Patent Description:
In a joint that bonds members made of the same or different materials to each other, there is a case where an anchor portion having an uneven shape is formed on a surface of one of the members in order to increase the bonding strength.

For example, Patent Literature <NUM> below suggests a method of forming an anchor portion by bonding approximately spherical metal powder to a bonding surface, by performing laser cladding to a surface to which the metal powder adheres after making the metal powder adhere to the bonding surface of one of the members.

In order to obtain a high anchor effect by forming the anchor portion on the bonding surface, it is important to increase the bonding strength of the anchor portion to the bonding surface while maintaining the shape that makes the anchor portion (metal powder) adhering to the bonding surface easily achieve the anchor effect.

However, in the method of Patent Literature <NUM>, when it is desired to improve the adhesive strength of the anchor portion to the bonding surface, the metal powder melts and deforms into a shape that does not easily achieve the anchor effect. When it is desired to maintain a shape that easily achieves the anchor effect, the metal powder becomes less likely to melt, and the adhesive strength of the anchor portion to the bonding surface decreases.

The <CIT> discloses a metal-plastic composite part. For a strong bond of a metal-plastic layered composite part, it discloses a fiber-reinforced thermoplastic and a surface structure embedded in the plastic and penetrating a fiber reinforcement of the plastic with pins of the metal.

The <CIT> discloses a composite component comprising a first component made of a fiber-reinforced or lattice-reinforced thermoplastic composite material and a second component, the first component having a first joining surface and the second component having a second joining surface, and the first component and the second component being joined to one another via the first and second joining surfaces, wherein the second joining surface has surface protrusions that engage the fiber or grid reinforced thermoplastic composite material and penetrate the fiber or grid reinforcement of the fiber or grid reinforced composite material.

The <CIT> discloses a method for connecting a surface-structured workpiece and a plastic workpiece using a joining tool including a sonotrode, said surface-structured workpiece comprising a structured contact surface section, said structured contact surface section comprising pin-like elements extending away from the structured contact surface section, said method comprising the following steps: positioning the surface-structured workpiece and the plastic workpiece on an anvil such that the structured contact surface section faces a contact surface of the plastic workpiece, positioning the joining tool on the metal workpiece so as to bring the sonotrode into contact with an outer surface of the metal workpiece, the outer surface being opposite to the structured contact surface section, applying a pressure to the sonotrode and/or the anvil perpendicular to the contact surface to hold the workpieces fixed between the anvil and the sonotrode and applying ultrasonic vibrations to the workpieces by the sonotrode for a predetermined period of time, so that softening of the plastic workpiece is induced and the pin-like elements penetrate into the plastic workpiece.

The <CIT> discloses a composite material comprising two materials, wherein at least one first material is metal-containing and at least one second material is plastic-containing, and these materials are bonded to one another without adhesion via at least one claw.

The <CIT> discloses a joining arrangement comprising at least two joining partners, of which a first joining partner has a thermoplastic material and a second joining partner has at least one joining element, in particular with an undercut contour, the second joining partner being driven with its joining element into the first joining partner in a joining direction in the case of plasticized plastic material with material displacement. According to the invention, the connecting element of the second joining partner is driven in to a joining depth while maintaining a residual base thickness towards the remote component side of the first joining partner, in particular with backflow of the still plasticized plastic material into the undercut contour of the connecting element.

The <CIT> discloses a method for joining a first structural member and a metallic substrate. This method involves drawing projections from a metallic substrate using a Co-Meld or other like process. Individual plies of composite materials are laid upon the metallic substrate and projections. These projections penetrate the individual ply or layers of the composite material. A mechanical feature that serves as a retaining device is located at the distal end of the projections in order to prevent separation of the composite materials from the metallic substrate. The composite materials is infused with a resin or other material to complete the formation of the composite material. Additionally, other layers of composite material are placed over the mechanical features located at the distal ends.

The <CIT> discloses that sand blast is applied to the surface of a steel plate to form primary recesses and secondary recesses are formed by the action of mineral acid. A fluororesin film is introduced into a reduced pressure furnace from above so as to be pressed by a roll against the surface of the plate wherein the recesses have been formed and which has been heated to a temperature to soften or melt the film. Just after the steel plate has passed the furnace, the surface of the film is strongly pressed into the recesses because the atmospheric pressure is larger than the air pressure in the recesses. A final finishing roll smoothens the surface.

The <CIT> discloses a method of manufacturing a hybrid component comprising building up a metal part layer by layer by a 3D printing method, wherein a bonding surface of the metal part is formed with a plurality of protruding pins, disposing a fiber-reinforced plastic part having a plurality of reinforcing fibers embedded in a thermoplastic matrix material on the bonding surface of the metal part, heating the matrix material to a temperature at which the matrix material is flowable, pressing the fiber-reinforced plastic part and the metal part together so that the pins of the metal part penetrate the flowable matrix material of the fiber-reinforced plastic part, and consolidating the matrix material while applying a consolidation pressure.

The <CIT> discloses a method of modifying the structure of workpiece is provided. The method comprises a first step of causing relative movement between a power beam and the workpiece so that a region of the workpiece is melted, and the melted material displaced to form a projection at a first location in the region and a hole at a different location in the region. The melted material is then allowed to at least partially solidify after which the first step is repeated one or more times, with the region corresponding to each repeat intersecting the region of the first step.

