Next structure

Abstract

To enable an adhesive layer and a second adherent to be peeled from a first adherent along an interface between the first adherent and the adhesive layer.SOLUTION: An adhesion structure 10 has a structure in which a first adherent 11 and a second adherent 12 are bonded. An adhesive 14 containing moisture curable hot-melt urethane is heated and melted to be applied on the first adherent 11. The applied adhesive 14 is cured with moisture, and the moisture-cured adhesive 14 is heated and melted. The second adherent 12 is bonded to the heated and melted adhesive 14.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a bonded structure, and to a bonded structure. [Background technology]

[0002] Conventionally, bonded structures in which two adherends (first adherend, second adherend) are bonded with a hot melt adhesive have been known. For example, the first adherend has a smooth bonding surface and is made of a material harder than the second adherend (metal, resin, plastic, ceramic, natural rubber, synthetic rubber, polyurethane, melamine, etc.). The second adherend has a rough bonding surface (natural rubber, synthetic rubber, polyurethane, melamine foam, paper, nonwoven fabric, natural leather, synthetic leather, etc.). Examples of adhesives include those containing moisture-curing hot melt urethane (see Patent Documents 1 and 2).

[0003] The bonding procedure for bonded structures is as follows: First, a moisture-curing hot melt adhesive is placed in a hot melt applicator (Bag Melter PUR-20 manufactured by ITW Dynatec, Inc.) and heated to melt. The adhesive is applied to a first adherend, and before it hardens, a second adherend is brought into contact with the adhesive. Next, the adhesive is allowed to cool naturally to harden. Then, the structure is left at room temperature (23°C) for one day to complete the moisture hardening process. This completes the bonded structure.

[0004] An example of the use of the bonded structure is a cleaning member in which a first adherend and a second adherend are bonded together and the second adherend is used for cleaning. The first adherend and the second adherend are plate-shaped or rod-shaped. Depending on the accumulation of dirt or the degree of damage, the second adherend is removed and then reattached.

[0005] In a bonded structure, it is conceivable that the second adherend may be physically peeled from the first adherend in the shear direction, peeling direction, etc. However, as shown in Figure 11, for example, the second adherend 2 may break, leaving the adhesive layer 3 and a portion of the broken second adherend 2 on the surface of the first adherend 1. This type of peeling is likely to occur when the skeleton or fibers of the second adherend are weaker than the first adherend or adhesive layer.

[0006] For example, if a typical non-reactive EVA hot melt adhesive is used as the adhesive, the adhesive melts when reheated, allowing the two adherends to be peeled apart. However, this requires a heating device. Since the adhesive remains on the surfaces of both adherends, it must be wiped off while heated. Furthermore, if a typical acrylic double-sided tape is used as the adhesive medium, it is easy for adhesive residue to remain on one of the adherends. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 49-98445 [Patent Document 2] Japanese Patent Application Publication No. 50-122534 [Patent Document 3] Japanese Patent Application Laid-Open No. 2002-327163 [Patent Document 4] Japanese Patent Application Laid-Open No. 2003-286465 [Patent Document 5] Japanese Patent Application Publication No. 2017-186527 Summary of the Invention [Problem to be solved by the invention]

[0008] Patent Document 3 discloses a configuration in which a halogen-based organic solvent is brought into contact with the bonded portion of a bonded structure. This configuration reduces the adhesive strength of the bonded portion, and then the bonded structure can be peeled from the bonded portion. However, there are concerns that the organic solvent may have an adverse effect on the environment, and that it is difficult to handle.

[0009] Patent Document 4 discloses an adhesive composition comprising a urethane adhesive, a release agent, and a foaming agent. When using such an adhesive, the two adherends can be easily separated by irradiating the adhesive with energy such as laser light. However, the energy irradiating device must be a closed device due to the effects on the human body, and it is difficult to keep such a device ready at all times.

[0010] Patent Document 5 discloses a configuration in which a hot melt resin containing a SEEPS block copolymer as a main component is used as an adhesive. However, when the adherend has a smooth surface such as iron, there is a risk that peeling will occur at the interface between the adherend and the adhesive due to impact during transportation, etc., and the adhesive state will not be able to be maintained.

[0011] As described above, with current technology, it is difficult to easily separate only one of the adherends in a bonded structure in which two adherends are bonded via an adhesive. Therefore, there is a need for a technology that can cause separation along the interface between the adherend and the adhesive layer in such a bonded structure.

