Joining structure and joining method

Abstract

Provided is a joining method capable of ensuring sufficient joining strength even with respect to a hardly adhesive material. In the present invention, plasma treatment is performed on surfaces (2Ca, 3Ca) of a first material 2C and a second material 3C to cut bonds in the surfaces (2Ca, 3Ca) of the first material 2C and the second material 3C and to form hydrophilic groups (fig. 6(a)-(b)). The surface 2Ca of the first material 2C and the surface 3Ca of the second material 3C having hydrophilic groups formed thereon are superimposed in an air atmosphere (fig. 6(c)). Then, in the air atmosphere, the surface 2Ca of the first material 2C and the surface 3Ca of the second material 3C are brought close to each other to a distance where a chemical reaction occurs therebetween by applying a prescribed pressure, and, by causing dehydration condensation to occur therebetween, the surface 2Ca of the first material 2C and the surface 3Ca of the second material 3C are chemically joined by means of covalent bonds (fig. 6(d)-(e)).

Description

Bonding Structure and Bonding Method

[0001] The present invention relates to a bonding structure and a bonding method capable of bonding predetermined materials to each other without using an adhesive.

[0002] Conventionally, when bonding predetermined materials to each other, an adhesive has been used, for example, as shown in Patent Document 1.

[0003] Japanese Unexamined Patent Application Publication No. 2018-43415

[0004] However, when bonding difficult-to-bond materials such as materials with incompatible properties or non-polar materials, there has been a problem that sufficient bonding strength cannot be secured if an adhesive is used.

[0005] In view of the above problems, an object of the present invention is to provide a bonding structure and a bonding method capable of securing sufficient bonding strength even for a difficult-to-bond material.

[0006] The above object of the present invention is achieved by the following means. Note that reference numerals of embodiments described later are given in parentheses, but the present invention is not limited thereto.

[0007] The bonding structure according to claim 1 is characterized in that, when bonding a first material (2A) where at least one of the materials is a difficult-to-bond material and a second material (3A), a connecting material (4A) is provided between the first material (2A) and the second material (3A), and the first material (2A) and the second material (3A) are bonded via the connecting material (4A) by a bonding method that does not use an adhesive.

[0008] The joining method according to claim 2 is a method for joining a first material (2C) and a second material (3C), comprising the steps of: performing plasma treatment on the surfaces (2Ca, 3Ca) of the first material (2C) and the second material (3C) to break the bond between the surfaces (2Ca, 3Ca) of the first material (2C) and the second material (3C) and form hydrophilic groups (see Figures 6(a) to (b)); The present invention is characterized by comprising the steps of: overlapping the surface (2Ca) of the first material (2C) and the surface (3Ca) of the second material (3C), on which the hydrophilic groups are formed, in an air atmosphere (see Figure 6(c)); then, in an air atmosphere, applying a predetermined pressure to the surface (2Ca) of the first material (2C) and the surface (3Ca) of the second material (3C) to a distance at which a chemical reaction occurs between them, thereby bringing the surfaces (2Ca) of the first material (2C) and the surface (3Ca) of the second material (3C) closer together and causing dehydration condensation to chemically join them by covalent bonds (see Figures 6(d) to (e)).

[0009] The joining method according to claim 3, in joining a first material (2A) and a second material (3A) by providing a connecting material (4A) between the first material (2A) and the second material (3A), the steps of: performing plasma treatment on the surfaces (2Aa, 4Aa) of the first material (2A) and the connecting material (4A) to break the bond between the surfaces (2Aa, 4Aa) of the first material (2A) and the connecting material (4A) to form hydrophilic groups (see Figures 5(a) to (b)); and overlapping the surfaces (4Aa) of the first material (2A) and the connecting material (4A) to form the hydrophilic groups in an air atmosphere (see Figures 5(c) to (d)). The process involves applying plasma treatment to the surface (10Ba) of the intermediate material (10B) formed by overlapping the surface (2Aa) of the first material (2A) and the surface (4Aa) of the binder material (4A), and to the surface (3Aa) of the second material (3A), thereby breaking the bond between the intermediate material (10B) and the surfaces (10Ba, 3Aa) of the second material (3A) and forming hydrophilic groups (see Figures 5(e) to (f)). The present invention is characterized by comprising the steps of: overlapping the surface (10Ba) of the intermediate material (10B) on which the hydrophilic groups are formed with the surface (3Aa) of the second material (3A) in an air atmosphere (see Figures 5(g) to (h)); then, in an air atmosphere, applying a predetermined pressure to the surface (10Ba) of the intermediate material (10B) and the surface (3Aa) of the second material (3A) to a distance at which a chemical reaction occurs between them, thereby bringing the surfaces (10Ba) of the intermediate material (10B) and the surface (3Aa) of the second material (3A) closer together and causing dehydration condensation to chemically bond them together by covalent bonds (see Figures 5(i) to (j)).

[0010] The joining method according to claim 4 is a joining method for a first material (2C) and a second material (3C), comprising the step of placing a silicon-based material (7) on the back surfaces (2Cb, 3Cb) of the first material and / or the second material, which do not have a silicon layer formed thereon (see Figure 8 (a-1), (b-1)), The process involves performing plasma treatment on the surfaces (2Aa, 3Aa, 7a) of the first material on which the silicon-based material is placed and the second material on which the silicon-based material is placed, or the first material on which a silicon layer is formed and the second material on which the silicon-based material is placed, thereby breaking the bonds between the surfaces of the first material and the second material, and the surface of the silicon-based material, forming hydrophilic groups on the surfaces of the first material and the second material, and forming a silicon layer on the surfaces of the first material on which the silicon-based material is placed and / or the second material on which the silicon-based material is placed (see Figures 8 (a-2), (b-2), (c)), The present invention is characterized by comprising the steps of: overlapping the surface (2Ca) of the first material (2C) and the surface (3Ca) of the second material (3C) in an air atmosphere; then, in an air atmosphere, applying a predetermined pressure to bring the surfaces of the first material and the second material closer together by a distance at which a chemical reaction occurs between them, thereby causing dehydration condensation and chemically joining them by covalent bonds (see Figures 8(d) to (e)).