The <CIT> discloses that when irradiating the only specific area on the surface of the base material with the ultraviolet laser beam, there are the following methods. By arranging a mask opened as a window at the front of the base material, the window corresponds to an area for forming a film, the whole surface is irradiated by the ultraviolet laser beam. Scanning is performed on the mask with a beam-shape ultraviolet laser. By providing a scanning mechanism such as a galvanomirror in front of the insulating base material, scanning is performed with a beam-shape ultraviolet laser. At the state in which the surface of the base material is irradiated with a beam-shape ultraviolet laser, the base material is allowed to move by an X-Y table, etc., to relatively scan with the ultraviolet laser beam.

PTL <NUM>: Japanese Unexamined Patent Publication <CIT>.

The present disclosure was made in consideration of the above-described points, and an object thereof is to form an anchor portion having a shape that easily achieves the anchor effect and having high bonding strength to the bonding surface, thereby improving the bonding strength of the joint.

The invention is defined in a first aspect by a joint according to claim <NUM> and in a second aspect by a method for manufacturing a joint according to claim <NUM>.

In the present disclosure, it is possible to form an anchor portion that has a shape that easily achieves the anchor effect and has high bonding strength to the bonding surface, thereby obtaining the joint having high bonding strength.

Hereinafter, a first embodiment of the present disclosure will be described with reference to the drawings. In the drawings, there is a case where the size or the like of the members are written being exaggerated for the sake of description.

First, a joint <NUM> of the present embodiment will be described. As illustrated in <FIG>, the joint <NUM> includes a first member (hereinafter, there is also a case of being referred to as "metal member") <NUM> made of metal, and a second member (hereinafter, there is also a case of being referred to as "synthetic resin member") <NUM> made of thermoplastic resin. The metal member <NUM> has a first bonding surface (hereinafter, there is a case of being referred to as "metal bonding surface") <NUM> with an anchor portion <NUM> formed on the surface thereof. The synthetic resin member <NUM> has a second bonding surface (hereinafter, there is a case of being referred to as "resin bonding surface") <NUM> on the surface thereof. The joint <NUM> is made by bonding the resin bonding surface <NUM> to the metal bonding surface <NUM> to integrate the metal member <NUM> and the synthetic resin member <NUM>.

The synthetic resin member <NUM> is a member made by molding the thermoplastic resin into a predetermined shape, such as a block, plate, or wire shape. The synthetic resin member <NUM> may be a coating film of thermoplastic resin or an adhesive layer made of thermoplastic resin adhesive. Specific examples of the thermoplastic resin that makes the synthetic resin member <NUM> include polypropylene resin (PP resin), polyacetal resin (POM resin), polyphenylene sulfide resin (PPS resin), polyetheretherketone resin (PEEK), acrylonitrile/butadiene/styrene resin (ABS resin), polyethylene resin (PE resin), polybutylene terephthalate resin (PBT resin), polyamide resin (PA resin) such as nylon <NUM> (PA66), epoxy resin, liquid crystal polymer (LCP resin), modified polyphenylene ether resin (modified PPE), reactor type soft polypropylene resin (metallocene reactor type TPO resin), perfluoroalkoxy alkanes (PFA), and ethylene tetrafluoroethylene copolymer (ETFE). The synthetic resin member <NUM> may be made of a carbon fiber reinforced thermoplastic resin (CFRTP), in which carbon fibers are blended into the above- described thermoplastic resin, or a resin, in which a reinforcing material such as glass fiber or talc, flame retardants, degradation inhibitors, and elastomer components are blended into the above-described thermoplastic resin.

The metal member <NUM> is a member obtained by molding the metal into a predetermined shape, such as a block, plate, or wire shape. A metal that makes the metal member <NUM> is not particularly limited, and various types of metals can be used. For example, copper (Cu), iron (Fe), aluminum (Al), titanium (Ti), nickel (Ni), chromium (Cr), and the like can be used as the metal that makes the metal member <NUM>. The metal member <NUM> may be made of an alloy consisting of two or more metals, such as copper alloy, iron alloy (steel material), aluminum alloy, stainless steel, titanium alloy, nickel alloy, and chromium alloy.

The metal member <NUM> preferably has a higher hardness than the synthetic resin member <NUM> at normal temperature (<NUM>). When bonding the metal member <NUM> and the synthetic resin member <NUM> to each other, the hardness of the metal member <NUM> is preferably higher than that of the synthetic resin member <NUM>. When bonding the metal member <NUM> and the synthetic resin member <NUM> to each other, the hardness of the metal member <NUM> may be higher than that of the synthetic resin member <NUM>, and after the bonding, the hardness of the synthetic resin member <NUM> may be higher than that of the metal member <NUM> under normal temperature. Here, hardness under normal temperature is Vickers hardness measured in accordance with JIS Z <NUM>, and in a case where the metal member <NUM> and the synthetic resin member <NUM> are under high temperature when bonding the metal member <NUM> and the synthetic resin member <NUM> to each other, hardness is high-temperature Vickers hardness measured in accordance with JIS Z <NUM>.

The shape of the metal member <NUM> can be any desired shape depending on the application or the like. As the method for molding the metal member <NUM>, any method can be applied, and casting by pouring molten metal into a mold having a desired shape, cutting using a machine tool or the like, punching using a press machine or the like, and the like may be used.

The metal member <NUM> may also have an oxide film (metal oxide) formed on the metal bonding surface <NUM> or in an anchor portion <NUM> which will be described later. The oxide film may be a natural oxide film which is naturally formed on the surface of metal. The oxide film may be formed on the surface of the metal member <NUM> by surface treatment with an oxidant, electrolytic treatment with anodic oxidation, plasma oxidation treatment, or heat oxidation treatment in the oxygen-containing gas, and the like.