[0012] The present disclosure has been made to solve at least one of the above-mentioned problems, and aims to provide a method for manufacturing a bonded structure, and a bonded structure, in which an adhesive layer and a second adherend can be peeled from a first adherend along the interface between the first adherend and the adhesive layer. The present disclosure can be realized in the following forms. [Means for solving the problem]

[0013] [1] A method for manufacturing a bonded structure in which a first adherend and a second adherend are bonded, comprising: an adhesive containing a moisture-curable hot-melt urethane is heated and melted and applied to the first adherend; The applied adhesive is moisture-cured; A method for manufacturing a bonded structure, comprising heating and melting the moisture-cured adhesive, and bonding the second adherend to the heat-melted adhesive. [2] A bonded structure in which a first adherend and a second adherend are bonded, an adhesive containing a moisture-curable hot-melt urethane is heated and melted and applied to the first adherend; The applied adhesive is moisture-cured; A bonded structure produced by heating and melting the moisture-cured adhesive and bonding the second adherend to the heat-melted adhesive. [3] A bonded structure in which a first adherend and a second adherend are bonded, The first adherend and the second adherend are bonded together with an adhesive containing a moisture-curing hot-melt urethane, A bonded structure that can be separated at the interface between the first adherend and the adhesive layer made of the adhesive by sliding the first adherend and the second adherend against each other. [Effects of the Invention]

[0014] According to the present disclosure, it is possible to provide a method for manufacturing a bonded structure, and a bonded structure, in which the adhesive layer and the second adherend can be peeled off from the first adherend along the interface between the first adherend and the adhesive layer. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a perspective view of a bonded structure of the present disclosure. [Figure 2] FIG. 2 is a diagram showing the preparation of a first adherend in the method for manufacturing a bonded structure according to the present disclosure. [Figure 3] FIG. 10 is a diagram showing the placement of a spacer relative to a first adherend. [Figure 4] FIG. 10 is a diagram showing the application of adhesive onto a first adherend. [Figure 5] This is a diagram showing scraping off adhesive with a scraper. [Figure 6] FIG. 10 is a diagram showing a state in which the thickness of the adhesive has been made uniform. [Figure 7] FIG. 10 is a view showing the spacer removed from the first adherend. [Figure 8] FIG. 10 is a diagram showing a second adherend placed on the adhesive. [Figure 9] FIG. 10 is a diagram showing the second adherend being pressed in the shear direction with a finger. [Figure 10] FIG. 10 is a diagram showing the adhesive layer and the second adherend peeled off from the first adherend. [Figure 11] FIG. 1 is a diagram showing a state in which two adherends in a conventional bonded structure have been peeled off. DETAILED DESCRIPTION OF THE INVENTION

[0016] The present disclosure will be described in detail below. In this specification, when a numerical range is indicated using "to" it is intended to include both the lower limit and the upper limit unless otherwise specified. For example, the expression "10 to 20" includes both the lower limit "10" and the upper limit "20". In other words, "10 to 20" has the same meaning as "10 or more and 20 or less".

[0017] 1. Adhesive structure 1, the bonded structure 10 is a structure in which a first adherend 11 and a second adherend 12 are bonded together. The bonded structure 10 includes the first adherend 11, the second adherend 12, and an adhesive layer 13. The first adherend 11 and the second adherend 12 are bonded together by the adhesive layer 13.

[0018] The first adherend 11 has, for example, a rectangular plate shape. The surface of the first adherend 11 that is bonded to the adhesive layer 13 is smooth. The first adherend 11 is made of a material that is harder than the second adherend 12, which will be described later. Examples of materials for the first adherend 11 include metal, resin, plastic, ceramic, natural rubber, synthetic rubber, polyurethane, and melamine.

[0019] The second adherend 12 is, for example, a rectangular plate. The surface of the second adherend 12 that is bonded to the adhesive layer 13 has projections and recesses. Examples of materials for the second adherend 12 include natural rubber, synthetic rubber, polyurethane, melamine foam, paper, nonwoven fabric, natural leather, and synthetic leather.

[0020] The adhesive layer 13 is formed by moisture-curing an adhesive 14. The adhesive 14 contains a moisture-curing hot-melt urethane. The specific composition of the moisture-curing hot-melt urethane will be described in detail later. The adhesive 14 can be melted by heating even after moisture-curing.

[0021] The adhesive 14 is heated and melted, and then applied to the first adherend 11. The adhesive 14 applied to the first adherend 11 is then moisture-cured. The moisture-cured adhesive 14 is then heated and melted again to bond the second adherend 12. In this manner, the bonded structure 10 is produced.

