Low outgassing urethane hot melt adhesive composition

Abstract

To provide a hot melt adhesive composition having both good thermal properties (particularly, moist heat resistance and thermal stability) and low outgassing properties. [Solution] A urethane hot melt adhesive composition with low outgassing properties, comprising a urethane prepolymer (I) made from a polyol component (A) and a polyisocyanate component (B) as raw materials, and a catalyst (II), wherein the polyisocyanate component (B) contains more than 0.5 mass % and not more than 10 mass % of a carbodiimide-modified diphenylmethane diisocyanate relative to the entire polyisocyanate component (B), and the catalyst (II) contains a reactive catalyst having a functional group that reacts with an isocyanate group.

Description

Technical Field

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

Background Art

[0002] Conventionally, a skin material covering the surface of a vehicle seat cushion is produced by attaching a skin layer to the surface of a laminated sheet in which a back base cloth layer is formed on the back surface of a foam buffer layer and then sewing. The back base cloth layer is provided for improving slipperiness to facilitate operations during sewing and when attaching to the seat cushion after sewing, and for protecting the back surface of the buffer layer.

[0003] Here, since vehicle seat cushions often contain a lot of polar materials such as urethane-based and nylon-based materials and require heat resistance, reactive urethane hot melt is generally applied. Regarding vehicle seats using such reactive urethane hot melt, for example, it is disclosed in Patent Document 1.

[0004] However, as an adhesive used for vehicle seat cushions, it is desired that there be little organic volatile matter that affects the human body.

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

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, even though it is possible to achieve low VOC with olefin-based hot melt adhesives, their applications are limited from the perspective of heat resistance and the like, and it has been difficult to use them for vehicles and the like.

[0008] Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art and provide a hot melt adhesive composition having good thermal properties (particularly, heat and humidity resistance and thermal stability) and low outgassing properties.

Means for Solving the Problems

[0009] As a result of intensive research, the present inventors have found that the above problems can be solved by using a specific adhesive composition, and have completed the present invention. That is, the present invention is as follows.

[0010] The present invention is a urethane hot melt adhesive composition containing a urethane prepolymer (I) made from a polyol component (A) and a polyisocyanate component (B) as raw materials, and a catalyst (II), the polyisocyanate component (B) contains carbodiimide-modified diphenylmethane diisocyanate in an amount of more than 0.5% by mass and not more than 10% by mass based on the total amount of the polyisocyanate component (B), the catalyst (II) contains a reactive catalyst having a functional group that reacts with an isocyanate group, and is a low outgassing urethane hot melt adhesive composition. The reactive catalyst may be a catalyst having one functional group that reacts with the isocyanate group and having a tertiary amine structure. The polyol component (A) contains a crystalline polyester polyol (a-1) formed 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), The content of the polyether polyol (a-2) in the polyol component (A) may be 30 to 80% by mass based on 100% by mass of the polyol component (A). The crystalline polyester polyol (a-1) may have a number average molecular weight in the range of 1,000 to 5,000. The polyether polyol (a-2) may have a number average molecular weight in the range of 1,000 to 4,000. The polyol component (A) may further contain a polyol (a-3) which is one or more polyols selected from the group consisting of an amorphous polyester polyol, a polycarbonate polyol, and a low molecular weight diol having a molecular weight of 500 or less. The content of the polyol (a-3) may be 30% by mass or less based on 100% by mass of the polyol component (A). The low outgassing urethane hot melt adhesive composition may have an amount of organic volatile matter generated when heated at 90 °C of 150 ppm or less in terms of toluene conversion value. The low outgassing urethane hot melt adhesive composition may be for vehicle members having a foam, natural leather, synthetic leather, film, woven fabric, and non-woven fabric.

Advantages of the Invention

[0011] According to the present invention, it is possible to provide a hot melt adhesive composition having good thermal properties (particularly, heat and humidity resistance and thermal stability) and low outgassing properties.

Embodiments for Carrying Out 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 Component 2 Manufacturing Method 3 Physical Properties 4 Applications 5 Application Method

[0013] <<<Component>>> The hot melt adhesive composition according to the present invention is a reaction-type urethane hot melt with low outgassing properties. The hot melt adhesive composition according to the present invention contains an isocyanate-terminated polyurethane prepolymer (I) as a base resin and a catalyst (II). Further, other components may be included in the adhesive composition as necessary.