As a preferable aspect, the oxide film may be formed on the surface of the metal member <NUM> by rapidly heating the surface of the metal member <NUM> under an atmosphere of the oxygen-containing gas, such as in the air. It is preferable that the rising temperature of the surface of the metal member <NUM> per minute during rapid heating is equal to or higher than the melting point temperature of the metal that makes the metal member <NUM>. By rapidly heating the surface of the metal member <NUM> in this manner, a dense oxide film can be formed on the surface of the metal member <NUM>. Furthermore, by rapidly heating the surface of the metal member <NUM>, microcracks are generated on the surface of the oxide film, and a bonding area with the synthetic resin member <NUM> becomes larger.

Although the surface of the metal member <NUM> can be heated rapidly by various methods such as laser heating, induction heating, or resistor heating, the temperature raising speed at the time of heating is fast and the temperature control is easy, and thus, it is preferable to heat the surface of the metal member <NUM> by irradiating a laser beam to form the oxide film.

On the metal bonding surface <NUM> of the metal member <NUM>, the roughening treatment is performed and the anchor portion <NUM> is provided.

The anchor portion <NUM> formed on the metal bonding surface <NUM> has a plurality of projections <NUM> protruding from the metal bonding surface <NUM>, as illustrated in <FIG> and <FIG>. The plurality of projections <NUM> is provided side by side along a predetermined direction (hereinafter, the direction is referred to as a first direction) X.

In the present embodiment, as illustrated in <FIG>, five anchor portions <NUM> are provided on the metal bonding surface <NUM> in a direction (hereinafter, the direction is a second direction) Y perpendicular to the first direction X with a gap. However, one anchor portion <NUM> may be provided on the metal bonding surface <NUM>, and the plurality of anchor portions <NUM> may be provided on the metal bonding surface <NUM> in the second direction <NUM> with a gap. In a case where the plurality of anchor portions <NUM> is provided on the metal bonding surface <NUM>, one anchor portion <NUM> may be provided parallel to the other anchor portions <NUM>, as illustrated in <FIG>, or may be provided so as to be inclined to the other anchor portions <NUM>.

Each projection <NUM> that configures the anchor portion <NUM> has a protrusion strip portion 35a protruding from the first bonding surface <NUM> and an inflation portion 35b provided above the protrusion strip portion 35a.

The protrusion strip portion 35a has a narrow protrusion strip shape that extends in the first direction X. As a preferable aspect, the protrusion strip portion 35a may be linked to the protrusion strip portion 35a of the adjacent projection <NUM> in the first direction X. The protrusion strip portions 35a may be continuously linked to each other to connect all of the projections <NUM> that configure the anchor portion <NUM> as illustrated in <FIG> and <FIG>, or some protrusion strip portions 35a may not be connected to the protrusion strip portions 35a of the adjacent projection <NUM> in the first direction X, and the protrusion strip portions 35a may be divided in the middle of the first direction X.

The inflation portion 35b provided above the protrusion strip portion 35a has a shape that widens to both sides from the protrusion strip portion 35a in the second direction Y. Accordingly, each projection <NUM> is narrowly constricted in the second direction Y at the protrusion strip portion 35a provided below the inflation portion 35b, and undercut portions 35c are provided on both sides of the projection <NUM> in the second direction Y. The inflation portion 35b can have various shapes, such as a substantial sphere, a substantial ellipse, or a solid in which a plurality of substantial spheres is connected to each other.

In each of the projections <NUM> that configure the anchor portion <NUM>, a shape of a cross section (hereinafter, there is also a case of being referred to as "first directional cross section") along the first direction X including the top portion 35d of the projection <NUM> as illustrated in <FIG> is a shape that widens in the first direction X as approaching the metal bonding surface <NUM> such that the length along the first direction X on the metal bonding surface <NUM> side (that is, a contact part with the metal bonding surface <NUM>) is the longest.

In other words, in each of the projections <NUM> that configure the anchor portion <NUM>, a stem part (a part on the metal bonding surface <NUM> side) is narrowly constricted when viewed from the first direction X (refer to <FIG>), and the stem part widens in the first direction X when viewed from the second direction Y (refer to <FIG>).

As an example of the various dimensions of the plurality of projections <NUM> that configure the anchor portion <NUM>, it is possible to set the length from the metal bonding surface <NUM> to the top portion 35d of the projection <NUM> (protrusion height of the projection <NUM>) to be <NUM> to <NUM>, the length of the protrusion strip portion 35a in the second direction Y to be <NUM> to <NUM>, the length of the inflation portion 35b in the second direction Y to be <NUM> to <NUM>, the length of the protrusion strip portion 35a in the first direction X to be <NUM> or more, and the gap between the adjacent projections <NUM> in the first direction X to be <NUM> to <NUM>. The length of the protrusion strip portion 35a in the first direction X may be equal to the length of the anchor portion <NUM> in the first direction X.

As a preferable aspect, in each projection <NUM> that configures the anchor portion <NUM>, a length Lx of the contact part with the metal bonding surface <NUM> in the first directional cross section as illustrated in <FIG> is longer than a length Ly of the contact part with the metal bonding surface <NUM> in the cross section (hereinafter, there is also a case of being referred to as "second directional cross section") along the second direction Y including the top portion 35d as illustrated in <FIG>.