[0022] It is conceivable to initially moisture-cure the adhesive 14 applied to the first adherend 11, but the viscosity would increase due to the slight moisture cure. This makes it difficult to dispense moisture-cure adhesive using a typical adhesive applicator. It is impossible to measure the viscosity of such moisture-cure adhesive. On the other hand, adhesive 14 that is heated after moisture cure is close to a gel and has a higher viscosity than the viscosity measurement range.

[0023] The bonded structure 10 can be separated at the interface between the first adherend 11 and the adhesive layer 13 by sliding the first adherend 11 and the second adherend 12 against each other. As shown in FIG. 9 , the bonded structure 10 peels at the interface between the first adherend 11 and the adhesive layer 13 only when a force is applied in the shear direction (sliding direction). That is, the adhesive layer 13 and the second adherend 12 can be peeled from the first adherend 11 along the interface between the first adherend 11 and the adhesive layer 13. The adhesive layer 13 and the second adherend 12 can be peeled from the first adherend 11 without damaging the second adherend 12. The adhesive, which becomes more viscous as it cures with moisture, is less likely to penetrate into the second adherend, which is thought to make it less likely that the second adherend will be damaged when attempting to peel it from the first adherend.

[0024] The bonded structure 10 allows the adhesive layer 13 and the second adherend 12 to be peeled off from the first adherend 11 with bare hands without using any special equipment. Only one type of adhesive 14 is used, and no primer treatment or other process is required.

[0025] 2. Composition of moisture-curing hot melt urethane The moisture-curable hot-melt urethane composition is a hot-melt adhesive composition containing a urethane prepolymer obtained by reacting a polyol component (A) with a polyisocyanate component (B). During the reaction, the polyisocyanate component (B) is typically reacted in a stoichiometric excess. Other components may also be included within the range that does not impair the effects of the invention. The urethane prepolymer, other components, and the amounts of each component are described below. To achieve a configuration that allows the adhesive layer 13 and second adherend 12 to be peeled from the first adherend 11 along the interface between the first adherend 11 and the adhesive layer 13, the urethane prepolymer preferably has the following composition:

[0026] <<Urethane prepolymer>> The urethane prepolymer is obtained by reacting a polyol component (A) with a polyisocyanate component (B).

[0027] <Polyol component (A)> The polyol component contains an alicyclic polycarbonate polyol (a-1), a crystalline polyester polyol (a-2), and a polyether polyol (a-3), and preferably further contains a low-molecular-weight diol (a-4). Each of these components will be described below.

[0028] (a-1: Alicyclic polycarbonate polyol) The alicyclic polycarbonate polyol of the present disclosure is a polycarbonate polyol that is a linear polymer having a carbonate ester bond in the main chain and two or more hydroxyl groups in the molecule, and that also has an alicyclic structure having six or more carbon atoms in the molecule. The alicyclic polycarbonate polyol of the present disclosure is preferably a solid at room temperature. The alicyclic structure is not particularly limited as long as it has six or more carbon atoms, and examples include those with 6 to 10 carbon atoms, but those with six carbon atoms are widely used and preferred. The alicyclic structure is a cyclic aliphatic hydrocarbon, and includes cycloalkanes, cycloalkenes, cycloalkynes, etc., with cycloalkanes containing no double or triple bonds being preferred.

[0029] Such alicyclic polycarbonate polyols are not particularly limited as long as they have an alicyclic structure with 6 or more carbon atoms in the molecule, and for example, those described in Japanese Patent No. 5303846 can be used.

[0030] More specifically, for example, 1,4-cyclohexanediol, 1,6-cyclohexanediol, cycloheptanediol, cyclooctanediol, 1,4-cyclohexanedimethanol, hydroxypropylcyclohexanol, tricyclo[5,2,1,02,6]decane-dimethanol, bicyclo[4,3,0]-nonanediol, dicyclohexanediol, tricyclo[5,3,1,1]dodecanediol, bicyclo[4,3,0]nonanedimethanol, tricyclo[5,3,1,1]dodecane-diethanol, hydroxypropyltricyclo[5,3,1,1]dodecanol, spiro[3,4]octanediol, butylcyclohexanediol, 1,1'-bicyclohexylidenediol, cyclohexanetriol, and hydrogenated bisphenol A. Examples of the reaction product include a reaction product of an alicyclic polyol such as 1,3-adamantanediol with a dialkyl carbonate such as dimethyl carbonate, a cyclic carbonate such as ethylene carbonate, or phosgene.

