JP2021020354A - Method for manufacturing joining object, joining object and object to be joined - Google Patents

Abstract

To provide an improved technique that joins two objects.SOLUTION: A method for manufacturing a joining object by joining two objects includes the steps of: irradiating each joint surface of two objects with plasma under atmospheric pressure; and adhering the joint surfaces, irradiated with plasma, to each other at a temperature lower than the melting point of a substance included in the objects. Functional groups are generated on the joint surfaces by irradiating the joint surfaces with plasma under atmospheric pressure, and the two objects join by a chemical bond between the functional groups.SELECTED DRAWING: Figure 1

Description

The present invention relates to a technique for joining objects, and more particularly to a method of joining two objects to produce a joined object, a joined object formed by joining two objects, and an object to be joined.

As a method of joining two objects, there are a method of joining with an adhesive, a method of joining with bolts, a method of joining by welding, and the like. An appropriate joining method is selected according to the material of the object and the required joining strength.

Each of the above joining methods has a problem. For example, when an adhesive is used, aging deterioration of the adhesive and generation of volatile organic compounds (VOCs) can be a problem. Further, when bolts are used, a decrease in the strength of the objects to be joined may become a problem. Further, in the case of welding, deterioration of the object due to heating may become a problem.

The present invention has been made in view of such a situation, and one of the objects thereof is to improve a technique for joining objects.

In order to solve the above problems, the method for producing a bonded product according to an embodiment of the present invention is a method for producing a bonded product by joining two objects, and the bonding surface of each of the two objects is under atmospheric pressure. The step of irradiating the plasma with the above step and the step of adhering the bonded surfaces irradiated with the plasma at a temperature lower than the melting point of the substance contained in the object are provided.

Another aspect of the invention is a conjugate. In this bonded object, two objects are bonded by a chemical bond between functional groups generated on the bonded surface by irradiating the bonded surface of each of the two objects with plasma under atmospheric pressure.

Yet another aspect of the present invention is a method of producing a conjugate. This method is a method of joining two objects to produce a bonded object, in which a step of irradiating the joint surface of each of the two objects with plasma under reduced pressure or atmospheric pressure, and after irradiating the plasma. After a lapse of a predetermined period, the step of adhering the bonded surfaces irradiated with plasma at a temperature lower than the melting point of the substance contained in the object is provided.

Yet another aspect of the present invention is the object to be joined. This bonding object has a bonding surface in which a functional group is generated by irradiation with plasma under reduced pressure or atmospheric pressure.

It should be noted that any combination of the above components, a conversion of the expression of the present invention between methods, devices, and the like are also effective as aspects of the present invention. In addition, an appropriate combination of the above-mentioned elements may be included in the scope of the invention for which protection by the patent is sought by the present patent application.

According to the present invention, the technique for joining objects can be improved.

It is a figure which shows typically the principle of joining by the joining method which concerns on embodiment. It is a figure which shows schematic structure of the rotary drum type plasma irradiation apparatus used in an Example. It is a figure which shows typically the principle of the T type peeling test performed for evaluating the strength of a joint. It is a figure which shows typically the principle of the tensile shear test performed in order to evaluate the strength of a joint. It is a figure which shows the change of the contact angle of water on the object surface before and after plasma irradiation. It is a figure which shows the measurement result of the X-ray photoelectron spectroscopy of the PPS film before and after the plasma irradiation. It is a figure which shows the measurement result of the X-ray photoelectron spectroscopy of the Al plate before and after the plasma irradiation. It is a figure which shows the scanning electron microscope image of the PPS film before and after plasma irradiation. It is a figure which shows the relationship between the number of times of plasma irradiation and the contact angle of water. It is a figure which shows the relationship between the number of times of plasma irradiation and the junction strength. It is a figure which shows the measurement result of the differential thermal analysis of a PPS film. It is a figure which shows the measurement result of the X-ray diffraction of a PPS film. It is a figure which shows the relationship between the bonding temperature and the bonding strength. It is a figure which shows the measurement result of X-ray photoelectron spectroscopy of a Cu plate before and after plasma irradiation. It is a figure which shows the infrared absorption spectrum of the surface of a Cu plate measured by the total reflection measurement method. It is a figure which shows the change of the contact angle of water on the object surface before and after plasma irradiation. It is a figure which shows the relationship between the number of times of plasma irradiation and the contact angle of water. It is a figure which shows the change of the contact angle of water on the object surface before and after plasma irradiation. It is a figure which shows the scanning electron microscope image of the PC film before and after plasma irradiation. It is a figure which shows the relationship between the number of times of plasma irradiation and the contact angle of water. It is a figure which shows the relationship between the number of times of plasma irradiation and the junction strength. It is a figure which shows the measurement result of the X-ray photoelectron spectroscopy of the PC film before and after plasma irradiation. It is a figure which shows the change of the kind of bonding of the surface of a PC film before and after plasma irradiation calculated from the measurement result of X-ray photoelectron spectroscopy. It is a figure which shows the result of having calculated the number of functional groups introduced into the surface of an object by plasma irradiation. It is a figure which shows the change of the contact angle of water on the object surface before and after plasma irradiation. It is a figure which shows the measurement result of the X-ray photoelectron spectroscopy of the PA6 film before and after the plasma irradiation. It is a figure which shows the measurement result of the sum frequency generation spectroscopy of PA6 film before and after plasma irradiation. It is a figure which shows the change of the contact angle of water on the object surface before and after plasma irradiation. It is a figure which shows the measurement result of the X-ray photoelectron spectroscopy of the PP film before and after plasma irradiation. It is a figure which shows the measurement result of the X-ray photoelectron spectroscopy of the carbon fiber reinforced plastic which uses PA6 as a base material before and after plasma irradiation. It is a figure which shows the dimension of the test piece used for the tensile test of a single wrap joint. It is a figure which shows the result of the tensile test of the single wrap joint of CF / PA6. It is a figure which shows the result of the tensile test of the single wrap joint of CF / PA66. It is a figure which shows the result of the tensile test of the single wrap joint of CF / PEEK. It is a figure which shows the measurement result of the shear stress of a joint. It is a figure which shows the measurement result of the shear stress of a joint. It is a figure which shows schematic structure of the joint which concerns on this Example. It is a figure which shows the time change of the contact angle of water on the surface of PA6 before and after the atmospheric pressure plasma irradiation. It is a figure which shows the time change of the contact angle of water on the surface of PET before and after the atmospheric pressure plasma irradiation. It is a figure which shows the relationship between the irradiation time of atmospheric pressure plasma and the junction strength. It is a figure which shows the measurement result of the X-ray photoelectron spectroscopy of the PA6 film before and after the atmospheric pressure plasma irradiation. It is a figure which shows the C1s peak of the X-ray photoelectron spectroscopy spectrum shown in FIG. 41. It is a figure which shows the O1s peak of the X-ray photoelectron spectroscopy spectrum shown in FIG. 41. It is a stress-displacement diagram of a test piece in which carbon fiber reinforced plastics having PEKK as a base material irradiated with atmospheric pressure plasma are joined to each other. It is a figure which shows the relationship between the elapsed days after the atmospheric pressure plasma irradiation of the carbon fiber reinforced plastic which uses PA6 as a base material, and the bonding strength.

