Reactive hot-melt adhesive, bonded body, method for producing the same, and garment

Abstract

To provide a reactive hot-melt adhesive excellent in both initial adhesive force and initial tackiness.SOLUTION: A reactive hot-melt adhesive contains an urethane prepolymer having: a polymer chain containing a polyol-derived structural unit and a polyisocyanate-derived structural unit; and an isocyanate group bonded to a terminal of the polymer chain. The polyol-derived structural unit contains 60 mass% or more of structural units derived from aromatic ring-containing polyester polyols. The aromatic ring-containing polyester polyols include a polyester polyol having number average molecular weight of 700 or less and a polyester polyol having number average molecular weight of 2,000 or more. The content of a structural unit derived from the polyester polyol having the number average molecular weight of 700 or less is 1-10 mass% in the polyol-derived structural unit.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a reactive hot melt adhesive, an adhesive body and a method for producing the same, and to clothing. [Background technology]

[0002] Hot melt adhesives are solvent-free, so they are less harmful to the environment and the human body, and can bond in a short time, making them suitable for improving productivity. Hot melt adhesives can be broadly divided into two types: those that use thermoplastic resins as the main component, and those that use reactive resins as the main component. Urethane prepolymers with isocyanate groups at the terminals are mainly used as reactive resins.

[0003] Reactive hot melt adhesives whose main component is urethane prepolymers exhibit a certain degree of adhesive strength in a short time after application, as the adhesive itself cools and hardens. The terminal isocyanate groups of the urethane prepolymer then react with moisture (in the air or on the surface of the adherend), increasing the molecular weight and causing crosslinking, which results in heat resistance. Such adhesives are called moisture-curing reactive hot melt adhesives. Reactive hot melt adhesives whose main component is urethane prepolymers exhibit good adhesive strength even when heated.

[0004] For example, Patent Document 1 discloses a reactive hot melt adhesive made of a polyisocyanate and a urethane prepolymer containing 75% by mass or more of an aromatic ring-containing polyester polyol as a polyol. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2021-161219 A Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, solvent-free reactive hot melt adhesives have been used in various applications in order to be environmentally friendly. However, it is extremely important for reactive hot melt adhesives to have both initial adhesive strength and initial tackiness. However, in conventional reactive hot melt adhesives, the initial adhesive strength and the initial tackiness are in a trade-off relationship, so that the compatibility between them is still insufficient, and there are problems such as the adhesive having low tackiness when the initial adhesive strength is high and being unable to be bonded to a substrate.

[0007] The present disclosure has been made in consideration of the above-mentioned problems in the conventional art, and an object of the present disclosure is to provide a reactive hot melt adhesive that is excellent in both initial adhesive strength and initial tackiness, an adhesive body using the reactive hot melt adhesive and a manufacturing method thereof, and clothing. [Means for solving the problem]

[0008] One aspect of the present disclosure that solves the above problems is as follows.

[0009] (1) A urethane prepolymer having a polymer chain including a structural unit derived from a polyol and a structural unit derived from a polyisocyanate, and an isocyanate group bonded to an end of the polymer chain, The structural units derived from the polyol contain 60 mass % or more of structural units derived from a polyester polyol having an aromatic ring, the polyester polyol having an aromatic ring comprises a polyester polyol having a number average molecular weight of 700 or less and a polyester polyol having a number average molecular weight of 2000 or more, A reactive hot melt adhesive, wherein the content of structural units derived from the polyester polyol having a number average molecular weight of 700 or less is 1 to 10 mass % in the structural units derived from the polyol.

[0010] (2) The reactive hot melt adhesive according to (1), wherein the polyester polyol having an aromatic ring further comprises a polyester polyol having a number average molecular weight of more than 700 and less than 2,000.

[0011] (3) The reactive hot melt adhesive according to (1) or (2), wherein the structural units derived from the polyol contain 20% by mass or more and less than 40% by mass of structural units derived from a polyester polyol having no aromatic ring.

[0012] (4) The reactive hot melt adhesive according to (1) or (2) above, which is used for bonding a plurality of adherends selected from cloth and paper to each other.

