Reactive hot melt adhesives and structures

Abstract

This reactive hot-melt adhesive contains a urethane prepolymer and satisfies at least one of the following condition A or condition B.　Condition A: the proportion of aromatic rings in the total amount of the urethane prepolymer is 22 mass% or less. Condition B: the glass transition temperature in a cured state is 25 °C or less.

Description

Technical Field

[0001] The present invention relates to a reactive hot melt adhesive and a structure.

Background Art

[0002] A technique has been proposed for producing clothing such as inners and sportswear using an adhesive instead of sewing. For example, Patent Document 1 describes a sheet-like or tape-like hot melt adhesive for adhering stretchable materials.

[0003] A hot melt adhesive is a solid at room temperature, which is brought into contact with an adherent in a liquefied state by heating, and develops an adhesive force by cooling and solidifying. Hot melt adhesives can be roughly classified into two types: those containing a thermoplastic resin as the main component and those containing a reactive resin. As a hot melt adhesive containing a reactive resin (hereinafter also referred to as a reactive hot melt adhesive), a hot melt adhesive containing a urethane prepolymer is known. The hot melt adhesive containing a urethane prepolymer not only develops a certain adhesive force in a short time by cooling and solidifying, but also reacts with moisture present in the air or on the surface of the adherent and cures due to the terminal isocyanate groups of the urethane prepolymer. As a result, a strong adhesive force that cannot be achieved with hot melt adhesives containing thermoplastic resins is developed.

[0004] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2017-179195

Summary of the Invention

Problems to be Solved by the Invention

[0005] Reactive hot melt adhesives are promising materials as adhesives for clothing that utilize high-speed adhesiveness and excellent adhesive force. On the other hand, there is still room for improvement in the properties such as stretchability required for adhesives for clothing in reactive hot melt adhesives. In view of the above circumstances, one aspect of this disclosure aims to provide a reactive hot-melt adhesive that exhibits excellent elasticity after curing, and a structure obtained using a reactive hot-melt adhesive that exhibits excellent elasticity after curing. [Means for solving the problem]

[0006] The means for solving the above problems include the following embodiments. <1> A reactive hot-melt adhesive containing a urethane prepolymer and satisfying at least one of the following conditions A or B. Condition A: The proportion of aromatic rings in the total amount of urethane prepolymer is 22% by mass or less. Condition B: The glass transition temperature in the cured state is 25°C or lower. <2> The proportion of structural units derived from amorphous polyols to structural units derived from polyols in the aforementioned urethane prepolymer is 70% by mass or more. <1> The reactive hot melt adhesive described above. <3> The equivalent ratio (NCO / OH) of the isocyanate groups (NCO) of the polyisocyanate to the hydroxyl groups (OH) of the polyol used as a raw material for the urethane prepolymer is 2.0 or less. <1> or <2> The reactive hot melt adhesive described above. <4> For bonding objects that are stretchable, <1> ~ <3> A reactive hot melt adhesive as described in any one of the following items. <5> Two or more objects that are stretchable, and the two or more objects are bonded together. <1> ~ <4> A structure comprising a cured product of a reactive hot melt adhesive as described in any one of the items. <6> The two or more objects mentioned above are fabrics. <5> The structure described above. <7> It is clothing, <5> The structure described above. [Modes for carrying out the invention]

[0007] The embodiments of this disclosure are described below. However, this disclosure is not limited to the embodiments described below.

[0008] In this disclosure, "polyol" means a compound having two or more hydroxyl groups in its molecule. In this disclosure, "polyisocyanate" means a compound having two or more isocyanate groups in its molecule. In this disclosure, "urethane prepolymer" means a compound that is a reaction product of a polyol and a polyisocyanate and has an isocyanate group at the end of the molecule. That is, "urethane prepolymer" means a compound that includes a polymerization chain containing structural units derived from a polyol and structural units derived from a polyisocyanate, and has an isocyanate group as the terminal group of the polymerization chain.