Embodiments of the present invention relate to a technique for joining two objects. Specifically, after irradiating the bonding surfaces of the two objects to be bonded with plasma, the bonding surfaces are bonded to each other at a temperature lower than the melting point of the substance contained in the objects to bond the two objects. .. First, an example in which plasma is irradiated by a reduced pressure plasma irradiation device will be described, and then an example in which plasma is irradiated by an atmospheric pressure plasma irradiation device will be described. Furthermore, the sustainability of the effect of plasma irradiation will be described.

FIG. 1 schematically shows the principle of joining by the joining method according to the embodiment. FIG. 1A schematically shows a state after irradiating the bonding surface of each of the two objects to be bonded with plasma. By irradiation with plasma, functional groups such as carboxy groups and hydroxy groups are generated on each bonding surface. FIG. 1B schematically shows a state after the joint surfaces are adhered to each other. When the bonding surfaces are bonded to each other, a chemical bond is formed between the functional groups at close positions, and the two objects are bonded by the formed chemical bond. In the case of this figure, it is on the ester bond formed by dehydration condensation of the hydroxy group on the junction surface of one object and the carboxy group on the junction surface of the other object, or on the junction surface of both objects. Two objects are firmly bonded by a large number of covalent bonds, such as an ether bond formed by dehydration condensation of hydroxy groups. The chemical bond between the functional groups may be a hydrogen bond, a van der Waals bond, or the like, but it is more desirable that the functional groups are bonded by a covalent bond, which is the strongest bond among the chemical bonds.

As described above, according to the method of the present embodiment, since the two objects can be joined without using an adhesive, problems such as deterioration of the adhesive and generation of volatile organic compounds do not occur. Further, since the two objects can be joined without using bolts, it is not necessary to perform processing such as drilling on the two objects, and problems such as a decrease in the strength of the two objects do not occur. Further, since the two objects can be joined without heating above the melting point, problems such as deterioration of the two objects due to heating do not occur.

The plasma irradiation device for irradiating the junction surface of two objects with plasma may be a plasma irradiation device using any plasma generation technique. In the examples described later, a drum type plasma irradiation device is used, but other types of plasma irradiation devices, for example, a flat plate type plasma irradiation device may be used.

The conditions for irradiating the joint surface of two objects with plasma may be selected according to the type of plasma irradiation device, the type and size of the object to be joined, the required joint strength, the state of the joint surface, and the like. Good. As will be described later, it is preferable that the plasma is irradiated under the condition that the amount of etching on each bonding surface is suppressed to less than a predetermined value and a predetermined number or more of functional groups are generated on each bonding surface. Specific conditions will be described later in relation to the examples.

The junction surface of two objects may be irradiated with plasma of any substance. For example, plasma of substances that are gaseous at room temperature such as carbon dioxide, oxygen, nitrogen, water vapor, helium, neon, and argon may be irradiated, or a mixture of any two or more of these substances, such as air. Plasma may be irradiated.

The type of functional group generated on the bonding surface of the two objects may be selected according to the type and size of the objects to be bonded, the required bonding strength, the state of the bonding surface, and the like. The same kind of functional groups may be generated or different kinds of functional groups may be generated on the bonding surface of each of the two objects. In the latter case, it is preferable to select an appropriate combination of functional groups according to the type and size of the object to be joined, the required strength of joining, the state of the joining surface, and the like. That is, the type of plasma to be irradiated and the type of gas to be introduced at the time of recompression are selected so that functional groups that easily cause a chemical reaction are generated on each joint surface when the joint surfaces are adhered to each other. Is preferable.

Objects that can be joined by the method of this embodiment include objects such as resins, carbon fiber reinforced plastics (CFRP), metals, metal oxides, and glass. More specifically, as an example of the resin, PET (polyethylene terephthalate), PA (polyetherimide), PI (polyetherimide), PPS (polyphenylene sulfide), PP (polypropylene), PC (polycarbonate), PEEK (polyether ether ketone) , PMMA (polymethyl methacrylate), PEI (polyetherimide), epoxy resin, and other carbon fiber reinforced plastics include CF / PP (polypropylene-based carbon fiber reinforced plastic) and CF / PA (polypropylene). Carbon fiber reinforced plastic used as a base material), CF / PPS (carbon fiber reinforced plastic using polyphenylene sulfide as a base material), CF / PET (carbon fiber reinforced plastic using polyethylene terephthalate as a base material), CF / PC (polypropylene) Carbon fiber reinforced plastic as base material), CF / PEEK (carbon fiber reinforced plastic using polyetherether ketone as base material), CF / PEI (carbon fiber reinforced plastic using polyetherimide as base material), CF / epoxy Examples of metals such as (carbon fiber reinforced plastic using epoxy resin as a base material) include strontium as an example of metal oxides such as Al (aluminum), Cu (copper), Ti (titanium), and stainless steel (SUS). The same or different kinds of objects including perovskite type metal oxides such as titanate (STO) and lanthanum aluminate (LAO) and magnesium oxide (MgO) can be bonded by the above method. In addition, an object composed of a plurality of substances or materials can also be joined by the above method.

In particular, carbon fiber reinforced plastic is lighter than metal and has high strength, so that it is expected to be widely applied in fields such as automobiles and aircraft. However, according to the method of the present embodiment, carbon is used. High-strength bonding can be easily realized between fiber-reinforced plastics or between carbon fiber-reinforced plastics and a metal, resin, or the like while suppressing the above-mentioned problems.

The shape of the objects to be joined may be arbitrary as long as the joint surfaces have a shape that can be adhered to each other. For example, film and film, film and flat plate, flat plate and flat plate, curved surface and curved surface, and the like may be used.

According to the method of the present embodiment, since two objects can be joined by a strong covalent bond, it can be applied to a field where very high strength joining is required, such as a part of a transportation facility. Further, since high airtightness can be ensured at the joint portion, it can be applied to a tank for storing hydrogen inside and a container that needs to keep the inside in a vacuum. In addition, since it does not generate volatile organic compounds, it can be applied to bonding for manufacturing microchannel chips used in fields such as medical tests, pharmaceuticals, cell biology research, and protein crystallization.

The fact that PA has water absorption can be a practical problem, but by bonding a film such as PPS to prevent the ingress of water on the surface of PA or carbon fiber reinforced plastic using PA as a base material, Water resistance can be improved. Further, by bonding a film of a fluororesin to the surface, deterioration due to ultraviolet rays can be prevented, and weather resistance can be improved. In this way, even if the material is inferior in water resistance and weather resistance, by joining a film capable of improving water resistance and weather resistance to the surface, a product that can be used for a long time even in a harsh environment can be obtained. It can be realized.

[Example]
The inventor has conducted experiments to join various types of objects. The details of the experiment will be described below.

