Hot melt adhesive composition

Abstract

To provide a hot-melt adhesive composition capable of shortening the time until a sufficient adhesive force is exhibited when substrates are adhered to each other, and excellent in workability.SOLUTION: One embodiment of the present invention is a hot melt adhesive composition comprising an isocyanate group-terminated urethane prepolymer and a compound represented by the following formula (1): Wherein R1, R2, and R3 are each independently hydrogen or a hydrocarbyl group. ) SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a hot melt adhesive composition. [Background technology]

[0002] Moisture-curing hot melt adhesives, which cure in response to moisture, can be applied to an adherend, pressed against another adherend, and then cooled and solidified to bond the adherends. This makes them easy to work with, and they are used in a variety of fields, including construction, electrical engineering, and automotive.

[0003] Isocyanate-terminated urethane prepolymers are used as materials for hot melt adhesives. Hot melt adhesives whose main component is urethane prepolymers develop a certain degree of adhesive strength in a short time after bonding as the adhesive itself cools and solidifies. The terminal isocyanate groups of the urethane prepolymer then react with moisture in the air or on the surface of the adherend, resulting in high molecular weight and crosslinking.

[0004] Patent Document 1 discloses a polyurethane-based moisture-curable hot melt adhesive containing a urethane prepolymer, which is a reaction product of a crystalline polyester polyol, a non-crystalline polyester polyol and / or a non-crystalline polyether polyol, and a specific polyisocyanate. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-077817 Summary of the Invention [Problem to be solved by the invention]

[0006] While such polyurethane-based moisture-curing hot melt adhesives can exhibit excellent adhesive strength, when substrates are laminated using a polyurethane-based hot melt adhesive, if the laminate is transported in a state where the substrates are not sufficiently bonded to each other, there is a possibility that the laminate will peel off during shaking during transportation or loading. Therefore, in order to sufficiently increase the adhesive strength, a curing process may be performed until sufficient curing and crosslinking are achieved. Polyurethane-based hot melt adhesives according to conventional technology require a long curing time, which may also lead to deterioration of workability.

[0007] Therefore, an object of the present invention is to provide a hot melt adhesive composition that can shorten the time until sufficient adhesive strength is achieved when bonding substrates together and that has excellent workability. [Means for solving the problem]

[0008] The present inventors have conducted extensive research and found that the above problems can be solved by using a hot melt adhesive containing a specific component, and have completed the present invention.

[0009] One aspect of the present invention is a hot melt adhesive composition comprising an isocyanate group-terminated urethane prepolymer and a compound represented by the following formula (1): [ka] (In formula (1), R1, R2, and R3 are each independently a hydrogen atom or a hydrocarbon group.)

[0010] In the formula (1), it is preferable that R1 and R2 each independently represent a hydrogen atom, an alkyl group, an alkenyl group, or an alkynyl group. The hot melt adhesive composition is preferably used for interior materials of vehicles.

[0011] Another aspect of the present invention is The first substrate and the second substrate are laminated together via an adhesive, the adhesive is a cured product of the hot melt adhesive composition, The first substrate and the second substrate are each independently a laminate selected from the group consisting of a foam, natural leather, synthetic leather, a film, a woven fabric, and a nonwoven fabric. [Effects of the Invention]

[0012] According to the present invention, there is provided a hot melt adhesive composition that can shorten the time required for sufficient adhesive strength to be exerted when bonding substrates together, and that has excellent workability. DETAILED DESCRIPTION OF THE INVENTION

[0013] In the present specification, when isomers exist in the compounds described, all possible isomers are included unless otherwise specified.

[0014] In this specification, the number average molecular weight and the weight average molecular weight are measured using gel permeation chromatography.

[0015] In this specification, when an upper limit value and a lower limit value are separately described, it is considered that a numerical range combining any upper limit value and any lower limit value is substantially disclosed.

[0016] In this specification, unless otherwise specified, various measurements are carried out at room temperature (25°C).

[0017] The components, properties / characteristics, applications, etc. of the hot melt adhesive composition according to the present disclosure will be described below, but the present invention is not limited thereto.

[0018] <<<Ingredients>>> The hot melt adhesive composition according to the present disclosure contains a urethane prepolymer and an oxazolidine compound (a compound having one or more oxazolidine rings). The hot melt adhesive composition according to the present disclosure may also contain other components. Each component will be described below.