[0031] The alicyclic polycarbonate polyol preferably has a number average molecular weight of 500 to 3,000. When the number average molecular weight of the alicyclic polycarbonate polyol is 500 or more, the mechanical strength of the adhesive after curing is improved, and when it is 3,000 or less, the final adhesive strength of the adhesive after curing can be maintained. The number average molecular weight of the alicyclic polycarbonate polyol is more preferably 800 or more and more preferably 2,000 or less. In the present disclosure, the number average molecular weight is determined by gel permeation chromatography using a PEG standard in accordance with ASTM standard test D5296.

[0032] When the moisture-curable hot-melt urethane composition of the present disclosure contains such an alicyclic polycarbonate polyol in an amount described below, the cohesion of the adhesive composition is enhanced, and volume shrinkage upon cooling and solidification can be prevented.

[0033] (a-2: Crystalline polyester polyol) As the crystalline polyester polyol, a polyester polyol having a melting point of 60°C to 80°C can usually be used. The crystalline polyester polyol (a1-2) is an essential component in that it provides excellent adhesiveness (initial adhesive strength and final adhesive strength), and for example, a reaction product of a compound having two or more hydroxyl groups with a polybasic acid can be used. In the present disclosure, "crystalline" refers to a material in which a peak of the heat of crystallization or heat of fusion can be confirmed in DSC (differential scanning calorimetry) measurement in accordance with JIS K7121-1987, and "amorphous" refers to a material in which such a peak cannot be confirmed.

[0034] Specific examples of the crystalline polyester polyol include polyester polyols obtained by reacting 1,6-hexanediol with adipic acid, 1,6-hexanediol with sebacic acid, 1,4-butanediol with 1,12-dodecanedicarboxylic acid, 1,6-hexanediol with 1,12-dodecanedicarboxylic acid, 1,10-nonanediol with succinic acid, 1,10-nonanediol with adipic acid, and 1,8-octanediol with adipic acid. Among these, polyester polyols represented by the following formula (1) (wherein n is an integer of 3 to 40), R 1 and R 2 are each independently a linear alkylene group having an even number of Cs, and R 1 and R 2 It is preferable that the total number of C's is 12 or more. TIFF0007720449000001.tif25169

[0035] The crystalline polyester polyol preferably has a number average molecular weight of 2,000 to 10,000.

[0036] (a-3: Polyether polyol) Examples of polyether polyols include polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, etc., which are obtained by ring-opening and addition polymerization of cyclic ethers such as ethylene oxide, propylene oxide, and tetrahydrofuran, respectively, and copolyethers thereof. Polyether polyols can also be obtained by polymerizing the above-mentioned cyclic ethers using polyhydric alcohols such as glycerin and trimethylolethane. Among these, polytetramethylene ether glycol is preferred.

[0037] The polyether polyol preferably has a number average molecular weight of 1,000 to 3,000. By adding polyether polyol to the moisture-curable hot-melt urethane composition, a certain amount of soft segments are formed molecularly, and the adhesive after reaction curing has excellent hydrolysis resistance, moist heat aging resistance, and weather resistance.

[0038] (a-4: low molecular weight diol) The low molecular weight diol is not particularly limited, but examples thereof include cyclohexanedimethanol, cyclohexanediethanol, adamantane dimethanol, adamantane diethanol, cyclopentane dimethanol, and cyclopentane diethanol.

[0039] The low molecular weight diol preferably has a number average molecular weight of 500 or less.

[0040] The polyol component (A) may contain other polyols (for example, acrylic polyols) within the range that does not impair the effects of the invention.

[0041] <<Polyisocyanate (B)>> The polyisocyanate (B) is not limited in any way as long as it is a polyisocyanate that is used in the production of a normal urethane prepolymer, and examples thereof include tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), polymethylene polyphenyl polyisocyanate, hydrogenated MDI, 1,5-naphthalene diisocyanate, tolylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), isophorone diisocyanate, xylylene diisocyanate (XDI), hydrogenated XDI, tetramethylxylene diisocyanate (TMXDI), 1,8-diisocyanatomethyloctane, lysine ester triisocyanate, 1,3,6-hexamethylene triisocyanate, 1,6,11-undecane triisocyanate, bicycloheptane triisocyanate, and modified products and derivatives thereof.

[0042] <<Other ingredients>> The adhesive 14 composition of the present disclosure may contain various additives in addition to the components described above, provided that the additives do not impair the object of the invention. Examples of additives include fillers, plasticizers, pigments, dyes, antioxidants, antioxidants, antistatic agents, flame retardants, adhesion promoters, antibacterial agents, light stabilizers, stabilizers, dispersants, and solvents.