[Plasma irradiation device]
FIG. 2 schematically shows the configuration of the rotary drum type plasma irradiation device used in the embodiment. The rotary drum type plasma irradiation device 10 includes a rotary drum 24 that is rotated at a predetermined angular speed by a drive mechanism such as a motor (not shown), an electrode 22 for generating an electric discharge, and a sample holder provided on the side surface of the rotary drum 24. 26, a bell jar 20 in which these configurations are arranged, a gas introduction port 28 for introducing a gas for processing into the bell jar 20, and a cylinder 30 for supplying a gas for processing are provided. When the sample 32 to be plasma-treated is placed in the sample holder 26, the inside of the bell jar 20 is depressurized to vacuum, the gas for processing is introduced into the bell jar 20, and a high voltage is supplied to the electrode 22, the inside of the bell jar 20 is used for processing. The gas is discharged to a plasma state, and the surface of the sample 32 is irradiated. The sample 32 is rotated together with the rotating drum 24. When the rotating drum 24 is rotated two or more times, the plasma is irradiated to the surface of the sample 32 every time the sample 32 passes through the plasma irradiation range.

[T-type peeling test]
FIG. 3 schematically shows the principle of the T-type peeling test performed to evaluate the strength of the joint. FIG. 3A shows the upper surface of the test piece 46 used in the T-type peeling test. The test piece 46 is formed by joining two objects cut to the same size at a shaded portion. The parts not shaded are not joined and separated. FIG. 3B schematically shows the T-type peeling test apparatus 40. One of the unjoined portions of the test piece 46 is attached to the grip 42, and the other is attached to the movable grip 44. While fixing the grip 42, the movable grip 44 was moved at a speed of 10 mm per minute, and the peeling distance and the force applied to the grip were recorded.

[Tension shear test]
FIG. 4 schematically shows the principle of the tensile shear test performed to evaluate the strength of the joint. FIG. 4A shows the upper surface of the test piece 56 used in the tensile shear test. In the test piece 56, two objects cut to the same size are overlapped by shifting them in the long side direction, and tabs 55 for reinforcing the portion gripped by the gripper are provided at both ends of the joint at the shaded portion. It is adhered with an adhesive. FIG. 4B schematically shows the tensile shear test apparatus 50. The tab 55 at one end of the two objects of the test piece 56 is gripped by the gripper 52, and the tab 55 at the other end is gripped by the gripper 54. The grip 52 and the grip 54 are moved at a constant speed (0.05 mm / min, 1.0 mm / min, or 2.0 mm / min), and the maximum breaking force is recorded as the breaking force of the test piece 56. did. The shear stress was calculated by dividing the breaking force by the shear cross-sectional area.

[Example 1]
In order to confirm the principle of joining by the joining method according to the present embodiment, an experiment was conducted in which a PPS film and an Al flat plate were joined. A test piece was prepared by cutting the PPS film and the Al plate, and the surface was washed with ethanol. After irradiating the joint surfaces of the two test pieces with plasma using a rotary drum type plasma irradiator, the joint surfaces are bonded to each other by a vacuum press to bond the Al plate and PPS film, and the tensile shear stress of the joint is obtained. Was measured. Table 1 shows the experimental conditions.

FIG. 5 shows the change in the contact angle of water on the surface of the object before and after plasma irradiation. As shown in FIG. 5 (a), the contact angle of water on the surface of the Al plate before plasma irradiation is 94.59 °, whereas as shown in FIG. 5 (b), the Al plate after plasma irradiation. The contact angle of water on the surface of is 38.60 °. Further, as shown in FIG. 5 (c), the contact angle of water on the surface of the PPS film before plasma irradiation is 93.14 °, whereas as shown in FIG. 5 (d), after plasma irradiation. The contact angle of water on the surface of the PPS film is 19.61 °. As described above, in both the Al plate and the PPS film, the contact angle of water on the surface is remarkably reduced by the irradiation of plasma.

FIG. 6 shows the measurement results of X-ray Photoelectron Spectroscopy (XPS) of the PPS film before and after plasma irradiation. As shown in FIG. 6A, in the X-ray photoelectron spectrum of the PPS film after plasma irradiation, the intensity of the O1s peak is higher than that before plasma irradiation, and O is increased on the surface of the PPS film by plasma irradiation. It is suggested that it was done. Further, in FIGS. 6 (b) and 6 (c) in which the spectrum of FIG. 6 (a) is enlarged in the vicinity of 150 to 170 eV, and FIGS. 6 (d) and 6 (e) in which the vicinity of 280 to 300 eV is enlarged. As shown, in the X-ray photoelectron spectrum after plasma irradiation, the intensities of the S2p peak and the C1s peak change, suggesting an increase in hydroxy groups and formation of sulfonyl groups on the surface of the PPS film by plasma irradiation.

FIG. 7 shows the measurement results of X-ray photoelectron spectroscopy of the Al plate before and after plasma irradiation. As shown in FIG. 7, in the X-ray photoelectron spectrum of the Al plate after plasma irradiation, the intensity of the C1s peak is reduced and the intensity of the peak derived from Al is increased as compared with that before plasma irradiation. It is suggested that the organic matter on the surface was removed and the oxide film was exposed.

FIG. 8 shows scanning electron microscope (SEM) images of PPS film before and after plasma irradiation. Comparing the images before and after the plasma irradiation, it can be seen that the organic matter adhering to the surface of the PPS film has been removed. No etching due to plasma irradiation is observed on the surface of the PPS film.

In this way, considering the measurement results of the water contact angle, XPS, and SEM on the surfaces of the PPS film and Al plate before and after plasma irradiation, the resin removes organic substances adhering to the surface by plasma irradiation and is hydrophilic. It is suggested that a sex functional group was generated, and that in the case of metal, the organic matter adhering to the surface was removed to expose the oxide film.

FIG. 9 shows the relationship between the number of plasma irradiations and the contact angle of water. In both the Al plate and the PPS film, the contact angle becomes smaller as the number of plasma irradiations increases, but the contact angle becomes sufficiently smaller with one plasma irradiation than before the plasma irradiation, and the second and subsequent times. The decrease in contact angle due to plasma irradiation was slight. In the PPS film, the contact angle is smaller when the plasma irradiation voltage is 3 kV than when the plasma irradiation voltage is 2 kV, but in Al, the plasma irradiation voltage is both 3 kV and 2 kV. The contact angles were about the same.

FIG. 10 shows the relationship between the number of plasma irradiations and the bonding strength. Regardless of whether the plasma irradiation voltage is 2 kV or 3 kV, the shear stress is larger when the plasma is irradiated twice than when it is irradiated once, but when the plasma is irradiated twice and when the plasma is irradiated three times. The shear stresses of the cases were about the same.

In this way, since there is a correlation between the contact angle of water on the bonding surface and the bonding strength, covalent bonds, hydrogen bonds, and van der Waals bonds are formed by chemical reactions between hydrophilic functional groups. Is suggested.

FIG. 11 shows the measurement results of the differential thermal analysis (DTA) of the PPS film. An exothermic peak due to crystallization can be seen around 131 ° C, and an endothermic peak due to melting can be seen around 277 ° C.

FIG. 12 shows the measurement results of X-ray Diffraction (XRD) of the PPS film. The crystallinity of PPS in the PPS film calculated from the X-ray diffraction data shown in FIG. 12 (a) is shown in FIG. 12 (b). It can be seen that when the DTA is heated above the temperature at which the exothermic peak due to crystallization is observed, the recrystallization of PPS proceeds and the degree of crystallinity increases.