[0013] (5) a first adherend; and A second adherend; and an adhesive layer that bonds the first adherend and the second adherend to each other; 3. An adhesive body comprising: a reactive hot melt adhesive according to claim 1, wherein the adhesive layer contains a cured product of the reactive hot melt adhesive according to claim 1 or 2.

[0014] (6) A garment comprising the adhesive structure according to (5) above, wherein the first adherend and the second adherend are fabrics.

[0015] (7) forming an adhesive layer by melting the reactive hot melt adhesive according to (1) or (2) above and applying it to a first adherend; a step of placing a second adherend on the adhesive layer and pressing the second adherend to obtain a laminate; a step of obtaining an adhesive body by curing the adhesive layer in the laminate; Equipped with A method for producing an adhesive body. Effect of the Invention

[0016] According to the present disclosure, it is possible to provide a reactive hot melt adhesive having both excellent initial adhesive strength and initial tackiness, an adhesive body using the reactive hot melt adhesive and a manufacturing method thereof, and clothing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, embodiments of the present disclosure will be described in detail. However, the present disclosure is not limited to the following embodiments.

[0018] In this specification, the term "polyol" refers to a compound having one or more hydroxyl groups in the molecule, some of which may be capped with a monool or monocarboxylic acid.

[0019] In this specification, "polyisocyanate" means a compound having two or more isocyanate groups in the molecule.

[0020] In this specification, "amorphous" and "crystalline" can be judged based on the state at 25° C. In this specification, an amorphous polyol means a polyol that is amorphous at 25° C., and a crystalline polyol means a polyester polyol that is crystalline at 25° C.

[0021] [Reactive hot melt adhesive] The reactive hot melt adhesive of one embodiment contains a urethane prepolymer having a polymer chain containing a structural unit derived from a polyol and a structural unit derived from a polyisocyanate, and an isocyanate group bonded to the end of the polymer chain. In general, reactive hot melt adhesives are polymerized by chemical reaction and can exhibit adhesive strength. The urethane prepolymer having an isocyanate group bonded to the end of the polymer chain reacts with moisture to harden (to form a hardened product), so that the urethane prepolymer alone can act as a reactive hot melt adhesive. The reactive hot melt adhesive may contain components other than the urethane prepolymer.

[0022] <Urethane prepolymer> As described above, the urethane prepolymer has a polymer chain containing a structural unit derived from a polyol and a structural unit derived from a polyisocyanate, and an isocyanate group bonded to the end of the polymer chain. The structural unit derived from the polyol includes a structural unit derived from a polyester polyol having an aromatic ring. In this embodiment, the content of the structural unit derived from the polyester polyol having an aromatic ring is 60 mass% or more based on the total amount of structural units derived from the polyol. The urethane prepolymer can usually be obtained by reacting a polyol containing a polyester polyol having a predetermined content of aromatic rings with a polyisocyanate. That is, the urethane prepolymer may be a reaction product of a polyol containing a polyester polyol having an aromatic ring and a polyisocyanate. The content of the structural unit can be adjusted by adjusting the mixing amount of the polyester polyol having an aromatic ring that provides the structural unit and the polyol other than the polyester polyol having an aromatic ring that provides the structural unit. In addition, since a urethane bond is formed by the reaction of a polyol with a polyisocyanate, the polymer chain of the urethane prepolymer may have a urethane bond. Also, by increasing the equivalent weight of polyisocyanate relative to the equivalent weight of polyol, an isocyanate group can be introduced at the end of the polymer chain. Hereinafter, the polyol from which the structural units derived from polyol are derived will be referred to as component (a), and the polyisocyanate from which the structural units derived from polyisocyanate are derived will be referred to as component (b).

[0023] {Component (a): Polyol} In this embodiment, the structural units derived from the component (a) include 60% by mass or more of structural units derived from a polyester polyol having an aromatic ring. The structural units derived from the polyester polyol having an aromatic ring include structural units derived from a polyester polyol having a number average molecular weight of 700 or less (hereinafter, sometimes referred to as "component (a1)").) and structural units derived from a polyester polyol having a number average molecular weight of 2000 or more (hereinafter, sometimes referred to as "component (a2)").) The structural units derived from the component (a) may further include structural units derived from a polyol other than the polyester polyol having an aromatic ring (hereinafter, sometimes referred to as "component (a3)").