The first directional cross section of each projection <NUM> that configures the anchor portion <NUM> may have a shape of which the length in the first direction X gradually increases as approaching the metal bonding surface <NUM> from the top portion 35d, as in a projection <NUM>-<NUM>, or may have a shape that has a part which is narrowly constricted in the first direction X, as in a projection <NUM>-<NUM>, and that widens in the first direction X such that the constricted part on the metal bonding surface <NUM> side is the longest in the first direction X (refer to <FIG>).

Next, a method for manufacturing the joint <NUM> will be described.

First, the synthetic resin member <NUM> and the metal member <NUM>, which are molded into a predetermined shape, are prepared. An anchor formation process of forming the anchor portion <NUM> on the metal bonding surface <NUM> of the metal member <NUM>, is executed. After this, a bonding process of bonding the resin bonding surface <NUM> of the synthetic resin member <NUM> to the metal bonding surface <NUM> on which the anchor portion <NUM> is formed, is performed. Accordingly, the joint <NUM> in which the synthetic resin member <NUM> is bonded to the metal bonding surface <NUM> of the metal member <NUM>, is obtained. Hereinafter, the anchor formation process and the bonding process will be described in detail.

In the anchor formation process, the metal bonding surface <NUM> of the metal member <NUM> to which the synthetic resin member <NUM> is bonded is preferably irradiated with a pulsed laser beam that satisfies a coefficient R of <NUM> or higher and <NUM> or lower expressed in Equation (<NUM>) below while moving (scanning) in the first direction X. [Equation <NUM>] <MAT>.

In Equation (<NUM>), h is the frequency of the laser beam, k is the thermal diffusion coefficient of the metal material that makes the metal member <NUM> (m<NUM>/sec), t is the pulse width of the laser beam (sec), and v is the scanning speed at which the laser beam is scanned (m/sec).

When the metal bonding surface <NUM> is irradiated with the pulsed laser beam with the above-described coefficient R of <NUM> or higher and <NUM> or lower, the projections <NUM> of which the stem part is narrowly constricted when viewed from the first direction X and the stem part widens in the first direction X when viewed from the second direction Y are provided side by side along the first direction X.

When the anchor portion <NUM> is formed by irradiating with the laser beam as described above in oxygen-containing gas, metal oxide is formed on the surface of the anchor portion <NUM>.

In a case of forming the plurality of anchor portions <NUM> in the second direction Y with a gap, the metal bonding surface <NUM> is irradiated with the pulsed laser beam while scanning in the first direction X at the position with a predetermined gap in the second direction Y.

Before irradiating the metal bonding surface <NUM> of the metal member <NUM> with the pulsed laser beam to form the anchor portion <NUM>, pretreatment of irradiating a location where the anchor portion <NUM> is formed with the laser beam on the metal bonding surface <NUM> and removing impurities adhering to the metal bonding surface <NUM>, may be performed.

In the bonding process, a softening process of softening the resin bonding surface <NUM> of the synthetic resin member <NUM> by heating the metal member <NUM> and the synthetic resin member <NUM>, is executed. Thereafter, a pressurizing process of bringing the metal bonding surface <NUM> into contact with the resin bonding surface <NUM> while pressurizing by making the plurality of projections <NUM> enter the synthetic resin member <NUM>, by pressuring the synthetic resin member <NUM> to the metal member <NUM> while bringing the resin bonding surface <NUM> into contact with the plurality of projections <NUM>, is executed. Accordingly, the joint <NUM> in which the resin bonding surface <NUM> is bonded to the metal bonding surface <NUM> is obtained. In the present embodiment, the softening process and the pressurizing process are performed using a bonding device <NUM> as illustrated in <FIG> and <FIG> to manufacture the joint <NUM>.

The bonding device <NUM> includes: a stage <NUM> on which the metal member <NUM> is placed; a heating device <NUM> that inductively heats the metal member <NUM> placed on the stage <NUM>; and a pressing device <NUM> that pressurizes and bonds the synthetic resin member <NUM> to the metal member <NUM>.

The metal member <NUM> is placed on the stage <NUM> such that the metal bonding surface <NUM> provided with the anchor portion <NUM> faces the synthetic resin member <NUM>.

The heating device <NUM> includes an induction heating coil connected to a power source device (not illustrated), and when a drive power source is input from the power source device, a magnetic field is generated from the induction heating coil to inductively heat the metal bonding surface <NUM> of the metal member <NUM> placed on the stage <NUM>.

The pressing device <NUM> includes: a rod <NUM> formed of an insulator such as ceramics; and a pressurizing unit <NUM> that moves the rod <NUM> to press the synthetic resin member <NUM> against the metal bonding surface <NUM> of the metal member <NUM>. The rod <NUM> may be inserted into a hollow part of the induction heating coil of the heating device <NUM> and disposed to face the synthetic resin member <NUM>, as illustrated in <FIG>. The pressurizing unit <NUM> preferably includes a pneumatic cylinder controlled by an electro-pneumatic regulator, a spring type pressurizer, or the like, and can control the speed at which the synthetic resin member <NUM> is moved together with the rod <NUM> and the pressure at which the synthetic resin member <NUM> is pressed against the metal member <NUM>.

In order to manufacture the joint <NUM> using the bonding device <NUM>, first, the metal member <NUM> is placed on the stage <NUM> such that the metal bonding surface <NUM> provided with the anchor portion <NUM> faces the synthetic resin member <NUM> to be set after this in an atmosphere where gas is present.

