the total OH groups of components b) and c).

Description

Technical Field

[0001] The present invention relates to a reactive hot melt adhesive composition and its uses. Specifically, the present invention provides an adhesive having excellent wash resistance, especially excellent tolerance to antibacterial laundry detergents. In addition, the adhesive has a particularly short open time and good flexibility upon curing. Background Art

[0002] Reactive hot melt adhesives have been widely used to bond fabric to fabric, especially in the field of clothing or particularly underwear manufacturing, to replace stitching and heat-sealing tapes, which simplifies the process, saves costs, reduces delivery time, and results in a more competitive product in the market.

[0003] For example, H.F. Hüber and H. Müller described in "Shaping Reactive Hotmelts Using LMW Copolyesters", Adhesives Age, November 1987, pages 32 to 35, a reactive hot melt adhesive based on an isocyanate-terminated (also known as "NCO-terminated") polyurethane prepolymer.

[0004] However, existing reactive hot melt adhesives cannot withstand frequent washing, especially when using antibacterial laundry detergents. Therefore, there is a need in the art for a reactive hot melt adhesive that overcomes this drawback. Summary of the Invention

[0005] Disclosed herein is a reactive hot melt adhesive composition comprising at least one NCO-terminated polyurethane prepolymer, the NCO-terminated polyurethane prepolymer comprising the reaction product of the following components:

[0006] a) at least one polyisocyanate,

[0007] b) at least one polyol selected from the group consisting of polytetrahydrofuran, polybutadiene polyol, hydrogenated polybutadiene polyol, polycarbonate polyol, and combinations thereof, and

[0008] c) optionally present at least one polyol different from component b),

[0009] wherein the NCO / OH ratio is greater than 1, preferably from about 1.5 to about 2.5, and the NCO / OH ratio is the molar ratio of the NCO groups of component a) to the total OH groups of components b) and c).

[0010] Also disclosed herein is a cured product of the reactive hot melt adhesive composition according to the present invention.

[0011] The present invention also discloses the use of the reactive hot melt adhesive composition according to the present invention for bonding two substrates, in particular two substrates in clothing or underwear, wherein at least one of the two substrates is a fabric.

[0012] Other features and aspects of the subject matter are set forth in greater detail below. Detailed Description

[0013] Those of ordinary skill in the art will understand that this discussion is only a description of exemplary embodiments and is not intended to limit the broader aspects of the present invention.

[0014] In one aspect, the present invention generally relates to a reactive hot melt adhesive composition comprising at least one NCO-terminated polyurethane prepolymer, the NCO-terminated polyurethane prepolymer comprising the reaction product of, consisting essentially of the reaction product of, or consisting of the reaction product of the following components:

[0015] a) at least one polyisocyanate,

[0016] b) at least one polyol selected from the group consisting of polytetrahydrofuran, polybutadiene polyol, hydrogenated polybutadiene polyol, polycarbonate polyol, and combinations thereof, and

[0017] c) optionally present at least one polyol different from component b),

[0018] wherein the NCO / OH ratio is greater than 1, preferably about 1.5 to about 2.5, and the NCO / OH ratio is the molar ratio of the NCO groups of component a) to the total OH groups of components b) and c).

[0019] As used herein, "about" in connection with a numerical value means the numerical value ± 10% of that value, preferably the numerical value ± 5% of that value. For example, "about 20% by weight" thus refers to 20 ± 2% by weight, preferably 20 ± 1% by weight.

[0020] As used herein, "room temperature" refers to a temperature of about 20°C to about 25°C, preferably about 25°C.

[0021] According to the present invention, the polyurethane prepolymer has an NCO / OH ratio greater than 1, and the NCO / OH ratio is calculated by dividing the molar amount of the NCO groups of component a) by the total molar amount of the OH groups of components b) and c).