[0024] The component (a1) is a polyester polyol having an aromatic ring and a number average molecular weight of 700 or less.

[0025] From the viewpoint of tackiness, the number average molecular weight (Mn) of the (a1) component is preferably not more than 500. In this specification, the number average molecular weight (Mn) is a value measured by gel permeation chromatography (GPC) and converted into a standard polystyrene equivalent value.

[0026] In this specification, the GPC measurement for determining the number average molecular weight (Mn) can be carried out, for example, under the following conditions. Columns: "Gelpack GLA130-S", "Gelpack GLA150-S" and "Gelpack GLA160-S" (Hitachi Chemical Co., Ltd., HPLC packed columns) Eluent: Tetrahydrofuran Flow rate: 1.0mL / min Column temperature: 40℃ Detector: RI

[0027] The component (a1) may be a polycondensation reaction product of a polyhydric alcohol and a polycarboxylic acid, or may partially contain a monocarboxylic acid or a monool, but the number of functional groups is preferably 1.3 or more. If the functionality is 1.3 or less, the final adhesive strength may deteriorate. In addition, it may be reacted with a triol or tricarboxylic acid to give it a branched structure.

[0028] The component (a1) can be obtained by using an aromatic polyhydric alcohol (a polyhydric alcohol having an aromatic ring) and / or an aromatic polycarboxylic acid (a polycarboxylic acid having an aromatic ring). The component (a1) may be used alone or in combination of two or more.

[0029] The component (a1) may be a linear polyester diol produced from a diol and a dicarboxylic acid, or a branched polyester triol produced from a triol and a dicarboxylic acid, so long as it has an aromatic ring. The branched polyester triol can also be obtained by reacting a diol with a tricarboxylic acid.

[0030] Examples of polyhydric alcohols include aliphatic or alicyclic diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, isomers of butanediol, isomers of pentanediol, isomers of hexanediol, 2,2-dimethyl-1,3-propanediol, 2-methylpropanediol, 2,4,4-trimethyl-1,6-hexanediol, 2,2,4-trimethyl-1,6-hexanediol, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol; and aromatic diols (diols having an aromatic ring) such as 4,4'-dihydroxydiphenylpropane, bisphenol A, bisphenol F, pyrocatechol, resorcinol, and hydroquinone. The polyhydric alcohol may be used alone or in combination of two or more. Among these, aliphatic diols are preferable, and aliphatic diols having 2 to 6 carbon atoms are more preferable.

[0031] Examples of polycarboxylic acids include aromatic polycarboxylic acids (polycarboxylic acids having an aromatic ring) such as phthalic acid, isophthalic acid, terephthalic acid, and 1,2,4-benzenetricarboxylic acid; and aliphatic or alicyclic polycarboxylic acids such as maleic acid, fumaric acid, aconitic acid, 1,2,3-propanetricarboxylic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, cyclohexane-1,2-dicarboxylic acid, and 1,4-cyclohexanediene-1,2-dicarboxylic acid. The aromatic polycarboxylic acid may be a polycarboxylic acid having a benzene ring and two or more carboxy groups bonded to the benzene ring, and may be at least one selected from the group consisting of phthalic acid, isophthalic acid, and terephthalic acid. The polycarboxylic acid may be used alone or in combination of two or more.

[0032] Instead of polycarboxylic acid, polycarboxylic acid derivatives such as carboxylic acid anhydrides and compounds in which a part of the carboxyl group is esterified, and monocarboxylic acids can also be used. Examples of polycarboxylic acid derivatives include phthalic anhydride and dimethyl terephthalate, and monocarboxylic acids such as benzoic acid.

[0033] When the component (a1) is a polycondensation reaction product of a polyhydric alcohol and a polycarboxylic acid including an aromatic polycarboxylic acid (a polycarboxylic acid having an aromatic ring, preferably at least one selected from the group consisting of phthalic acid, isophthalic acid, and terephthalic acid), the content of structural units derived from aromatic polycarboxylic acid may be 20 to 100 mol %, 25 to 100 mol %, or 50 to 100 mol % based on the total amount of structural units derived from polycarboxylic acid.