FIG. 13 shows the relationship between the bonding temperature and the bonding strength. It can be seen that when the PPS film and the Al plate are bonded, the bonding temperature is increased and the bonding strength is improved, and the maximum value is around 110 ° C. However, if the bonding temperature is further increased, the bonding strength is rather decreased. .. It is considered that this is due to the recrystallization of PPS in the PPS film.

In this way, considering the relationship between the DTA and XRD measurement results of the PPS film and the bonding temperature and bonding strength of the PPS film and Al plate, the activity of the chemical reaction that occurs between the functional groups on the surface of each object. It is suggested that high bonding strength can be obtained by bonding two objects at a temperature higher than sufficient for the chemical reaction to proceed beyond the chemical energy and lower than the crystallization temperature of the resin.

As with the Al plate, it was confirmed that the contact angle of water on the surface of the SUS plate was reduced by plasma irradiation. It is also considered that this is because the organic matter adhering to the surface was removed by plasma irradiation and the oxide film was exposed. In addition, SEM images of the surfaces of the SUS plate and Ti plate after being irradiated with plasma were taken, and it was confirmed that etching due to plasma irradiation was not observed on the surface.

[Example 2]
An experiment was conducted in which a PPS film and a Cu flat plate were joined in the same manner as in Example 1. The experimental conditions are the same as in Table 1. When the PPS film and the Cu plate were bonded at 110 ° C., the PPS film and the Al plate could be bonded firmly as in the case of the Al plate.

FIG. 14 shows the measurement results of X-ray photoelectron spectroscopy of the Cu plate before and after plasma irradiation. As shown in FIG. 14A, in the X-ray photoelectron spectrum of the Cu plate after plasma irradiation, the intensity of the C1s peak is lower than that before plasma irradiation, and organic substances are removed from the surface of the Cu plate by plasma irradiation. It is suggested that it was done. In addition, the change in the intensity of the Cu2p peak before and after plasma irradiation suggests that Cu ²⁺ was reduced to Cu ⁺ by plasma irradiation. In addition, from FIG. 14 (b) showing the O1s peak before plasma irradiation and FIG. 14 (c) showing the O1s peak after plasma irradiation, it was found that OH ⁻ decreased and O ^2- increased due to plasma irradiation. It is suggested that Cu ²⁺ was reduced to Cu ⁺ .

FIG. 15 shows the infrared absorption spectrum of the surface of the Cu plate measured by the Attenuated Total Reflection (ATR) method. The ATR spectrum at a depth of several μm is almost unchanged before and after plasma irradiation.

Thus, considering the measurement results of the XPS spectrum and ATR spectrum, CuO film of several nm in the surface of the Cu plate, is considered to have changed to Cu ₂ O by plasma irradiation.

FIG. 16 shows changes in the contact angle of water on the surface of an object before and after plasma irradiation. As shown in FIG. 16 (a), the contact angle of water on the surface of the Cu plate before plasma irradiation is 83.33 °, whereas as shown in FIG. 16 (b), the Cu plate after plasma irradiation. The contact angle of water on the surface of is 49.90 °. As described above, in the Cu plate as well, as in the Al plate shown in FIG. 5, the contact angle of water on the surface is remarkably reduced by the plasma irradiation, and the organic substances adhering to the surface are removed by the plasma irradiation. It is suggested that the oxide film is exposed.

FIG. 17 shows the relationship between the number of plasma irradiations and the contact angle of water. In the Cu plate, unlike the Al plate and the PPS film, when the plasma is irradiated twice or more, the contact angle becomes larger than when the plasma is irradiated once. Considering the XPS results, it is considered that this is because Cu ²⁺ was reduced by plasma irradiation and changed to Cu ⁺ .

From the above experimental results, when bonding a Cu plate and a PPS film, when the surface of the Cu plate is irradiated with plasma, the CuO film of about several nm changes to Cu ₂ O, and when bonded to the PPS film, Cu ₂ O It is considered that the Cu plate and the PPS film are bonded to each other by chemically reacting with the O atom on the surface of the PPS film to form CuO.

In this way, the oxidation state and electronic state of the metal atoms on the surface of the metal plate can be changed depending on the plasma irradiation conditions, so that the type of the object to be joined and the sensory introduced to the surface of the object to be joined can be changed. By appropriately controlling the oxidation state and electronic state of the metal according to the type or amount of the group, the joining temperature, the joining time, etc., the metal can be easily and firmly bonded to another object.

[Example 3]
An experiment was conducted in which the PC film and the PET film were bonded in the same manner as in Example 1. The experimental conditions are the same as in Table 1. The combination of the PC film and the PET film could be firmly bonded at both 25 ° C and 100 ° C.

FIG. 18 shows changes in the contact angle of water on the surface of an object before and after plasma irradiation. As shown in FIG. 18A, the contact angle of water on the surface of the PC film before the plasma irradiation was 95.6 °, whereas as shown in FIG. 18B, the plasma was irradiated twice. The contact angle of water on the surface of the later PC film is 16.83 °. Further, as shown in FIG. 18 (c), the contact angle of water on the surface of the PET film before plasma irradiation is 86.4 °, whereas as shown in FIG. 18 (d), the plasma is rotated twice. The contact angle of water on the surface of the PET film after irradiation is 18.81 °. As described above, in both the PC film and the PET film, the contact angle of water on the surface is remarkably reduced by the irradiation of plasma.

FIG. 19 shows scanning electron microscope images of the PC film before and after plasma irradiation. Comparing the images before and after the plasma irradiation, it can be seen that the organic substances adhering to the surface of the PC film have been removed. No etching due to plasma irradiation is observed on the surface of the PC film.

FIG. 20 shows the relationship between the number of plasma irradiations and the contact angle of water. In both the PC film and the PET film, the contact angle of water decreases as the number of plasma irradiations increases.

FIG. 21 shows the relationship between the number of plasma irradiations and the bonding strength. When the plasma is not irradiated, the PC film and the PET film are not bonded, but when the plasma is irradiated once, the PC film and the PET film are bonded, and when the plasma is irradiated twice, the peeling strength is further increased.

In this way, since there is a correlation between the contact angle of water on the bonding surface and the bonding strength, covalent bonds, hydrogen bonds, and van der Waals bonds are formed by chemical reactions between hydrophilic functional groups. Is suggested.

FIG. 22 shows the measurement results of X-ray photoelectron spectroscopy of the PC film before and after plasma irradiation. As shown in FIG. 22, in the X-ray photoelectron spectrum of the PC film after plasma irradiation, the intensity of the C1s peak changed, suggesting that the plasma irradiation changed the C bonding state on the surface of the PC film. Will be done.

FIG. 23 shows the change in the type of bonding on the surface of the PC film before and after plasma irradiation, which was calculated from the measurement results of X-ray photoelectron spectroscopy. As shown in FIG. 23, it is suggested that the plasma irradiation reduced the carbonate groups on the surface of the PC film and increased the carboxy groups.