[0014] When such a hot melt adhesive composition is used, adhesiveness is exhibited when the polyurethane prepolymer heated to a molten state cools and solidifies. Further, the unreacted isocyanate-terminated groups react with moisture in the air to form a crosslinked structure, thereby exhibiting stronger adhesiveness. Such a hot melt adhesive composition may be referred to as a moisture-curing type hot melt adhesive composition, a reaction-type hot melt adhesive composition, or the like.

[0015] <<Polyurethane prepolymer (I)>> The polyurethane prepolymer (I) is obtained by using a polyol component (A) and a polyisocyanate component (B) as raw materials and usually reacting the polyisocyanate component (B) in a stoichiometric excess with the polyol component (A).

[0016] <Polyol component (A)> The polyol component (A) is not particularly limited as long as it is usually used in the production of polyurethane prepolymers, but preferably includes polyester polyols and polyether polyols. More specifically, it preferably includes a crystalline polyester polyol (a-1) formed 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).

[0017] Examples of aliphatic dicarboxylic acids having 10 to 12 carbon atoms include decanedioic acid (sebacic acid, C10), undecanedioic acid (C11), and dodecanedioic acid (C12). Examples of aliphatic diols 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.).

[0018] In the present invention, "crystalline polyester polyol" refers to a polyester polyol having a melting point of 30°C or higher, and "amorphous polyester polyol" refers to a polyester polyol having a melting point of less than 30°C or a polyester polyol having no melting point. Such crystallinity can be adjusted by appropriately selecting the carboxylic acid and alcohol constituting the polyester polyol. Here, using a differential scanning calorimeter, the melting peak in the range of -80°C to 100°C in the temperature program of 25°C ⇒ -80°C ⇒ 100°C (heating rate 5°C / min) is defined as the melting point.

[0019] The crystalline polyester polyol (a - 1) preferably has a number - average molecular weight in the range of 1000 to 5000, and more preferably in the range of 2000 to 4500.

[0020] 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, and tetrahydrofuran respectively, and copolymers thereof. Also, it can be obtained by polymerizing the above - mentioned cyclic ethers using polyhydric alcohols such as glycerin and trimethylolethane.

[0021] The polyether polyol (a - 2) preferably has a number - average molecular weight in the range of 1000 to 4000, and more preferably in the range of 1500 to 3000.

[0022] In addition, examples of polyols other than the crystalline polyester polyol (a-1) and the polyether polyol (a-2) include one or more polyols (a-3) selected from the group consisting of an amorphous polyester polyol, a polycarbonate polyol, and a low molecular weight diol having a number average molecular weight of 500 or less. The polyol component (A) may contain only the other polyol (a-3), but preferably contains the crystalline polyester polyol (a-1) and the polyether polyol (a-2), and further contains the polyol (a-3).

[0023] Examples of the amorphous polyester polyol include those obtained by dehydration condensation reaction of an aliphatic dicarboxylic acid (such as succinic acid, adipic acid, sebacic acid, azelaic acid, etc.), an aromatic dicarboxylic acid (such as phthalic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, etc.), an alicyclic dicarboxylic acid (such as hexahydrophthalic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, etc.), or an ester or acid anhydride thereof with 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 a mixture thereof; and polylactone diols obtained by ring-opening polymerization of lactone monomers such as ε-caprolactone and methylvalerolactone.

[0024] Examples of the polycarbonate polyol 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, and alicyclic dihydroxy compounds with diethylene carbonate, dimethyl carbonate, diethyl carbonate, or the like.

[0025] The low molecular weight diol is not particularly limited as long as it is a diol having a molecular weight of 500 or less. 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.

[0026] The other polyol (a-3) may be used alone or in combination of two or more. Further, the other polyol (a-3) may contain polyols other than those described above.

[0027] <Polyisocyanate component (B)> The polyisocyanate (having a plurality of isocyanate groups) contained as the polyisocyanate component (B) will be described.