[0011] The joining method according to claim 5 involves joining a first material (2A) and a second material (3A) by providing a connecting material (4A) between them, and includes the steps of placing a silicon-based material (7) on the back surfaces (2Ab, 3Ab) of the first material and / or the second material and / or the connecting material, which do not have a silicon layer formed thereon (see Figures 9(a), (e)), The steps include: performing plasma treatment on the surfaces (2Aa, 4Aa, 7a) of the first material on which the silicon-based material is placed and the connecting material on which the silicon-based material is placed, or the first material on which a silicon layer is formed and the connecting material on which the silicon-based material is placed, thereby breaking the bond between the surfaces (2Aa, 4Aa) of the first material and the connecting material, and the surface (7a) of the silicon-based material, thereby forming hydrophilic groups on the surfaces of the first material and the connecting material, and forming a silicon layer on the surfaces of the first material on which the silicon-based material is placed and / or the connecting material on which the silicon-based material is placed (see Figures 9(b), (c)); and overlapping the surfaces of the first material on which the hydrophilic groups and the silicon layer are formed and the surfaces of the connecting material in an air atmosphere (see Figure 9(d)). If a silicon layer is not formed on the surface (10B1a) of the intermediate material (10B1) formed by overlapping the surface of the first material and the surface of the connecting material, the silicon-based material is placed on it, and plasma treatment is performed on the surface of the intermediate material and the surface of the second material on which the silicon-based material is placed or not placed, thereby breaking the bond between the surfaces of the intermediate material, the second material and the silicon-based material, forming hydrophilic groups on the surfaces of the intermediate material and the second material, and forming a silicon layer on the surface of the intermediate material on which the silicon-based material is placed and / or the surface of the second material on which the silicon-based material is placed (Figure 9(f)).(g) The present invention is characterized by comprising the steps of: (see Figures 9(h) to (j)) (see Figures 9(h) to (j)),

[0012] The joining method according to claim 6 is characterized in that, in the joining method according to any one of claims 2 to 5 above, water vapor is introduced when performing the plasma treatment.

[0013] The joining method according to claim 7 is characterized in that, in the joining method according to any one of claims 2 to 5 above, the predetermined pressure is applied while heating is performed.

[0014] Next, the effects of the present invention will be described with reference to the reference numerals in the drawings. Note that the reference numerals in parentheses are those of embodiments described later, but the present invention is not limited thereto.

[0015] According to the invention of claim 1, the first material (2A) and the second material (3A) can be firmly joined together via the connecting material (4A), so sufficient bonding strength can be ensured even with materials that are difficult to bond.

[0016] According to the invention of claim 2, an adhesive is not required, and furthermore, because the bonding is chemical, a strong bond can be achieved between the first material (2C) and the second material (3C). Therefore, sufficient bonding strength can be ensured even with materials that are difficult to bond.

[0017] According to the invention of claim 3, an adhesive is not required, and furthermore, since the materials are chemically bonded, a strong bond can be achieved between the first material (2A) and the second material (3A) by providing a connecting material (4A) between them. Therefore, even with materials that are difficult to bond, sufficient bonding strength can be ensured.

[0018] According to the invention of claim 4, the first material (2C) and the second material (3C) can be bonded together by siloxane bonding by forming a silicon layer, thereby chemically joining the first material (2C) and the second material (3C). As a result, a strong bond can be achieved without using an adhesive. Therefore, sufficient bonding strength can be ensured even with materials that are difficult to bond.

[0019] According to the invention of claim 5, in addition to the invention of claim 4, the first material (2A) and the second material (3A) can be firmly joined together via a connecting material (4A). Therefore, sufficient bonding strength can be ensured even with materials that are difficult to bond.

[0020] According to the invention of claim 6, the formation of hydrophilic groups can be promoted.

[0021] According to the invention of claim 7, the dehydration condensation reaction can be accelerated.

[0022] (a) is a perspective view of a joining structure according to one embodiment of the present invention, and (b) is a longitudinal cross-sectional view of a joining structure showing a modified example of (a). (a) is a perspective view of a joining structure different from that shown in Figure 1, and (b) is a longitudinal cross-sectional view of a joining structure showing a modified example of (a). This is a schematic diagram for explaining a vacuum plasma apparatus. (a) to (c) are explanatory diagrams for explaining a method of joining materials together without adhesive. (a) to (j) are explanatory diagrams showing the process of manufacturing the joining structure shown in Figure 1(b). (a) to (e) are explanatory diagrams showing the process of manufacturing the joining structure shown in Figure 2(b). (a) to (e) are explanatory diagrams for explaining a method of joining materials together without adhesive, different from that shown in Figure 4. (a-1) to (e) are explanatory diagrams showing the process of manufacturing the joining structure shown in Figure 1(b) using the method shown in Figure 7. (a) to (j) are explanatory diagrams showing the process of manufacturing the joining structure shown in Figure 2(b) using the method shown in Figure 7.

[0023] Hereinafter, one embodiment of the joint structure according to the present invention will be specifically described with reference to the drawings. In the following description, when the directions of up, down, left, and right are indicated, they refer to the up, down, left, and right directions as viewed from the front as shown in the drawings.

[0024] <Description of Joining Structure> The joining structure according to this embodiment can ensure sufficient bonding strength even with materials that are difficult to bond. Specifically, as shown in Figure 1(a), the joining structure 1A is composed of a first material 2A, a second material 3A, and a connecting material 4A. Each component will be described in detail below. Note that at least one of the first material 2A and the second material 3A is made of a material that is difficult to bond.

[0025] The first material 2A is formed in a horizontally elongated rectangular shape, as shown in Figure 1(a), and examples of materials include polydimethylsiloxane (PDMS), glass, and nitrile rubber (NBR).