Next, the synthetic resin member <NUM> is disposed such that the resin bonding surface <NUM> faces the metal bonding surface <NUM> of the metal member <NUM> placed on the stage <NUM> with a gap therebetween. The distance between the metal bonding surface <NUM> of the metal member <NUM> and the resin bonding surface <NUM> of the synthetic resin member <NUM> is set at <NUM> to <NUM>, for example.

Next, the heating device <NUM> is disposed to face the metal bonding surface <NUM> of the metal member <NUM> across the synthetic resin member <NUM>. In a case illustrated in <FIG>, the heating device <NUM> is disposed above the synthetic resin member <NUM>, and the synthetic resin member <NUM> is disposed between the heating device <NUM> and the metal member <NUM>.

Next, the softening process of exposing the resin bonding surface <NUM> of the synthetic resin member <NUM> to a gas heated to a first temperature T1, is executed.

Specifically, the drive power source is supplied to the heating device <NUM> to generate a magnetic field from the induction heating coil provided in the heating device <NUM> and heat the metal bonding surface <NUM> of the metal member <NUM>. At this time, the drive power source supplied to the heating device <NUM>, the position of the induction heating coil provided in the heating device <NUM>, or the like are adjusted such that the metal bonding surface <NUM> of the metal member <NUM> reaches the first temperature T1.

As the metal member <NUM> is heated as described above, the gas between the metal member <NUM> and the synthetic resin member <NUM> is heated to the first temperature T1. Accordingly, the resin bonding surface <NUM> of the synthetic resin member <NUM> facing the metal bonding surface <NUM> of the metal member <NUM> is exposed to the gas heated to the first temperature T1, and the resin bonding surface <NUM> reaches the first temperature T1. Then, the heating device <NUM> heats the metal bonding surface <NUM> of the metal member <NUM> for a predetermined time S1 (for example, <NUM> to <NUM> seconds) to execute the softening process of softening the resin bonding surface <NUM> side of the synthetic resin member <NUM>, and then completes the softening process and moves to the pressurizing process.

When the softening process is completed, in order to continue executing the pressurizing process, the heating device <NUM> stops heating or reduces the amount of heating of the metal member <NUM> such that the temperature of the resin bonding surface <NUM>, the metal bonding surface <NUM>, and the surrounding thereof (the gas between the metal member <NUM> and the synthetic resin member <NUM>) is lowered (cooled) until reaching a second temperature T2. The synthetic resin member <NUM> and the metal member <NUM> are bonded to each other at the second temperature T2.

In other words, in the pressurizing process, at a temperature (second temperature T2) lower than the first temperature T1, the pressing device <NUM> moves the synthetic resin member <NUM> at a predetermined speed V to make the synthetic resin member <NUM> collide with the metal member <NUM>. At this time, the synthetic resin member <NUM> is pressed strongly against the metal member <NUM> at the position corresponding to a distal end of the rod <NUM>, and is pressed against the metal member <NUM> at a predetermined pressure P. Accordingly, the joint <NUM> is obtained by making the plurality of projections <NUM> provided on the metal bonding surface <NUM> enter the resin bonding surface <NUM> side of the synthetic resin member <NUM>, and bringing the resin bonding surface <NUM> into contact with the metal bonding surface <NUM> in a pressurized state. Then, the second process is completed.

The first temperature T1 can be a temperature which is equal to or higher than a deflection temperature under load Tf of the thermoplastic resin that makes the synthetic resin member <NUM> when a load of <NUM> MPa is applied. In a case where the synthetic resin member <NUM> is made of a resin in which a reinforcing material, such as carbon fiber, glass fiber, or talc, is blended into the thermoplastic resin, the deflection temperature under load Tf of the thermoplastic resin that makes the synthetic resin member <NUM> when a load of <NUM> MPa is applied is the deflection temperature under load Tf of the thermoplastic resin that does not contain the reinforcing material when a load of <NUM> MPa is applied.

An upper limit value of the first temperature T1 can be a temperature which is equal to or lower than a decomposition temperature of the thermoplastic resin that makes the synthetic resin member <NUM>, that is, can be a temperature which is lower than a temperature at which the thermoplastic resin begins to vaporize. As an example, the upper limit value of the first temperature T1 may be <NUM>. Preferably, the upper limit value of the first temperature T1 can be set to a temperature which is <NUM> higher than a melting point Tm of the thermoplastic resin that makes the synthetic resin member <NUM>.

The second temperature T2 may be a temperature lower than the first temperature T1, but is preferably equal to or higher than the deflection temperature under load Tf of the thermoplastic resin that makes the synthetic resin member <NUM> when a load of <NUM> MPa is applied. The second temperature T2 is preferably lower than the melting point Tm of the thermoplastic resin that makes the synthetic resin member <NUM>. The temperature difference between the first temperature T1 and the second temperature T2 is preferably <NUM> or higher and <NUM> or lower.

In the present specification, the melting point Tm of the thermoplastic resin is a value measured at a temperature raising speed of <NUM> per minute using a differential scanning calorimeter according to JIS K7121. The melting points of typical thermoplastic resins are <NUM> for polypropylene resin, <NUM> for nylon <NUM>, <NUM> to <NUM> for polybutylene terephthalate resin, and <NUM> for polyphenylene sulfide resin.

The deflection temperature under load Tf of the thermoplastic resin is a deflection temperature under load measured by a method according to JIS K7191 when a load of <NUM> MPa is applied. The deflection temperatures under load Tf of typical thermoplastic resins when a load of <NUM> MP is applied are <NUM> to <NUM> for polypropylene resin, <NUM> to <NUM> for nylon <NUM>, <NUM> for polybutylene terephthalate resin, and <NUM> for polyphenylene sulfide resin.