[0022] A polyurethane prepolymer is obtained by reacting a polyisocyanate a) with a polyol b) and c) (if present). By setting the NCO / OH ratio to be greater than 1, the polyurethane prepolymer contains free isocyanate groups and is end-capped with isocyanate groups. As an intermediate for crosslinking polyurethanes, the isocyanate-capped polyurethane prepolymer reacts with moisture on the substrate surface or in the environment to extend the main chain and thus form a polyurethane polymer. The polyurethane prepolymer cures under atmospheric conditions by moisture diffusing from the atmosphere or the substrate into the adhesive and then reacting. Thus, the polyurethane hot melt adhesive composition is reactive and moisture-curable. The cured adhesive product is a crosslinked material bonded mainly through urea groups and urethane groups.

[0023] In one embodiment, the polyurethane prepolymer has an NCO / OH ratio of from about 1.5 to about 2.5. When the NCO / OH ratio falls within the above range, the polyurethane prepolymer crosslinks sufficiently upon exposure to moisture and has the desired viscosity that is easy to spray but does not string or penetrate the fabric.

[0024] In one embodiment, based on the total weight of the polyurethane prepolymer, the polyurethane prepolymer according to the present invention has an NCO content of from about 1 wt% to about 5 wt%, preferably from about 1.2 wt% to about 4 wt%. When the NCO content falls within the above range, the polyurethane prepolymer crosslinks sufficiently upon exposure to moisture and has the desired viscosity that is easy to spray but does not string or penetrate the fabric.

[0025] According to the present invention, the polyurethane prepolymer is prepared by reacting component a) at least one polyisocyanate with component b) at least one polyol selected from polytetrahydrofuran, polybutadiene polyol, hydrogenated polybutadiene polyol, polycarbonate polyol, and combinations thereof, optionally further reacting with component c) at least one polyol different from component b).

[0026] As used herein, the term "polyisocyanate" is understood to preferably have 2 to 4 isocyanate groups per molecule. Preferably, the polyisocyanate is a diisocyanate, including aliphatic, cycloaliphatic or aromatic diisocyanates.

[0027] In one embodiment, the aromatic diisocyanate is selected from 2,2'-methylenediphenyl diisocyanate (MDI), 4,4'-methylenediphenyl diisocyanate, 2,4'-methylenediphenyl diisocyanate, 2,4-toluene diisocyanate (TDI), 2,6-toluene diisocyanate, 1,3-phenylene diisocyanate (PDI), 1,4-phenylene diisocyanate, 1,4-naphthylene diisocyanate (NDI), 1,5-naphthylene diisocyanate, tetramethylxylylene diisocyanate (TMXDI), 4,4'-dibenzyl diisocyanate, xylylene diisocyanate (XDI), and combinations thereof.

[0028] In one embodiment, the aliphatic isocyanate is selected from butane-1,4-diisocyanate, 1,6-hexamethylene diisocyanate (HMDI), 1,6-diisocyanato-2,2,4-trimethylhexane, 1,12-diisocyanato-dodecane, and combinations thereof.

[0029] In one embodiment, the cycloaliphatic isocyanate is selected from isophorone diisocyanate (IPDI), 4,4-dicyclohexylmethane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, 1-methyl-2,4-diisocyanato-cyclohexane, and combinations thereof.

[0030] Preferably, the polyisocyanate is selected from 2,2'-methylenediphenyl diisocyanate, 4,4'-methylenediphenyl diisocyanate, 2,4'-methylenediphenyl diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, or combinations thereof. More preferably, MDI is used as the polyisocyanate.

[0031] In the reactive hot melt adhesive composition according to the present invention, based on the total weight of the polyurethane prepolymer, the amount of component a) at least one polyisocyanate is about 10% by weight to about 40% by weight, preferably about 15% by weight to about 35% by weight.

[0032] According to the present invention, component b) is at least one polyol selected from polytetrahydrofuran, polybutadiene polyol, hydrogenated polybutadiene polyol, polycarbonate polyol, and combinations thereof. These specific polyols impart excellent chemical resistance and excellent hydrolysis resistance to the cured product.

[0033] In one embodiment, the functionality of each of component b) and c) is 2. In other words, each polyol b) and c) is independently a diol. Functionality refers to the average number of hydroxyl groups per molecule of the polyol.