[0026] The second material 3A is formed in a horizontally elongated rectangular shape, as shown in Figure 1(a). Examples of materials include glass, acrylonitrile butadiene styrene copolymer (ABS), metals (e.g., copper, iron, stainless steel (SUS), aluminum (Al), etc.), polyphenylene sulfide (PPS), polybutylene terephthalate (PBT), polycarbonate ABS (PC / ABS), printed glass, triacetate film (TAC), polyethylene terephthalate (PET), polyetherimide (PEI), nitrile rubber (NBR), etc.

[0027] The bonding material 4A is formed in a rectangular shape, as shown in Figure 1(a), and examples of materials include polycarbonate (PC), ABS (ABS alloy), acrylonitrile butadiene styrene copolymer (ABS), polypropylene (PP), glass, polyurethane (PU), polyimide (PI), aluminum (Al), and polydimethylsiloxane (PDMS).

[0028] Thus, the bonded structure 1A constructed in this manner is bonded in the following way: as shown in Figure 1(a), the right side of the first material 2A and the left side of the connecting material 4A are joined by conventional bonding methods that do not use adhesives, such as ultrasonic bonding. The left side of the second material 3A and the right side of the connecting material 4A are joined.

[0029] Therefore, in this manner, the first material 2A and the second material 3A can be firmly joined via the connecting material 4A. Thus, even with materials that are difficult to bond, sufficient bonding strength can be ensured.

[0030] In this embodiment, the example shown is that the right side of the first material 2A and the left side of the connecting material 4A are joined, and the left side of the second material 3A and the right side of the connecting material 4A are joined, but the embodiment is not limited to this. For example, as shown in Figure 1(b), the bottom surface of the first material 2A and the top surface of the connecting material 4A may be joined, and the top surface of the second material 3A and the bottom surface of the connecting material 4A may be joined. In other words, any configuration is acceptable as long as the first material 2A and the second material 3A can be joined via the connecting material 4A.

[0031] On the other hand, if it is not necessary to provide a connecting material 4A, the joint structure can be configured as shown in Figure 2(a) (1C) and Figure 2(b) (1D). To explain this in more detail below, the joint structure 1C shown in Figure 2(a) and the joint structure 1D shown in Figure 2(b) are composed of a first material 2C and a second material 3C.

[0032] The first material 2C is formed in a horizontally elongated rectangular shape, as shown in Figures 2(a) and (b). Examples of materials include polycarbonate (PC), acrylonitrile-butadiene-styrene copolymer (ABS), polydimethylsiloxane (PDMS), polypropylene (PP), fluorosilicone rubber (FVMQ), polyurethane (PU), acrylic (PMMA), polyethylene (PE), polyimide (PI), aluminum (Al), glass, and nitrile rubber (NBR).

[0033] The second material 3C is formed in a horizontally elongated rectangular shape, as shown in Figures 2(a) and (b). Examples of materials include polydimethylsiloxane (PDMS), acrylonitrile-butadiene-styrene copolymer (ABS), polyamide (PA), polyethylene naphthalate (PEN), polycarbonate (PC), polyetherimide (PEI), ethylene propylene rubber (EPDM), polyurethane (PU), acrylic (PMMA), polyethylene (PE), metals (e.g., copper, iron, stainless steel (SUS), aluminum (Al), etc.), polyphenylene sulfide (PPS), polybutylene terephthalate (PBT), polycarbonate-ABS (PC / ABS), printed glass, triacetate film (TAC), polyethylene terephthalate (PET), nitrile rubber (NBR), etc.

[0034] Thus, in the joint structure 1C shown in Figure 2(a), the right side of the first material 2C and the left side of the second material are joined by a conventional bonding method that does not use adhesives, such as ultrasonic bonding. In the joint structure 1D shown in Figure 2(b), the bottom surface of the first material 2C and the top surface of the second material are joined by a conventional bonding method that does not use adhesives, such as ultrasonic bonding.

[0035] <Explanation of Manufacturing Method for Joined Structures> While conventional bonding methods that do not use adhesives, such as ultrasonic bonding, were given as examples for manufacturing the joined structures 1A to 1D described above, it is preferable to manufacture them using the novel manufacturing method shown below. This will be explained in detail below.

[0036] First, a vacuum plasma apparatus 5 as shown in Figure 3 is prepared. This vacuum plasma apparatus 5 is equipped with a chamber 5a, which is under vacuum, as shown in Figure 3, and the first materials 2A, 2C, the second materials 3A, 3C, and the binder material 4A are placed inside this chamber 5a. By applying an AC voltage 5b to the chamber 5a, plasma is generated, and plasma treatment is performed on the surfaces of the first materials 2A, 2C, the second materials 3A, 3C, and the binder material 4A. Examples of the introduction gas 5c to be introduced into the chamber 5a shown in Figure 3 include nitrogen and water vapor.

[0037] By the way, the reason for performing plasma treatment on the surfaces of the first materials 2A and 2C, the second materials 3A and 3C, and the binder material 4A is as follows. This will be explained in detail with reference to Figure 4. In Figure 4, the first material 2C and the second material 3C are shown as examples, and further, the case in which polydimethylsiloxane (PDMS) is used as the material for the first material 2C and the second material 3C will be explained as an example.

[0038] As shown in Figure 4(a), the molecular structure is modified by irradiating the surface 2Ca of the first material 2C, which is made of polydimethylsiloxane (PDMS), and the surface 3Ca of the second material 3C, which is also made of polydimethylsiloxane (PDMS), with plasma PL. In other words, by modifying the surface 2Ca of the first material 2C and the surface 3Ca of the second material 3C, the surface bonds (shown in the figure as -CH) are modified. ３ The ) is cut. As a result, hydrophilic groups (-OH in the figure) are formed on the surface 2Ca of the first material 2C and the surface 3Ca of the second material 3C, as shown in Figure 4(b).

