Low outgassing urethane hot melt adhesive composition

Abstract

To provide a hot melt adhesive composition that has good resistance to moist heat and low outgassing properties even when used to bond foams and the like. [Solution] One aspect of the present invention is a urethane hot melt adhesive composition containing a urethane prepolymer made from polyol component (A) and polyisocyanate (B). The polyol component (A) contains a crystalline polyester polyol (a-1) having a number average molecular weight of 1,000 or more, which is obtained by a condensation reaction of an aliphatic dicarboxylic acid having 10 to 12 carbon atoms with an aliphatic diol having 4 to 6 carbon atoms, and a polyether polyol (a-2) having a number average molecular weight of 1,000 or more. The polyol component (A) further contains one or more polyols selected from the group consisting of amorphous polyester polyols and diols having a molecular weight of 500 or less.

Description

[Technical Field]

[0001] The present invention relates to a novel hot melt adhesive composition with low outgassing properties. [Background technology]

[0002] Conventionally, a cover material covering the surface of a vehicle seat cushion has been produced by adhering a cover layer to the surface of a laminated sheet in which a backing fabric layer is formed on the back surface of a cushioning layer made of foam, and then sewing the laminated sheet together. The backing fabric layer is provided to improve slipperiness to facilitate sewing and attachment to the seat cushion after sewing, and to protect the back surface of the cushioning layer.

[0003] Here, since vehicle seat cushions often contain polar materials such as urethane and nylon, which require heat resistance, reactive urethane hot melts are generally used. Vehicle seats using such reactive urethane hot melts are disclosed, for example, in Patent Document 1.

[0004] However, adhesives used in vehicle seat cushions are desired to contain less organic volatile components that can have an adverse effect on the human body.

[0005] As such a low outgassing hot melt adhesive, Patent Document 2 discloses an olefin-based low outgassing hot melt adhesive. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2017-136735 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-31273 Summary of the Invention [Problem to be solved by the invention]

[0007] However, although olefin-based hot melt adhesives can achieve low VOCs, their applications are limited due to factors such as heat resistance, making them difficult to use in vehicles.

[0008] Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional art and to provide a hot melt adhesive composition that combines good moist heat resistance and low outgassing properties. A second object of the present invention is to provide a hot melt adhesive composition that has sufficient initial adhesion even when bonding foams and the like. [Means for solving the problem]

[0009] The present inventors have conducted extensive research and found that the above problems can be solved by using a specific adhesive composition, and have thus completed the present invention.

[0010] The present invention (1) is A urethane hot melt adhesive composition containing a urethane prepolymer made from a polyol component (A) and a polyisocyanate (B), The polyol component (A) contains a crystalline polyester polyol (a-1) obtained by a condensation reaction of an aliphatic dicarboxylic acid having 10 to 12 carbon atoms and an aliphatic diol having 4 to 6 carbon atoms, and a polyether polyol (a-2), In the low outgassing urethane hot melt adhesive composition, the content of the polyether polyol (a-2) in the polyol component (A) is 30 to 80 parts by mass per 100 parts by mass of the polyol component (A). The present invention (2) is In the low outgassing urethane hot melt adhesive composition of invention (1), the crystalline polyester polyol (a-1) has a number average molecular weight in the range of 1,000 to 5,000. The present invention (3) is In the low outgassing urethane hot melt adhesive composition of invention (1) or (2), the polyether polyol (a-2) has a number average molecular weight in the range of 1,000 to 4,000. The present invention (4) is In the low outgassing urethane hot melt adhesive composition of any of inventions (1) to (3), the polyol component (A) further contains one or more polyols selected from the group consisting of amorphous polyester polyols, polycarbonate polyols, and low molecular weight diols having a number average molecular weight of 500 or less. The present invention (5) is In the low outgassing urethane hot melt adhesive composition of invention (4), the total content of the amorphous polyester polyol, polycarbonate diol, and low molecular weight diol having a number average molecular weight of 500 or less in the polyol component (A) is 30 parts by mass or less per 100 parts by mass of the polyol component (A). The present invention (6) is The low outgassing urethane hot melt adhesive composition of any one of inventions (1) to (5) above generates an amount of organic volatile matter, calculated as toluene, of 150 ppm or less when heated at 90°C. The present invention (7) is The low outgassing urethane hot melt adhesive composition according to any one of the above inventions (1) to (6) is for vehicle parts having foams, natural leather, synthetic leather, films, woven fabrics, and nonwoven fabrics. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a hot melt adhesive composition that has both good moist heat resistance and low outgassing properties. DETAILED DESCRIPTION OF THE INVENTION