[0043] Here, the NCO group content of the polyurethane prepolymer is not particularly limited, but is preferably 0.5 to 10%, more preferably 0.7 to 2.5%, even more preferably 0.8 to 2.0%, and particularly preferably 1.0 to 1.8%. When it is 0.5% or more, heat resistance is improved. When it is 10% or less, thermal stability during heat melting is improved. Note that such NCO group content is measured in accordance with JIS K1603-1.

[0044] <<Amount of each ingredient>> The content of the alicyclic polycarbonate polyol (a-1) relative to the entire polyol component (A) is preferably 5 to 50% by weight, more preferably 5 to 45% by weight, and even more preferably 10 to 40% by weight.

[0045] The content of the crystalline polyester polyol (a-2) in the entire polyol component (A) is preferably 20 to 60% by weight, more preferably 30 to 50% by weight.

[0046] The content of the polyether polyol (a-3) in the entire polyol component (A) is preferably 20 to 60% by weight, more preferably 25 to 45% by weight.

[0047] The content of the low molecular weight diol (a-4) in the entire polyol component (A) is preferably 1 to 10% by weight, more preferably 2 to 8% by weight.

[0048] Here, in the moisture-curable hot-melt urethane composition of the present disclosure, the content of the alicyclic structure in the alicyclic polycarbonate polyol (a-1) in the prepolymer is in the range of more than 1 wt % and less than 10 wt %, preferably in the range of 3 to 9 wt %.

[0049] The content of the above other components in the moisture-curing hot-melt urethane composition according to this embodiment is not particularly limited, but may be, for example, 10% by weight or less of the entire moisture-curing hot-melt urethane composition.

[0050] 3.Application examples of adhesive structures The bonded structure 10 is used, for example, as a cleaning member. Cleaning is performed using the second adherend 12 while the first adherend 11 and the second adherend 12 are bonded together with the adhesive layer 13. The second adherend 12 is removed from the first adherend 11 depending on the amount of dirt accumulated on the second adherend 12 and the state of damage. A second adherend 12 different from the removed second adherend 12 is then bonded to the first adherend 11 using the adhesive 14.

[0051] The bonded structure 10 can also be applied to roller members such as transfer rollers and supply rollers. The first adherend 11 is configured as a metal shaft. The second adherend 12 is configured as a polyurethane foam covering the outer periphery of the first adherend 11. The shapes of the first adherend 11 and the second adherend 12 are not limited to those exemplified.

[0052] 4. Manufacturing method of bonded structure The bonded structure 10 includes an application step, a moisture curing step, and a bonding step. First, as shown in FIG. 2, a first adherend 11 is prepared. The first adherend 11 is, for example, a rectangular plate. Next, as shown in FIG. 3, a plurality of spacers 22, 23 (a pair of spacers 22 and a pair of spacers 23 in FIG. 3) are arranged so as to surround the longitudinal center portion (bonding region 21) on the upper surface of the first adherend 11. The thickness of the spacer 22 is greater than the thickness of the first adherend 11 and the thickness of the spacer 23. The spacer 22 has a thickness equal to the sum of the thickness of the first adherend 11 and the thickness of the spacer 23. The pair of spacers 22 are arranged at positions sandwiching the first adherend 11 in the lateral direction. The pair of spacers 23 are respectively arranged at both ends of the longitudinal direction on the upper surface of the first adherend 11.

[0053] Next, the adhesive 14 is put into a melter (applicator, not shown) and heated to melt it. As shown in FIG. 4, the heated and melted adhesive 14 is applied onto the bonding area 21 (application process). The adhesive 14 spills out of the bonding area 21 and is also applied to parts of the spacers 22 and 23 surrounding the bonding area 21. Next, as shown in FIG. 5, a scraper 24 is used to remove the adhesive 14 that spills out of the bonding area 21. This makes the thickness of the adhesive 14 uniform, as shown in FIG. 6. The uniform thickness of the adhesive 14 makes it easier for the moisture curing, which will be described later, to occur uniformly.

[0054] Next, the adhesive 14 is cooled and moisture-cured (moisture-curing step). Subsequently, as shown in FIG. 7, the spacers 22 and 23 are removed. A second adherend 12 is placed on top of the moisture-cured adhesive 14 (see FIG. 8). Next, the adhesive 14 is heated and melted, and the second adherend 12 is bonded to the adhesive 14 (bonding step). Subsequently, the adhesive 14 is cooled and solidified. This results in the production of a bonded structure 10 in which the first adherend 11 and the second adherend 12 are bonded together by the adhesive layer 13, as shown in FIG. 8.