[0009] <Reactive hot melt adhesive> The reactive hot melt adhesive of this disclosure comprises a urethane prepolymer and satisfies at least one of the following conditions A or B. Condition A: The proportion of aromatic rings in the total amount of urethane prepolymer is 22% by mass or less. Condition B: The glass transition temperature in the cured state is 25°C or lower.

[0010] The reactive hot-melt adhesive of this disclosure contains a urethane prepolymer as a reactive component. Therefore, it exhibits excellent adhesive strength, as it exhibits adhesiveness due to both cooling and solidification after heating and melting, and adhesiveness due to the curing reaction between the urethane prepolymer and water. Furthermore, in the reactive hot-melt adhesive of this disclosure, the proportion of aromatic rings in the total amount of urethane prepolymer (hereinafter also referred to as the aromatic ring ratio of the urethane prepolymer) is 22% by mass or less, or the glass transition temperature in the cured state is 25°C or less.

[0011] Our investigations revealed that reactive hot-melt adhesives having an aromatic ring ratio of 22% by mass or less in the urethane prepolymer, or a glass transition temperature of 25°C or less in the cured state, exhibit superior elasticity after curing compared to reactive hot-melt adhesives that do not meet either of these conditions.

[0012] The aromatic ring ratio of the urethane prepolymer can be set considering the balance with properties other than elasticity. For example, the aromatic ring ratio of the urethane prepolymer may be 20% by mass or less. There is no particular lower limit to the aromatic ring ratio of the urethane prepolymer. For example, the aromatic ring ratio of the urethane prepolymer may be 5% by mass or more.

[0013] A urethane prepolymer containing an aromatic ring may have both the structural units derived from the polyol and the structural units derived from the polyisocyanate containing an aromatic ring, or it may have only one of the structural units derived from the polyol or the structural units derived from the polyisocyanate containing an aromatic ring. A urethane prepolymer containing an aromatic ring may contain both structural units containing an aromatic ring and structural units without an aromatic ring as structural units derived from polyols, or it may contain only one of them. A urethane prepolymer containing an aromatic ring may also contain a structural unit containing an aromatic ring as a structural unit derived from polyisocyanate.

[0014] The aromatic ring ratio of the urethane prepolymer is calculated using the following formula. In the formula below, "total mass of raw materials for the urethane prepolymer" refers to the mass including raw materials that do not contain aromatic rings. If polyester polyol or polyether polyol is not used as the polyol raw material, the item for the unused polyol can be omitted. The molecular weight of the aromatic ring is 78 (in the case of a benzene ring).

[0015] Aromatic ring ratio of urethane prepolymer (%) = {(Aromatic ring ratio of polyester polyols containing aromatic rings × Mass of polyester polyols containing aromatic rings) + (Aromatic ring ratio of polyether polyols containing aromatic rings × Mass of polyether polyols containing aromatic rings) + (Aromatic ring ratio of polyisocyanates containing aromatic rings × Mass of polyisocyanates) / Total mass of raw materials for urethane prepolymer} × 100

[0016] In the above formula, the aromatic ring ratio of the polyester polyol having an aromatic ring is calculated by the following formula. Aromatic ring ratio of the polyester polyol having an aromatic ring = (Molecular weight of the aromatic ring × Mole composition ratio (%) in the raw material carboxylic acid of the polycarboxylic acid having an aromatic ring) / (Molecular weight of each polycarboxylic acid × Mole composition ratio (%) in the raw material carboxylic acid) + (Molecular weight of each polyhydric alcohol × Mole composition ratio (%) in the raw material alcohol)

[0017] In the above formula, the aromatic ring ratio of the polyether polyol having an aromatic ring is calculated by the following formula. Aromatic ring ratio of the polyether polyol having an aromatic ring = Molecular weight of the aromatic ring × Number of moles of the aromatic ring in 1 mole of the polyether polyol / Molecular weight of the polyether polyol

[0018] In the above formula, the aromatic ring ratio of the polyisocyanate having an aromatic ring is calculated by the following formula. Aromatic ring ratio of the polyisocyanate having an aromatic ring = Molecular weight of the aromatic ring × Number of moles of the aromatic ring in 1 mole of the polyisocyanate / Molecular weight of the polyisocyanate

[0019] From the viewpoint of the stretchability after curing, it is preferable that the glass transition temperature in the cured state of the reactive hot melt adhesive is 25°C or lower. When the glass transition temperature in the cured state is 25°C or lower, the cured product of the reactive hot melt adhesive becomes rubbery in an environment of 25°C or higher and exhibits excellent stretchability. The glass transition temperature in the cured state of the reactive hot melt adhesive is measured by the method shown in the examples.