[0039] Next, as shown in Figure 4(b), the first material 2C and the second material 3C, which have undergone plasma treatment to form hydrophilic groups (shown as -OH in the figure) on the surface 2Ca of the first material 2C and the surface 3Ca of the second material 3C, are removed from the chamber 5a shown in Figure 3. Then, in an air atmosphere, as shown in Figure 4(c), a predetermined pressure is applied to bring the surface of the first material 2C and the surface of the second material 3C closer together by dehydration condensation, thereby chemically joining them by covalent bonds.

[0040] Thus, this method eliminates the need for adhesives, and furthermore, because the bonding is chemical, a strong bond is possible. Therefore, even with materials that are difficult to bond, sufficient bonding strength can be ensured.

[0041] Here, a method of manufacturing the bonding structures 1A to 1D described above will be described in further detail with reference to FIGS. 5 and 6. Since the bonding structures 1A and 1B differ only in the bonding position of the connecting material 4A, only the method of manufacturing the bonding structure 1B will be described with reference to FIG. 5. Further, since the bonding structures 1C and 1D differ only in the bonding position, only the method of manufacturing the bonding structure 1D will be described with reference to FIG. 6.

[0042] In manufacturing the bonding structure 1B, first, as shown in FIG. 5(a), a first material 2A and a connecting material 4A are placed in a chamber 5a. Then, in this state, the inside of the chamber 5a is evacuated, and as shown in FIG. 5(b), plasma PL is irradiated to perform plasma treatment on the surface 2Aa of the first material 2A (see FIG. 5(c)) and the surface 4Aa of the connecting material 4A (see FIG. 5(c)). As a result, as described above, hydrophilic groups are formed on the surface 2Aa of the first material 2A (see FIG. 5(c)) and the surface 4Aa of the connecting material 4A (see FIG. 5(c)). It is preferable to introduce water vapor as the introduction gas 5c introduced into the chamber 5a shown in FIG. 3. This is because the formation of hydrophilic groups is promoted.

[0043] Next, the first material 2A and the connecting material 4A that have undergone the above treatment are taken out from the chamber 5a, and as shown in FIG. 5(c), in an air atmosphere, the surface 2Aa of the first material 2A on which hydrophilic groups are formed and the surface 4Aa of the connecting material 4A on which hydrophilic groups are formed are superimposed on each other and temporarily bonded. As a result, the intermediate material 10B shown in FIG. 5(d) is manufactured.

[0044] Next, as shown in FIG. 5(e), the second material 3A and the intermediate material 10B are placed in the chamber 5a. Then, in this state, the inside of the chamber 5a is evacuated, and as shown in FIG. 5(f), plasma PL is irradiated to perform plasma treatment on the surface 3Aa (see FIG. 5(g)) of the second material 3A and the surface 10Ba (see FIG. 5(g)) of the intermediate material 10B. As a result, as described above, hydrophilic groups are formed on the surface 3Aa (see FIG. 5(g)) of the second material 3A and the surface 10Ba (see FIG. 5(g)) of the intermediate material 10B. It is preferable that water vapor is introduced as the introduction gas 5c to be introduced into the chamber 5a shown in FIG. 3. This is because the formation of hydrophilic groups is promoted.

[0045] Next, the second material 3A and the intermediate material 10B that have completed the above treatment are taken out from the chamber 5a, and as shown in FIG. 5(g), in an air atmosphere, the surface 3Aa of the second material 3A on which hydrophilic groups are formed and the surface 10Ba of the intermediate material 10B on which hydrophilic groups are formed are superimposed and temporarily bonded together. As a result, the state shown in FIG. 5(h) is obtained.

[0046] Next, the material in the state shown in FIG. 5(h) is sandwiched between the upper press plate 6A and the lower press plate 6B shown in FIG. 5(i), and a predetermined pressure is applied. Accordingly, the surface 3Aa of the second material 3A and the surface 10Ba of the intermediate material 10B are brought close to each other to a distance where a chemical reaction occurs between the surface 3Aa of the second material 3A and the surface 10Ba of the intermediate material 10B, and they are chemically bonded by a covalent bond through dehydration condensation. It is preferable to heat when applying the predetermined pressure. This is because the dehydration condensation reaction can be promoted.

[0047] Thus, through such treatment, the bonded structure 1B shown in FIG. 5(j) is manufactured. It should be noted that, in manufacturing the bonded structure 1A shown in FIG. 1(a), the same treatment as described above is performed, and thus a description thereof is omitted.

[0048] In manufacturing the bonded structure 1D, first, as shown in Figure 6(a), the first material 2C and the second material 3C are placed in the chamber 5a. Then, in this state, the chamber 5a is evacuated, and as shown in Figure 6(b), plasma PL is irradiated to perform plasma treatment on the surface 2Ca of the first material 2C (see Figure 6(c)) and the surface 3Ca of the second material 3C (see Figure 6(c)). As a result, hydrophilic groups are formed on the surface 2Ca of the first material 2C (see Figure 6(c)) and the surface 3Ca of the second material 3C (see Figure 6(c)), as described above. It is preferable to introduce water vapor as the introduction gas 5c into the chamber 5a shown in Figure 3, because it promotes the formation of hydrophilic groups.

[0049] Next, the first material 2C and the second material 3C, having undergone the above processing, are removed from the chamber 5a and, as shown in Figure 6(c), are temporarily bonded together in an air atmosphere by overlapping the surfaces 2Ca of the first material 2C and the surfaces 3Ca of the second material 3C, where hydrophilic groups have been formed. Then, the temporarily bonded materials are sandwiched between the upper press plate 6A and the lower press plate 6B shown in Figure 6(d), and a predetermined pressure is applied. This brings the surfaces 2Ca of the first material 2C and the surfaces 3Ca of the second material 3C closer together to a distance where a chemical reaction occurs, and chemically joins them by covalent bonding through dehydration condensation. It is preferable to heat the materials when applying the predetermined pressure, as this can promote the dehydration condensation reaction.