[0012] Next, the hot melt adhesive composition of the present invention will be specifically described in the following order, but the present invention is not limited thereto. 1 ingredient 2 Manufacturing method 3 Physical properties 4 Uses 5 How to apply

[0013] Ingredients The hot melt adhesive composition according to the present invention is a reactive urethane hot melt with low outgassing properties. The hot melt adhesive composition according to the present invention contains an isocyanate-terminated polyurethane prepolymer as a base resin. Furthermore, if necessary, the adhesive composition may contain other components. When such a hot melt adhesive composition is used, adhesiveness is exhibited by cooling and solidifying the molten polyurethane prepolymer, and further, stronger adhesiveness is exhibited by the uncured isocyanate terminals reacting with moisture in the air to form a crosslinked structure. Hereinafter, such a hot melt adhesive composition may be referred to as a moisture-curable hot melt adhesive composition or a reactive hot melt adhesive composition.

[0014] Base resin (polyurethane prepolymer) Polyurethane prepolymers are produced by using polyol component (A) and polyisocyanate (B) as raw materials, and reacting a stoichiometric excess of polyisocyanate (B) with polyol component (A), thereby obtaining polyurethane prepolymers.

[0015] The polyol component (A) used in the present invention essentially contains a polyester polyol and a polyether polyol, more specifically, a crystalline polyester polyol (a-1) obtained by a condensation reaction of an aliphatic dicarboxylic acid having 10 to 12 carbon atoms with an aliphatic diol having 4 to 6 carbon atoms, and a polyether polyol (a-2).

[0016] The crystalline polyester polyol (a-1) according to the present invention is a polyol obtained by a condensation reaction between an aliphatic dicarboxylic acid having 10 to 12 carbon atoms and an aliphatic diol having 4 to 6 carbon atoms. Specific examples of the aliphatic dicarboxylic acid (a-11) include decanedioic acid (sebacic acid, C10), undecanedioic acid (C11), and dodecanedioic acid (C12). Examples of the aliphatic diol having 4 to 6 carbon atoms include butanediol (e.g., 1,3-butanediol, 1,4-butanediol, etc.), pentanediol (e.g., 1,5-pentanediol, etc.), and hexanediol (e.g., 1,6-hexanediol, etc.).

[0017] In the present invention, "crystalline polyester polyol" refers to a polyol having a melting point of 30°C or higher, and "amorphous polyester polyol" refers to a polyol having a melting point of 30°C or lower or not present at all. Such crystallinity can be adjusted by appropriately selecting the acid and glycol components. Here, the melting point is determined by measuring the melting peak in the range of -80°C to 100°C using a differential scanning calorimeter with a temperature program of 25°C → -80°C → 100°C (heating rate of 5°C / min).

[0018] The crystalline polyester polyol (a-1) preferably has a number average molecular weight in the range of 1,000 to 5,000, and more preferably in the range of 2,000 to 4,500.

[0019] Examples of the polyether polyol (a-2) include polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, etc., which are obtained by polymerizing cyclic ethers such as ethylene oxide, propylene oxide, tetrahydrofuran, etc., and copolyethers thereof. Polyether polyols can also be obtained by polymerizing the above-mentioned cyclic ethers using polyhydric alcohols such as glycerin and trimethylolethane.

[0020] The polyether polyol (a-2) preferably has a number average molecular weight in the range of 1,000 to 4,000, more preferably in the range of 1,500 to 3,000.

[0021] It is also preferred that the other polyol (a-3) further contains one or more polyols selected from the group consisting of amorphous polyester polyols, polycarbonate polyols, and low molecular weight diols having a number average molecular weight of 500 or less.

[0022] Examples of amorphous polyester polyols include aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and azelaic acid; aromatic dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid; alicyclic dicarboxylic acids such as hexahydrophthalic acid, hexahydroterephthalic acid, and hexahydroisophthalic acid; and acid esters or acid anhydrides thereof with ethylene glycol, 1,3-propylene glycol, 1,2-propanediol, and the like. Examples include polyester polyols obtained by a dehydration condensation reaction with 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 the like, or a mixture thereof; and polylactone diols obtained by ring-opening polymerization of lactone monomers such as ε-caprolactone and methylvalerolactone.