[0020] As a result of the study by the present inventors, it was found that the glass transition temperature in the cured state of the reactive hot melt adhesive tends to be lower as the aromatic ring ratio of the urethane prepolymer contained in the reactive hot melt adhesive is smaller. Therefore, the glass transition temperature can be controlled by the aromatic ring ratio of the urethane prepolymer contained in the reactive hot melt adhesive.

[0021] From the viewpoint of elasticity after curing, it is preferable that the structural units derived from the polyol in the urethane prepolymer include structural units derived from amorphous polyol. In this disclosure, crystalline polyols refer to polyols that exhibit an endothermic peak (melting point Tm) associated with melting when measured by DSC, and amorphous polyols refer to polyols that do not exhibit an endothermic peak (melting point Tm) associated with melting when measured by DSC. The proportion of structural units derived from amorphous polyols to the total structural units derived from polyols in the urethane prepolymer may be 70% by mass or more, 80% by mass or more, or 95% by mass.

[0022] From the viewpoint of adjusting the solidification time and viscosity of reactive hot-melt adhesives, it is preferable that the urethane prepolymer contains structural units derived from polyester polyol as structural units derived from polyol. In other words, it is preferable that the raw material for the urethane prepolymer contains polyester polyol as the polyol.

[0023] As the polyester polyol, a compound produced by the polycondensation reaction of a polyhydric alcohol and a polycarboxylic acid can be used. The polyester polyol may be, for example, a polycondensate of a polyhydric alcohol having 2 to 15 carbon atoms and 2 or 3 hydroxyl groups and a polycarboxylic acid having 2 to 14 carbon atoms (including carbon atoms in the carboxyl groups) and 2 to 6 carboxyl groups.

[0024] 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. Furthermore, branched polyester triols can also be obtained by the reaction of a diol and a tricarboxylic acid.

[0025] Examples of polyhydric alcohols include isomers of ethylene glycol, 1,2-propanediol, 1,3-propanediol, and butanediol, isomers of pentanediol, isomers of hexanediol, aliphatic or alicyclic diols such as 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 such as 4,4'-dihydroxydiphenylpropane, bisphenol A, bisphenol F, pyrocatechol, resorcinol, and hydroquinone. Polyhydric alcohols may be used individually or in combination of two or more. Among these, aliphatic diols are preferred, and more preferably aliphatic diols having 2 to 6 carbon atoms.

[0026] Examples of polycarboxylic acids include aromatic polycarboxylic acids 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. Polycarboxylic acids may be used individually or in combination of two or more.

[0027] Instead of the polycarboxylic acids mentioned above, polycarboxylic acid derivatives such as carboxylic acid anhydrides and compounds in which some of the carboxyl groups are esterified can also be used. Examples of polycarboxylic acid derivatives include dodecyl maleic acid and octadecenyl maleic acid.

[0028] The polyester polyol used as a raw material for the urethane prepolymer may be of one type only, or it may be of two or more types.

[0029] The number-average molecular weight (Mn) of the polyester polyol is preferably in the range of 500 to 10000, more preferably in the range of 1000 to 8000, and even more preferably in the range of 1500 to 6000, from the viewpoint of improving the waterproofness and adhesive strength of the cured product of the reactive hot-melt adhesive.