[0019] <<Urethane prepolymer>> The urethane prepolymer is an isocyanate group-terminated urethane prepolymer having an isocyanate group at the end.

[0020] A urethane prepolymer can be obtained by reacting a polyol compound with a polyisocyanate compound. Hydroxyl groups contained in the polyol compound react with isocyanate groups contained in the polyisocyanate compound to form urethane bonds, thereby obtaining a urethane prepolymer. In this case, by using an excess amount of the polyisocyanate compound relative to the polyol compound, an isocyanate-terminated urethane prepolymer is formed.

[0021] <Polyol compounds> The polyol compound is not particularly limited, and examples thereof include polyether polyol, polyester polyol, polycarbonate polyol, and the like.

[0022] The average number of functional groups of the polyol compound is not particularly limited, and may be 2, or 3 or more.

[0023] Examples of polyether polyols include polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, etc., obtained by polymerizing cyclic ethers such as alkylene oxides (ethylene oxide, propylene oxide, etc.) and tetrahydrofuran, and copolyethers thereof. Polyether polyols can also be obtained by polymerizing cyclic ethers using polyhydric alcohols such as glycerin and trimethylolethane. Polyether polyols may also be used, including alkylene oxide adducts of polyhydric phenol compounds such as monocyclic polyphenols such as pyrogallol and hydroquinone; and bisphenols such as bisphenol A, bisphenol F, and bisphenol sulfone.

[0024] Examples of polyester polyols include: polyester polyols such as polyalkylene glycols obtained by a dehydration condensation reaction of a carboxylic acid component [aliphatic dicarboxylic acids (e.g., succinic acid, adipic acid, sebacic acid, azelaic acid, etc.), aromatic dicarboxylic acids (e.g., phthalic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, etc.), alicyclic dicarboxylic acids (e.g., hexahydrophthalic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, etc.), or acid esters or acid anhydrides thereof] with a polyol component [ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, etc., or mixtures thereof]; Polylactone diols obtained by ring-opening polymerization of lactone monomers such as ε-caprolactone and methylvalerolactone; The following can be mentioned:

[0025] Examples of polycarbonate polyols include those obtained by reacting at least one polyhydric alcohol such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, or diethylene glycol with diethylene carbonate, dimethyl carbonate, diethyl carbonate, or the like.

[0026] The polyol compounds can be used alone or in combination.

[0027] <Polyisocyanate compounds> The polyisocyanate compound may be an aromatic polyisocyanate or an aliphatic polyisocyanate, and the aliphatic polyisocyanate may be a cyclic or chain polyisocyanate.

[0028] The average number of functional groups of the polyisocyanate compound is not particularly limited, and may be 2 or 3 or more.

[0029] Examples of bifunctional polyisocyanates include: Examples of aromatic polyisocyanates include toluene diisocyanate (TDI), phenylene diisocyanate, diphenylmethane diisocyanate (MDI), hydrogenated MDI, xylylene diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate, 3,3'-dimethoxy-4,4'-biphenylene diisocyanate, polymethylene polyphenyl polyisocyanate, 1,5-naphthalene diisocyanate, xylylene diisocyanate (XDI), hydrogenated XDI, and tetramethylxylene diisocyanate (TMXDI). Examples of aliphatic polyisocyanates include cyclohexane-1,4-diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, methylcyclohexane diisocyanate, methylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate (HDI), pentamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, and isopropylene diisocyanate.

[0030] Examples of tri- or higher functional polyisocyanate compounds include: Examples of the triisocyanate include 1-methylbenzene-2,4,6-triisocyanate, 1,3,5-trimethylbenzene-2,4,6-triisocyanate, biphenyl-2,4,4'-triisocyanate, diphenylmethane-2,4,4'-triisocyanate, methyldiphenylmethane-4,6,4'-triisocyanate, 4,4'-dimethyldiphenylmethane-2,2',5,5'tetraisocyanate, triphenylmethane-4,4',4"-triisocyanate, polymeric MDI, lysine ester triisocyanate, 1,3,6-hexamethylene triisocyanate, 1,6,11-undecane triisocyanate, bicycloheptane triisocyanate, and 1,8-diisocyanatomethyloctane.

[0031] Furthermore, the polyisocyanate may include modified products thereof (for example, carbodiimide modified products such as carbodiimide modified MDI), derivatives, and the like.

[0032] The polyisocyanate compounds can be used alone or in combination.