In this way, considering the measurement results of the water contact angle, XPS, and SEM on the surfaces of the PC film and PET film before and after plasma irradiation, the organic substances adhering to the surface of both the PC film and PET film due to plasma irradiation. Was removed, suggesting that hydrophilic functional groups were produced. In particular, in the PC film, it is suggested that a carboxy group was generated on the surface by plasma irradiation. Therefore, a strong bond between the PC film and the PET film is an ester bond between the carboxy group generated on the PC film by plasma irradiation and the hydroxy group exposed or formed on the surface of the PET film by plasma irradiation. It is suggested that it is brought about by.

FIG. 24 shows the result of calculating the number of functional groups introduced into the surface of the object by plasma irradiation. The atomic composition percentage was calculated from the peak area of XPS, and the number of hydroxy groups and carboxy groups contained in the outermost surface volume of 1 cm × 1 cm × 10 nm was calculated from the atomic composition percentage. It is presumed that the functional groups are not uniformly present in the depth direction, and that the closer to the surface, the more functional groups are present. In any of the resins of PPS, PET, and PC, hydroxy groups and carboxy groups are generated on the surface after plasma irradiation. As shown in Example 7 described later, these resins can be bonded to the same or different kinds of objects by the method according to the present embodiment. Therefore, it can be seen that by irradiating the bonding surface with plasma so that the number of functional groups shown in FIG. 24 is generated on the bonding surface, it is possible to bond to another object by the method according to the present embodiment. ..

[Example 4]
An experiment was conducted in which the PA6 film was irradiated with plasma and changes in the surface state were observed.

FIG. 25 shows the change in the contact angle of water on the surface of the object before and after plasma irradiation. As shown in FIG. 25 (a), the contact angle of water on the surface of the PA6 film before plasma irradiation is 79.83 °, whereas as shown in FIG. 25 (b), the PA6 film after plasma irradiation. The contact angle of water on the surface of is 19.19 °. As described above, even in the PA6 film, the contact angle of water on the surface is remarkably reduced by the irradiation of plasma.

FIG. 26 shows the measurement results of X-ray photoelectron spectroscopy of the PA6 film before and after plasma irradiation. FIG. 26 (a) shows the X-ray photoelectron spectrum of the PA6 film before plasma irradiation, and FIG. 26 (b) shows the X-ray photoelectron spectrum of the PA6 film after plasma irradiation. In the X-ray photoelectron spectrum of the PA6 film after plasma irradiation, the intensity of the C1s peak has changed, and the peak of CN or CO in the C1s peak and the peak of C (= O) -N or C (=). O) The peak of -O increased. Therefore, it is considered that the contact angle of water was reduced due to the formation of functional groups containing these bonds on the surface.

FIG. 27 shows the measurement results of Sum-Frequency Generation (SFG) spectroscopy of the PA6 film before and after plasma irradiation. In the wavenumber region of 2800-3000 cm- ¹ , plasma irradiation increased the intensity of the 2877 cm- ¹ band. Considering the experimental results of the contact angle of water, it is suggested that the methylene chain of PA6 was radicalized by plasma irradiation.

From the above experimental results, by irradiating the surface of the PA6 film with plasma, functional groups containing CN or CO and C (= O) -N or C (= O) -O are formed on the surface. As it is formed, the methylene chains are radicalized, suggesting that their functional groups and radicals form chemical bonds with the atoms or functional groups on the surface of the object to be bonded.

[Example 5]
An experiment was conducted in which the PP film was irradiated with plasma and changes in the surface state were observed.

FIG. 28 shows the change in the contact angle of water on the surface of the object before and after plasma irradiation. As shown in FIG. 28 (a), the contact angle of water on the surface of the PP film before plasma irradiation is 99.82 °, whereas as shown in FIG. 28 (b), the PP film after plasma irradiation. The contact angle of water on the surface of is 16.68 °. As described above, even in the PP film, the contact angle of water on the surface is remarkably reduced by the irradiation of plasma.

FIG. 29 shows the measurement results of X-ray photoelectron spectroscopy of the PP film before and after plasma irradiation. FIG. 29 (a) shows the X-ray photoelectron spectrum of the PP film before plasma irradiation, and FIG. 29 (b) shows the X-ray photoelectron spectrum of the PP film after plasma irradiation. In the X-ray photoelectron spectrum of the PP film after plasma irradiation, the intensity of the C1s peak changed, and the C—O peak and the C (= O) -O peak in the C1s peak increased. Therefore, it is considered that the contact angle of water was reduced due to the formation of functional groups containing these bonds on the surface.

From these experimental results, by irradiating the surface of the PP film with plasma, functional groups containing C-O and C (= O) -O are generated on the surface, and these functional groups are the objects to be bonded. It is suggested that it forms a chemical bond with an atom or functional group on the surface of the plasma.

[Example 6]
An experiment was conducted to join carbon fiber reinforced plastics to each other.

FIG. 30 shows the measurement results of X-ray photoelectron spectroscopy of carbon fiber reinforced plastic (CF / PA6) using PA6 as a base material before and after plasma irradiation. FIG. 30 (a) shows the X-ray photoelectron spectrum of CF / PA6 before plasma irradiation, and FIG. 30 (b) shows the X-ray photoelectron spectrum of CF / PA6 after plasma irradiation. In the X-ray photoelectron spectrum of CF / PA6 after plasma irradiation, the intensity of the C1s peak is changed, and the peak of CN or CO in the C1s peak and C (= O) -N or C ( = O) -O peak increased. Therefore, it is suggested that functional groups containing these bonds were formed on the surface.

FIG. 31 shows the dimensions of the test piece used in the tensile test. About carbon fiber reinforced plastic (CF / PA6) using PA6 as a base material, carbon fiber reinforced plastic (CF / PA66) using PA66 as a base material, and carbon fiber reinforced plastic (CF / PEEK) using PEEK as a base material. The test piece shown in FIG. 31 was prepared in accordance with JIS standards, and the surface was irradiated with plasma to join the test pieces, and then a tensile test of the single wrap joint was carried out. The test results are shown in FIGS. 32 to 34.

The bonding strength between these CFRTPs is considered to be the strictest in the world from the viewpoint of safety, and at room temperature, which is the specification for adhesives for airplanes for bonding metals, "US Federal Standard MMM-A-132-A-Type1 Class1". It approaches a value of 38 MPa, and it is possible to form a member of a moving body such as an airplane with a material such as CFRTP. Further, CF / PA6 and CF / PEEK are the highest values in the world in the tensile test of a single wrap joint in which carbon fiber reinforced plastics are joined to each other.

[Example 7]
Objects such as resins, metals, carbon fiber reinforced plastics, metal oxides, and glass were joined in various combinations. The experimental conditions are shown in Table 2. In Table 2, (melting point) is the melting point of the substance constituting the surface of the object to be joined, and when joining different kinds of objects, it is the melting point of the substance having the lower melting point. For some combinations, the tensile shear stress was measured, and for other combinations, the joint strength was evaluated by a T-type peeling test or by pulling the test piece by hand. The results are shown in FIGS. 35, 36 and Tables 3-8.