[0055] 5.Method of peeling off bonded structures As shown in FIG. 9, the second adherend 12 is pressed with a finger in the shear direction against the fixed first adherend 11. The shear direction is parallel to the plate surface of the first adherend 11 and is the direction in which the first adherend 11 and the second adherend 12 slide relative to each other. For example, the side of the second adherend 12 is pressed with a finger. As shown in FIG. 10, peeling occurs at the interface between the first adherend 11 and the adhesive layer 13, and the second adherend 12 and the adhesive layer 13 separate from the first adherend 11 while remaining integral with each other. Neither the second adherend 12 nor the adhesive layer 13 remains on the top surface of the first adherend 11.

[0056] The reason for the peeling at the interface between the first adherend 11 and the adhesive layer 13 is thought to be that the adhesive 14 was moisture-cured before bonding the second adherend 12. The NCO group content of the polyurethane prepolymer contained in the adhesive 14 was relatively low, which is thought to have prevented sufficient moisture curing.

[0057] The reason why no damage occurred in the second adherend 12 is thought to be that the adhesive 14 was moisture-cured before bonding the second adherend 12. It is thought that the moisture-curing increases the viscosity of the adhesive 14, reducing the amount of adhesive 14 that seeps into the second adherend 12. This makes it difficult for the adhesive 14 to solidify within the second adherend 12, and the solidified adhesive 14 is thought to prevent damage to the second adherend 12. [Example]

[0058] The present disclosure will be explained in more detail below with reference to examples. Examples 1 to 3 correspond to examples of the present invention, and Examples 4 and 5 correspond to comparative examples. Details of the examples are shown in Table 1, which will be described later.

[0059] (1) Experimental Examples 1 to 3 (1-1) First attachment In Experimental Examples 1 and 2, stainless steel (SUS303, 50 mm×150 mm×2 mm) was used as the first adherend, and in Experimental Example 3, polyethylene resin was used as the first adherend.

[0060] (1-2) Second attachment In Experimental Examples 1 and 3, the second adherend was made of urethane foam (manufactured by Inoac Corporation, Urethane Foam EMM, density 52 kg / m 3 In Experimental Example 2, a melamine foam (Melamine Foam W, manufactured by Inoac Corporation, density 9 kg / m) was used as the second adherend. 3 , 50mm x 50mm x 3.5mm) was used.

[0061] (1-3) Adhesive In Experimental Examples 1 to 3, the adhesive used was a moisture-curable hot-melt urethane (moisture-curable urethane hot-melt manufactured by Inoac Corporation). The adhesive used was remeltable after moisture curing. The raw materials for the adhesive are listed below.

[0062] <<Raw materials>> <Polyol component (A)> (a-1: Alicyclic polycarbonate polyol) Eternacol UC-100: Manufactured by Ube Industries, Ltd.: 1,4-cyclohexanedimethanol-based polycarbonate diol (number average molecular weight approximately 1,000, alicyclic structure content 49.5% by weight) Eternacol UM90 (3 / 1): manufactured by Ube Industries, Ltd.: 1,4-cyclohexanedimethanol / 1,6-hexanediol = 3 / 1 (molar ratio) copolymer polycarbonate diol (number average molecular weight: approximately 1,000, alicyclic structure content 34.8% by weight) (a-2: Crystalline polyester polyol) HS2H500S (Toyokuni Oil, molecular weight 5,000) (a-3: Polyether polyol) Polytetramethylene ether glycol (product name: PTMG2000, number average molecular weight 2,000) (manufactured by Mitsubishi Chemical Corporation) (a-4: low molecular weight diol) Butylethylpropanediol (BEPG) <Polyisocyanate (B)> MDI (monomeric methylene diphenyl diisocyanate) <Aliphatic polycarbonate diol> Polyhexamethylene carbonate diol (Asahi Kasei Chemicals Corporation, Duranol T6002, number average molecular weight 2,000)

[0063] (1-4) Preparation of adhesive structures In Experimental Examples 1 to 3, the bonded structures were fabricated in the following manner. First, a first adherend is prepared. The first adherend is, for example, a rectangular plate. Next, a plurality of spacers are arranged so as to surround the longitudinal center portion (adhesion area) on the upper surface of the first adherend (see FIG. 3). A pair of spacers is arranged at positions sandwiching the first adherend in the lateral direction. The pair of spacers is respectively arranged at both ends in the longitudinal direction on the upper surface of the first adherend. The lateral width of the spacers sandwiching the first adherend in the lateral direction is, for example, 50 mm. The thickness of the spacers sandwiching the first adherend in the lateral direction is, for example, 2.4 mm. The thickness of the spacers arranged on the first adherend is, for example, 0.4 mm.