[0033] <NCO%> The NCO group content (NCO%) of the isocyanate-terminated polyurethane prepolymer is preferably 0.1% by mass or more, 0.5% by mass or more, or 1.0% by mass or more, and preferably 10.0% by mass or less, 5.0% by mass or less, or 3.0% by mass or less. From another perspective, the NCO group content (NCO%) of the hot melt adhesive composition is preferably 0.1% by mass or more, 0.5% by mass or more, or 1.0% by mass or more, and preferably 10.0% by mass or less, 5.0% by mass or less, or 3.0% by mass or less. Setting the NCO% within this range facilitates the production of a hot melt adhesive composition with excellent reactivity and workability. The NCO% can be measured in accordance with Method A (toluene / dibutylamine, hydrochloric acid method) of JIS K 1603-2007, "Test Method for Aromatic Isocyanates in Plastics - Polyurethane Raw Materials, Part 1: Determination of Isocyanate Group Content."

[0034] <Number average molecular weight> The number average molecular weight of the urethane prepolymer is preferably 3,000 or more or 5,000 or more, and preferably 15,000 or less or 10,000 or less. From another perspective, the number average molecular weight of the hot melt adhesive composition is preferably 3,000 or more or 5,000 or more, and preferably 15,000 or less or 10,000 or less.

[0035] <Method of manufacturing urethane prepolymer> The urethane prepolymer can be produced according to a known method. Specifically, for example, a predetermined amount of polyisocyanate compound is placed in a container and stirred under a nitrogen gas atmosphere. A predetermined amount of polyol compound is then added dropwise. The mixture is stirred for a predetermined period of time to complete the reaction. A portion of the reaction product may be sampled and the isocyanate group content measured to confirm that it is within the desired range. A catalyst may be added as needed to promote the reaction.

[0036] <<Oxazolidine compounds>> The oxazolidine compound is a compound having one or more, preferably two or more, more preferably two oxazolidine rings in the molecule. The oxazolidine compound is preferably a compound represented by the following formula (1):

[0037] [ka]

[0038] In formula (1), R1, R2, and R3 each independently represent a hydrogen atom or a hydrocarbon group. The hydrocarbon group is preferably an alkyl group, an alkenyl group, or an alkynyl group, and more preferably an alkyl group.

[0039] It is particularly preferred that R1 and R2 are each independently hydrogen or a hydrocarbon group having 1 to 10 carbon atoms, hydrogen or a hydrocarbon group having 1 to 5 carbon atoms, hydrogen or a hydrocarbon group having 1 to 3 carbon atoms, or hydrogen.

[0040] R3 is preferably hydrogen or a hydrocarbon group having 1 to 10 carbon atoms, hydrogen or a hydrocarbon group having 1 to 8 carbon atoms, hydrogen or a hydrocarbon group having 1 to 5 carbon atoms, or a hydrocarbon group having 1 to 3 carbon atoms.

[0041] The oxazolidine compound is particularly preferably a compound represented by the following formula (2).

[0042] [ka]

[0043] In hot-melt adhesive compositions containing such oxazolidine compounds, a ring-opening product derived from the oxazolidine compound (a compound having a secondary amino group and a hydroxyl group, generated by hydrolysis of the oxazolidine ring, etc.) reacts with an isocyanate-terminated urethane prepolymer. In addition, combined with the moisture-curing properties of the isocyanate-terminated urethane prepolymer, the use of a compound represented by formula (1) or (2) (a specific compound having two oxazolidine rings) can moderately increase the curing reaction rate and moderately reduce the curing time. Furthermore, the use of a compound represented by formula (1) or (2) can easily suppress the melt viscosity (e.g., viscosity at 140°C).

[0044] In the hot melt adhesive composition, the content of the oxazolidine compound (or the compound represented by formula (1)) is preferably 0.1 parts by mass or more, 0.3 parts by mass or more, or 0.5 parts by mass or more, and is preferably 10 parts by mass or less, 7 parts by mass or less, 5.0 parts by mass or less, 3.0 parts by mass or less, or 1.0 part by mass or less, relative to 100.0 parts by mass of the urethane prepolymer. By setting the content of the oxazolidine compound (or the compound represented by formula (1)) within this range, the above-mentioned effects can be further enhanced.