The softening process is preferably executed in the oxygen-containing gas such as air. In other words, it is preferable to heat the metal bonding surface <NUM> and the resin bonding surface <NUM> to the first temperature T1 in an atmosphere of oxygen-containing gas, and expose the metal bonding surface <NUM> and the resin bonding surface <NUM> to the oxygen-containing gas heated to the first temperature T1.

When the softening process is executed in an atmosphere of the oxygen-containing gas, the resin bonding surface <NUM> of the synthetic resin member <NUM> reacts with the oxygen contained in the oxygen-containing gas to generate functional groups that can be chemically bound by neutralization reactions with basic or amphoteric oxides, on the resin bonding surface <NUM> of the synthetic resin member <NUM>.

In general, the surface of the metal member <NUM> is oxidized and coated with an oxide film made of metal oxides, and thus, the functional groups generated on the resin bonding surface <NUM> are bonded to the metal oxides on the metal bonding surface <NUM> of the metal member <NUM> by van der Waals forces or hydrogen bonds. In addition, by bonding the synthetic resin member <NUM> and the metal member <NUM> to each other in a heated and pressurized state, the functional groups of the resin bonding surface <NUM> form covalent binding with the metal oxide of the metal member <NUM> by a neutralization reaction (dehydration condensation).

One example of the functional group generated on the resin bonding surface <NUM> includes at least one of a carboxyl group (-COOH), a carbonyl group (-CO-), or a hydroxy group (-OH) which are generated by the oxidative decomposition of the thermoplastic resin that makes the synthetic resin member <NUM>. When the thermoplastic resin that makes the synthetic resin member <NUM> is a resin that contains sulfur atoms (heteroatoms), such as polyphenylene sulfide resin (PPS), as the functional group contained in the resin bonding surface <NUM>, in addition to carboxyl groups, carbonyl groups, and hydroxy groups, the functional group containing heteroatoms such as sulfone groups (-SO3H), sulfonyl groups (-SO2-), sulfanyl groups (-SH), and disulfide groups (-SS-) may be contained.

As an example of the neutralization reaction that occurs by bonding the metal member <NUM> and the synthetic resin member <NUM> to each other, in a case where the resin bonding surface <NUM> has a carboxyl group (R-COOH) as a functional group and the metal member <NUM> is made of a divalent metal, the neutralization reaction occurs as illustrated in Equation (<NUM>) below.

In Equation (<NUM>), R is the main chain of the thermoplastic resin that makes the synthetic resin member <NUM>, and Me is the metal that makes the metal member <NUM>.

In a case where the softening process is executed in an atmosphere of the oxygen-containing gas, the second temperature T2 is preferably a temperature at which the functional group of the resin bonding surface <NUM> of the synthetic resin member <NUM> and the metal oxide formed on the metal bonding surface <NUM> of the metal member <NUM> can form the covalent binding by the neutralization reaction. The second temperature T2 is preferably a temperature at which the water generated by the neutralization reaction is removed from the reaction system. Since the second temperature T2 varies depending on the functional group and the type of metal oxide, it is difficult to specify the second temperature T2 in general, but the second temperature T2 is more preferable to be equal to or higher than <NUM> because the water generated by the neutralization reaction is easily removed.

In the softening process, the metal member <NUM> and the synthetic resin member <NUM> may be heated such that the entire metal member <NUM> and the synthetic resin member <NUM> reach the first temperature T1, but the resin bonding surface <NUM> may be exposed to gas heated to the first temperature T1, and the metal member <NUM> and the synthetic resin member <NUM> may be heated such that at least the metal bonding surface <NUM> and the resin bonding surface <NUM> reach the first temperature T1. Accordingly, the resin bonding surface <NUM> side of the synthetic resin member <NUM> is softened, it becomes easy for the projection <NUM> to enter the synthetic resin member <NUM> during the pressurizing process, and the deformation of the synthetic resin member <NUM> can be suppressed. The softening process is preferably performed such that the hardness on the resin bonding surface <NUM> side of the synthetic resin member <NUM> becomes less than that of the metal member <NUM>.

In the pressurizing process, the pressure P when the synthetic resin member <NUM> is pressed against the metal member <NUM> is preferably a pressure which is equal to or higher than the compressive yield stress of the thermoplastic resin that makes the synthetic resin member <NUM>. Since the pressure P varies depending on the thermoplastic resin that makes the synthetic resin member <NUM>, it is difficult to specify the pressure P in general, but the pressure P is preferable to be <NUM> to <NUM> MPa.

In the present embodiment, a case where the pressing device <NUM> moves the synthetic resin member <NUM> toward the metal member <NUM> is described, but the metal member <NUM> may be moved toward the synthetic resin member <NUM>.

In a case of locally bonding the metal member <NUM> and the synthetic resin member <NUM> as described in the present embodiment, the flat-surface shape of the bonding location may be any shape, such as point, line, or surface.

In the pressurizing process, the synthetic resin member <NUM> may be pressed against the metal member <NUM> such that all of the anchor portions <NUM> provided on the metal bonding surface <NUM> are pressurized, or the synthetic resin member <NUM> may be pressed against the metal member <NUM> locally (spot-like) such that some of the anchor portions <NUM> are pressurized.