It was found that almost all combinations of objects can be bonded by appropriately selecting conditions such as temperature, pressure, and time when bonding the bonded surfaces to each other. Specifically, a combination of polypropylene with polypropylene, polyamide, polyphenylene sulfide, polyethylene terephthalate, polycarbonate, polymethyl methacrylate, aluminum, copper, titanium, stainless steel, strontium titanate, lanthanum aluminate, magnesium oxide, or glass. , Polypropylene and polyamide, polyphenylene sulfide, polyethylene terephthalate, polycarbonate, polymethyl methacrylate, aluminum, copper, titanium, or stainless steel, polyphenylene sulfide and polyphenylene sulfide, polyethylene terephthalate, polycarbonate, polymethyl methacrylate, aluminum , Combination with copper, titanium, or stainless steel, combination of polyethylene terephthalate with polyethylene terephthalate, polycarbonate, polymethyl methacrylate, aluminum, copper, titanium, or stainless steel, polycarbonate with polycarbonate, polymethyl methacrylate, aluminum. , Combination with copper, titanium, or stainless steel, combination of polymethylmethacrylate with polymethylmethacrylate, aluminum, copper, titanium, or stainless steel, carbon fiber reinforced plastic based on polypropylene, polypropylene, Polypropylene, polyphenylene sulfide, polyethylene terephthalate, polycarbonate, polymethyl methacrylate, carbon fiber reinforced plastic based on polypropylene, carbon fiber reinforced plastic based on polyamide, carbon fiber reinforced plastic based on polyphenylene sulfide, polyethylene Carbon fiber reinforced plastic with terephthalate as the base material, carbon fiber reinforced plastic with polypropylene as the base material, carbon fiber reinforced plastic with polyether ether ketone as the base material, carbon fiber reinforced plastic with polyetherimide as the base material, epoxy Resin-based carbon fiber reinforced plastic, aluminum, copper, titanium, stainless steel, strontium titanate, lanthanum aluminate, magnesium oxide, or a combination with glass, polyamide-based carbon fiber reinforced plastic, and polypropylene , Polypropylene, Polyphenylene sulfide, Polyethylene terephthalate, Polypropylene, Polymethyl methacrylate, Carbon fiber reinforced plastic based on polypropylene CK, carbon fiber reinforced plastic with polyphenylene sulfide as the base material, carbon fiber reinforced plastic with polyethylene terephthalate as the base material, carbon fiber reinforced plastic with polycarbonate as the base material, carbon fiber reinforced with polyether ether ketone as the base material Plastic, carbon fiber reinforced plastic with polyetherimide as the base material, carbon fiber reinforced plastic with epoxy resin as the base material, combination with aluminum, copper, titanium, or stainless steel, carbon fiber reinforced with polyphenylene sulfide as the base material Plastics and carbon fiber reinforced plastics based on polypropylene, polyamide, polyphenylene sulfide, polyethylene terephthalate, polycarbonate, polymethyl methacrylate, polyphenylene sulfide, carbon fiber reinforced plastics based on polyethylene terephthalate, and polycarbonate are used as base materials. Carbon fiber reinforced plastics, carbon fiber reinforced plastics based on polyether ether ketone, carbon fiber reinforced plastics based on polyetherimide, carbon fiber reinforced plastics based on epoxy resin, aluminum, copper, titanium, Or in combination with stainless steel, carbon fiber reinforced plastic based on polyethylene terephthalate, and carbon fiber reinforced plastic and polycarbonate based on polypropylene, polyamide, polyphenylene sulfide, polyethylene terephthalate, polycarbonate, polymethyl methacrylate, and polyethylene terephthalate. Carbon fiber reinforced plastic with the base material, carbon fiber reinforced plastic with polyether ether ketone as the base material, carbon fiber reinforced plastic with polyether imide as the base material, carbon fiber reinforced plastic with epoxy resin as the base material, aluminum , Copper, titanium, or stainless steel, carbon fiber reinforced plastic with polycarbonate as the base material, and carbon fiber reinforced with polypropylene, polyamide, polyphenylene sulfide, polyethylene terephthalate, polycarbonate, polymethyl methacrylate, and polycarbonate as the base material. Plastics, carbon fiber reinforced plastics based on polyether ether ketone, carbon fiber reinforced plastics based on polyetherimide, carbon fiber reinforced plastics based on epoxy resin, aluminum, copper, titanium, or stainless steel Union with Set, carbon fiber reinforced plastic based on polyether ether ketone, carbon fiber reinforced plastic based on polypropylene, polyamide, polyphenylene sulfide, polyethylene terephthalate, polycarbonate, polymethyl methacrylate, polycarbonate, polyether ether ketone Carbon fiber reinforced plastic as base material, carbon fiber reinforced plastic with polyetherimide as base material, carbon fiber reinforced plastic with epoxy resin as base material, combination with aluminum, copper, titanium, or stainless steel, polyetherimide Carbon fiber reinforced plastic based on, polypropylene, polyamide, polyphenylene sulfide, polyethylene terephthalate, polycarbonate, polymethyl methacrylate, carbon fiber reinforced plastic based on polycarbonate, carbon fiber based on polyether ether ketone Reinforced plastic, carbon fiber reinforced plastic with polyetherimide as the base material, carbon fiber reinforced plastic with epoxy resin as the base material, combination with aluminum, copper, titanium, or stainless steel, carbon fiber with epoxy resin as the base material Reinforced plastics, polypropylene, polyamide, polyphenylene sulfide, polyethylene terephthalate, polycarbonate, polymethyl methacrylate, carbon fiber reinforced plastics based on polycarbonate, carbon fiber reinforced plastics based on polyether ether ketone, polyetherimide A combination of a carbon fiber reinforced plastic as a base material, a carbon fiber reinforced plastic using an epoxy resin as a base material, aluminum, copper, titanium, or stainless steel can be bonded.

In particular, in the combination of some objects, it is possible to bond the two objects by adhering the bonding surfaces to each other at room temperature. Room temperature is the temperature of the surrounding environment in which the steps of bonding the joint surfaces are performed, and means that neither heating nor cooling is performed. However, depending on conditions such as cold regions, highlands, and winter, the room temperature is normal temperature (5 to 5). When the temperature is lower than 35 ° C., or when the room temperature is higher than the room temperature due to conditions such as tropical, sunlight, and surrounding heating elements, the room temperature may be heated or cooled to the normal temperature. Further, even if the combination of objects can be joined at room temperature, the joining surface may be heated to an appropriate temperature for joining in order to improve the strength and speed of joining.