[0030] In this disclosure, the number-average molecular weight of polyols is measured by gel permeation chromatography (GPC) and converted to standard polystyrene equivalent. GPC measurements can be performed under the following conditions: Columns: "Gelpack GLA130-S", "Gelpack GLA150-S", and "Gelpack GLA160-S" (packed columns for HPLC, manufactured by Showa Denko Materials Co., Ltd.) Eluent: Tetrahydrofuran Flow rate: 1.0mL / min Column temperature: 40℃ Detector: RI

[0031] The amount of polyester polyol used as a raw material for the urethane prepolymer may be, for example, within the range of 70% to 100% by mass of the total polyol.

[0032] From the viewpoint of workability during application of reactive hot-melt adhesives, as well as adhesion, waterproofing, and flexibility after curing, it is preferable that the urethane prepolymer contains structural units derived from polyether polyols as structural units derived from polyols. In other words, it is preferable that the raw material of the urethane prepolymer contains polyether polyols as polyols.

[0033] Examples of polyether polyols include aromatic polyether polyols such as polyether polyols having a bisphenol skeleton, polyethylene glycol, polypropylene glycol, polybutylene glycol, polytetramethylene glycol, and ethylene oxide-modified polypropylene glycol.

[0034] The polyether polyol used as a raw material for the urethane prepolymer may be of one type only, or of two or more types.

[0035] The manganese content of the polyether polyol is preferably in the range of 500 to 2000, more preferably in the range of 700 to 2000, and even more preferably in the range of 1000 to 2000, from the viewpoint of initial adhesive strength, adhesive strength after curing, and appropriate open time after application.

[0036] The amount of polyether polyol used as a raw material for the urethane prepolymer may be, for example, within the range of 0% to 10% by mass of the total polyol.

[0037] The polyisocyanate used as a raw material for the urethane prepolymer is not particularly limited. Examples of polyisocyanates include aromatic isocyanates such as 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 adhesion, aromatic diisocyanates are preferred as polyisocyanates, and diphenylmethane diisocyanate is more preferred.

[0038] The polyisocyanate used as a raw material for the urethane prepolymer may be of one type only, or it may be of two or more types.

[0039] The equivalent ratio (NCO / OH) of the isocyanate groups (NCO) of the polyisocyanate to the hydroxyl groups (OH) of the polyol used as a raw material for the urethane prepolymer is preferably 2.0 or less. When the NCO / OH ratio is 2.0 or less, the residue of unreacted polyisocyanate is suppressed when the polyol and polyisocyanate react, and good elasticity after curing is maintained.

[0040] The equivalent ratio (NCO / OH) of the isocyanate groups (NCO) of the polyisocyanate to the hydroxyl groups (OH) of the polyol used as a raw material for the urethane prepolymer is preferably 1.6 or higher. When the NCO / OH ratio is 1.6 or higher, the viscosity of the resulting urethane prepolymer during melting does not become too high, and good workability is maintained.

[0041] The temperature and time for reacting the polyol and polyisocyanate may be, for example, 85 to 120°C and 1 minute to 48 hours. When mixing the polyol and polyisocyanate, degassing under reduced pressure may be performed.

[0042] Reactive hot-melt adhesives may further contain a catalyst to promote the curing reaction of the urethane prepolymer. Examples of catalysts include dibutyltin dilaurate, dibutylthion octate, dimethylcyclohexylamine, dimethylbenzylamine, trioctylamine, and dimorpholinodiethyl ether (bis(2-morpholinoethyl) ether). The catalyst content may be, for example, 0% to 0.5% by mass of the total reactive hot melt adhesive.

[0043] Reactive hot-melt adhesives may further contain thermoplastic polymers to enhance the rubber elasticity of the cured product and improve its impact resistance. Examples of thermoplastic polymers include polyurethane, ethylene copolymers, propylene copolymers, vinyl chloride copolymers, acrylic copolymers, and styrene-conjugated diene block copolymers.

[0044] Reactive hot-melt adhesives may further contain a tackifying resin to provide stronger adhesion to the cured product. Examples of tackifying resins 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, epoxy resin, and the like.

[0045] Reactive hot melt adhesives may contain, as needed, components such as antioxidants, pigments, UV absorbers, surfactants, flame retardants, silane coupling agents, and fillers.