[0034] Component b) preferably has at least one terminal hydroxyl group, more preferably two terminal hydroxyl groups, which promotes the formation of the polyurethane prepolymer.

[0035] In one embodiment, polytetrahydrofuran, polybutadiene polyol, and hydrogenated polybutadiene polyol each have a number average molecular weight (Mn) of about 1,000 to about 5,000 g / mol, preferably about 1,000 to about 3,500 g / mol. An Mn falling within the above range renders these specific polyether polyols compatible with other components in the formulation and modulates the adhesive strength and open time of the adhesive composition.

[0036] In the present specification, the number average molecular weight (Mn) can be determined by gel permeation chromatography (GPC) according to DIN 55672, in particular DIN 55672-1 using THE as the eluent.

[0037] As used herein, the term "polytetrahydrofuran" may be interchanged with poly(tetramethylene ether) glycol (PTMEG) and is represented by the formula HO-(-CH 2 ) 4 O-) n -H. Polytetrahydrofuran has excellent chemical resistance and excellent hydrolysis resistance and imparts these properties to the derived polyurethane adhesive composition.

[0038] In some embodiments, polytetrahydrofuran is a white waxy solid or liquid at room temperature. It melts into a colorless or light yellow color at about 25 °C to about 40 °C.

[0039] Polytetrahydrofuran can be prepared by cationic ring-opening polymerization of tetrahydrofuran. Polytetrahydrofuran is commercially available from Korea PTG Co., Ltd. under, for example, PTMEG 1000, PTMEG 1800, PTMEG 2000, and PTMEG 3000.

[0040] In one embodiment, polybutadiene diol has a main chain represented by the formula HO-(-C-C=C-C-) n -OH. Hydrogenated polybutadiene diol has a main chain represented by the formula HO-(-C-C-C-C-) n -OH. Polybutadiene diol and hydrogenated polybutadiene diol may have one or more side groups grafted onto their main chains for property modification. The side groups may be, for example, C1-C10 alkyl groups. Polybutadiene diol and hydrogenated polybutadiene diol have excellent chemical resistance, hydrolysis resistance, aging resistance, and yellowing resistance and impart these properties to the derived polyurethane adhesive composition. Hydrogenated polybutadiene diol is more excellent in these properties and is therefore preferred.

[0041] In some embodiments, polybutadiene diol and hydrogenated polybutadiene diol are colorless or light yellow liquids at room temperature. Some polybutadiene diols and hydrogenated polybutadiene diols do not have a glass transition temperature (Tg). If they do, their glass transition temperature (Tg) is generally below 0 °C, for example, about -30 °C to about -50 °C, preferably about -30 °C to about -45 °C.

[0042] As mentioned herein, the glass transition temperature (Tg) is measured by differential scanning calorimetry (DSC).

[0043] Polybutadiene diol and hydrogenated polybutadiene diol are commercially available. For example, they are sold by Cray Valley Corporation under the product name Krasol. Specific examples of polybutadiene diol include Krasol LBH-P 2000, Krasol LBH 3000, and Krasol LBH-P 3000. Specific examples of hydrogenated polybutadiene diol include Krasol HLBH-P2000 and Krasol HLBH-P3000.

[0044] In one embodiment, the term "polycarbonate polyol" is understood to have a repeating unit -O-C(O)O- and is terminated by one or more, preferably two, hydroxyl groups. Polycarbonate polyols, preferably polycarbonate diols, have excellent weather resistance and hydrolysis resistance and impart these properties to the derived polyurethane adhesive compositions.

[0045] In one embodiment, the polycarbonate polyol is amorphous, so it imparts good sprayability to the polyurethane prepolymer and good softness to the cured product. The polycarbonate polyol can be a solid or a liquid at room temperature. For an amorphous solid, its glass transition temperature (Tg) is higher than room temperature. The glass transition temperature (Tg) of an amorphous liquid, if it has one, is lower than room temperature.

[0046] The polycarbonate polyol can be prepared, for example, by reacting an aliphatic diol such as propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, or a mixture thereof with a diaryl carbonate or a dialkyl carbonate such as dimethyl carbonate.