Combinations of objects that can be bonded at room temperature include polypropylene and polypropylene, polyamide, polyphenylene sulfide, polyethylene terephthalate, polycarbonate, polymethyl methacrylate, stainless steel, strontium titanate, lanthanum aluminate, or glass combinations, polyamide and Polyamide, polyethylene terephthalate, combination with polymethyl methacrylate, polyethylene terephthalate and polyethylene terephthalate, polycarbonate, combination with polymethyl methacrylate, polycarbonate and polycarbonate, or combination with polymethyl methacrylate, polymethyl methacrylate, Combination with polymethylmethacrylate, carbon fiber reinforced plastic based on polypropylene, polypropylene, polyamide, polyphenylene sulfide, polyethylene terephthalate, polycarbonate, carbon fiber reinforced plastic based on polypropylene, carbon based on polyamide Fiber reinforced plastics, carbon fiber reinforced plastics based on polypropylene sulfide, carbon fiber reinforced plastics based on polyethylene terephthalate, carbon fiber reinforced plastics based on polycarbonate, aluminum, stainless steel, strontium titanate, lantern aluminum Combination with nate or glass, carbon fiber reinforced plastic with polyamide as the base material, polypropylene, polyamide, polyethylene terephthalate, carbon fiber reinforced plastic with polyamide as the base material, or carbon fiber reinforced plastic with polyethylene terephthalate as the base material Combination with, carbon fiber reinforced plastic with polyphenylene sulfide as a base material, and polypropylene, carbon fiber reinforced plastic with polyethylene terephthalate as a base material, polypropylene, polyamide, carbon fiber with polycarbonate as a base material It is a combination of reinforced plastic and polypropylene.

When joining different types of objects, if the joint surface is heated and pressure-welded, the joint may bend or deform due to the difference in the coefficient of thermal expansion of each object. Since it is possible to join by pressure welding at room temperature, it is possible to suppress bending and deformation of the joined body.

As described above, it is considered that the bonding of the objects by the method according to the present embodiment is brought about by the chemical reaction between the functional groups generated on the bonding surface. Therefore, in general, the higher the reaction temperature, the higher the reaction rate. As the speed increases, the number of reactive groups increases, and the strength of the bond increases. Therefore, the temperature, time, pressure, and the like of the joint may be selected according to the required strength of the joint. The joining may be performed under conditions different from those shown in Tables 1 and 2. For example, the joining pressure and time may be smaller than the values shown in Tables 1 and 2.

In the method according to the present embodiment, the two objects are bonded by adhering the bonding surfaces at a temperature lower than the melting point or the softening point of the substances contained in the two objects. The object is not heat-sealed. Even if heating is required for bonding, it is only heated to accelerate the reaction rate of the chemical reaction between the functional groups, and the surface of the object is not melted or softened.

[Example 8]
To be able to join two objects that are difficult to join directly, or to join two objects that require heating to join directly at room temperature, with both objects A bonded object was prepared by sandwiching a film or sheet of a substance that can be bonded.

FIG. 37 schematically shows the configuration of the joint according to this embodiment. The joint 60 includes two objects 62 and 64 to be joined and a film 66 arranged between the two objects 62 and 64. One surface of the film 66 is joined to the object 62, and the other side of the film 66 is joined to the object 64. As a result, even if it is difficult for the two objects 62 and 64 to be directly bonded, if the film 66 that can be bonded to both of the two objects 62 and 64 is selected, the two objects via the film 66 can be selected. 62 and 64 can be firmly joined. Further, even if heating is required for the two objects 62 and 64 to be directly bonded, if a film 66 capable of bonding to both of the two objects 62 and 64 at room temperature is selected, the film 66 can be used. The two objects 62 and 64 can be joined at room temperature. Further, although the carbon fiber reinforced plastic using a woven sheet such as plain weave has a non-flat joint surface, it can be bonded to another object by sandwiching a film 66 between them. A joint having the structure shown in FIG. 37 was prepared, and it was confirmed that the two objects were firmly joined.

[Atmospheric pressure plasma irradiation device]
In the above embodiment, the low pressure plasma irradiator irradiates the joint surface of the object with plasma, but when the atmospheric pressure plasma irradiator irradiates the joint surface of the object with plasma, the two objects are firmly strengthened by the same technique. Can be joined. Hereinafter, an example of irradiating plasma with an atmospheric pressure plasma irradiation device will be described. Table 9 shows the experimental conditions in the examples shown below. The points not specified in particular are the same as those in the embodiment using the low-pressure plasma irradiation device described above.

[Example 9]
An experiment was conducted in which the surfaces of PA6 and PET sample pieces were irradiated with atmospheric pressure plasma and changes in the surface state were observed. Experiments were performed 5 times for each sample piece, and the average value was calculated and plotted. Table 10 shows the results of five experiments for each sample piece. FIG. 38 shows the time change of the contact angle of water on the surface of PA6 before and after irradiation with atmospheric pressure plasma. FIG. 39 shows the time change of the contact angle of water on the surface of PET before and after irradiation with atmospheric pressure plasma. In all the sample pieces, the contact angle of water on the surface of the object was sharply reduced by the irradiation of the atmospheric pressure plasma, and the contact angle of water on the surface of the object after irradiation for 60 seconds was about 30 °. In all the sample pieces, the decrease in the contact angle of water almost reached a plateau in the irradiation time of about 60 seconds, and the contact angle of water did not decrease so much even if the atmospheric pressure plasma was further irradiated.

[Example 10]
An experiment was conducted to join carbon fiber reinforced plastics using PA6 as a base material. FIG. 40 shows the relationship between the irradiation time of atmospheric pressure plasma and the junction strength. The bonding strength increased sharply with the increase in the irradiation time of the atmospheric pressure plasma, and the increase in the bonding strength became gentle when the irradiation time exceeded 60 seconds. This tendency almost corresponds to the decrease in the contact angle of water shown in FIG. 38. The bonding strength when irradiated with atmospheric pressure plasma for 180 seconds was about 19 MPa. This value is lower than the bonding strength of 33.8 MPa when the low-pressure plasma irradiation device shown in FIG. 32 is used, but a sufficiently strong bond is realized.

FIG. 41 shows the measurement results of X-ray photoelectron spectroscopy of the PA6 film before and after the atmospheric pressure plasma irradiation. FIG. 41 (a) shows the X-ray photoelectron spectrum of the PA6 film before irradiation with atmospheric pressure plasma, and FIG. 41 (b) shows the X-ray photoelectron spectrum of the PA6 film after irradiation with atmospheric pressure plasma for 30 seconds. FIG. 41 (c) shows the X-ray photoelectron spectrum of the PA6 film after being irradiated with atmospheric pressure plasma for 60 seconds. In the X-ray photoelectron spectrum of the PA6 film after irradiation with atmospheric pressure plasma, the intensity of the O1s peak increased. Therefore, it is considered that the contact angle of water was reduced due to the formation of oxygen-containing functional groups on the surface.

FIG. 42 shows the C1s peak of the X-ray photoelectron spectroscopy spectrum shown in FIG. 41. FIG. 42 (a) shows the C1s peak of the X-ray photoelectron spectrum of the PA6 film before irradiation with atmospheric pressure plasma, and FIG. 41 (b) shows the X-ray photoelectrons of the PA6 film after irradiation with atmospheric pressure plasma for 30 seconds. The C1s peak of the spectral spectrum is shown, and FIG. 41 (c) shows the C1s peak of the X-ray photoelectron spectral spectrum of the PA6 film after irradiation with atmospheric pressure plasma for 60 seconds. In the X-ray photoelectron spectrum of PA6 film after atmospheric pressure plasma irradiation, the peak of CN or CO in the C1s peak and the peak of C (= O) -N or C (= O) -O increase. did. Therefore, it is suggested that functional groups containing these bonds, that is, hydroxy groups and carboxy groups, were formed on the surface.