[0034] The content of the structural units derived from the (a1) component in the structural units derived from the polyol is 1 to 10 mass%, preferably 1 to 8 mass%, and more preferably 2 to 6 mass%. When the content is 1 to 10 mass%, the resulting urethane polymer (reactive melt adhesive) has excellent tackiness.

[0035] The content of the (a2) component (structural unit derived from the (a2) component) in the structural unit derived from the polyol is preferably 46 to 62 mass%, more preferably 48 to 60 mass%, and even more preferably 50 to 59 mass%. When the content of the (a2) component is 46 to 62 mass% based on the total amount of the polyol component, the initial adhesive strength of the resulting urethane prepolymer (reactive hot melt adhesive) tends to be excellent. On the other hand, when the content of the (a2) component is less than 46 mass% in the structural unit derived from the polyol, the initial adhesiveness tends to be insufficient. When the content of the (a1) component is more than 62 mass% in the structural unit derived from the polyol, the initial adhesiveness is excellent, but the tackiness tends to be insufficient.

[0036] The number average molecular weight (Mn) of the component (a2) is 2000 or more from the viewpoint of adhesive strength.

[0037] The polymer chain contains a structural unit derived from a polyester polyol, so that the solidification time and viscosity of the reactive hot melt adhesive can be adjusted. The polyester polyol may be a polycondensation reaction product of a polyhydric alcohol and a polycarboxylic acid. The polyester polyol may be a linear polyester diol produced from a diol and a dicarboxylic acid, or a branched polyester triol produced from a triol and a dicarboxylic acid. The branched polyester triol may also be obtained by the reaction of a diol and a tricarboxylic acid.

[0038] The component (a2) can be obtained by using an aromatic polyhydric alcohol (a polyhydric alcohol having an aromatic ring) and / or an aromatic polycarboxylic acid (a polycarboxylic acid having an aromatic ring). The component (a2) may be used alone or in combination of two or more.

[0039] The component (a2) may be a linear polyester diol produced from a diol and a dicarboxylic acid, or a branched polyester triol produced from a triol and a dicarboxylic acid, so long as it has an aromatic ring. The branched polyester triol can also be obtained by reacting a diol with a tricarboxylic acid.

[0040] The polyhydric alcohol and polycarboxylic acid used to obtain the component (a2) are the same as those described for the component (a1) above. Therefore, the description of the component (a1) above also applies to the component (a2).

[0041] When the component (a2) is a polycondensation reaction product of a polyhydric alcohol and a polycarboxylic acid including an aromatic polycarboxylic acid (a polycarboxylic acid having an aromatic ring, preferably at least one selected from the group consisting of phthalic acid, isophthalic acid, and terephthalic acid), the content of structural units derived from aromatic polycarboxylic acid may be 20 to 100 mol %, or 50 to 100 mol %, based on the total amount of structural units derived from polycarboxylic acid.

[0042] In addition to the components (a1) and (a2), the component (a) may contain a polyester polyol having a number average molecular weight of more than 700 and less than 2,000 in order to reduce viscosity.

[0043] From the viewpoints of tackiness, viscosity adjustment, and foaming inhibition, the component (a) may contain, as the component (a3), at least one selected from the group consisting of amorphous polyester polyols having no aromatic rings and crystalline polyester polyols having no aromatic rings. Also, from the viewpoint of lowering the viscosity, the component (a) may contain a polyether polyol.

[0044] The number average molecular weight (Mn) of the component (a3) ​​may be 1,000 to 7,000 from the viewpoint of reducing viscosity.

[0045] The content of the (a3) ​​component (structural units derived from the (a3) ​​component) in the structural units derived from the polyol is preferably 20 mass % or more and less than 45 mass %, more preferably 30 to 43 mass %, and even more preferably 35 to 40 mass %.

[0046] The component (a3) ​​is a polyol other than a polyester polyol having an aromatic ring. Examples of the component (a3) ​​include an amorphous polyester polyol having no aromatic ring, a crystalline polyester polyol having no aromatic ring, a polyether polyol, a polycarbonate polyol, and a polyolefin polyol.