In the present embodiment, while the synthetic resin member <NUM> is pressed against the metal member <NUM>, the temperature of the synthetic resin member <NUM>, the metal member <NUM>, and the surrounding thereof may be maintained at the second temperature T2. Otherwise, the synthetic resin member <NUM> may be continuously in contact with the metal member <NUM> in a pressurized state until the temperature of the synthetic resin member <NUM>, the metal member <NUM>, and the surrounding thereof is cooled to be equal to or lower than a predetermined temperature. In such a case, it is preferable to bring the synthetic resin member <NUM> into contact with the metal member <NUM> in a pressurized state until the temperature of the synthetic resin member <NUM>, the metal member <NUM>, and the surrounding thereof is cooled to be equal to or lower than a glass transition temperature Tg of the thermoplastic resin that makes the synthetic resin member <NUM>.

In the present embodiment, a case where the synthetic resin member <NUM> molded into a predetermined shape in advance is compressed to the metal member <NUM> while being heated is described as the bonding process. However, by inserting the metal member <NUM> in which the anchor portion <NUM> is formed into an injection mold, and injecting the molten synthetic resin material toward the metal bonding surface <NUM> within the injection mold, the synthetic resin member <NUM> may be bonded to the metal member <NUM>.

In the joint <NUM> of the present embodiment, the undercut portions 35c are provided on both sides in the second direction Y of the plurality of projections <NUM> that configure the anchor portion <NUM>, and thus, it is possible to increase the bonding strength between the synthetic resin member <NUM> and the metal member <NUM>.

In the plurality of projections <NUM>, the shape of the first directional cross section is a shape that widens in the first direction X as approaching the metal bonding surface <NUM> such that the length along the first direction X is the longest on the metal bonding surface <NUM> side. Therefore, while maintaining the shape that easily achieves the anchor effect, the bonding strength of the plurality of projections <NUM> to the metal bonding surface <NUM> increases, the projection <NUM> itself is less likely to be damaged during or after the bonding of the synthetic resin member <NUM>, and as a result, it is possible to improve the bonding strength of the joint <NUM>.

Moreover, since the plurality of projections <NUM> that configure the anchor portion <NUM> is provided side by side along the first direction X, multiple projections <NUM> can be provided on the metal bonding surface <NUM> with an appropriate gap, and it is possible to improve the bonding strength of the joint <NUM>.

In the present embodiment, in a case where the protrusion strip portions 35a of the projections <NUM> adjacent to each other in the first direction X are linked to each other, the bonding strength of the projections <NUM> to the metal bonding surface <NUM> can be further improved.

In the present embodiment, in a case where the first directional cross section of the projection <NUM> is a shape of which the length in the first direction X gradually increases as approaching the metal bonding surface <NUM> from the top portion 35d, as in the projection <NUM>, the bonding strength of the projection <NUM> to the metal bonding surface <NUM> can be further improved.

In the present embodiment, in a case where the hardness of the metal member <NUM> is higher than that of the synthetic resin member <NUM>, it becomes easy for the plurality of projections <NUM> provided in the metal member <NUM> to enter the synthetic resin member <NUM>, the plurality of projections <NUM> is less likely to be damaged, and high anchor effect can be obtained.

In the present embodiment, in a case where the metal oxide is formed on the surface of the anchor portion <NUM>, the functional groups of the resin bonding surface <NUM> of the synthetic resin member <NUM> bond to the metal oxide of the anchor portion <NUM> by dipolar interaction. In addition, the functional groups of the resin bonding surface <NUM> form a covalent binding with the metal oxide through a neutralization reaction (dehydration condensation). Therefore, it is possible to improve the bonding strength of the joint <NUM>.

Next, a second embodiment of the present disclosure will be described with reference to <FIG> and <FIG>. The same configurations as those of the first embodiment will be given the same reference numerals, and the description of the configurations will be omitted.

In the present embodiment, a groove <NUM> that extends along the first direction X is formed on the resin bonding surface <NUM>. The groove <NUM> is provided at a position corresponding to the plurality of projections <NUM> that configures the anchor portion <NUM> provided in the metal member <NUM>. In the bonding process, the plurality of projections <NUM> provided on the metal bonding surface <NUM> are fitted into the grooves <NUM> to obtain a joint <NUM>.

It is preferable that a filling process of filling the groove <NUM> provided on the resin bonding surface <NUM> with a third member (hereinafter, there is also a case of being referred to as "filling member") <NUM> is performed. Any material can be used as a material that makes the filling member <NUM>, but it is preferable to use a material having a lower hardness than the metal member <NUM> when bonding the metal member <NUM> and the synthetic resin member <NUM> to each other, and more preferable to use a material that is heat-cured after bonding the metal member <NUM> and the synthetic resin member <NUM> to each other. It is preferable to use a thermosetting resin such as epoxy resin or phenolic resin as the filling member <NUM>.

In such a joint <NUM> of the second embodiment, the softening process of softening the filling member <NUM> by heating the metal member <NUM> and the filling member <NUM>, is executed. Thereafter, the pressurizing process of bringing the metal bonding surface <NUM> into contact with the resin bonding surface <NUM> while pressurizing by making the plurality of projections <NUM> enter the filling member <NUM>, by pressuring the synthetic resin member <NUM> to the metal member <NUM> while bringing the filling member <NUM> into contact with the plurality of projections <NUM>, is executed. Accordingly, the joint <NUM> in which the resin bonding surface <NUM> is bonded to the metal bonding surface <NUM> is obtained.

In the present embodiment, since the plurality of projections <NUM> provided on the metal bonding surface <NUM> is fitted into the grooves <NUM> provided on the resin bonding surface <NUM>, it becomes easy to enter the synthetic resin member <NUM> and the bonding process can be easily performed.