[0050] Thus, by performing this process, the joint structure 1D shown in Figure 6(e) is manufactured. Note that the same process is performed when manufacturing the joint structure 1C shown in Figure 2(a), so a detailed explanation is omitted.

[0051] Therefore, according to the novel manufacturing method described above, adhesives are not required, and furthermore, because the bonding is chemical, a strong bond is possible. As a result, sufficient bonding strength can be ensured even with materials that are difficult to bond.

[0052] <Explanation of Experimental Examples> To confirm the above, the inventors conducted the following experiment. Note that the experimental examples shown below are merely examples and are not limiting.

[0053] First, experiments were conducted to manufacture the joint structure 1A shown in Figure 1(a) and the joint structure 1B shown in Figure 1(b). Polypropylene (PP) was prepared as the material for the first material 2A, glass was prepared as the material for the second material 3A, and polydimethylsiloxane (PDMS) was prepared as the material for the bonding material 4A. Then, the manufacturing process was carried out as described with reference to Figure 5. The output conditions of the plasma PL were 10W / 30s / 50Pa, and the predetermined pressure was 1.0MPa / 300s without heating. Water vapor was introduced as the introduced gas 5c.

[0054] Based on these results, a strong bond was confirmed even without the use of adhesive.

[0055] Next, polyimide (PI) was prepared as the material for the first material 2A, glass was prepared as the material for the second material 3A, and polydimethylsiloxane (PDMS) was prepared as the material for the binder material 4A. Then, the manufacturing process was carried out as described with reference to Figure 5. The output conditions for the plasma PL were 10W / 30s / 50Pa, and the predetermined pressure was 1.0MPa / 300s without heating. Nitrogen was introduced as the introduction gas 5c.

[0056] Based on these results, a strong bond was confirmed even without the use of adhesive.

[0057] Next, experiments were conducted to manufacture the bond structure 1C shown in Figure 2(a) and the bond structure 1D shown in Figure 2(b). Acrylonitrile butadiene styrene copolymer (ABS) was prepared as the material for the first material 2C, and polyamide (PA) was prepared as the material for the second material 3C. The manufacturing process was carried out as described with reference to Figure 6. The output conditions of the plasma PL were 10 W / 30 s / 50 Pa, and the predetermined pressure was 1.0 MPa / 300 s after heating at 100°C. Water vapor was introduced as the introduction gas 5c.

[0058] Based on these results, a strong bond was confirmed even without the use of adhesive.

[0059] Next, polypropylene (PP) was prepared as the material for the first material 2C, and polydimethylsiloxane (PDMS) was prepared as the material for the second material 3C. Then, the manufacturing process was carried out as described with reference to Figure 6. The output conditions for the plasma PL were 10 W / 30 s / 50 Pa, and the predetermined pressure was 1.0 MPa / 300 s without heating. In addition, water vapor was introduced as the introduced gas 5c.

[0060] Based on these results, a strong bond was confirmed even without the use of adhesive.

[0061] Next, polypropylene (PP) was prepared as the material for the first material 2C, and ethylene propylene rubber (EPDM) was prepared as the material for the second material 3C. Then, the manufacturing process was carried out as described with reference to Figure 6. The output conditions for the plasma PL were 10W / 30s / 50Pa, and the predetermined pressure was 1.0MPa / 300s after heating at 100°C. In addition, nitrogen and water vapor were introduced as the introduction gas 5c in a ratio of 1:9.

[0062] As a result of the above, a strong bond was confirmed without the use of adhesive. In the case of EPDM sponge, bonding is possible by slightly fusing the surface and improving its flatness.

[0063] Next, polypropylene (PP) was prepared as the material for the first material 2C, and polyethylene (PE) was prepared as the material for the second material 3C. Then, the manufacturing process was carried out as described with reference to Figure 6. The output conditions for the plasma PL were 10W / 30s / 50Pa, and the predetermined pressure was set by heating the upper press plate 6A on the first material 2C side to 100°C and the lower press plate 6B on the second material 3C side to 80°C, and operating at 1.0 MPa / 300s. Nitrogen was introduced as the introduction gas 5c.

[0064] Based on these results, a strong bond was confirmed even without the use of adhesive.

[0065] Therefore, the experimental results above confirm that the novel manufacturing method can ensure sufficient bonding strength even with materials that are difficult to bond.

[0066] <Description of an alternative embodiment of the method for manufacturing the joint structure> In this embodiment, the above-described novel manufacturing method was given as an example of a method for manufacturing the joint structures 1A to 1D, but it can also be manufactured as follows. The manufacturing method is described below.

[0067] First, a vacuum plasma apparatus 5, as shown in Figure 3, is prepared, similar to the novel manufacturing method described above. This vacuum plasma apparatus 5 is equipped with a chamber 5a, as shown in Figure 3, which is under vacuum. The first materials 2A and 2C, the second materials 3A and 3C, and the binder material 4A are placed inside this chamber 5a. By applying an AC voltage 5b to the chamber 5a, plasma is generated, and plasma treatment is performed on the surfaces of the first materials 2A and 2C, the second materials 3A and 3C, and the binder material 4A. Examples of the introduced gas 5c to be introduced into the chamber 5a shown in Figure 3 include nitrogen and water vapor.

[0068] By the way, the reason for performing plasma treatment on the surfaces of the first materials 2A and 2C, the second materials 3A and 3C, and the bonding material 4A is as follows. This will be explained in detail with reference to Figure 7. In Figure 7, as a specific example, the joining of the first material 2C and the second material 3C is illustrated, and further, the case in which polycarbonate ABS (PC / ABS) is used as the material for the first material 2C and the second material 3C will be explained as an example.