[0047] Polycarbonate diols are commercially available. For example, they are sold by Asahi Kasei Corporation under the trade name DuranoI TM as a series of products. Specific examples of polycarbonate diols include DuranoI TM T5652, DuranoI TM T5651, DuranoI TM T5650J, DuranoITM T5650E, DuranoI TM T4672, DuranoI TM T4671, DuranoI TM T4692, DuranoI TM T4691, DuranoI TM T6001, DuranoI TM T6002, DuranoI TM G3452 and DuranoI TM G3450J。

[0048] In the reactive hot melt adhesive composition according to the invention, based on the total weight of the polyurethane prepolymer, the amount of component b) is from about 5% to about 70% by weight, preferably from about 10% to about 60% by weight, more preferably from about 20% to about 60% by weight.

[0049] In one embodiment, component c), i.e., at least one polyol different from component b), is included in the reactants for preparing the polyurethane prepolymer. There is no specific limitation on component c), and polyether polyols or polyester polyols commonly used in the preparation of polyurethanes can be used herein as long as they do not adversely affect the desired properties of the hot melt adhesive composition of the invention.

[0050] In one embodiment, component c) is selected from polyether polyols, polyester polyols, and combinations thereof.

[0051] Component c) can be crystalline, amorphous, or a mixture thereof.

[0052] In one embodiment, component c) is crystalline and has a melting point of about 40 to about 100 °C. If component c) is crystalline and has a melting point of about 40 to about 100 °C, the aggregation of the grains dries the surface in a short time, so the adhesive composition has a very short open time, for example, about 1 minute to no more than about 5 minutes, preferably about 1 minute to about 2 minutes.

[0053] In another embodiment, component c) is amorphous and has a glass transition temperature (Tg) of about -40 to about 40 °C. Preferably, the glass transition temperature (Tg) of component c) is equal to or higher than the Tg of component b).

[0054] If component c) is amorphous and has a glass transition temperature (Tg) of from about -40 °C to about 40 °C, especially when the Tg of component c) is equal to or higher than the Tg of component b), the adhesive composition has a relatively high viscosity, which contributes to the surface drying in a short time, and thus the adhesive composition has a very short open time, for example from about 1 minute to not more than about 5 minutes, preferably from about 1 minute to about 2 minutes.

[0055] Component c) is commercially available. For example, commercial products of component c) include the Dnyacoll series from Evonik Corporation, such as amorphous liquid polyols with a Tg of from about -30 °C to about -10 °C, such as Dnyacoll 7210, Dnyacoll 7230, and Dnyacoll 7231; amorphous polyols with a Tg of from about 10 °C to about 50 °C, such as Dnyacoll 7110, Dnyacoll 7111, Dnyacoll 7130, Dnyacoll 7131, Dnyacoll 7140, and Dnyacoll 7150; crystalline polyols with a melting point of from about 40 °C to about 100 °C, such as Dnyacoll 7320, Dnyacoll 7330, Dnyacoll 7340, Dnyacoll 7360, Dnyacoll 7362, Dnyacoll 7363, Dnyacoll 7365, Dnyacoll 7380, and Dnyacoll 7381. Commercial products of component c) also include aromatic polyester polyols sold by Stepan Company under the Stepanpol series, such as Stepanpol PH-56, PHN-56, PDP-70, and PN-110.

[0056] In the reactive hot melt adhesive composition according to the present invention, based on the total weight of the polyurethane prepolymer, the amount of component c) is from about 0 wt% to about 75 wt%, preferably from about 20 wt% to about 60 wt%.

[0057] In one embodiment, the NCO-terminated polyurethane prepolymer comprises, consists essentially of, or consists of the reaction product of the following components:

[0058] a) from about 10 wt% to about 40 wt%, preferably from about 15 wt% to about 35 wt% of at least one polyisocyanate,

[0059] b) from about 5% to about 70% by weight, preferably from about 10% to about 60% by weight, more preferably from about 20% to about 60% by weight of at least one polyol selected from the group consisting of polytetrahydrofuran, polybutadiene polyol, hydrogenated polybutadiene polyol, polycarbonate polyol, and combinations thereof, and

[0060] c) 0% to about 75% by weight, preferably from about 20% to about 60% by weight of at least one polyol different from component b),

[0061] All of the above are based on the total weight of the polyurethane prepolymer.