In a case where the grooves <NUM> provided on the resin bonding surface <NUM> are filled with the filling member <NUM>, the plurality of projections <NUM> is less likely to come out of the grooves <NUM>, and it is possible to improve the bonding strength of the joint <NUM>.

The present disclosure is not limited to the above-described embodiments. Each of the above-described embodiments is presented as examples and is not intended to limit the scope of the disclosure. The new embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the disclosure.

For example, in the above-described first and second embodiments, a case of bonding the metal member <NUM> in which the anchor portion <NUM> is formed and the synthetic resin member <NUM> made of thermoplastic resin to each other is described, but the present disclosure can also be applied to a case of bonding the metal members made of metal to each other or a case of bonding the resin members made of resin to each other.

In the above-described first and second embodiments, the softening process of softening the resin bonding surface <NUM> side of the synthetic resin member <NUM> by heating is executed in the manufacture of the joint <NUM>. However, in addition to or instead of heating, the softening process may be performed by humidification or other methods.

Hereinafter, Example and Comparative Examples <NUM> and <NUM> of the present disclosure will be described. The present disclosure is not limited to Example.

In the Example and Comparative Examples <NUM> and <NUM>, by irradiating the metal bonding surface of the metal member with the laser beam in the second direction Y while scanning in the first direction X every <NUM> gap, the anchor portion is formed on the entire location of the metal bonding surface that is in contact with the resin bonding surface. Then, a synthetic resin member is bonded to the metal bonding surface on which the anchor portion is formed. The conditions of the irradiated laser beam on the metal bonding surface of Example and Comparative Examples <NUM> and <NUM> are illustrated in Table <NUM> described below.

The details of the metal member and the synthetic resin member which are used in Example and Comparative Examples <NUM> and <NUM>, the dimension of the metal member, the dimension of the synthetic resin member, and the bonding area (overlap area) between the synthetic resin member and the metal member, are as follows.

·Metal member: SUS304 with a surface oxidized and roughened by heating to the melting point of SUS304, which is <NUM> or higher, for one second by laser irradiation.

For the metal members of Example and Comparative Examples <NUM> and <NUM>, in which the anchor portion is formed on the metal bonding surface, SEM observation of the anchor portion is performed in a state where the synthetic resin member is not bonded. <FIG> illustrate a plan view and sectional views of the metal member of Example. In <FIG>, the sign X indicates the first direction, which is the scan direction of the laser beam, and the sign Y indicates the second direction.

As illustrated in <FIG>, on the metal bonding surface of the metal member in Example, the plurality of projections is provided side by side along the first direction X. In the plurality of projections provided on the metal bonding surface, as illustrated in <FIG>, the first directional cross section of the plurality of projections is a shape of which the length in the first direction X increases as approaching the metal bonding surface from the top portion of the projection. As illustrated in <FIG>, the plurality of projections has a protrusion strip portion and an inflation portion that widens to both sides from the protrusion strip portions in the second direction Y above the protrusion strip portion, and are provided with the undercut portion on both sides of the projection in the second direction Y.

In the plurality of projections, the cross-sectional shape along the first direction including the top portion is a shape that widens in the first direction X as approaching the metal bonding surface such that the length is the longest in the first direction X on the metal bonding surface side, and the length of the contact part with the metal bonding surface in the first directional cross section is longer than the length of the contact part with the metal bonding surface <NUM> in the second directional cross section.

On the metal bonding surface of the metal member in Comparative Example <NUM>, the plurality of protrusion strip portions extending in the first direction X is provided in the second direction Y with a gap, but no inflation portion is formed above the protrusion strip portion.

On the metal bonding surface of the metal member in Comparative Example <NUM>, a plurality of recessed grooves extending in the first direction X is provided in the second direction Y with a gap, but no protrusion strip portion or inflation portion is formed.

In the test method specified in JIS K <NUM>, the dimension of the metal member, the dimension of the synthetic resin member, and the bonding area between the synthetic resin member and the metal member are changed as described above, and with the other conditions set in accordance with the same standard, the measurement is performed at a tensile speed of <NUM>/min and a measurement temperature of <NUM> using a tensile tester (SHIMADZU CORPORATION, AUTOGRAPH AGX-V). Four specimens of Example and Comparative Examples <NUM> and <NUM> are made respectively, and the average value of the four measured values is used as the respective bonding strength.

Claim 1:
A joint (<NUM>) including a first member (<NUM>) having a first bonding surface (<NUM>) provided with an anchor portion (<NUM>) and a second member (<NUM>) having a second bonding surface (<NUM>), and bonds the second bonding surface (<NUM>) to the first bonding surface (<NUM>), wherein
the anchor portion (<NUM>) has a plurality of projections (<NUM>) that protrude from the first bonding surface (<NUM>) and are provided side by side along a first direction,
wherein the projections (<NUM>) have a protrusion strip portion (35a) that protrudes from the first bonding surface (<NUM>) and extends along the first direction, an inflation portion (35b) that is provided above the protrusion strip portion (35a) and widens in a second direction which is a direction perpendicular to the first direction from the protrusion strip portion (35a), and undercut portions (35c) provided on both sides of the protrusion strip portion (35a) in the second direction, as well as
a cross-sectional shape along the first direction including a top portion (35d), which widens in the first direction as approaching the first bonding surface (<NUM>) such that a length along the first direction is the longest on the first bonding surface side.