[0069] As shown in Figure 7(a), a silicon-based material 7 is placed on the back surface 2Cb of the first material 2C made of polycarbonate ABS (PC / ABS) and on the back surface 3Cb of the second material 3C made of polycarbonate ABS (PC / ABS). In this embodiment, polydimethylsiloxane (PDMS) is used as an example of the silicon-based material 7.

[0070] Incidentally, as shown in Figure 7(a), the silicon-based material 7 is formed with a larger width (see W1, W2) than the first material 2C and the second material 3C. For example, the width of the silicon-based material 7 is formed to be 20 mm or more larger than the width of the first material 2C and the second material 3C. That is, the width W1 shown in Figure 7(a) is 20 mm or more, and the width W2 is 20 mm or more.

[0071] Thus, as shown in Figure 7(a), the molecular structure is modified by irradiating the surface 2Ca of the first material 2C on which the silicon-based material 7 is placed, the surface 3Ca of the second material 3C on which the silicon-based material 7 is placed, and the surface 7a of the silicon-based material 7 with plasma PL using water vapor gas. In other words, by modifying the surface 2Ca of the first material 2C and the surface 3Ca of the second material 3C, the surface bonding (shown in the figure as -CH) is modified. ３ The bonds (-H) are severed. Furthermore, by modifying the surface 7a of the silicon-based material 7, the surface bonds (in the figure, -Si-CH) are broken. ３ The surface 7a of the silicon-based material 7 is cut. As a result, as shown in Figure 7(b), the cut Si is scattered from the surface 7a of the silicon-based material 7 to the surface 2Ca of the first material 2C and the surface 3Ca of the second material 3C. Thus, the scattered Si is deposited onto the surface 2Ca of the first material 2C and the surface 3Ca of the second material 3C, and as a result, as shown in Figure 7(c), a silicon layer (Si layer) is formed on the surface 2Ca of the first material 2C and the surface 3Ca of the second material 3C. Furthermore, as shown in Figure 7(c), hydrophilic groups (-OH in the figure) are also formed on the surface 2Ca of the first material 2C and the surface 3Ca of the second material 3C.

[0072] Next, as shown in Figure 7(d), the first material 2C and the second material 3C, which have undergone plasma treatment to form a silicon layer (Si layer) and hydrophilic groups (-OH in the figure) on the surface 2Ca of the first material 2C and the surface 3Ca of the second material 3C, are removed from the chamber 5a shown in Figure 3. Then, the surface 2Ca of the first material 2C and the surface 3Ca of the second material 3C are placed facing each other as shown in Figure 7(d). Next, under an air atmosphere, a predetermined pressure is applied to bring the surface 2Ca of the first material 2C and the surface 3Ca of the second material 3C closer together to the distance at which a chemical reaction occurs, so that the state shown in Figure 7(e) is reached, and a dehydration condensation occurs, causing them to chemically bond together by covalent bonds. At this time, since a silicon layer (Si layer) is formed, the first material 2C and the second material 3C will be bonded by siloxane bonds.

[0073] Thus, by this method, the first material 2C and the second material 3C can be chemically bonded together by siloxane bonding, enabling a strong bond without the use of adhesives. Therefore, sufficient bonding strength can be ensured even with materials that are difficult to bond.

[0074] Here, the methods for manufacturing the joint structures 1A to 1D described above will be explained in more detail with reference to Figures 8 and 9. Since joint structures 1C and 1D differ only in the joint location, only the method for manufacturing joint structure 1D will be explained using Figure 8. Furthermore, since joint structures 1A and 1B differ only in the joint location of the connecting material 4A, only the method for manufacturing joint structure 1B will be explained using Figure 9.

[0075] In manufacturing the bonded structure 1D, as shown in Figure 8(a-1), the first material 2C, on which the silicon-based material 7 is placed, is placed in the chamber 5a. In this state, the chamber 5a is evacuated, and as shown in Figure 8(a-2), plasma PL is irradiated to perform plasma treatment on the surface 2Ca of the first material 2C and the surface 7a of the silicon-based material 7. As a result, as described above, a silicon layer (Si layer) and hydrophilic groups are formed on the surface 2Ca of the first material 2C (see Figure 7(c)). It is preferable to introduce water vapor as the introduction gas 5c into the chamber 5a shown in Figure 3, because it promotes the formation of hydrophilic groups.

[0076] On the other hand, similarly to the above, as shown in Figure 8(b-1), a second material 3C with a silicon-based material 7 placed on it is placed in the chamber 5a. In this state, the chamber 5a is evacuated, and as shown in Figure 8(b-2), plasma PL is irradiated to perform plasma treatment on the surface 3Ca of the second material 3C and the surface 7a of the silicon-based material 7. As a result, as described above, a silicon layer (Si layer) and hydrophilic groups are formed on the surface 3Ca of the second material 3C (see Figure 7(c)).

[0077] Next, the first material 2C and the second material 3C, having undergone the above processing, are removed from the chamber 5a and, as shown in Figure 8(c), are temporarily bonded together in an air atmosphere by overlapping the surfaces 2Ca of the first material 2C, which have a silicon layer (Si layer) and hydrophilic groups formed on them, with the surfaces 3Ca of the second material 3C, which also have a silicon layer (Si layer) and hydrophilic groups formed on them. Then, the temporarily bonded materials are sandwiched between the upper press plate 6A and the lower press plate 6B shown in Figure 8(d), and a predetermined pressure is applied. This brings the surfaces 2Ca of the first material 2C and the surfaces 3Ca of the second material 3C closer together to a distance where a chemical reaction occurs, and chemically joins them by covalent bonding through dehydration condensation. At this time, since a silicon layer (Si layer) is formed, a siloxane bond is formed. It is preferable to heat the materials when applying the predetermined pressure, as this can promote the dehydration condensation reaction.

[0078] Thus, by performing this process, the joint structure 1D shown in Figure 8(e) is manufactured.