[0023] 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, diethylene glycol, or an alicyclic dihydroxy compound with diethylene carbonate, dimethyl carbonate, diethyl carbonate, or the like.

[0024] The low molecular weight diol is not particularly limited as long as it has a number average molecular weight of 500 or less, and examples thereof include ethylene glycol, propanediol, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, and 2-ethyl-1,3-hexanediol.

[0025] The other polyols (a-3) may be used alone or in combination of two or more thereof. The other polyols (a-3) may also contain polyols other than those mentioned above.

[0026] Examples of the polyisocyanate (B) include tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), polymethylene polyphenyl polyisocyanate, hydrogenated MDI, 1,5-naphthalene diisocyanate, tolylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), isophorone diisocyanate, xylylene diisocyanate (XDI), hydrogenated XDI, tetramethylxylene diisocyanate (TMXDI), 1,8-diisocyanatomethyloctane, lysine ester triisocyanate, 1,3,6-hexamethylene triisocyanate, 1,6,11-undecane triisocyanate, bicycloheptane triisocyanate, and modified products and derivatives thereof.

[0027] The polyisocyanate (B) may be used alone or in combination of two or more kinds.

[0028] Here, the NCO group content of the isocyanate-terminated polyurethane prepolymer is not particularly limited, but is preferably 1.0 to 2.5%. By setting it in this range, it is possible to promote curing by moisture while suppressing foaming during work. The NCO group content is measured in accordance with JIS K1603-1.

[0029] The content of the polyurethane prepolymer is preferably 70 to 100% by mass (more preferably 80 to 100% by mass) based on the total mass of the composition.

[0030] Other ingredients Other components that can be blended include known additives used in hot melt adhesives, such as oil components (plasticizers), tackifier resins, antioxidants, waxes, etc., as long as the VOC content remains below 150 ppm. Heat stabilizers, fillers, catalysts, etc. may also be blended.

[0031] Examples of the oil component include paraffinic oil, naphthenic oil, aromatic oil, etc. Vegetable oil may also be used as the oil component.

[0032] Examples of the tackifying resin include one or more tackifying resins selected from the group consisting of aliphatic petroleum resins, aromatic petroleum resins, hydrogenated aliphatic petroleum resins, hydrogenated aromatic petroleum resins, terpene resins, styrene resins, rosin resins, and modified resins thereof.

[0033] Examples of antioxidants include phenol-based antioxidants (e.g., Irganox 1010 (manufactured by BASF)), sulfur-based antioxidants (e.g., SUMILIZER TP-D (manufactured by Sumitomo Chemical Co., Ltd.)), and phosphorus-based antioxidants (e.g., Irgafos 168 (manufactured by BASF) and JP-650 (manufactured by Johoku Chemical Co., Ltd.)).

[0034] Examples of waxes include natural waxes {e.g., animal waxes (beeswax, spermaceti, etc.), plant waxes (wood wax, etc.), petroleum waxes (paraffin wax, etc.)} and synthetic waxes {e.g., synthetic hydrocarbons (low molecular weight polyethylene, etc.), fatty acid esters (polyethylene glycol, etc.)}.

[0035] Examples of the catalyst include metal catalysts, amine catalysts, etc. These catalysts may be used alone or in combination of two or more.

[0036] These additives may be used alone or in combination of two or more.

[0037] The content of the crystalline polyester polyol (a-1) in the polyol component (A) is preferably 10 to 60 parts by mass, more preferably 20 to 40 parts by mass, per 100 parts by mass of the polyol component (A). By setting the content in this range, it becomes possible to maintain an appropriate solidification time and high peel strength.

[0038] The content of the polyether polyol (a-2) in the polyol component (A) is 30 to 80 parts by mass, preferably 40 to 60 parts by mass, per 100 parts by mass of the polyol component (A). By setting the content in this range, it is possible to achieve both high flexibility and peel strength.

[0039] The ratio of the content of the crystalline polyester polyol (a-1) to the content of the polyether polyol (a-2) in the polyol component (A) is preferably 20:80 to 70:30, and more preferably 30:70 to 50:50.