[0028] The polyisocyanate component (B) contains at least carbodiimide-modified diphenylmethane diisocyanate (b-1) and a polyisocyanate other than carbodiimide-modified diphenylmethane diisocyanate (other polyisocyanate (b-2)).

[0029] The carbodiimide-modified diphenylmethane diisocyanate (b-1) is a compound represented by the following formula.

Chemical formula

[0030] Other polyisocyanates (b-2) are not particularly limited, and examples thereof include tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), polymethylene polyphenyl polyisocyanate (polymeric MDI), hydrogenated MDI, 1,5-naphthalene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), isophorone diisocyanate, xylylene diisocyanate (XDI), hydrogenated XDI, tetramethylxylylene diisocyanate (TMXDI), 1,8-diisocyanatomethyloctane, lysine ester triisocyanate, 1,3,6-hexamethylene triisocyanate, 1,6,11-undecane triisocyanate, bicycloheptane triisocyanate, and modified products, derivatives, etc. thereof.

[0031] Other polyisocyanates (b-2) preferably contain MDI (pure MDI).

[0032] The average functionality number (average isocyanate group number) of all the polyisocyanates contained in the polyisocyanate component (B) is preferably 2.0 to 4.0, 2.0 to 3.0, 2.0 to 2.5, 2.0 to 2.3, or 2.0 to 2.1.

[0033] Note that the average functionality number of all the polyisocyanates contained in the polyisocyanate component (B) can be calculated based on the method disclosed in JP-A-10-231347 and the like. For example, when it contains modified diphenylmethane diisocyanate and diphenylmethane diisocyanate (purified p-MDI, 4,4'-MDI), it can be calculated from the following formula 1 based on the measurement result of the NCO group content when the modified diphenylmethane diisocyanate and diphenylmethane diisocyanate are weighed so as to have the same ratio.

Equation

[0034] The NCO group content of the polyurethane prepolymer (I) is not particularly limited, but is preferably 1.0 to 2.5%. By setting it within such a range, it becomes possible to promote curing by moisture while suppressing foaming during work. The NCO group content is measured in accordance with JIS K1603-1.

[0035] <Catalyst (II)> As the catalyst (II), it includes a reactive catalyst having a functional group that reacts with an isocyanate group.

[0036] In the reactive catalyst, the functional group that reacts with the isocyanate group is, for example, an active hydrogen group that reacts with a polyisocyanate, and is preferably at least one functional group among a hydroxyl group and an amino group.

[0037] The reactive catalyst preferably has one functional group that reacts with an isocyanate group and has a tertiary amine structure.

[0038] Examples of the reactive catalyst include (1) amine-based catalysts having a hydroxyl group as a functional group (for example, N,N-dimethylaminohexanol, N,N-dimethylaminoethoxyethoxyethanol, N,N-dimethylaminoethoxyethanol, diethanolamine, triethanolamine), and (2) amine-based catalysts having an amino group as a functional group (for example, N,N,N",N"-tetramethyldiethylenetriamine).

[0039] These reactive catalysts may be used alone or in combination of two or more.

[0040] In addition, as the catalyst (II), within a range that does not inhibit the effects of the present invention, it may include catalysts other than the reactive catalyst (for example, metal-based catalysts and amine-based catalysts having no such functional groups).

[0041] <Other components> As other components, known additives used in hot melt adhesives, such as oil components (plasticizers), tackifying resins, antioxidants, waxes, etc., can be blended preferably within the range where the VOC is 150 ppm or less. Also, heat stabilizers, fillers, etc. may be blended.

[0042] Examples of the oil component include paraffinic oil, naphthenic oil, aromatic oil, etc. In addition, vegetable oil, etc. may be used as the oil component.

[0043] Examples of the tackifying resin can be 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.

[0044] Examples of the antioxidant include phenolic antioxidants (e.g., Irganox 1010 (manufactured by BASF)), sulfur antioxidants (e.g., SUMILIZER TP-D (manufactured by Sumitomo Chemical)), and phosphorus antioxidants (e.g., Irgafos 168 (manufactured by BASF), JP-650 (manufactured by Johoku Chemical)).

[0045] Examples of the wax include natural waxes (e.g., animal waxes (beeswax, whale wax, 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.)).