[0062] The reactive hot melt adhesive composition according to the present invention has a Brookfield viscosity of about 10,000 to about 30,000 cps, preferably about 15,000 to about 20,000 cps, at 120 °C. The Brookfield viscosity is measured according to ASTM 1084-1997 using a Brookfield viscometer RVDVII equipped with a Thermosel heating unit and a spindle 27 at 2.5 to 10 rpm.

[0063] In one embodiment, the melting temperature of the adhesive composition is from about 100 to about 140 °C.

[0064] In this specification, unless otherwise stated, the melting temperature refers to the value measured by a differential scanning calorimeter (DSC) according to ISO 11357, particularly ISO 11357-3. Specifically, the peak top of the endothermic peak observed when the temperature is raised from -50 °C to 250 °C at a rate of 10 °C / minute is regarded as the melting temperature.

[0065] After washing, especially after washing with an antibacterial laundry detergent, the adhesion strength retention rate of the cured composition is about 75% or higher, preferably about 80% or higher, more preferably about 83% or higher. The adhesion strength retention rate is calculated by dividing the adhesion strength of the washed cured product by the adhesion strength of the cured product before washing.

[0066] The adhesion strength of the cured product is measured according to the JIS L1093 method A-1. The antibacterial laundry detergent contains at least one detergent and at least one antibacterial agent. There are no particular limitations on the detergent and the antibacterial agent, and those commonly used for laundry are suitable herein. For example, commercially available examples of detergents include Head & Shoulder available from P&G Corporation. Commercially available examples of antibacterial agents include products sold under the trade names and products.

[0067] In some embodiments, the reactive hot melt adhesives according to the present invention have a very short open time, e.g., from about 1 minute to no more than about 5 minutes, preferably from about 1 minute to about 2 minutes. "Open time" refers to the minimum required time from when the adhesive is applied until installation can begin.

[0068] In some embodiments, the reactive hot melt adhesive compositions according to the present invention are wash - tolerant at high temperatures, e.g., at temperatures of about 60 °C or higher, about 70 °C or higher, about 80 °C or higher, and about 90 °C or higher, e.g., washing at about 92 °C.

[0069] In some embodiments, the cured compositions according to the present invention have a soft touch, which makes them suitable for use in clothing, especially suitable for underwear.

[0070] Although the adhesive composition can be used directly as described above, if desired, the adhesive compositions of the present invention can also be formulated with conventional additives that are compatible with the composition. Such additives include defoamers, plasticizers, compatible tackifiers, curing catalysts, dissociation catalysts, fillers, rheology modifiers, antioxidants, pigments, adhesion promoters, stabilizers, flame retardants, etc. Conventional additives compatible with the compositions according to the present invention can be determined simply by combining the potential additive with the composition and determining whether they are compatible. If the additive is homogeneous in the product, it is compatible.

[0071] Generally, the reactive hot melt adhesive compositions according to the present invention can be used to bond two substrates, especially two substrates in clothing or underwear, where at least one of the two substrates is a fabric. The other substrate can be a fabric or a foam. Specifically, the reactive hot melt adhesive compositions according to the present invention can be used to bond fabric to fabric or fabric to foam in clothing, especially in underwear.

[0072] The reactive hot melt adhesive according to the present invention is heated to melting, and the molten adhesive is applied to one or both of the substrates to be bonded.

[0073] Final curing can be carried out using various conditions. In particular, curing is achieved by the action of moisture in the air, where the relative humidity is not less than 10%, preferably not less than 25%, more preferably not less than 50%.

[0074] The composition is generally distributed and stored in its solid form in the absence of moisture. When the composition is ready for use, the solid is heated and melted before application. Thus, the present invention includes both the reactive hot melt adhesive composition in solid form, as it is generally to be stored and distributed, and the reactive hot melt adhesive composition in liquid form just after it has been melted, immediately before its application.