[0040] Furthermore, the content of the other polyol (a-3) in the polyol component (A) is preferably 30 parts by mass or less per 100 parts by mass of the polyol component (A). By setting the content within this range, it is possible to satisfy physical properties such as resistance to moist heat aging and peel strength. The lower limit is not particularly limited, but is, for example, 5 parts by mass per 100 parts by mass of the polyol component (A).

[0041] ≪Manufacturing method≫ The method for producing the moisture-curable hot melt adhesive composition according to the present invention may be any known method, and is not particularly limited as long as the produced moisture-curable hot melt adhesive composition does not impair the object of the present invention. For example, (1) a predetermined amount of isocyanate is dropped into a reaction vessel containing a predetermined amount of polyol, followed by heating and reacting under conditions where the isocyanate groups of the polyisocyanate are in excess relative to the hydroxyl groups of the polyol to prepare a polyurethane prepolymer. (2) A desired moisture-curable hot melt adhesive composition is produced by dropping predetermined amounts of other components into the polyurethane prepolymer and stirring. The reaction is carried out at a temperature of, for example, 50 to 120°C, preferably 60 to 100°C. The reaction time is, for example, 1 to 15 hours.

[0042] <Physical Properties> Next, the physical properties of the hot melt adhesive composition according to the present invention will be described.

[0043] (VOC) The hot melt adhesive composition of the present invention preferably generates an organic volatile component of 150 ppm or less in toluene equivalent when heated at 90°C. By keeping the VOC content within this range, the regulatory limit can be met for all vehicle seat products. VOC can be adjusted mainly by adjusting the type and amount of polyol and catalyst added.

[0044] (Initial peel strength) The hot melt adhesive composition of the present invention preferably exhibits a peel strength of 1 N / 25 mm or more (more preferably 1.3 N / 25 mm or more) after 30 seconds of bonding a urethane foam and a skin material. The initial peel strength can be adjusted by controlling the addition and amount of amorphous ester polyol, polycarbonate diol, and low molecular weight diol.

[0045] (Normal peel strength) The hot melt adhesive composition according to the present invention adheres a urethane foam to a skin material, and after one day the normal peel strength is 3 N / 25 mm or more. The normal peel strength can be adjusted by adjusting the amount of crystalline ester polyol added and the types of other polyol components.

[0046] (Solidification time) The hot melt adhesive composition of the present invention preferably has a solidification time of 6±4 minutes. If the solidification time is too long, materials with gaps, such as knitted fabrics, will be wound up before the adhesive has solidified, causing blocking due to the adhesive seeping out. Conversely, if the solidification time is too short, adhesion to the substrate will decrease and the normal peel strength will decrease. The solidification time can be adjusted by adjusting the amount of crystalline ester polyol added or by using a crystal nucleating agent.

[0047] (Heat and humidity resistance) The hot melt adhesive composition according to the present invention preferably has a moist heat resistance of 80% of the normal peel strength for 400 hours or more at 80°C / 95%RH. The moist heat resistance can be adjusted by improving compatibility and reducing the ester group concentration.

[0048] ≪Applications≫ The hot melt adhesive composition according to the present invention is a reactive hot melt adhesive composition capable of laminating and bonding a surface material and a substrate. In particular, when the composition is formed into a specific fibrous form as described below, it forms an adhesive layer (a layer made of the cured hot melt adhesive composition) that exhibits excellent texture, breathability, and penetration resistance. Therefore, it is applicable to any type of surface material and substrate, including resin foam, resin film, synthetic leather, natural leather, woven fabric, or nonwoven fabric. Furthermore, because it is applicable to urethane resin foam substrates, it can be used in long products in which a continuous sheet of substrate and a surface material are laminated and bonded, and it can also be used for vehicle interiors, which are difficult to apply with conventional thermoplastic hot melt adhesives.

[0049] ≪How to apply≫ Next, an example of a method for applying the hot melt adhesive composition according to the present invention will be described. In this example, the hot melt adhesive composition is applied to form a predetermined pressure-sensitive adhesive layer using a non-contact method (for example, a spray method), but the method for applying the hot melt adhesive composition according to the present invention is not limited to this, and the composition may be applied to the surface to be bonded by a known method.

[0050] <Melting process> First, the hot melt adhesive composition according to the present invention is maintained in a molten state (melting step). If the hot melt adhesive composition is a moisture-curable type, the melting step must be performed in a moisture-free atmosphere.