[0046] These additives may be used alone or in combination of two or more.

[0047] <<Content of Each Component>> The content of the polyurethane prepolymer (I) is preferably 80 to 99.99% by mass (more preferably 95 to 99.99% by mass) based on the total composition.

[0048] The content of the catalyst (II) varies depending on the type of the polyurethane prepolymer (I), but is preferably 0.01 to 0.1% by mass (more preferably 0.01 to 0.05% by mass) based on the whole composition.

[0049] When the polyol component (A) contains a crystalline polyester polyol (a-1) and a polyether polyol (a-2), the content of the crystalline polyester polyol (a-1) in the polyol component (A) is preferably 10 to 60% by mass, more preferably 20 to 40% by mass, based on the whole polyol component (A). By setting it within such a range, it becomes possible to maintain an appropriate solidification time and a high peel strength.

[0050] Also, the content of the polyether polyol (a-2) in the polyol component (A) is preferably 30 to 80% by mass, more preferably 40 to 60% by mass, based on the whole polyol component (A). By setting it within such a range, it becomes possible to achieve both high flexibility and peel strength.

[0051] In addition, 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, more preferably 30:70 to 50:50.

[0052] Furthermore, the content of other polyol (a-3) in the polyol component (A) is preferably 30% by mass or less based on the whole polyol component (A). By setting it within such a range, it becomes possible to satisfy physical properties such as wet heat aging resistance and peel strength. The lower limit is not particularly limited, but is, for example, 5% by mass or more based on the whole polyol component (A).

[0053] In the polyisocyanate component (B), the content of the carbodiimide-modified diphenylmethane diisocyanate (b-1) is more than 0.5% by mass, 0.6% by mass or more, 0.7% by mass or more, 0.8% by mass or more, 0.9% by mass or more, or 1% by mass or more, and 10% by mass or less, based on the total amount of the polyisocyanate component (B). By setting the blending amount of the carbodiimide-modified diphenylmethane diisocyanate (b-1) within this range, it is possible to improve the moisture and heat resistance and thermal stability of the adhesive due to the modified groups while suppressing the increase in the viscosity of the composition. Among them, it is preferable that the content of the carbodiimide-modified diphenylmethane diisocyanate (b-1) is 1 to 10% by mass based on the total amount of the polyisocyanate component (B).

[0054] Preferably, 50% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, 99% by mass or more, or 100% by mass of the other polyisocyanate (b-2) is MDI (pure MDI).

[0055] <<<Manufacturing method>>> The manufacturing method of the urethane hot melt adhesive composition according to the present invention may be a known method, and is not particularly limited as long as the manufactured urethane hot melt adhesive composition does not impair the object of the present invention. For example, it can be manufactured as follows. (1) A predetermined amount of polyisocyanate is dropped into a reaction vessel containing a predetermined amount of polyol and then heated, and the reaction is carried out under the condition that the isocyanate groups of the polyisocyanate are stoichiometrically excessive with respect to the hydroxyl groups of the polyol to prepare a polyurethane prepolymer (I). (2) A method of manufacturing a desired urethane hot melt adhesive composition by dropping a predetermined amount of other components including a catalyst (II) into the polyurethane prepolymer (I) and stirring can be mentioned. The reaction is carried out, for example, at a temperature of 50 to 120°C, preferably 60 to 100°C. The reaction time is, for example, 1 to 15 hours.

[0056] <<<Physical properties>>> Next, each physical property of the hot melt adhesive composition according to the present invention will be described.

[0057] < <voc>> The hot-melt adhesive composition according to the present invention preferably has an amount of organic volatile matter generated when heated at 90 °C of 150 ppm or less in terms of toluene conversion value. By setting the VOC within this range, the regulatory values can be satisfied for all products of vehicle seats.

[0058] <<Moisture and heat resistance>> The hot-melt adhesive composition according to the present invention preferably has a moisture and heat resistance evaluated as the time during which the peel strength can be maintained at 80% or more of the normal peel strength when left standing in a moist heat environment (80 °C, 95%) of 400 hours or more.