[0045] <<Other ingredients>> The other components are not particularly limited and include known additives that can be blended into hot melt adhesive compositions. The other components may be appropriately selected taking into consideration the use and composition of the hot melt adhesive composition. Examples of the other components include antioxidants, antifoaming agents, nucleating agents (crystal nucleating agents), catalysts, hydrolysis stabilizers, fillers, plasticizers, pigments, dyes, antioxidants, antistatic agents, flame retardants, adhesion promoters, antibacterial agents, light stabilizers, stabilizers, dispersants, solvents, hydrophilicity promoters, waxes, etc. These can be used alone or in combination.

[0046] In the hot melt adhesive composition, the content of other components (components other than the urethane prepolymer and the oxazolidine compound) is, for example, 10.0 parts by mass or less, 8.0 parts by mass or less, 5.0 parts by mass or less, or 3.0 parts by mass or less per 100.0 parts by mass of the urethane prepolymer.

[0047] The hydrolysis stabilizer is preferably a carbodiimide compound, such as dicyclohexylcarbodiimide, diisopropylcarbodiimide, 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide, cyanamide, N,N'-diisopropylcarbodiimide, N,N'-dicyclohexylcarbodiimide, N-cyclohexylcarbodiimide, N'-methylpolystyrene, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, metho-p-toluene. Examples include 1-cyclohexyl-3-(2-morpholinoethyl)carbodiimide sulfonate, bis(2,6-diisopropylphenyl)carbodiimide, bis(trimethylsilyl)carbodiimide, 1-cyclohexyl-3-(2-morpholinoethyl)carbodiimide metho-p-toluenesulfonate, N,N'-di-tert-butylcarbodiimide, 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide methiodide, etc. The carbodiimide compound may be a commercially available product.

[0048] The content of the carbodiimide compound is, for example, preferably 0.1 parts by mass or more, 0.3 parts by mass or more, or 0.5 parts by mass or more, and preferably 5.0 parts by mass or less, 4.0 parts by mass or less, or 3.0 parts by mass or less, where the total amount of the polyol compounds blended in the urethane prepolymer is taken as 100 parts by mass. By setting the content of the carbodiimide compound within such a range, when containing, the performance of the humidity heat aging resistance of the cured product obtained by curing the hot melt adhesive composition can be further improved.

[0049] <<<Physical properties / properties>>> <<Gel fraction>> The 48-hour gel fraction of the hot melt adhesive composition according to the present disclosure is preferably 25% or more, 40% or more, or 55% or more. When the 48-hour gel fraction is within this range, crosslinking of the urethane prepolymer proceeds even in a relatively short time, and it is thought that the time until sufficient adhesive strength is achieved is short. In particular, when the 48-hour gel fraction is 55% or more, sufficient adhesive strength can be achieved without carrying out a curing step. The 168-hour gel fraction of the hot melt adhesive composition according to the present disclosure is preferably 60% or more, or 65% or more, and is preferably 95% or less, 90% or less, 85% or less, or 80% or less. When the 168-hour gel fraction is in this range, the adhesive strength of a laminate obtained using the hot melt adhesive composition tends to be appropriate. The gel fraction of the hot melt adhesive composition according to the present disclosure is measured by the following method.

[0050] (Method for measuring gel fraction) The hot melt adhesive composition is melted at 140°C, placed on a release film, and formed into a thin film with a thickness of 500 μm using a bar coater. After that, the composition is cured for a predetermined time in a thermostatic chamber at 5°C, and then the sample (cured product) is removed. 0.045 g of a sample is weighed into a 20 ml vial, 9 g of THF is added, and the mixture is stirred at room temperature for 20 hours using a roller stirrer. The sample is taken out and placed in a vacuum dryer, and the heated state is maintained at 50°C for 4 hours to remove the THF. The remainder of the sample is weighed and divided by the original weight to give the gel fraction. The curing time (predetermined time) is changed to N hours (N is a multiple of 24), and the gel fraction of the urethane polymer is measured every N hours, and this is taken as the Nh gel fraction.

[0051] <<Viscosity>> The viscosity of the hot melt adhesive composition (E-type viscosity at 140°C) is preferably 10,000 mPa·s or less, 8,000 mPa·s or less, or 5,000 mPa·s or less. Having a hot melt adhesive composition with a viscosity in this range facilitates coating, reducing uneven coating and facilitating the production of laminates with excellent adhesive strength. Furthermore, a low-viscosity hot melt adhesive composition may allow spray application when applying the hot melt adhesive to a substrate.