[0047] {Component (b): Polyisocyanate} The polyisocyanate can be used without any particular limitation as long as it is a compound having two or more isocyanate groups. The polyisocyanate may be a compound (diisocyanate) having two isocyanate groups. Examples of the polyisocyanate include aromatic isocyanates such as diphenylmethane diisocyanate (4,4'-diphenylmethane diisocyanate), dimethyldiphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, and p-phenylene diisocyanate; alicyclic isocyanates such as dicyclohexylmethane diisocyanate and isophorone diisocyanate; and aliphatic isocyanates such as hexamethylene diisocyanate. From the viewpoint of reactivity and adhesive strength, the polyisocyanate preferably contains an aromatic diisocyanate, and more preferably contains diphenylmethane diisocyanate. The polyisocyanate may be used alone or in combination of two or more.

[0048] The urethane prepolymer can be synthesized by reacting the (a) component, which contains the (a1) component and the (a2) component in a predetermined content, with the (b) component. The urethane prepolymer has a polymer chain containing a structural unit derived from the (a1) component, a structural unit derived from the (a2) component, and a structural unit derived from the (b) component, and an isocyanate group bonded to the end of the polymer chain. When synthesizing such a urethane prepolymer, the equivalent ratio of the isocyanate group (NCO) of the (b) component to the hydroxyl group (OH) of the (a) component (isocyanate group (NCO) equivalent of the (b) component / hydroxyl group (OH) equivalent of the (a) component, NCO / OH) may be 1.1 or more, may be 1.1 to 2.5, may be 1.3 to 2.3, may be 1.5 to 2.2, or may be 1.7 to 2.0. When the NCO / OH ratio is 1.1 or more, the urethane prepolymer has an isocyanate group bonded to the end of the polymer chain, and the increase in the viscosity of the urethane prepolymer can be suppressed, which tends to improve workability.When the NCO / OH ratio is 2.5 or less, foaming is less likely to occur during the moisture curing reaction of the reactive hot melt adhesive, which tends to make it easier to suppress a decrease in adhesive strength.

[0049] The temperature and time for reacting the components (a) and (b) when synthesizing the urethane prepolymer are not particularly limited, but may be, for example, 85 to 120° C. and 0.5 to 6 hours.

[0050] The reactive hot melt adhesive may further contain a catalyst from the viewpoint of promoting the curing of the urethane prepolymer and exhibiting higher adhesive strength. Examples of the catalyst include dibutyltin dilaurate, dibutylthione octate, dimethylcyclohexylamine, dimethylbenzylamine, trioctylamine, dimorpholinodiethyl ether (bis(2-morpholinoethyl)ether), etc. The content of the catalyst may be 0.001 to 0.5 mass% based on the total amount of the reactive hot melt adhesive.

[0051] The reactive hot melt adhesive may further contain a thermoplastic polymer from the viewpoint of increasing the rubber elasticity of the formed adhesive layer and further improving the impact resistance. Examples of the thermoplastic polymer include polyurethane, ethylene copolymer, propylene copolymer, vinyl chloride copolymer, acrylic copolymer, styrene-conjugated diene block copolymer, etc. The content of the thermoplastic polymer may be 0.1 to 50 mass% based on the total amount of the reactive hot melt adhesive.

[0052] The reactive hot melt adhesive may further contain a tackifier resin from the viewpoint of imparting stronger adhesive strength to the adhesive layer formed. Examples of the tackifier resin include rosin resin, rosin ester resin, hydrogenated rosin ester resin, terpene resin, terpene phenol resin, hydrogenated terpene resin, petroleum resin, hydrogenated petroleum resin, coumarone resin, ketone resin, styrene resin, modified styrene resin, xylene resin, and epoxy resin. The content of the tackifier resin may be 0.1 to 50 mass% based on the total amount of the reactive hot melt adhesive.

[0053] The reactive hot melt adhesive may further contain other components as necessary. Examples of the other components include antioxidants, pigments, ultraviolet absorbers, light stabilizers, surfactants, flame retardants, fillers, photocoloring agents, thermal coloring inhibitors, fragrances, imaging agents, and thermal crosslinking agents. The content of the other components may be 0.001 to 10% by mass based on the total amount of the reactive hot melt adhesive.