[0046] The method for obtaining a cured product of a reactive hot-melt adhesive is not particularly limited. For example, the curing reaction of a urethane prepolymer may be carried out in an environment with a temperature of 20°C to 30°C and a relative humidity of 40% to 60%, and the cured product may be obtained.

[0047] From the viewpoint of workability during application, the viscosity of the reactive hot melt adhesive measured using a rotational viscometer at 120°C is preferably 20 Pa·s or less, more preferably 15 Pa·s or less, and even more preferably 10 Pa·s or less. The lower limit of the viscosity of the reactive hot melt adhesive measured using a rotational viscometer at 120°C is not limited, but may be, for example, 1 Pa·s or more.

[0048] The reactive hot melt adhesive of this disclosure is in a solid state before use. The form of the reactive hot melt adhesive in its solid state is not particularly limited. For example, it may be in the form of pellets, blocks, powder, sheets, etc.

[0049] The reactive hot-melt adhesive of this disclosure is solid at room temperature and is heated to liquefy it before use. The method of applying the liquefied reactive hot-melt adhesive to an object is not particularly limited. For example, the liquefied reactive hot-melt adhesive may be brought into contact with the object using a dispenser or the like, or a non-liquefied reactive hot-melt adhesive, such as an adhesive sheet, may be heated in contact with the object to liquefy it.

[0050] The reactive hot-melt adhesive of this disclosure exhibits excellent elasticity after curing. Therefore, the reactive hot-melt adhesive of this disclosure is useful as an adhesive for bonding stretchable objects. The material of the stretchable object is not particularly limited. For example, it may be natural fibers, synthetic fibers, plastics, etc. In one embodiment, the stretchable object may be a fabric such as a knitted or woven fabric, or a fabric for clothing.

[0051] <Structure> The structure of the present disclosure comprises two or more stretchable objects and a cured product of the reactive hot-melt adhesive described above that is used to bond the two or more objects together.

[0052] In the structure of this disclosure, the cured product of a reactive hot-melt adhesive bonding two or more objects exhibits excellent elasticity. The material of the stretchable object is not particularly limited. For example, it may be natural fibers, synthetic fibers, plastics, etc. In one embodiment, the stretchable object may be a fabric such as a knitted fabric, woven fabric, or nonwoven fabric, and may also be a fabric for clothing.

[0053] The method for fabricating the structures of this disclosure is not particularly limited. For example, a heated reactive hot-melt adhesive is brought into contact with a predetermined area of ​​one object, and the other object is brought into contact with the reactive hot-melt adhesive, and the reactive hot-melt adhesive is allowed to cool and solidify in this state. Then, a curing reaction of the urethane prepolymer contained in the reactive hot-melt adhesive is allowed to occur. This makes it possible to obtain a structure in which two or more objects are bonded together with the cured product of the reactive hot-melt adhesive. [Examples]

[0054] The present disclosure will be described in detail below based on examples, but the present invention is not limited thereto.

[0055] <Preparation of Composition> Polyols, as raw materials for urethane prepolymers, were added to the reaction vessel in the amounts (parts by mass) shown in Table 1 and mixed. Next, polyisocyanate was added to the reaction vessel in the amounts (parts by mass) shown in Table 1 and mixed, and the mixture was reacted at 110°C for 1 hour. Subsequently, the mixture was defoamed and stirred under reduced pressure at 110°C for another 1 hour to obtain a composition containing urethane prepolymers.