[0052] <<<Method for producing hot melt adhesive composition>>> The method for producing the hot melt adhesive composition is not particularly limited, and any known method can be used. Specifically, for example, the hot melt adhesive composition can be produced by placing a predetermined amount of urethane prepolymer in a container, adding other components (an oxazolidine compound and other additives) to the container, and stirring the mixture.

[0053] <<<Application methods and uses of hot melt adhesive compositions>>> The hot melt adhesive composition can be applied to an object to be adhered according to a conventionally known method.

[0054] For example, first, a hot melt adhesive composition is heated to melt it and applied to a first substrate. Then, before the hot melt adhesive composition cools and solidifies, a second substrate is laminated to the first substrate via the hot melt adhesive composition. The hot melt adhesive composition is then cooled and solidified to form a laminate in which the first substrate and the second substrate are bonded together.

[0055] Before the hot melt adhesive composition is applied, the surface of the first substrate and / or the second substrate may be subjected to a known surface treatment.

[0056] As a means for application, known methods can be used, such as a brush, a spatula, a syringe, a sealing gun, a dispenser, etc. Application may also be a non-contact method (e.g., a spray method). When a spray method is used, known methods such as a curtain spray, an omega spray, a spiral spray, and a summit spray can be applied.

[0057] The coating amount of the hot melt adhesive composition (or the basis weight of the hot melt adhesive composition) can be changed as appropriate depending on the application and substrate.

[0058] A component containing a cured product of the hot melt adhesive composition according to the present embodiment (for example, a laminate or a vehicle interior material containing a cured product of the hot melt adhesive composition according to the present embodiment as an adhesive layer) is likely to have sufficient adhesive strength even when not cured or when cured for a short period of time, and production efficiency is likely to be improved.

[0059] Thus, the technology according to the present disclosure may be provided as a cured product of the hot melt adhesive composition or a laminate including the cured product of the hot melt adhesive composition. The technology according to the present disclosure may also be a laminate in which a first substrate and a second substrate are laminated via an adhesive layer, and this adhesive layer is a cured product of the hot melt adhesive composition according to the present disclosure. In this case, the materials and shapes of the first substrate and the second substrate are not particularly limited. The first substrate and the second substrate are preferably each independently selected from the group consisting of foams (e.g., resin foams such as urethane foams), natural leather, synthetic leather, films (resin films), woven fabrics, and nonwoven fabrics. Such laminates can be used as architectural interior materials such as the decorative sheet covering materials described above, furniture components, and components constituting interior materials for vehicles such as airplanes, ships, and vehicles (automobiles and railway cars). The hot melt adhesive composition according to this embodiment is suitable for use in vehicle interior materials (for fixing interior materials), and is particularly suitable for use in vehicle interior materials. More specifically, the material for vehicle interiors can be used to secure the surface of automobile interiors (instrument panels, pillars, door trims, etc.). [Example]

[0060] The effects of the hot melt adhesive composition will be specifically described below using examples, but the present invention is not limited to the following examples.

[0061] <<Raw materials>> <Polyol compounds> Product name: D1000 (Mitsui Chemicals) PPG, number average molecular weight 1000, difunctional Product name: BP-5P (manufactured by Sanyo Chemical Industries, Ltd.) PO adduct of bisphenol A, number average molecular weight 500, bifunctional Product name: 2H-500S (Toyokuni Oil Mill) Sebacic acid-based polyester polyol, number average molecular weight 5000, bifunctional

[0062] <Polyisocyanate compounds> Monomeric MDI (product name: Luplanate MI, manufactured by Mitsui Chemicals, Inc.) NCO%: 33.58% Carbodiimide-modified MDI (product name: Lupranate MM103, manufactured by Mitsui Chemicals, Inc.) NCO%: 36.92%

[0063] <Oxazolidine compounds> Product name: ZOLDINE ZE (manufactured by ANGUS) A compound represented by the following formula (3): [ka] Product name: ZOLDINE MS PLUS (manufactured by ANGUS) A compound represented by the following formula (4): [ka]

[0064] <Other ingredients> Other components used were the antioxidants, antifoaming agents, nucleating agents, catalysts, and hydrolysis stabilizers shown in Table 1.