[0051] <Coating process> Next, the hot melt adhesive composition in a molten state is applied to the surface of the adherend (preferably the surface of a foam) by an appropriate application method (preferably a non-contact application method). The specific shape of the application is not particularly limited, but for example, an adhesive layer may be formed by applying it in a line shape, a dot shape, a fiber shape, or the like. Alternatively, the adhesive layer may be formed in a sheet shape. The adhesive layer is preferably formed by applying the adhesive composition in an amount of 5 to 50 g / m. 2 (More preferably 10 to 30 g / m 2 ) etc. The adhesive composition may be applied to both surfaces to be bonded.

[0052] The specific coating conditions are not particularly limited, and for example, when a non-contact coating method is used as described above, the pressure may be 0.01 to 0.4 MPa, the temperature may be 100 to 160°C, and the like.

[0053] Here, the non-contact application method refers to a method in which the adhesive composition is applied without contacting the member to be bonded with the application equipment, and examples thereof include application by a spray method.

[0054] Before the application step, the surface to be bonded may be subjected to a known pretreatment (for example, primer treatment, corona treatment, plasma treatment, etc.).

[0055] <Contact process, curing process> After the application step, another member is brought into contact with the surface to be adhered (coated surface) on which the adhesive layer is provided, and the hot melt adhesive composition is cooled and cured. In the case of a moisture-curable hot melt adhesive composition, as described above, after cooling and curing, uncured isocyanate terminals react with moisture in the air to form crosslinked structures, thereby exhibiting stronger adhesive properties.

[0056] When the hot melt adhesive composition according to the present invention is applied by the method described in the application step above, it can be bonded to any object. Specifically, it can provide excellent texture, breathability, and adhesiveness to resin foams, resin films, synthetic leather, natural leather, woven fabrics, or nonwoven fabrics, and can prevent penetration into the object. In particular, this effect is achieved even when the object to be bonded is a urethane resin foam.

[0057] In this manner, a laminate having an adhesive layer that is a cured product of the hot melt adhesive composition according to the present invention can be obtained, particularly a laminate having a foam and an adhesive layer provided on the surface of the foam. The specific configuration of the laminate is preferably a laminate consisting of a urethane foam substrate and a skin material or a backing fabric. Such a laminate can be preferably used as a vehicle interior material, i.e., a laminate material (laminate sheet) consisting of a laminate sheet having a cushioning layer made of a foam substrate and a backing fabric layer formed on the back surface thereof, to which a skin layer is attached. [Example]

[0058] Next, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these in any way.

[0059] <Synthesis of urethane prepolymer> A predetermined polyol component (A) was placed in a reactor, and diphenylmethane diisocyanate and an amine catalyst were added in an amount of 0.05 parts by mass based on the total amount, and the mixture was reacted at 100°C for 3 to 4 hours to obtain a urethane prepolymer with NCO% = 2.0.

[0060] <Polyol component (A)> Example 1 Crystalline polyester polyol (sebacic acid / butanediol) melting point 60℃ Number average molecular weight 4000 35 parts by mass Polypropylene glycol addition type PO alone Number average molecular weight 2000 50 parts by mass Amorphous polyester polyol (phthalic acid / neopentyl glycol) Number average molecular weight 1000 15 parts by mass Example 2 Crystalline polyester polyol (dodecanedioic acid / hexanediol) melting point 70℃ Number average molecular weight 4000 35 parts by mass Polypropylene glycol addition type PO alone Number average molecular weight 2000 50 parts by mass Polycarbonate diol, addition type PO alone, melting point 50℃ Number average molecular weight 1000 15 parts by mass Example 3 Crystalline polyester polyol (dodecanedioic acid / hexanediol) melting point 70℃ Number average molecular weight 4000 35 parts by mass Polypropylene glycol addition type PO alone Number average molecular weight 2000 50 parts by mass Butyl ethyl propanediol, addition type PO alone, melting point 43°C 15 parts by mass Example 4 Crystalline polyester polyol (dodecanedioic acid / hexadecanediol) Melting point 70℃ Number average molecular weight 4000 40 parts by mass Polypropylene glycol addition type PO alone Number average molecular weight 2000 30 parts by mass Butyl ethyl propanediol, melting point 43°C 30 parts by mass Example 5 Crystalline polyester polyol (sebacic acid / hexanediol) Melting point 65℃ Number average molecular weight 4000 20 parts by mass Polypropylene glycol addition type PO alone Number average molecular weight 2000 80 parts by mass Example 6 Crystalline polyester polyol (sebacic acid / hexanediol) Melting point 70℃ Number average molecular weight 10000 20 parts by mass Polypropylene glycol addition type PO alone Number average molecular weight 2000 80 parts by mass (Comparative Example 1) Crystalline polyester polyol (adipic acid / butanediol) melting point 58°C Number average molecular weight 2000 100 parts by mass (Comparative Example 2) Crystalline polyester polyol (adipic acid / butanediol) melting point 58°C Number average molecular weight 2000 30 parts by mass Polypropylene glycol Number average molecular weight 1000 70 parts by mass