[0064] Next, the adhesive is poured into a hot melt applicator (Bag Melter PUR-20 manufactured by ITW Dynatec Corporation) and heated to melt at 120°C. The heated and melted adhesive is applied to the bonding area (application process, see Figure 4). The adhesive overflows from the bonding area and is also applied to part of the spacer surrounding the bonding area. Next, a scraper is used to scrape off the adhesive that has overflowed from the bonding area (see Figure 5). This ensures a uniform thickness of the adhesive. The adhesive is applied to the top surface of the first adherend in an area of 50 mm x 50 mm x 0.4 mm.

[0065] Next, the adhesive is cooled and moisture-cured (moisture-curing process). For example, it is left to cool for three days in an environmental chamber at a room temperature of 23°C and a relative humidity of 55%. Next, the spacer is removed. A second adherend is placed on top of the moisture-cured adhesive (see Figure 8). Next, the adhesive is heated to melt and adhere to the second adherend (adhesion process). The adhesive is heated in a thermostatic chamber (Kusumoto Chemicals, ETAC HIFLEX FX414C). The viscosity of the adhesive is 60,000 mPa·s at 120°C. The viscosity was measured using a measuring device (Anton Paar, Modular Compact Rheometer MCR302). Next, the adhesive is naturally cooled to 23°C and solidified. This produces a bonded structure in which the first adherend and the second adherend are bonded together with an adhesive layer.

[0066] (2) Experimental Example 4 (2-1) First attachment In Experimental Example 4, stainless steel (SUS303, 50 mm×150 mm×2 mm) was used as the first adherend.

[0067] (2-2) Second attachment In Experimental Example 4, the second adherend was made of urethane foam (manufactured by Inoac Corporation, Urethane Foam EMM, density 52 kg / m 3 , 50mm x 50mm x 3.5mm) was used.

[0068] (2-3) Adhesive In Experimental Example 4, an olefin-based hot melt adhesive (NSH-784, manufactured by Nakagawa Shokai) was used as the adhesive. This adhesive is a non-moisture curing type.

[0069] (2-4) Preparation of adhesive structures In Experimental Example 4, a bonded structure was fabricated using the following procedure. First, as in Experimental Examples 1 to 3, a plurality of spacers were placed on the first adherend (see FIG. 3). Next, the adhesive was poured into a hot melt applicator (Nordson AB10TT melter) and heated to 150°C to melt. The heated and melted adhesive was applied to the bonding area (application step, see FIG. 4). As in Experimental Examples 1 to 3, a scraper was used to scrape off any adhesive that had spilled out of the bonding area (see FIG. 5). As a result, the adhesive was applied to the top surface of the first adherend 11 in a size of 50 mm x 50 mm x 0.4 mm.

[0070] Next, the adhesive is naturally cooled to 23°C and solidified. Then, the spacer is removed. A second adherend is placed on top of the solidified adhesive. Next, the adhesive is heated and melted to bond the second adherend to the adhesive (bonding process). The adhesive is heated using a thermostatic oven (Kusumoto Chemicals, ETAC HIFLEX FX414C thermostatic oven). Next, the adhesive is naturally cooled to 23°C and solidified. This produces a bonded structure in which the first adherend and the second adherend are bonded together with an adhesive layer.

[0071] (3) Experimental Example 5 (3-1) First attachment In Experimental Example 5, stainless steel (SUS303, 50 mm×150 mm×2 mm) was used as the first adherend.

[0072] (3-2) Second attachment In Experimental Example 5, the second adherend was made of urethane foam (manufactured by Inoac Corporation, Urethane Foam EMM, density 52 kg / m 3 , 50mm x 50mm x 3.5mm) was used.

[0073] (3-3) Adhesive In Experimental Example 5, a moisture-curable hot-melt urethane adhesive (moisture-curable urethane hot-melt manufactured by Inoac Corporation) was used. The moisture-curable hot-melt urethane was remeltable after moisture curing. The adhesive ingredients were the same as those in Experimental Example 1.

[0074] (3-4) Preparation of adhesive structures In Experimental Example 5, a bonded structure was fabricated using the following procedure. First, as in Experimental Examples 1 to 3, multiple spacers were placed on the first adherend (see Figure 3). Next, the adhesive was poured into a hot melt applicator (Bag Melter PUR-20 manufactured by ITW Dynatec Corporation) and heated to 120°C to melt. The heated and melted adhesive was applied to the bonding area (application step, see Figure 4). As in Experimental Examples 1 to 3, a scraper was used to scrape off any adhesive that had spilled out of the bonding area (see Figure 5). This resulted in the adhesive being applied to the top surface of the first adherend in a size of 50 mm x 50 mm x 0.4 mm.