FIG. 43 shows the O1s peak of the X-ray photoelectron spectroscopy spectrum shown in FIG. 41. FIG. 43 (a) shows the O1s peak of the X-ray photoelectron spectrum of the PA6 film before irradiation with atmospheric pressure plasma, and FIG. 43 (b) shows the X-ray photoelectrons of the PA6 film after irradiation with atmospheric pressure plasma for 30 seconds. The O1s peak of the spectral spectrum is shown, and FIG. 43 (c) shows the O1s peak of the X-ray photoelectron spectral spectrum of the PA6 film after irradiation with atmospheric pressure plasma for 60 seconds. In the X-ray photoelectron spectrum of the PA6 film after irradiation with atmospheric pressure plasma, the peak of OH in the peak of O1s increased. Therefore, it is suggested that a functional group containing this bond, that is, a hydroxy group and a carboxy group was generated on the surface.

[Example 11]
An experiment was conducted to join carbon fiber reinforced plastics using polyetherketoneketone (PEKK) as a base material. FIG. 44 shows a stress-displacement diagram of a test piece in which carbon fiber reinforced plastics based on PEKK irradiated with atmospheric pressure plasma for 300 seconds are bonded to each other at 300 ° C. and 9.6 MPa. The bonding strength was about 13 MPa. Therefore, even in carbon fiber reinforced plastics using PEKK as a base material, sufficiently strong bonding is realized.

From the above experimental results, even when plasma is irradiated by the atmospheric pressure plasma irradiation device, functional groups such as carboxy groups and hydroxy groups are generated on the surface as in the case of plasma irradiation by the low pressure plasma irradiation device, and the bonding partner is formed. It was suggested that it forms a chemical bond with an atom or functional group on the surface of the plasma. That is, even when the plasma is irradiated using the atmospheric pressure plasma irradiation device, the two objects can be joined by the same principle as when the plasma is irradiated using the low pressure plasma irradiation device. Therefore, not only the carbon fiber reinforced plastics using PA6 as the base material shown in Example 10 but also the combination of the objects shown in Examples 1 to 8 can be similarly bonded by the atmospheric pressure plasma. Further, not only carbon fiber reinforced plastics but also reinforced plastics reinforced with an arbitrary filler such as glass fiber can be bonded by irradiating the bonding surface with plasma under low pressure or atmospheric pressure.

When using an atmospheric pressure plasma irradiation device, plasma can be irradiated without depressurizing, so restrictions such as the size of the object to be joined and the processing location are significantly reduced, and the range of applications can be greatly expanded. it can.

[Durability of plasma irradiation effect]
The sustainability of the effect of irradiating the surface of the object with atmospheric pressure plasma was verified. The surfaces of two sample pieces of carbon fiber reinforced plastic using PA6 as a base material are irradiated with plasma under atmospheric pressure, and each sample piece is stored in air at 25 ° C. and 30% humidity, and then the sample piece. The joint strength was measured by joining them together.

FIG. 45 shows the relationship between the number of days elapsed after irradiation with atmospheric pressure plasma and the bonding strength of a carbon fiber reinforced plastic using PA6 as a base material. It was shown that even if the bonding is performed 7 days after the atmospheric pressure plasma irradiation, the bonding can be firmly performed with the bonding strength almost the same as that immediately after the atmospheric pressure plasma irradiation.

As described above, it is suggested that by irradiating the surface of the object with atmospheric pressure plasma under the conditions shown in this example, the life of the functional group can be extended, which was impossible by the conventional plasma treatment. .. As a result, the adhesiveness of only the surface can be continuously improved for a long period of time without changing the properties of the object itself to be joined.

According to the technique of the present embodiment, since it is possible to firmly bond two objects even after a considerable period of time has passed after irradiating the atmospheric pressure plasma, it is possible to separate the plasma irradiation process and the bonding process. it can. Therefore, it is possible to carry an object whose surface is irradiated with atmospheric pressure plasma to another site and join the two objects at the site.

From this point of view, the method for producing a bonded product according to the present embodiment includes a step of irradiating the bonding surface of each of the two objects with plasma under atmospheric pressure, and a plasma is generated after a predetermined period of time has passed since the plasma was irradiated. It may include a step of adhering the irradiated joint surfaces to each other at a temperature below the melting point of the substance contained in the object. The predetermined period may be a period in which a predetermined number or more of functional groups generated on the bonding surface by irradiation with atmospheric pressure plasma or a predetermined ratio or more remain, for example, 1 hour, 2 hours, 5 hours, 10 hours. , 20 hours, 1 day, 2 days, 5 days, 10 days, 20 days, 1 month, 2 months, 3 months, 4 months, 5 months, 6 months, 7 months, 8 months, 9 months, 10 months, 11 It may be months, 1 year, 2 years, 3 years, 4 years, 5 years, 6 years, 7 years, 8 years, 9 years, 10 years, 15 years or more.

Since two objects can be bonded even after a considerably long period of time has passed after being irradiated with plasma, it has a bonding surface in which functional groups are generated by irradiation with plasma under atmospheric pressure. It is also possible to sell and distribute objects as joint objects such as building materials and parts. The purchaser who obtained the object before the generated functional group disappears can manufacture the bonded object by joining the bonding surfaces of the two bonding objects to each other.

Although the present invention has been described above with reference to the above-described embodiments, the present invention is not limited to the above-described embodiments, and the configurations of the embodiments are appropriately combined or substituted. Those are also included in the present invention. Further, it is also possible to appropriately rearrange the combinations and the order of processes in each embodiment based on the knowledge of those skilled in the art, and to add modifications such as various design changes to each embodiment, and such modifications. The embodiment to which is added may also be included in the scope of the present invention.

10 rotary drum type plasma irradiator, 20 bell jar, 22 electrodes, 24 rotary drum, 26 sample holder, 28 gas inlet, 30 cylinder, 32 samples.

Claims (7)

It is a method of joining two objects to manufacture a joint.
The step of irradiating the joint surface of each of the two objects with plasma under atmospheric pressure,
A step of adhering plasma-irradiated joint surfaces to each other at a temperature below the melting point of the substance contained in the object.
A method for producing a joint, which comprises. The method for producing a bonded product according to claim 1, wherein the bonding step is performed at room temperature. A step of joining one surface of a film that can be joined to both of the two objects and one of the two objects.
A step of joining the other surface of the film and the other of the two objects,
The method for producing a bonded product according to claim 1 or 2, further comprising. A bonded product characterized in that the two objects are bonded by a chemical bond between functional groups generated on the bonded surface by irradiating the bonding surface of each of the two objects with plasma under atmospheric pressure. Further provided with a film placed between the two objects
The bonded product is formed by bonding one surface of the film and one of the two objects, and bonding the other surface of the film and the other of the two objects. The joint according to claim 4. It is a method of joining two objects to manufacture a joint.
The step of irradiating the joint surface of each of the two objects with plasma under atmospheric pressure,
A step of adhering the bonded surfaces irradiated with the plasma to each other at a temperature lower than the melting point of the substance contained in the object after a lapse of a predetermined period from the irradiation of the plasma.
A method for producing a joint, which comprises. A bonding object having a bonding surface in which a functional group is generated by irradiation with plasma under atmospheric pressure.