[0059] <<Thermal stability 1 (storage stability): Medium temperature / long-term thermal stability>> The hot-melt adhesive composition according to the present invention preferably has a storage stability evaluated as the residual ratio of NCO% (NCO% after standing / NCO% before standing × 100) of 80% or more when left standing in an aluminum bag sealed for 3 months at 50 °C.

[0060] <<Thermal stability 2: High temperature / short-term thermal stability>> The hot-melt adhesive composition according to the present invention preferably has a thermal stability evaluated as the viscosity increase rate (viscosity after the test / viscosity before the test × 100) of the hot-melt adhesive heated at 140 °C for 4 hours in a nitrogen atmosphere of 200% or less.

[0061] <Measurement method> A rotor No. 4 connected to a Brookfield digital viscometer LVDV-I+ of Brookfield was placed in 150 ± 15 g of a sample heated and melted at 140 °C in a cylindrical glass container, and the viscosity was measured. The viscosity before the test is the viscosity after 0 hours, and the viscosity after the test is the viscosity after 4 hours.

[0062] <<Normal peel strength>> The hot-melt adhesive composition according to the present invention preferably has a normal peel strength evaluated as the peel strength after 1 day of bonding a urethane foam and a skin material of 3 N / 25 mm or more.

[0063] <<<Use>>> The hot melt adhesive composition according to the present invention is a reactive hot melt adhesive composition capable of laminating and bonding a skin material and a base material. In particular, when it has a specific fibrous form described later, it forms an adhesive layer (a layer made of a cured hot melt adhesive composition) excellent in texture, breathability, and anti-permeation property. Therefore, the skin material and the base material can be applied regardless of their types, such as resin foams, resin films, synthetic leathers, natural leathers, woven fabrics, or non-woven fabrics. Further, since it can also be applied to a urethane resin foam as the base material, it can be applied to a long product for laminating and bonding a base material made of a continuous sheet and a skin material, or can be used for vehicle members (particularly, vehicle interior parts) which are difficult to apply with a normal thermoplastic hot melt adhesive.

[0064] <<<Application method>>> Next, an example of the application method of the hot melt adhesive composition according to the present invention will be described. In this example, the case where the hot melt adhesive composition is applied to form a predetermined adhesive layer by a non-contact method (for example, a spray method) will be described. However, the application method of the hot melt adhesive composition according to the present invention is not limited to this, and it may be applied to the adhesion target surface by a known method.

[0065] <<<Melting process>>> First, the hot melt adhesive composition according to the present invention is heated and held in a molten state (melting process). Usually, it is necessary to have a moisture-free atmosphere in the melting process.

[0066] <<<Coating process>>> Next, the molten hot melt adhesive composition is applied to the adhesion target surface (preferably the surface of the foam) of the adherend by an appropriate coating method (preferably a non-contact coating method). The specific shape during coating is not particularly limited. For example, it may be applied in a linear shape, a dot shape, a fibrous shape, etc. to form an adhesive layer. In addition, an adhesive layer may be formed in a sheet shape. The coating amount of the adhesive composition for the adhesive layer is preferably 5 to 50 g / m 2 (More preferably, it may be 10 to 30 g / m 2 ) or the like. Note that the adhesive composition may be applied to both surfaces that will be the adhesion target surfaces.

[0067] Note that the specific coating conditions are not particularly limited. For example, when using a non-contact coating method as described above, it may be carried out at a pressure of 0.01 to 0.4 MPa, a temperature of 100 to 160 °C, etc.

[0068] Here, the non-contact coating method is a method of applying the adhesive composition without the coating equipment contacting the member to be adhered, and examples thereof include spraying.

[0069] Note that before the coating step, a known pretreatment (for example, primer treatment, corona treatment, plasma treatment, etc.) may be performed on the adhesion target surface.

[0070] <<Contact step, curing step>> After the coating step, another member is brought into contact with the adhesion target surface (coating surface) provided with the adhesive layer, and the hot melt adhesive composition is cooled and cured. Usually, as described above, after cooling and curing, the uncured isocyanate terminal reacts with moisture in the air to form a crosslinked structure, thereby exhibiting stronger adhesiveness.