[0075] Examples

[0076] The following examples illustrate the present invention and are not intended to limit the present invention.

[0077] Raw materials

[0078] Component a):

[0079] MDI: 4,4'-methylenediphenyl diisocyanate, commercially available from Convestro.

[0080] Component b):

[0081] PTMEG 2000: Polytetrahydrofuran, Mn: 2000 g / mol, Tg: -76 °C, melting point: 32 °C, commercially available from PTG Co., Ltd.

[0082] HLBH-P 2000: Hydrogenated polybutadiene diol, Mn: 2100 g / mol, liquid, Tg: -30 °C, commercially available from Cray Valley Corporation.

[0083] Duranol T 5652: Polycarbonate diol, amorphous, liquid, Tg: -54 °C, commercially available from Asahi Kasei Corporation.

[0084] Component c):

[0085] Dynacoll 7130: Polyester polyol, amorphous, solid, Tg: 30 °C, available from Evonik Corporation.

[0086] Dynacoll 7210: Polyester polyol, amorphous, liquid, Tg: -15 °C, available from Evonik Corporation.

[0087] Dynacoll 7231: Polyester polyol, amorphous, liquid, Tg: -30 °C, available from Evonik Corporation.

[0088] Dynacoll 7360: Polyester polyol, crystalline, melting point: 55 °C, available from Evonik Corporation.

[0089] PES 9007: Liquid polyester polyol, amorphous, liquid, Tg: -20 °C, available from Xuchuan Corporation.

[0090] PN-110: Polyester polyol, amorphous, Tg: 25 °C, available from Stepan Company.

[0091] Preparation of prepolymer

[0092] Prepare the prepolymer according to the formulation listed in Table 1. The total weight of all components of the prepolymer is 100 parts by weight.

[0093] Add all the polyols to a three-necked round-bottom flask to melt and mix under vacuum until homogeneous, and dehydrate at 130 °C for 2 hours. Then add MDI to the mixture at 100 °C and carry out polymerization under vacuum stirring at 110 °C until the reaction is completed after 1.5 hours. Analyze the remaining NCO content by nitration to determine the completion of the reaction.

[0094] Testing methods and evaluation :

[0095] Retention rate of adhesion strength

[0096] Coat each of the prepolymers prepared as above onto a 10 m × 0.5 m polyester fabric (available from Xiaoshan Rongli Corporation) with a thickness of 20 μm by a gravure roll (X-TH13, available from Xinxin Corporation in Dongguan) at 90 to 120 °C, and then laminate it with another 10 m × 0.5 m polyester fabric to obtain a laminated sample. Cure the laminated sample at 23 °C and 50% relative humidity for 3 - 7 days. Measure the adhesion strength of the cured laminated sample according to JIS L1093 Method A-1. Each adhesion strength is measured 3 times, and the average value is recorded as N1. Then immerse the cured laminated sample in an aqueous mixture of Head & Shoulders (a detergent, available from P&G Corporation) and (an antibacterial agent) for 72 hours. Measure the adhesion strength after washing in the same manner as N1 and record it as N2.

[0097] Adhesion strength retention rate = N2 / N1 * 100%

[0098] Pot life

[0099] Coat a 10 cm × 1 cm paper with each of the prepolymers prepared as above with a thickness of 20 μm by a gravure roll (X-TH13, available from Xinxin Corporation in Dongguan) at 100 to 140 °C. Attach a paper strip (1.5 cm × 5.0 cm) to the coated paper by finger pressure every 30 seconds. The open time is defined as the time until the fibers of the paper strip are observed to tear.

[0100] Flexibility

[0101] Touch the cured laminate sample obtained above with the hands of 5 volunteers for measuring the adhesion strength N1. If all 5 volunteers have a soft feel, the cured laminate sample is considered to have good softness.

[0102] Table 1

[0103]

[0104] As shown by the results in Table 1, the adhesive compositions prepared in Examples 1 - 7 have a high adhesion strength retention rate of 78% or higher, a short open time of no more than 5 minutes, and good softness. In Examples 1 - 6, the content of component b) is greater than 10% by weight, the adhesion strength retention rate is desirably higher (83% or higher), and the open time is shorter (no more than 2 minutes).