[0054] The reactive hot melt adhesive can be cured, for example, by leaving it for 24 hours (curing) at a temperature of 23°C and 50% RH (relative humidity) because the isocyanate group of the urethane prepolymer contained in the reactive hot melt adhesive reacts with moisture in the air or moisture on the surface of the adherend. In this way, a cured product of the reactive hot melt adhesive can be obtained.

[0055] The adhesive strength measured after the adherends are bonded together using the reactive hot melt adhesive and before the reactive hot melt adhesive hardens (hereinafter sometimes referred to as "initial adhesive strength") is preferably 1 N / 8 mm or more. In this specification, the initial adhesive strength refers to a value measured by the method described in the Examples. In other words, the initial adhesive strength refers to the adhesive strength of a bonded body obtained by bonding adherends together using the reactive hot melt adhesive at 120°C, 5 minutes after the bonding.

[0056] The adhesive strength (hereinafter sometimes referred to as "final adhesive strength") measured after the reactive hot melt adhesive has hardened after the adherends have been bonded together with the reactive hot melt adhesive may be 10 N / 8 mm or more. In this specification, the final adhesive strength refers to a value measured by the method described in the Examples. In other words, the final adhesive strength refers to the adhesive strength of an adhesive body obtained by bonding adherends together with the reactive hot melt adhesive at 60°C, and curing the bonded body in a thermostatic chamber at 23°C and 50% RH for 3 days.

[0057] The tackiness of the reactive hot melt adhesive is preferably such that when an adhesive film is prepared by applying the adhesive to a thickness of approximately 100 μm, a digital force gauge (probe diameter: 1.5 cmΦ) is pressed against the film and then the film is pulled upwards with a maximum strength of 30 N or more.

[0058] The reactive hot melt adhesive can be used by, for example, melting at 60 to 130°C and then applying it to the adherend. The application method is not particularly limited, but examples thereof include methods using application devices such as a bar coater, a die coater, a roll coater, and a sprayer. A dispenser is suitable for application to small areas such as small parts. The application pattern of the reactive hot melt adhesive can be appropriately set, but examples thereof include application patterns such as dots, straight lines, zigzags, planes, and curves.

[0059] The reactive hot melt adhesive can bond various adherends via the cured product (adhesive layer) of the reactive hot melt adhesive. Examples of the adherend include metal substrates such as SUS and aluminum, and non-metal substrates such as cloth, paper, polycarbonate, polyamide, polyetherimide, glass, and carbon fiber. Among these, the adherend may be, for example, cloth or paper. The reactive hot melt adhesive can be suitably used to bond a plurality of adherends selected from cloth and paper to each other. In this case, the combination of adherends may be cloth and cloth, paper and paper, or cloth and paper. The reactive hot melt adhesive can be suitably used for clothing (apparel products) such as clothes, supporters, bags, wallets, interiors, various covers, cases, wearable devices, etc., and is particularly suitable for use in clothing.

[0060] The reactive hot melt adhesive may be formed into a film and used as an adhesive film. For example, the reactive hot melt adhesive may be applied to a support film such as a PET (polyethylene terephthalate) film to form an adhesive layer, thereby obtaining an adhesive film.

[0061] [Adhesive body and its manufacturing method] The adhesive article of one embodiment includes a first adherend, a second adherend, and an adhesive layer that adheres the first adherend and the second adherend to each other. The adhesive layer contains a cured product of the reactive hot melt adhesive. Examples of articles that include the adhesive article include clothing (particularly seamless clothing), semiconductor devices, electronic devices, and the like.

[0062] The first and second adherends can be exemplified by the same ones as those exemplified above. The first and second adherends can be, for example, cloth or paper, and the combination of the first and second adherends can be cloth and cloth, paper and paper, or cloth and paper. When the article having the adhesive is clothing, the first and second adherends are cloth.

[0063] The adhesive of this embodiment can be produced by a method comprising the steps of melting the reactive hot melt adhesive and applying it to a first adherend to form an adhesive layer, placing a second adherend on the adhesive layer and pressing the second adherend to obtain a laminate, and curing the adhesive layer to obtain the adhesive.

[0064] The temperature at which the reactive hot melt adhesive is melted may be, for example, 80 to 130° C. Examples of a method for applying the reactive hot melt adhesive to the first adherend include a method using an application device such as a die coater, a roll coater, or a sprayer. A dispenser is suitable for application to small areas such as small parts.