[0071] When applying the hot melt adhesive composition according to the present invention by the method described in the above coating step, it is possible to adhere regardless of the adhesion target. Specifically, even if it is a resin foam, a resin film, synthetic leather, natural leather, woven fabric or non-woven fabric, it is excellent in texture, breathability and adhesiveness, and can prevent infiltration into the adhesion target. In particular, even when the adhesion target is a urethane resin foam, such an effect is exhibited.

[0072] As described above, a laminate having an adhesive layer which is a cured product of the hot melt adhesive composition according to the present invention can be obtained. In particular, a laminate having a foam and an adhesive layer provided on the surface of the foam can be obtained. The laminate preferably has a specific configuration of a laminate composed of a urethane foam as a base material and a skin material or a back base fabric. Such a laminate can preferably be used as an interior material for vehicles, that is, a laminate (laminated sheet) in which an epidermal layer is adhered to the surface of a laminated sheet having a back base fabric layer formed on the back surface of a buffer layer made of a foam (base material).

Examples

[0073] Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[0074] <<<Production of Urethane Hot Melt Adhesive Composition>>> Hereinafter, the production methods of the urethane hot melt adhesive compositions according to each Example and each Comparative Example will be described.

[0075] <<Example 1>> The polyol component (A) was charged into a reactor, the polyisocyanate component (B-1) was added, and after reacting at 100 ° C for 3 to 4 hours, an OH group-containing tertiary amine catalyst was added and further reacted for 1 hour to obtain a urethane hot melt adhesive composition containing a urethane prepolymer having an NCO group content of 2.0%. The blending amounts of the respective components are 80 parts by mass of the polyol component (A), 20 parts by mass of the polyisocyanate component (B-1), and 0.03 parts by mass of the amine catalyst.

[0076] <Polyol Component (A)> Crystalline polyester polyol (sebacic acid / butanediol) melting point 60 °C Number average molecular weight 4000 40 parts by mass Polypropylene glycol addition type PO alone Number average molecular weight 2000 50 parts by mass Polycarbonate diol Number average molecular weight 1000 10 parts by mass

[0077] <Polyisocyanate component (B-1)> Diphenylmethane diisocyanate (MDI) 99 parts by mass Carbodiimide-modified MDI 1 part by mass

[0078] <<Example 2>> A urethane hot melt adhesive composition according to Example 2 was produced in the same manner as in Example 1, except that the polyisocyanate component (B-1) was changed to the polyisocyanate component (B-2).

[0079] <Polyisocyanate component (B-2)> Diphenylmethane diisocyanate (MDI) 90 parts by mass Carbodiimide-modified MDI 10 parts by mass

[0080] <<Comparative Example 1>> A urethane hot melt adhesive composition according to Comparative Example 1 was produced in the same manner as in Example 1, except that the polyisocyanate component (B-1) was changed to the polyisocyanate component (B-3).

[0081] <Polyisocyanate component (B-3)> Diphenylmethane diisocyanate (MDI) 100 parts by mass

[0082] <<Comparative Example 2>> A urethane hot melt adhesive composition according to Comparative Example 2 was produced in the same manner as in Example 1, except that the OH group-containing tertiary amine catalyst was changed to a high molecular weight type tertiary amine catalyst (main component: N,N'-dimethyldodecylamine).

[0083] <<Comparative Example 3>> A urethane hot melt adhesive composition according to Comparative Example 3 was produced in the same manner as in Example 1, except that the polyisocyanate component (B-1) was changed to the polyisocyanate component (B-4).

[0084] <Polyisocyanate component (B-4)> Diphenylmethane diisocyanate (MDI) 99.5 parts by mass Carbodiimide-modified MDI 0.5 parts by mass

[0085] <<Comparative Example 4>> A urethane hot melt adhesive composition according to Comparative Example 1 was produced in the same manner as in Example 1, except that the polyisocyanate component (B-1) was changed to the polyisocyanate component (B-5).

[0086] <Polyisocyanate component (B-5)> Diphenylmethane diisocyanate (MDI) 89 parts by mass Carbodiimide-modified MDI 11 parts by mass

[0087] <<<Evaluation>>> Next, each of the hot melt adhesive compositions obtained above was evaluated specifically by the following method. The evaluation results are shown in Table 1.