[0075] Next, the adhesive is naturally cooled to 23°C and solidified. The spacer is then removed. A second adherend is placed on top of the solidified adhesive (see Figure 8). The adhesive is then heated and melted, and the second adherend is bonded to the adhesive (bonding process). The adhesive is heated in a thermostatic chamber (Kusumoto Chemicals, ETAC HIFLEX FX414C). The viscosity of the adhesive is 60,000 mPa·s at 120°C. The viscosity was measured using a measuring device (Anton Paar, Modular Compact Rheometer MCR302). The adhesive is then cooled and moisture-cured. For example, the adhesive is left to cool for three days in an environmental chamber at room temperature of 23°C and relative humidity of 55%. This produces a bonded structure in which the first adherend and the second adherend are bonded together with an adhesive layer.

[0076] (4) Evaluation test (4-1) Test method The second adherend was pressed with a finger in the shear direction against the fixed first adherend (see Figure 9). The shear direction was parallel to the plate surface of the first adherend, and was the direction in which the first adherend and the second adherend slid against each other. For example, the side of the second adherend was pressed with a finger. The state of destruction of the second adherend was confirmed. That is, it was confirmed whether the second adherend had been destroyed and whether the adhesive and a part of the destroyed second adherend remained on the surface of the first adherend.

[0077] (4-2) Evaluation results The evaluation results are shown in Table 1. Criteria for peeling: "A": Peeling occurs at the interface between the first adherend and the adhesive, and neither the adhesive nor the second adherend remains on the surface of the first adherend. "B": The second adherend breaks, and the adhesive and fragments of the broken second adherend remain on the surface of the first adherend. "C": Peeling occurs at the interface between the second adherend and the adhesive, and the adhesive remains on the surface of the first adherend.

[0078] The peeling state of Experimental Examples 1 to 3 was evaluated as "A." In Experimental Examples 1 to 3, the second adherend was adhered after the adhesive was moisture-cured, so peeling occurred at the interface between the first adherend and the adhesive. Furthermore, in Experimental Examples 1 to 3, the second adherend was adhered after the adhesive was moisture-cured, so no damage occurred in the second adherend 12. Therefore, in Experimental Examples 1 to 3, the first adherend and the second adherend can be separated at the interface between the first adherend and the adhesive layer by sliding them against each other.

[0079] Experimental Example 4 was rated as "B" for the peeling condition. In Experimental Example 4, a non-moisture-curing adhesive was used, and the adhesive was applied to the first adherend and solidified, and then heated and melted to adhere the second adherend. As a result, the second adherend broke, and the adhesive and fragments of the broken second adherend remained on the surface of the first adherend.

[0080] Experimental Example 5 was rated as "C" for the peeling state. In Experimental Example 5, a moisture-curing adhesive was used, but the adhesive applied to the first adherend was solidified without moisture curing. The second adherend was then placed on the heat-melted adhesive and moisture cured. As a result, peeling occurred at the interface between the second adherend and the adhesive, and the adhesive remained on the surface of the first adherend.

[0081] [Table 1]

[0082] (5) Effects of the Example In Examples 1 to 3, it was possible to produce bonded structures in which the adhesive layer and the second adherend could be peeled from the first adherend along the interface between the first adherend and the adhesive layer.

[0083] The present invention is not limited to the above-described embodiments, and various modifications and variations are possible within the scope of the claims of the present invention. [Explanation of symbols]

[0084] 10…Adhesive structure 11...First attachment 12...Second wear 13...adhesive layer 14...Adhesive

Claims

[Claim 1] A bonded structure in which a first adherend and a second adherend are bonded, the material of the first adherend is selected from the group consisting of metal, resin, plastic, ceramic, natural rubber, synthetic rubber, polyurethane, and melamine; the material of the second adherend is selected from the group consisting of natural rubber, synthetic rubber, polyurethane, melamine foam, paper, nonwoven fabric, natural leather, and synthetic leather; the first adherend is made of a material harder than the second adherend; the first adherend and the second adherend are bonded together with an adhesive containing moisture-curing hot-melt urethane, The adhesive contains an alicyclic polycarbonate polyol as a raw material, A bonded structure that can be separated at the interface between the first adherend and the adhesive layer made of the adhesive by sliding the first adherend and the second adherend against each other.

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