[0079] By the way, the above explanation showed an example in which a silicon-based material 7 is placed on the first material 2C and the second material 3C. However, if a silicon layer (Si layer) is already formed as the material of the first material 2C or the second material 3C (for example, polydimethylsiloxane (PDMS)), it is not necessary to place the silicon-based material 7. That is, it is sufficient to irradiate the surface 2Ca of the first material 2C with plasma PL without placing the silicon-based material 7, or to irradiate the surface 3Ca of the second material 3C with plasma PL without placing the silicon-based material 7. This is because, since a silicon layer (Si layer) is already formed, irradiating it with plasma PL will form hydrophilic groups in that silicon layer (Si layer).

[0080] Next, we will explain how to manufacture the joint structure 1B.

[0081] As shown in Figure 9(a), a first material 2A with a silicon-based material 7 placed on it and a binder material 4A are placed in the chamber 5a. In this embodiment, the binder material 4A is exemplified as a material that already has a silicon layer (Si layer) formed on it (for example, polydimethylsiloxane (PDMS)). Therefore, the silicon-based material 7 is not placed on the binder material 4A. Needless to say, if the binder material 4A does not have a silicon layer (Si layer) formed on it, the silicon-based material 7 is placed on it. In this case, it is preferable to place the first material 2A and the binder material 4A in separate chambers 5a. This is to ensure that Si is deposited reliably.

[0082] Thus, in the state shown in Figure 9(a), the chamber 5a is evacuated, and as shown in Figure 9(b), plasma PL is irradiated to the surface 2Aa of the first material 2A, the surface 4Aa of the binder material 4A, and the surface 7a of the silicon-based material 7, thereby performing plasma treatment. As a result, as described above, a silicon layer (Si layer) and hydrophilic groups are formed on the surface 2Ab of the first material 2A, and hydrophilic groups are formed on the surface 4Aa of the binder material 4A. It is preferable to introduce water vapor as the introduction gas 5c into the chamber 5a shown in Figure 3, because it promotes the formation of hydrophilic groups.

[0083] Next, the first material 2A and the binder material 4A, which have undergone the above processing, are removed from the chamber 5a, and as shown in Figure 9(c), the surfaces 2Aa of the first material 2A, which have a silicon layer (Si layer) and hydrophilic groups formed thereon, and the surfaces 4Aa of the binder material 4A, which have hydrophilic groups formed thereon, are overlapped and temporarily bonded together in an air atmosphere. This produces the intermediate material 10B1 shown in Figure 9(d).

[0084] Next, as shown in Figure 9(e), the second material 3A, on which the silicon-based material 7 is placed, and the intermediate material 10B1 are placed in the chamber 5a. As explained above, the binder material 4A constituting the intermediate material 10B1 is exemplified as having a silicon layer (Si layer) already formed on it. Therefore, the silicon-based material 7 is not placed on the intermediate material 10B1. Needless to say, if the binder material 4A does not have a silicon layer (Si layer) formed on it, the silicon-based material 7 is placed on the intermediate material 10B1. In this case, it is preferable to place the second material 3A and the intermediate material 10B1 in separate chambers 5a. This is to ensure that Si is deposited reliably.

[0085] Thus, in the state shown in Figure 9(e), the chamber 5a is evacuated, and as shown in Figure 9(f), plasma PL is irradiated to the surface 3Aa of the second material 3A, the surface 10B1a of the intermediate material 10B1, and the surface 7a of the silicon-based material 7, thereby performing plasma treatment. As a result, as described above, a silicon layer (Si layer) and hydrophilic groups are formed on the surface 3Aa of the second material 3A, and hydrophilic groups are formed on the surface 10B1a of the intermediate material 10B1. It is preferable to introduce water vapor as the introduction gas 5c into the chamber 5a shown in Figure 3, because it promotes the formation of hydrophilic groups.

[0086] Next, the second material 3A and the intermediate material 10B1, having undergone the above processing, are removed from the chamber 5a, and as shown in Figure 9(g), the surfaces 3Aa of the second material 3A, which have a silicon layer (Si layer) and hydrophilic groups formed thereon, and the surfaces 10B1a of the intermediate material 10B1, which have hydrophilic groups formed thereon, are overlapped and temporarily bonded together in an air atmosphere. This results in the state shown in Figure 9(h).

[0087] Next, the material in the state shown in Figure 9(h) is sandwiched between the upper press plate 6A and the lower press plate 6B shown in Figure 9(i), and a predetermined pressure is applied. This brings the surface 3Aa of the second material 3A and the surface 10B1a of the intermediate material 10B1 close enough for a chemical reaction to occur between them, and chemically joins them by covalent bonding through dehydration condensation. At this time, since a silicon layer (Si layer) is formed, a siloxane bond is formed. It is preferable to heat the material when applying the predetermined pressure, as this can accelerate the dehydration condensation reaction.

[0088] Thus, by performing this process, the joint structure 1B shown in Figure 9(j) is manufactured.

[0089] By the way, the above explanation showed an example in which a silicon-based material 7 is placed on the first material 2A and the second material 3A. However, if a silicon layer (Si layer) is already formed as the material of the first material 2A or the second material 3A (for example, polydimethylsiloxane (PDMS)), it is not necessary to place the silicon-based material 7. That is, it is sufficient to irradiate the surface 2Aa of the first material 2A with plasma PL without placing the silicon-based material 7, or to irradiate the surface 3Aa of the second material 3A with plasma PL without placing the silicon-based material 7. This is because, since a silicon layer (Si layer) is already formed, irradiating it with plasma PL will form hydrophilic groups in that silicon layer (Si layer).

[0090] Therefore, according to the manufacturing method described above, a strong bond can be achieved without the use of adhesives because the materials are chemically bonded by siloxane bonding. As a result, just like the novel manufacturing method described above, sufficient bonding strength can be ensured even with materials that are difficult to bond.