[0065] The second adherend may be pressure-bonded, for example, by using a pressure roll or the like.

[0066] The reactive hot melt adhesive in the adhesive layer can be cured, for example, by leaving it (curing) for 48 hours at a temperature of 23° C. and 50% RH (relative humidity). As a result, the adhesive layer can contain a cured product of the reactive hot melt adhesive.

[0067] The adhesive layer may be formed by transferring an adhesive film made of a reactive hot melt adhesive that has been formed in advance on a releasable substrate onto the fabric, or the adhesive may be provided on the fabric and then bonded to the fabric.

[0068] [clothing] In one embodiment, a garment includes the above-mentioned adhesive structure. In this case, the first adherend and the second adherend are fabrics. The garment may be a seamless garment. EXAMPLES

[0069] The present embodiment will be described in more detail below with reference to examples, but the present embodiment is not limited to the following examples. In the following, "parts" such as "0.02 parts of acetic anhydride" refers to "parts by mass."

[0070] [Examples 1 to 6 and Comparative Examples 1 to 3] Preparation of reactive hot melt adhesives The types and parts by mass of polyol and polyisocyanate shown in Table 1 were used. The polyisocyanate was added to a reaction vessel so that the equivalent ratio ((NCO) equivalent / (OH) equivalent) of the isocyanate group of the polyisocyanate to the hydroxyl group of the polyol was the value shown in Table 1, and mixed at 110°C for 1 hour until uniform. Next, a urethane prepolymer was obtained by further degassing and stirring at 110°C for 1 hour. As shown in Table 1, since the (NCO) equivalent / (OH) equivalent is greater than 1, it is presumed that the obtained urethane prepolymer has a polymer chain containing a structural unit derived from a polyol and a structural unit derived from a polyisocyanate, and an isocyanate group bonded to the end of the polymer chain. In the following, the obtained urethane prepolymer was used as it is as a reactive hot melt adhesive.

[0071] Details of each component shown in Table 1 are as follows. (a) Polyol (a1)-1: Polyether polyol having an aromatic ring (bisphenol A PO type) (manufactured by Resonac Corporation, product name: SV-6413, number of hydroxyl groups: 1.34, molecular weight: 490) (a1)-2: Polyether polyol having an aromatic ring (bisphenol A·PO type) (manufactured by Resonac Co., Ltd., product name: PH-6102, number of hydroxyl groups: 2, molecular weight: 500) (a2)-1: A polyester polyol having an aromatic ring, mainly composed of phthalic acid and neopentyl glycol (manufactured by Toyokuni Oil Mills, product name: HS 2F-306P, number of hydroxyl groups: 2, number average molecular weight: 3000) (a2)-2: Aromatic ring-containing polyester polyol composed mainly of phthalic acid, ethylene glycol, and diethylene glycol (manufactured by Resonac Corporation, product name: TA22-739, number of hydroxyl groups: 2, number average molecular weight: 2000) (a3)-1: A polyester polyol without aromatic rings, mainly composed of adipic acid and 1,6-hexanediol (number of hydroxyl groups: 2, number average molecular weight: 5000) (a3)-2: A polyester polyol having no aromatic ring, mainly composed of adipic acid and 3-methyl-1,5-pentanediol (number of hydroxyl groups: 2, number average molecular weight: 4000) (a3)-3: A polyester polyol without an aromatic ring, mainly composed of adipic acid and neopentyl glycol (number of hydroxyl groups: 2, number average molecular weight: 2000)

[0072] (b) Polyisocyanate (b)-1: Diphenylmethane diisocyanate (manufactured by Tosoh Corporation, product name: Millionate MT, number of isocyanate groups: 2)

[0073] <Evaluation of reactive hot melt adhesives> (viscosity) The melt viscosity of the adhesive composition (sample amount: 15 g) was measured using a TVB-25H viscometer (manufactured by Toki Sangyo Co., Ltd.) with a No. 4 rotor at a rotor rotation speed of 20 rpm and 120°C. A value of 20 Pa s or less was marked as ◯, and a value less than 20 Pa s was marked as ×.