[0088] < <voc>> The hot melt adhesive was directly placed into the glass tube of the thermal desorption apparatus (Markes TD-100), and the outgassing was measured by GC / MS (Agilent GC / MS (6890 / 5973)). The sample was heated at 90 °C for 30 minutes, and the values up to C20 were calculated in terms of toluene conversion. If the measurement result is 150 ppm or less, it is judged as qualified.

[0089] <<Moisture and Heat Resistance>> The hot melt adhesive melted at 140 °C was spray-coated onto the urethane foam (150 × 25 × 5 mm) at 20 g / m 2 with a hand gun (manufactured by REKA), and the skin material was crimped. After 3 days, it was left standing in an environment of 80 °C and 95% humidity, and the peel strength was measured every 100 hours. The time until 80% of the normal peel strength could be maintained was measured. If the measurement result is 400 hours or more, it is judged as qualified. The normal peel strength was measured by the following method.

[0090] <Normal Peel Strength> The hot melt adhesive melted at 140 °C was spray-coated onto the urethane foam (150 × 25 × 5 mm) at 20 g / m 2 with a hand gun (manufactured by REKA), and the skin material was crimped. After 1 day, using an autograph (Shimadzu AG-Xplus), the measurement was carried out at a tensile speed of 200 mm / min. The numerical value obtained by averaging the peel strengths at three points each for the maximum value and the minimum value was calculated as the median value with N = 3.

[0091] <<Storage Stability>> The hot melt adhesive (12.5 g) was placed in an aluminum bag (volume 110 cc), left standing in a sealed state at 50 °C for 3 months, and the reduction rate of NCO% was measured. If the measurement result is 80% or more, it is judged as qualified.

[0092] <<Thermal Stability>> The viscosity increase rate of the hot melt adhesive after heating in a nitrogen atmosphere at 140 °C for 4 hours was measured. If the measurement result is 200% or less, it is judged as qualified.

[0093]

Table 1

Claims

1. A urethane hot melt adhesive composition containing a urethane prepolymer (I) made from a polyol component (A) and a polyisocyanate component (B), wherein the polyisocyanate component (B) contains carbodiimide-modified diphenylmethane diisocyanate in an amount exceeding 0.5% by mass and not exceeding 10% by mass based on the total amount of the polyisocyanate component (B), and the urethane hot melt adhesive composition has a measurement result obtained by the following heat resistance evaluation of 400 hours or more, and the amount of organic volatile matter generated when heated at 90 °C is 150 ppm or less in terms of toluene conversion value. (Heat resistance evaluation) The peel strength between the surface material and the urethane foam was measured using an autograph (AG-Xplus manufactured by Shimadzu Corporation) at a tensile speed of 200 mm / min, and the value was calculated as the median of N = 3, which is the average of the peel strengths at three points each for the maximum and minimum values. A hot melt adhesive melted at 140°C is spray-coated at 20 g / m onto a urethane foam (150 × 25 × 5 mm) with a hand gun (manufactured by REKA), and the skin material is crimped. Three days later, it is left standing in an environment of 80°C and 95%, the peel strength is measured every 100 hours, and the time during which 80% of the peel strength relative to the normal peel strength is maintained is defined as the heat resistance. ２ After three days, it is allowed to stand in an 80°C and 95% environment, the peel strength is measured every 100 hours, and the time during which 80% of the peel strength relative to the normal peel strength is maintained is defined as the heat resistance. The normal peel strength is the peel strength measured one day after a hot melt adhesive melted at 140°C was spray-applied at 20 g / m² onto a urethane foam (150 × 25 × 5 mm) with a hand gun (manufactured by REKA) and the skin material was pressure-bonded. ２ ​

2. A urethane hot melt adhesive composition containing a urethane prepolymer (I) made from a polyol component (A), a polyisocyanate component (B), and a reactive catalyst having a functional group that reacts with an isocyanate group, wherein the polyisocyanate component (B) contains carbodiimide-modified diphenylmethane diisocyanate in an amount exceeding 0.5% by mass and not exceeding 10% by mass based on the total amount of the polyisocyanate component (B). ​

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