[0091] <Explanation of Modifications> The shapes shown in this embodiment are merely examples, and various modifications and changes are possible within the scope of the gist of the present invention as described in the claims. The shapes of the joint structures 1A to 1D shown in this embodiment are merely examples, and can be changed to various shapes.

[0092] Furthermore, in this embodiment, an example was shown where pressure is applied by sandwiching the material between the upper press plate 6A and the lower press plate 6B, but the method is not limited to this, and pressure may also be applied by a person's fingers. However, the stronger the pressure, the stronger the joint strength.

[0093] By the way, although the bonding structures 1A to 1D in this embodiment have been described only from the perspective of bonding, from the perspective of delamination, if the first materials 2A and 2C, the second materials 3A and 3C, and the binder material 4A are combined in a way that exhibits a fracture mode greater than cohesive failure, delamination is also possible. Therefore, it can be applied to a wide range of industries such as medical, automotive, and electronic components.

[0094] 1A-1D Joint structure 2A, 2C First material 2Aa, 2Ca Surface (of the first material) 2Cb Back surface (of the first material) 3A, 3C Second material 3Aa, 3Ca Surface (of the second material) 3Cb Back surface (of the second material) 4A Bonding material 4Aa Surface (of the bonding material) 7 Silicon-based material 7a Surface (of the silicon-based material) 10B, 10B1 Intermediate material 10Ba, 10B1a Surface (of the intermediate material)

Claims

1. A joining structure comprising a first material, in which at least one of the materials is made of a material that is difficult to bond, and a second material, wherein a connecting material is provided between the first material and the second material, and the first material and the second material are joined via the connecting material by an adhesive bonding method that does not use adhesive.

2. A joining method comprising the steps of: joining a first material and a second material, wherein plasma treatment is performed on the surfaces of the first material and the second material to break the bond between the surfaces of the first material and the second material and form hydrophilic groups; and the surfaces of the first material and the second material, on which the hydrophilic groups have been formed, are superimposed in an air atmosphere, and then, in an air atmosphere, a predetermined pressure is applied between the surfaces of the first material and the second material to a distance at which a chemical reaction occurs, thereby bringing the surfaces of the first material and the second material closer together and chemically joining them by covalent bonding by causing dehydration condensation.

3. In joining a first material and a second material by providing a connecting material between them, the process involves: 1) Plasma treatment of the surfaces of the first material and the connecting material to break the bond between the surfaces of the first material and the connecting material and form hydrophilic groups; 2) Overlapping the surfaces of the first material and the connecting material, on which the hydrophilic groups have been formed, in an air atmosphere; 3) Plasma treatment of the surface of the intermediate material formed by overlapping the surfaces of the first material and the connecting material, and the surface of the second material to break the bond between the surfaces of the intermediate material and the second material and form hydrophilic groups; A joining method comprising the steps of: overlapping the surface of the intermediate material on which the hydrophilic groups are formed with the surface of the second material in an air atmosphere; then, in an air atmosphere, bringing the surfaces of the intermediate material and the second material closer together by applying a predetermined pressure until a distance occurs between them that allows a chemical reaction to occur, and chemically joining them by covalent bonding through dehydration condensation.

4. In joining the first material and the second material, the steps are: to place a silicon-based material on the back surface of the first material and / or the second material on which a silicon layer is not formed; and to perform plasma treatment on the surface of the first material on which the silicon-based material is placed and the second material on which the silicon-based material is placed, or the first material on which a silicon layer is formed and the second material on which the silicon-based material is placed, thereby breaking the bond between the surfaces of the first material and the second material and the surface of the silicon-based material, forming hydrophilic groups on the surfaces of the first material and the second material, and forming a silicon layer on the surface of the first material and / or the second material on which the silicon-based material is placed. A joining method comprising the steps of: overlapping the surface of the first material and the surface of the second material in an air atmosphere; then, in an air atmosphere, bringing the surfaces of the first material and the second material closer together by applying a predetermined pressure to a distance at which a chemical reaction occurs between them, and chemically joining them by covalent bonding through dehydration condensation.

5. In joining a first material and a second material by providing a connecting material between them, the steps include: placing a silicon-based material on the back surface of the first material and / or the second material and / or the connecting material on which a silicon layer is not formed; and performing plasma treatment on the surface of the first material on which the silicon-based material is placed and the connecting material on which the silicon-based material is placed, or the first material and the connecting material on which a silicon layer is formed, or the first material and the connecting material on which a silicon layer is formed, thereby breaking the bond between the surfaces of the first material and the connecting material, and the surface of the silicon-based material, forming hydrophilic groups on the surfaces of the first material and the connecting material, and forming a silicon layer on the surface of the first material and / or the connecting material on which the silicon-based material is placed. Steps include: overlapping the surface of the first material on which the hydrophilic groups and the silicon layer are formed with the surface of the connecting material in an air atmosphere; and, if a silicon layer is not formed on the surface of the intermediate material formed by overlapping the surfaces of the first material and the connecting material, placing the silicon-based material on it and performing plasma treatment on the surface of the intermediate material and the surface of the second material on which the silicon-based material is placed or not placed, thereby breaking the bond between the surfaces of the intermediate material, the second material and the silicon-based material, forming hydrophilic groups on the surfaces of the intermediate material and the second material, and forming a silicon layer on the surface of the intermediate material on which the silicon-based material is placed and / or the surface of the second material on which the silicon-based material is placed. A joining method comprising the steps of: overlapping the surface of the intermediate material on which the hydrophilic group and the silicon layer are formed with the surface of the second material in an air atmosphere; then, in an air atmosphere, bringing the surfaces of the intermediate material and the second material closer together by applying a predetermined pressure until a distance occurs between them that allows a chemical reaction to occur, and chemically joining them by covalent bonding by causing dehydration condensation.

6. The joining method according to any one of claims 2 to 5, wherein water vapor is introduced when performing the plasma treatment.

7. The joining method according to any one of claims 2 to 5, wherein the predetermined pressure is applied while heating.

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