[0074] (Initial and final adhesive strength) The reactive hot melt adhesives of Examples 1 to 6 and Comparative Examples 1 to 3 were melted at 100°C and applied onto an elastic fabric (spandex, Toray Oprontex Co., Ltd., Lycra (registered trademark)), and coated to a thickness of 80 μm using a bar coater to form an adhesive layer. The same elastic fabric was placed on the formed adhesive layer, and pressed at 80°C to obtain a pressed body. The adhesive strength of the pressed body 5 minutes after pressing was measured using a digital force gauge (IMADA Co., Ltd., DS250N), and this was taken as the initial adhesive strength of the reactive hot melt adhesive, with 2N / 8mm or more being indicated as ◯ and 2N / 8mm or less being indicated as ×. The pressure-bonded body was then aged in a thermostatic chamber at 23°C and 50% RH for one day to harden the adhesive layer, producing an adhesive body. The adhesive strength of the adhesive body was measured by a T-peel strength test using a tensile tester (Shimadzu Corporation, EZ-Test EZ-SX) at a measurement temperature of 25°C and a tensile speed of 100 mm / min. This was taken as the final adhesive strength, and 15 N / 8 mm or more was indicated as ◯, and 15 N / 8 mm or less was indicated as ×.

[0075] (tackiness) The reactive hot melt adhesives of Examples 1 to 6 and Comparative Examples 1 to 3 were melted at 100°C to form a film having a thickness of 100 μm. The film thus formed was then pressed against a digital force gauge (IMADA CORPORATION, DS250N) (probe diameter: 1.5 cmΦ) and then pulled upward to measure the maximum strength. A force of 30 N or more was marked as ◯, and a force of 30 N or less was marked as ×.

[0076] [Table 1]

[0077] From Table 1, it can be seen that all of Examples 1 to 6 were excellent in initial adhesive strength, final adhesive strength, and tackiness. In contrast, Comparative Example 1, which contained an excessive amount of structural units derived from a polyester polyol having a number average molecular weight of 700 or less, had poor initial adhesive strength. Comparative Example 2, which contained less than 60 mass% of structural units derived from a polyester polyol having an aromatic ring, also had poor initial adhesive strength. Furthermore, Comparative Example 3, which did not contain structural units derived from a polyester polyol having a number average molecular weight of 700 or less, had poor tackiness.

Claims

1. The present invention comprises a urethane prepolymer having a polymer chain including a structural unit derived from a polyol and a structural unit derived from a polyisocyanate, and an isocyanate group bonded to an end of the polymer chain, The structural units derived from the polyol contain 60 mass% or more of structural units derived from a polyester polyol having an aromatic ring, the polyester polyol having an aromatic ring comprises a polyester polyol having a number average molecular weight of 700 or less and a polyester polyol having a number average molecular weight of 2000 or more; a content of structural units derived from the polyester polyol having a number average molecular weight of 700 or less in the structural units derived from the polyol is 1 to 10 mass %.

2. The reactive hot melt adhesive according to claim 1 , wherein the polyester polyol having an aromatic ring further comprises a polyester polyol having a number average molecular weight of more than 700 and less than 2,000.

3. The reactive hot melt adhesive according to claim 1 or 2, wherein the structural units derived from the polyol contain 20 mass % or more and less than 45 mass % of structural units derived from a polyester polyol having no aromatic ring.

4. 3. The reactive hot melt adhesive according to claim 1 or 2, which is used for bonding a plurality of adherends selected from cloth and paper to each other.

5. A first adherend; A second adherend; and an adhesive layer that bonds the first adherend and the second adherend to each other; 3. An adhesive body comprising: a reactive hot melt adhesive according to claim 1, wherein the adhesive layer contains a cured product of the reactive hot melt adhesive according to claim 1 or 2.

6. A garment comprising the adhesive article according to claim 5, wherein the first adherend and the second adherend are fabrics.

7. forming an adhesive layer by melting the reactive hot melt adhesive according to claim 1 or 2 and applying it to a first adherend; a step of placing a second adherend on the adhesive layer and pressing the second adherend to obtain a laminate; a step of obtaining an adhesive body by curing the adhesive layer in the laminate; Equipped with A method for producing an adhesive body.

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