[0065] <<Production of Hot Melt Adhesive Composition>> Components other than the polyol compound and polyisocyanate compound, which had also been heated to 70°C, were added to a flask heated to 70°C in the amounts (parts by mass) shown in Table 1, and then the polyisocyanate compound was added to the flask. After the heat generated by the addition of the polyisocyanate compound subsided, the flask was heated to 85°C and reacted for 2 hours. In this way, the polyol compound and the polyisocyanate compound were reacted to obtain a urethane prepolymer. Furthermore, the oxazolidine compound and other components shown in Table 1 were blended and stirred for an additional hour or more to obtain hot melt adhesive compositions of Examples and Comparative Examples. In Table 1, the blending amounts of the oxazolidine compound and other components are shown in parts by mass when the urethane prepolymer is taken as 100 parts by mass. Additionally, the NCO% and number average molecular weight of the hot melt adhesive composition were measured. The measurement results are shown in Table 1. In this example, the NCO% and number average molecular weight of the urethane prepolymer were equivalent to the NCO% and number average molecular weight of the hot melt adhesive composition.

[0066] <<Physical properties / evaluation>> The Nh gel fraction (24 to 168 h gel fraction) and viscosity of the hot melt adhesive composition according to each Example and Comparative Example were measured according to the methods described above. The results are shown in Table 1.

[0067] We also checked whether the 48-hour gel fraction was 55% or more. If the 48-hour gel fraction was 55% or more, in other words, if the time required for the gel fraction to reach 55% or more was 48 hours or less, it was determined that the curing time required to increase the adhesive strength had been shortened.

[0068] [Table 1]

[0069] Furthermore, for Examples 4 and 5, the wet heat aging properties were evaluated according to the following method. The results are shown in Table 2. In the table, the unit of each number is "N / 25mm."

[0070] The hot melt adhesive composition was melted at 130°C and applied at a rate of 20 g / m using a hand gun. 2The coating was applied to the substrate so that the coating was uniform. The substrate used was a urethane foam (product name EL67F (manufactured by Inoac Corporation) or product name EL45 (manufactured by Inoac Corporation). The substrate was then bonded to a surface made of fabric (PET fabric) to obtain a laminate. The resulting laminate was molded into a size of 25 mm wide x 250 mm long and left to stand at room temperature for 30 minutes. Each laminate was then cured for 48 hours at 5°C, then stored in an environment of 85°C and 95% relative humidity for a predetermined period (0 hours, 100 hours, 200 hours, 400 hours, and 600 hours), and subjected to a moist heat treatment to obtain a test specimen for evaluation. A 180° peel test was performed on each test specimen at 25°C using a materials testing machine (Shimadzu Corporation, precision universal testing machine autograph), and the peel strength under each moist heat treatment condition was measured. When EL67F is used as the substrate, the peel strength after 200 hours of wet heat treatment is preferably 5.00 N / 25 mm or more, or 6.00 N / 25 mm or more. When EL67F is used as the substrate, the peel strength after 400 hours of wet heat treatment is preferably 0.50 N / 25 mm or more, or 1.50 N / 25 mm or more. When EL45 is used as the substrate, the peel strength after 400 hours of wet heat treatment is preferably 4.00 N / 25 mm or more, or 5.00 N / 25 mm or more. When EL45 is used as the substrate, the peel strength after 600 hours of wet heat treatment is preferably 3.00 N / 25 mm or more, or 4.00 N / 25 mm or more.

[0071] [Table 2]

[0072] As shown in Table 2, both Example 4 and Example 5 had excellent performance in terms of moist heat aging resistance. [Industrial Applicability]

[0073] The hot melt adhesive composition according to the present invention can shorten the time required for sufficient adhesive strength to be achieved when bonding substrates together, and has excellent workability, making it suitable for use in a variety of applications, including vehicle interior materials.

Claims

1. A hot melt adhesive composition comprising an isocyanate group-terminated urethane prepolymer and a compound represented by the following formula (1): 【Chemistry 1】 (In formula (1), R １ , R ２ , and R ３ are each independently hydrogen or a hydrocarbon group.

2. In the formula (1), the R １ , and the R ２ 10. The hot melt adhesive composition of claim 1, wherein each independently is hydrogen, an alkyl group, an alkenyl group, or an alkynyl group.

3. 3. The hot melt adhesive composition according to claim 1, which is used for interior materials of vehicles.

4. The first substrate and the second substrate are laminated together via an adhesive, The adhesive is a cured product of the hot melt adhesive composition according to claim 1 or 2, A laminate, wherein the first substrate and the second substrate are each independently selected from the group consisting of a foam, natural leather, synthetic leather, a film, a woven fabric, and a nonwoven fabric.

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