[0105] The adhesion strength in Examples 1 and 3 increased after washing. It is assumed that the reason for this phenomenon may lie in the rearrangement of the cured adhesive molecules when wetted with water.

[0106] The adhesive composition prepared in Comparative Example 1 does not contain component b), its adhesion strength retention rate is only 45.45%, and its open time is as long as 15 minutes.

[0107] Without departing from the spirit and scope of the present invention, those of ordinary skill in the art can implement these and other modifications and variations of the present invention. In addition, it should be understood that aspects of each embodiment can be interchanged in whole or in the reactants. In addition, those of ordinary skill in the art will understand that the foregoing description is merely exemplary and is not intended to limit the present invention as further described in the appended claims.

Claims

1. A reactive hot melt adhesive composition comprising at least one NCO-terminated polyurethane prepolymer, said NCO-terminated polyurethane prepolymer comprising the reaction product of the following components: a) 10% to 40% by weight of at least one polyisocyanate, b) 20% to 60% by weight of at least one polytetrahydrofuran, and c) 20% to 60% by weight of at least one crystalline polyester polyol having a melting point of 40 to 100 °C and an amorphous polyester polyol having a glass transition temperature (Tg) of -40 to 40 °C, All of the above are based on the total weight of the polyurethane prepolymer, wherein the NCO / OH ratio is greater than 1, and the NCO / OH ratio is the molar ratio of the NCO groups of component a) to the total OH groups of components b) and c).

2. The reactive hot melt adhesive composition according to claim 1, wherein the NCO content is 1% to 5% by weight based on the total weight of the polyurethane prepolymer.

3. The reactive hot melt adhesive composition according to claim 1, wherein the NCO / OH ratio is 1.5 to 2.

5.

4. The reactive hot melt adhesive composition according to claim 2, wherein the NCO content is 1.2% to 4% by weight based on the total weight of the polyurethane prepolymer.

5. The reactive hot melt adhesive composition according to any one of claims 1 to 4, wherein the at least one polyisocyanate is a diisocyanate.

6. The reactive hot melt adhesive composition according to claim 5, wherein the at least one polyisocyanate is a diisocyanate selected from the group consisting of 2,2'-methylenediphenyl diisocyanate, 4,4'-methylenediphenyl diisocyanate, 2,4'-methylenediphenyl diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, or combinations thereof.

7. The reactive hot melt adhesive composition according to any one of claims 1 to 4, wherein the polytetrahydrofuran has a number average molecular weight (Mn) of 1,000 to 5,000 g / mol.

8. The reactive hot melt adhesive composition according to claim 7, wherein the polytetrahydrofuran has a number average molecular weight (Mn) of 1,000 to 3,500 g / mol.

9. The reactive hot melt adhesive composition according to claim 1, wherein the amount of component a) is 15% to 35% by weight based on the total weight of the polyurethane prepolymer.

10. The reactive hot melt adhesive composition according to any one of claims 1 to 4, wherein the melting temperature of the adhesive composition is 100 °C to 140 °C.

11. A cured product of the reactive hot melt adhesive composition according to any one of claims 1 to 10.

12. The cured product according to claim 11, wherein after washing, the cured product has a bond strength retention rate of greater than 75%, and the bond strength retention rate is calculated by dividing the bond strength of the cured product after washing by the bond strength of the cured product before washing.

13. The cured product according to claim 12, wherein after washing, the cured product has a bond strength retention rate of greater than 80%.

14. The cured product according to claim 12, wherein after washing, the cured product has a bond strength retention rate of greater than 83%.

15. The cured product according to any one of claims 12 to 14, wherein the washing is carried out with an antibacterial laundry detergent.

16. Use of the reactive hot melt adhesive composition according to any one of claims 1 to 10 for bonding two substrates, wherein at least one of the two substrates is a fabric.

17. The use according to claim 16, wherein the two substrates are two substrates in a garment or undergarment.

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