[0056] [Table 1]

[0057] Details of the polyols and polyisocyanates shown in Table 1 are as follows. Polyol 1: An amorphous polyester polyol having aromatic rings, mainly composed of dicarboxylic acids (isophthalic acid and adipic acid) and diols (ethylene glycol and neopentyl glycol) (number of hydroxyl groups: 2, number average molecular weight: 2000, content of constituent units derived from compounds with aromatic rings: 25 mol% (based on the total amount of constituent units constituting the amorphous polyester polyol), 50 mol% (based on the total amount of constituent units derived from dicarboxylic acids)). Polyol 2: Crystalline polyether polyol with aromatic rings (bisphenol A·PO type) (manufactured by ADEKA Corporation, product name: BPX-11, number of hydroxyl groups: 2, melting point: 3℃) Polyol 3: An amorphous polyester polyol without aromatic rings, mainly composed of dicarboxylic acid (adipic acid) and diols (1,4-butanediol and neopentyl glycol) (number of hydroxyl groups: 2, number average molecular weight: 5000). Polyol 4: A crystalline polyester polyol without aromatic rings, mainly composed of dicarboxylic acid (adipic acid) and diol (1,6-hexanediol) (number of hydroxyl groups: 2, number average molecular weight: 5500). Polyol 5: An amorphous polyester polyol without aromatic rings, mainly composed of dicarboxylic acid (adipic acid) and diol (methylpentanediol) (number of hydroxyl groups: 2, number average molecular weight: 4000). Polyisocyanate: Diphenylmethane diisocyanate (manufactured by Tosoh Corporation, product name: Myrionate MT, number of isocyanate groups: 2)

[0058] (Glass transition temperature) The glass transition temperature of the urethane prepolymer was defined as the peak top temperature of tanδ when measured by dynamic mechanical analysis (DMA) under the following conditions. Test equipment: TA Instruments RSA-G2 Test mode: Tensile Test temperature: -100℃ to 250℃ Heating rate: 5°C / min Frequency: 1Hz Strain: 0.05% Atmosphere: Under nitrogen

[0059] (Elongation force decay rate) A hardened film with a thickness of approximately 100 μm was formed from the prepared composition to create a dumbbell-shaped test specimen (Type 1). Using this specimen, the tensile force decay rate (%) was measured by the repeated constant-speed elongation method in accordance with JIS L 1096:2010 (Testing Methods for Woven and Knitted Fabrics). Specifically, both ends of the test specimen were gripped with the grips of a tensile testing machine (grip spacing: 100 mm), and the specimen was stretched at a tensile speed of 300 mm / min until its elongation rate reached 40% (Step 1). Then, the grips were returned to their original positions at the same tensile speed (Step 2). The tensile force decay rate (%) of the test specimen was calculated using the following formula from the load at which the elongation rate of the test specimen reached 30% in Step 1 (Load 1) and the load at which the elongation rate of the test specimen reached 30% in Step 2 (Load 2). The results are shown in Table 1. Elongation force damping rate (%) = (Load 2 / Load 1) × 100

[0060] As shown in Table 1, the compositions of Examples 1 to 6, which satisfy the conditions for the reactive hot-melt adhesive of this disclosure, exhibited a greater rate of tensile force decay of the cured film and superior elasticity compared to the compositions of Comparative Examples 1 and 2, which do not satisfy the conditions for the reactive hot-melt adhesive of this disclosure.

[0061] The disclosure of Japanese Patent Application No. 2022-200325 is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually noted as being incorporated by reference.

Claims

1. It contains a urethane prepolymer and satisfies the following conditions A and B, A reactive hot-melt adhesive in which the proportion of structural units derived from amorphous polyester polyol to the structural units derived from polyol in the urethane prepolymer is 70% by mass or more. Condition A: The proportion of aromatic rings in the total amount of urethane prepolymer is 22% by mass or less. Condition B: The glass transition temperature in the hardened state is 25°C or lower.

2. The reactive hot melt adhesive according to claim 1, wherein the equivalent ratio (NCO / OH) of the isocyanate groups (NCO) of the polyisocyanate to the hydroxyl groups (OH) of the polyol used as a raw material for the urethane prepolymer is 2.0 or less.

3. A reactive hot-melt adhesive according to claim 1 for bonding stretchable objects.

4. A structure comprising two or more stretchable objects and a cured product of a reactive hot-melt adhesive according to any one of claims 1 to 3 that is used to bond the two or more objects.

5. The structure according to claim 4, wherein the two or more objects are fabrics.

6. The structure according to claim 4, which is a garment.

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