[0061] <Evaluation> Next, each hot melt adhesive composition obtained above was specifically evaluated by the following method. The evaluation results are shown in Table 1. In the overall evaluation, a case where all evaluations satisfied the evaluation criteria was marked ○, a case where VOC and moist heat resistance satisfied the evaluation criteria but other evaluations did not satisfy the evaluation criteria was marked △, and a case where at least one of VOC and moist heat resistance did not satisfy the evaluation criteria was marked ×.

[0062] <voc> The hot melt adhesive was placed directly into the glass tube of a thermal desorption apparatus (Markes TD-100), and the outgassing was measured using a GC / MS (Agilent GC / MS (6890 / 5973)). The sample was heated at 90°C for 30 minutes, and the outgassing up to C20 was calculated in toluene equivalent.

[0063] <Initial peel strength> A hot melt adhesive melted at 140°C was applied to a urethane foam (150 x 25 x 5 mm) at a rate of 20 g / m using a hand gun (manufactured by REKA). 2 After 30 seconds, a peel test is carried out at 200 mm / min using a digital force gauge DS2 (IMADA), and the maximum value and median value are measured with N=3.

[0064] <Normal peel strength> A hot melt adhesive melted at 140°C was applied to a urethane foam (150 x 25 x 5 mm) at a rate of 20 g / m using a hand gun (manufactured by REKA). 2 The coating was sprayed onto the surface and the covering material was pressed in place. One day later, measurements were taken using an autograph (Shimadzu AG-Xplus) at a tensile speed of 200 mm / min. The maximum and minimum peel strengths were averaged at three points, and the median value was calculated using N=3.

[0065] <Solidification time> At an ambient temperature of 25°C, 15g of hot melt adhesive melted to 140°C was poured onto a glass plate, and a thin film 500μm thick was created using a film applicator with a micrometer (Tester Sangyo SA-204). The time it took for the surface to lose its tackiness was measured by touching it with a finger.

[0066] <Moisture and heat resistance> A hot melt adhesive melted at 140°C was applied to a urethane foam (150 x 25 x 5 mm) at a rate of 20 g / m using a hand gun (manufactured by REKA). 2 After 3 days, the material is left to stand in an 80℃ 95% humidity environment, and the peel strength is measured every 100 hours. The time until 80% of the normal peel strength is maintained is measured.

[0067]

Table 1

Claims

1. A urethane hot melt adhesive composition containing an isocyanate-terminated urethane prepolymer made from a polyol component (A) and a polyisocyanate (B), The polyol component (A) contains a crystalline polyester polyol (a-1) having a number average molecular weight of 1,000 or more, which is obtained by a condensation reaction of an aliphatic dicarboxylic acid having 10 to 12 carbon atoms and an aliphatic diol having 4 to 6 carbon atoms, and a polyether polyol (a-2) having a number average molecular weight of 1,000 or more, the polyol component (A) further contains one or more polyols selected from the group consisting of amorphous polyester polyols and diols having a molecular weight of 500 or less; a total content of the amorphous polyester polyol and the diol having a molecular weight of 500 or less in the polyol component (A) is 30 parts by mass or less per 100 parts by mass of the polyol component (A), A urethane hot melt adhesive composition characterized in that the amount of organic volatile matter generated when heated at 90°C is 150 ppm or less in toluene equivalent (however, this does not include those containing an acrylic polyol as the polyol component (A) and those in which the urethane hot melt adhesive composition contains an acrylic copolymer).

2. The urethane hot melt adhesive composition according to claim 1, which is for use in vehicle parts having foam, natural leather, synthetic leather, film, woven fabric, or nonwoven fabric.

3. A laminate having an adhesive layer which is a cured product of the urethane hot melt adhesive composition according to claim 1 or 2.

Images